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Sample records for quasiparticle self-consistent gw

  1. QuasiParticle Self-Consistent, GW Theory

    NASA Astrophysics Data System (ADS)

    Kotani, Takao; van Schilfgaarde, Mark; Faleev, Sergey

    2005-03-01

    A formal justification for a new kind self-consistent GW approximation is developed. In this Landau-Silin picture the GW approximation is based on the ansatz of the existence of bare quasiparticles generated from a noninteracting Hamiltonian H0 and corresponding Green's function G0. In this picture, electrons and holes should have real meaning; W is computed from the time-dependent Hartree approximation; σ=iG0W means ``exchange effect'' + electrons and holes interacting. A key issue is how to construct the optimum H0. The true Green's function G should have corresponding one-particle excitations, and H0 should approximate the corresponding energies and eigenfunctions as well as possible. We present a prescription for H0 that approximately minimizes the difference between G-1 and G0-1. The theory is applied to sp bonded materials, simple and transition metals, transition-metal oxides, some magnetic compounds such as MnAs and some f systems (e.g. CeO2, and Gd). We compare to a variety of experimental data for these different materials classes. The errors are quite small and highly systematic in sp systems, they are somewhat larger but still systematic in transition-metal oxides, and are largest for Gd. Some analysis of the origin of the errors will be presented.

  2. Quasiparticle self-consistent GW study of cuprates: electronic structure, model parameters, and the two-band theory for Tc

    PubMed Central

    Jang, Seung Woo; Kotani, Takao; Kino, Hiori; Kuroki, Kazuhiko; Han, Myung Joon

    2015-01-01

    Despite decades of progress, an understanding of unconventional superconductivity still remains elusive. An important open question is about the material dependence of the superconducting properties. Using the quasiparticle self-consistent GW method, we re-examine the electronic structure of copper oxide high-Tc materials. We show that QSGW captures several important features, distinctive from the conventional LDA results. The energy level splitting between and is significantly enlarged and the van Hove singularity point is lowered. The calculated results compare better than LDA with recent experimental results from resonant inelastic xray scattering and angle resolved photoemission experiments. This agreement with the experiments supports the previously suggested two-band theory for the material dependence of the superconducting transition temperature, Tc. PMID:26206417

  3. Accurate energy bands calculated by the hybrid quasiparticle self-consistent GW method implemented in the ecalj package

    NASA Astrophysics Data System (ADS)

    Deguchi, Daiki; Sato, Kazunori; Kino, Hiori; Kotani, Takao

    2016-05-01

    We have recently implemented a new version of the quasiparticle self-consistent GW (QSGW) method in the ecalj package released at http://github.com/tkotani/ecalj. Since the new version of the ecalj package is numerically stable and more accurate than the previous versions, we can perform calculations easily without being bothered with tuning input parameters. Here we examine its ability to describe energy band properties, e.g., band-gap energy, eigenvalues at special points, and effective mass, for a variety of semiconductors and insulators. We treat C, Si, Ge, Sn, SiC (in 2H, 3C, and 4H structures), (Al, Ga, In) × (N, P, As, Sb), (Zn, Cd, Mg) × (O, S, Se, Te), SiO2, HfO2, ZrO2, SrTiO3, PbS, PbTe, MnO, NiO, and HgO. We propose that a hybrid QSGW method, where we mix 80% of QSGW and 20% of LDA, gives universally good agreement with experiments for these materials.

  4. Band structures for short-period (InAs) n (GaSb) n superlattices calculated by the quasiparticle self-consistent GW method

    NASA Astrophysics Data System (ADS)

    Otsuka, Jun; Kato, Takashi; Sakakibara, Hirofumi; Kotani, Takao

    2017-02-01

    We apply a hybrid quasiparticle self-consistent GW (QSGW) method, QSGW80+SO [Deguchi et al., Jpn. J. Appl. Phys. 55, 051201 (2016)], to a type-II superlattice, which is (InAs) n (GaSb) n (n = 1, 2, 3, and 4) for infrared sensors. For the first time, we successfully obtained reliable energy bands of the superlattice. The calculated band gaps as functions of n differ from those obtained on the basis of other theories, although they are consistent with the results of a recent photoluminescence experiment. Our real-space analysis of band-edge alignment obtained via core levels shows that the calculated band offset of InAs/GaSb for n = 4 is ∼0.5 eV, which is consistent with the value obtained in an X-ray photoelectron spectroscopy experiment.

  5. Electronic structure calculations of delafossite Cu-based transparent conducting oxides CuMO2 (M =B,Al,Ga,In) by quasiparticle self-consistent GW approximation and Tran-Blaha's modified Becke-Johnson exchange potential

    NASA Astrophysics Data System (ADS)

    Thatribud, Abdulmutta; Pengpan, Teparksorn

    2014-09-01

    In this work, band gaps of the delafossite Cu-based transparent conducting oxides CuMO2 (M =B,Al,Ga,In) are calculated by density functional theory (DFT) implemented with many-body perturbation theory (MBPT) based on quasiparticle self-consistent GW approximation (QPscGW) and with Tran-Blaha's modified Becke-Johnson functional (DFT-TB09). Their band gaps are explicitly improved from DFT within local density approximation (LDA). Their optical absorption spectra are also calculated by solving Bethe-Salpeter equation (BSE) that includes the electron-hole correlation effect; they show strong excitonic peaks.

  6. Self-consistent GW calculations for semiconductors and insulators

    NASA Astrophysics Data System (ADS)

    Shishkin, M.; Kresse, G.

    2007-06-01

    We present GW calculations for small and large gap systems comprising typical semiconductors (Si, SiC, GaAs, GaN, ZnO, ZnS, CdS, and AlP), small gap semiconductors (PbS, PbSe, and PbTe), insulators (C, BN, MgO, and LiF), and noble gas solids (Ar and Ne). It is shown that the G0W0 approximation always yields too small band gaps. To improve agreement with experiment, the eigenvalues in the Green’s function G (GW0) and in the Green’s function and the dielectric matrix (GW) are updated until self-consistency is reached. The first approximation leads to excellent agreement with experiment, whereas an update of the eigenvalues in G and W gives too large band gaps for virtually all materials. From a pragmatic point of view, the GW0 approximation thus seems to be an accurate and still reasonably fast method for predicting quasiparticle energies in simple sp -bonded systems. We furthermore observe that the band gaps in materials with shallow d states (GaAs, GaN, and ZnO) are systematically underestimated. We propose that an inaccurate description of the static dielectric properties of these materials is responsible for the underestimation of the band gaps in GW0 , which is itself a result of the incomplete cancellation of the Hartree self-energy within the d shell by local or gradient corrected density functionals.

  7. Full self-consistency versus quasiparticle self-consistency in diagrammatic approaches: Exactly solvable two-site Hubbard model

    DOE PAGES

    Kutepov, A. L.

    2015-07-22

    Self-consistent solutions of Hedin's equations (HE) for the two-site Hubbard model (HM) have been studied. They have been found for three-point vertices of increasing complexity (Γ = 1 (GW approximation), Γ₁ from the first-order perturbation theory, and the exact vertex ΓE). Comparison is made between the cases when an additional quasiparticle (QP) approximation for Green's functions is applied during the self-consistent iterative solving of HE and when QP approximation is not applied. Results obtained with the exact vertex are directly related to the present open question—which approximation is more advantageous for future implementations, GW + DMFT or QPGW + DMFT.more » It is shown that in a regime of strong correlations only the originally proposed GW + DMFT scheme is able to provide reliable results. Vertex corrections based on Perturbation Theory systematically improve the GW results when full self-consistency is applied. The application of QP self-consistency combined with PT vertex corrections shows similar problems to the case when the exact vertex is applied combined with QP sc. An analysis of Ward Identity violation is performed for all studied in this work's approximations and its relation to the general accuracy of the schemes used is provided.« less

  8. Full self-consistency versus quasiparticle self-consistency in diagrammatic approaches: Exactly solvable two-site Hubbard model

    SciTech Connect

    Kutepov, A. L.

    2015-07-22

    Self-consistent solutions of Hedin's equations (HE) for the two-site Hubbard model (HM) have been studied. They have been found for three-point vertices of increasing complexity (Γ = 1 (GW approximation), Γ₁ from the first-order perturbation theory, and the exact vertex ΓE). Comparison is made between the cases when an additional quasiparticle (QP) approximation for Green's functions is applied during the self-consistent iterative solving of HE and when QP approximation is not applied. Results obtained with the exact vertex are directly related to the present open question—which approximation is more advantageous for future implementations, GW + DMFT or QPGW + DMFT. It is shown that in a regime of strong correlations only the originally proposed GW + DMFT scheme is able to provide reliable results. Vertex corrections based on Perturbation Theory systematically improve the GW results when full self-consistency is applied. The application of QP self-consistency combined with PT vertex corrections shows similar problems to the case when the exact vertex is applied combined with QP sc. An analysis of Ward Identity violation is performed for all studied in this work's approximations and its relation to the general accuracy of the schemes used is provided.

  9. Self-Consistent Calculations of Quasiparticle States in Crystals

    NASA Astrophysics Data System (ADS)

    Schöne, W.-D.; Eguiluz, A. G.; Gaspar, J. A.

    1998-03-01

    We report self-consistent evaluations of the electron self-energy and quasiparticle (QP) states in crystals within the (fully-conserving) shielded-interaction approximation. Our method starts from the knowledge of the one-electron states within the LDA. These states are renormalized via the self-consistent solution of the Dyson equation for the one-particle Green's function. All the degrees of freedom of the many-electron system are allowed to ``relax'' as the propagators are dressed. Special care is placed in obtaining cutoff-independent dynamical polarizabilities. We present results for the spectral function, the density of states, the QP renormalization factor, and the QP band structure, for bcc K (the LDA states are obtained with the fhi96md code). The finite lifetime of the QP states blurs the (reduced-zone-) excited-state band structure for relatively low energies. We also discuss the impact of self-consistency on the calculated value of the band gap in Si.

  10. Self-consistent GW: All-electron implementation with localized basis functions

    NASA Astrophysics Data System (ADS)

    Caruso, Fabio; Rinke, Patrick; Ren, Xinguo; Rubio, Angel; Scheffler, Matthias

    2013-08-01

    This paper describes an all-electron implementation of the self-consistent GW (sc-GW) approach—i.e., based on the solution of the Dyson equation—in an all-electron numeric atom-centered orbital basis set. We cast Hedin's equations into a matrix form that is suitable for numerical calculations by means of (i) the resolution-of-identity technique to handle four-center integrals and (ii) a basis representation for the imaginary-frequency dependence of dynamical operators. In contrast to perturbative G0W0, sc-GW provides a consistent framework for ground- and excited-state properties and facilitates an unbiased assessment of the GW approximation. For excited states, we benchmark sc-GW for five molecules relevant for organic photovoltaic applications: thiophene, benzothiazole, 1,2,5-thiadiazole, naphthalene, and tetrathiafulvalene. At self-consistency, the quasiparticle energies are found to be in good agreement with experiment and, on average, more accurate than G0W0 based on Hartree-Fock or density-functional theory with the Perdew-Burke-Ernzerhof exchange-correlation functional. Based on the Galitskii-Migdal total energy, structural properties are investigated for a set of diatomic molecules. For binding energies, bond lengths, and vibrational frequencies sc-GW and G0W0 achieve a comparable performance, which is, however, not as good as that of exact-exchange plus correlation in the random-phase approximation and its advancement to renormalized second-order perturbation theory. Finally, the improved description of dipole moments for a small set of diatomic molecules demonstrates the quality of the sc-GW ground-state density.

  11. Self-consistent GW calculation of the electronic structure of co-doped ZnO

    NASA Astrophysics Data System (ADS)

    Kim, Maengsuk; Park, Chul Hong

    2012-01-01

    The electronic structure of Co-doped ZnO is presented using a first-principles self-consistent GW calculation based on the screened hybrid HSE06 functional and is compared to the structure calculated using the generalized gradient density approximation plus U (GGA+U) method. The obtained energy splittings between unoccupied Co t 2 and the occupied Co e states are about 3.0 eV and 5.1 eV for the GGA+U and the HSE06 calculations, respectively. Through a correction of the self-consistent GW calculations on the top of HSE06, the electronic energy levels of the occupied Co e band states are moved downward slightly while those at the unoccupied Co t 2 bands are shifted upward, and the occupied Co e and the empty Co t 2 levels of the minority spin are located, respectively, far below and far above the conduction band minimum.

  12. Self-consistent quasiparticle random-phase approximation for a multilevel pairing model

    SciTech Connect

    Hung, N. Quang; Dang, N. Dinh

    2007-11-15

    Particle-number projection within the Lipkin-Nogami (LN) method is applied to the self-consistent quasiparticle random-phase approximation (SCQRPA), which is tested in an exactly solvable multilevel pairing model. The SCQRPA equations are numerically solved to find the energies of the ground and excited states at various numbers {omega} of doubly degenerate equidistant levels. The use of the LN method allows one to avoid the collapse of the BCS (QRPA) to obtain the energies of the ground and excited states as smooth functions of the interaction parameter G. The comparison between results given by different approximations such as the SCRPA, QRPA, LNQRPA, SCQRPA, and LNSCQRPA is carried out. Although the use of the LN method significantly improves the agreement with the exact results in the intermediate coupling region, we found that in the strong coupling region the SCQRPA results are closest to the exact ones.

  13. Self-consistency and quasi-particle approximation in π- and Δ-propagation in nuclear matter

    NASA Astrophysics Data System (ADS)

    Cenni, R.; Dillon, G.

    1983-01-01

    The equations for the self-consistent π- and Δ-propagation in nuclear matter are solved numerically in the quasi-particle approximation. We have taken into account the full complexity of nucleon recoil and Fermi motion as well as the effects of binding and short-range correlations. Because of the much smoother behaviour of the self-consistent π and Δ self-energies it turns out that the quasi-particle approximation is still a good one even at normal nuclear density, whereas for kF ⩾ 1 fm -1 the first-order solution displays a multiple eigenmode propagation for the pion in the resonance region. The self-consistent π- and Δ-dispersion relations in the medium are then obtained for increasing densities by an iterative procedure which takes as a starting point, each time, the final result at the preceding density.

  14. Correlation effects of π electrons on the band structures of conjugated polymers using the self-consistent GW approximation with vertex corrections.

    PubMed

    Chang, Yao-Wen; Jin, Bih-Yaw

    2012-01-14

    Many-body perturbation theory is used to investigate the effect of π-electron correlations on the quasi-particle band structures of conjugated polymers at the level of the Pariser-Parr-Pople model. The self-consistent GW approximation with vertex corrections to both the self-energy and the polarization in Hedin's equations is employed in order to eliminate self-interaction errors and include the effects of electron-hole attraction in screening processes. The dynamic inverse dielectric function is constructed from the generalized plasmon-pole approximation with the static dressed polarization given by the coupled-perturbed Hartree-Fock equation. The bandgaps of trans-polyacetylene, trans-polyphenylenevinylene and poly(para)phenylene are calculated by both the Hartree-Fock and GW approximation, and a lowering of bandgaps due to electron correlations is found. We conclude that both dielectric screening and vertex corrections are important for calculating the quasi-particle bandgaps of conjugated polymers.

  15. Electronic band structure of Mg -IV -N2 compounds in the quasiparticle-self-consistent G W approximation

    NASA Astrophysics Data System (ADS)

    Jaroenjittichai, Atchara Punya; Lambrecht, Walter R. L.

    2016-09-01

    We present calculations of the lattice constants, structural parameters, bulk moduli, energies of formation, and band structures of Mg -IV -N2 compounds with IV=Si, Ge, Sn by using the full-potential linearized muffin-tin orbital method and the quasiparticle-self-consistent G W approach for the wurtzite-based P n a 21 crystal structure. The lattice parameters calculated with the generalized gradient approximation (GGA) are found to be in good agreement (within 1%) with experiment for the cases of MgSiN2 and MgGeN2, where data are available. Similar to the Zn-IV-N2 compounds, MgSiN2 is found to have an indirect gap slightly lower than the lowest direct gap, while the other materials have direct gaps. The direct gaps, calculated at the GGA lattice constant, range from 3.43 eV for MgSnN2 to 5.14 eV for MgGeN2 and 6.28 eV for MgSiN2 in the 0.8 Σ approximation, i.e., reducing the QS G W Σ by a factor 0.8 and including an estimated zero-point-motion correction. The symmetry character of the valence-band maximum states and their splittings and effective masses are determined. The conduction-band minima are found to have slightly higher Mg s - than Si s -like character in MgSiN2 but in MgGeN2 and MgSnN2, the group-IV-s character becomes increasingly dominant.

  16. Speeding up GW Calculations to Meet the Challenge of Large Scale Quasiparticle Predictions

    PubMed Central

    Gao, Weiwei; Xia, Weiyi; Gao, Xiang; Zhang, Peihong

    2016-01-01

    Although the GW approximation is recognized as one of the most accurate theories for predicting materials excited states properties, scaling up conventional GW calculations for large systems remains a major challenge. We present a powerful and simple-to-implement method that can drastically accelerate fully converged GW calculations for large systems, enabling fast and accurate quasiparticle calculations for complex materials systems. We demonstrate the performance of this new method by presenting the results for ZnO and MgO supercells. A speed-up factor of nearly two orders of magnitude is achieved for a system containing 256 atoms (1024 valence electrons) with a negligibly small numerical error of ±0.03 eV. Finally, we discuss the application of our method to the GW calculations for 2D materials. PMID:27833140

  17. Long-range Coulomb interactions in surface systems: a first-principles description within self-consistently combined GW and dynamical mean-field theory.

    PubMed

    Hansmann, P; Ayral, T; Vaugier, L; Werner, P; Biermann, S

    2013-04-19

    Systems of adatoms on semiconductor surfaces display competing ground states and exotic spectral properties typical of two-dimensional correlated electron materials which are dominated by a complex interplay of spin and charge degrees of freedom. We report a fully ab initio derivation of low-energy Hamiltonians for the adatom systems Si(111):X, with X=Sn, Si, C, Pb, that we solve within self-consistently combined GW and dynamical mean-field theory. Calculated photoemission spectra are in agreement with available experimental data. We rationalize experimentally observed trends from Mott physics toward charge ordering along the series as resulting from substantial long-range interactions.

  18. Self-consistent quasiparticle formulation of a multiphonon method and its application to the neutron-rich O20 nucleus

    NASA Astrophysics Data System (ADS)

    De Gregorio, G.; Knapp, F.; Lo Iudice, N.; Vesely, P.

    2016-04-01

    A Bogoliubov quasiparticle formulation of an equation-of-motion phonon method, suited for open-shell nuclei, is derived. Like its particle-hole version, it consists of deriving a set of equations of motions whose iterative solution generates an orthonormal basis of n -phonon states (n =0 ,1 ,2 ,... ), built of quasiparticle Tamm-Dancoff phonons, which simplifies the solution of the eigenvalue problem. The method is applied to the open-shell neutron-rich O20 for illustrative purposes. A Hartree-Fock-Bogoliubov canonical basis, derived from an intrinsic two-body optimized chiral Hamiltonian, is used to derive and solve the eigenvalue equations in a space encompassing a truncated two-phonon basis. The spurious admixtures induced by the violation of the particle number and the center-of-mass motion are eliminated to a large extent by a Gram-Schmidt orthogonalization procedure. The calculation takes into account the Pauli principle, is self-consistent, and is parameter free except for the energy cutoff used to truncate the two-phonon basis, which induces an increasing depression of the ground state through its strong coupling to the quasiparticle vacuum. Such a cutoff is fixed so as to reproduce the first 1- level. The two-phonon states are shown to enhance the level density of the low-energy spectrum, consistently with the data, and to induce a fragmentation of the E 1 strength which, while accounting for the very low E 1 transitions, is not sufficient to reproduce the experimental cross section in the intermediate energy region. This and other discrepancies suggest the need of including the three-phonon states. These are also expected to offset the action of the two phonons on the quasiparticle vacuum and, therefore, free the calculation from any parameter.

  19. Substrate-induced renormalization of the quasiparticle and optical gaps in monolayer transition metal dichalcogenides from GW and GW-BSE calculations

    NASA Astrophysics Data System (ADS)

    da Jornada, Felipe H.; Ong, Chin Shen; Qiu, Diana Y.; Louie, Steven G.

    There has been a considerable effort to experimentally characterize the electronic and optical properties of novel atomically thin 2D semiconductors, such as mono- and few-layer transition metal dichalcogenides (TMDs). However, the role that different substrates play in these experiments still remains unclear. From a theoretical perspective, it is hard to include the substrate in an ab initio framework, while in experiments, it is often difficult to suspend these samples. Here, we present a new method to compute the substrate effect on the quasiparticle and optical properties of quasi-2D materials based on state-of-the-art ab initio GW and GW plus Bethe-Salpeter equation (GW-BSE) methods. We compute the effects of different metallic and semiconducting substrates, and show that the quasiparticle gap and exciton binding energy can be dramatically reduced even with semiconducting substrates. This work was supported by the National Science Foundation under Grant No. DMR15-1508412 and the DOE under Contract No. DE-AC02-05CH11231.

  20. Ab initio GW quasiparticle energies of small sodium clusters by an all-electron mixed-basis approach

    NASA Astrophysics Data System (ADS)

    Ishii, Soh; Ohno, Kaoru; Kawazoe, Yoshiyuki; Louie, Steven G.

    2001-04-01

    A state-of-the-art GW calculation is carried out for small sodium clusters, Na2, Na4, Na6, and Na8. The quasiparticle energies are evaluated by employing an ab initio GW code based on an all-electron mixed-basis approach, which uses both plane waves and atomic orbitals as basis functions. The calculated ionization potential and the electron affinity are in excellent agreement with available experimental data. The exchange and correlation parts to the electron self-energy within the GW approximation are presented from the viewpoint of their size dependence. In addition, the effect of the off-diagonal elements of the self-energy corrections to the local-density-approximation exchange-correlation potential is discussed. Na2 and Na8 have a larger energy gap than Na4 and Na6, consistent with the fact that they are magic number clusters.

  1. All-electron GW quasiparticle band structures of group 14 nitride compounds

    NASA Astrophysics Data System (ADS)

    Chu, Iek-Heng; Kozhevnikov, Anton; Schulthess, Thomas C.; Cheng, Hai-Ping

    2014-07-01

    We have investigated the group 14 nitrides (M3N4) in the spinel phase (γ-M3N4 with M = C, Si, Ge, and Sn) and β phase (β-M3N4 with M = Si, Ge, and Sn) using density functional theory with the local density approximation and the GW approximation. The Kohn-Sham energies of these systems have been first calculated within the framework of full-potential linearized augmented plane waves (LAPW) and then corrected using single-shot G0W0 calculations, which we have implemented in the modified version of the Elk full-potential LAPW code. Direct band gaps at the Γ point have been found for spinel-type nitrides γ-M3N4 with M = Si, Ge, and Sn. The corresponding GW-corrected band gaps agree with experiment. We have also found that the GW calculations with and without the plasmon-pole approximation give very similar results, even when the system contains semi-core d electrons. These spinel-type nitrides are novel materials for potential optoelectronic applications because of their direct and tunable band gaps.

  2. All-electron GW quasiparticle band structures of group 14 nitride compounds

    SciTech Connect

    Chu, Iek-Heng; Cheng, Hai-Ping; Kozhevnikov, Anton; Schulthess, Thomas C.

    2014-07-28

    We have investigated the group 14 nitrides (M{sub 3}N{sub 4}) in the spinel phase (γ-M{sub 3}N{sub 4} with M = C, Si, Ge, and Sn) and β phase (β-M{sub 3}N{sub 4} with M = Si, Ge, and Sn) using density functional theory with the local density approximation and the GW approximation. The Kohn-Sham energies of these systems have been first calculated within the framework of full-potential linearized augmented plane waves (LAPW) and then corrected using single-shot G{sub 0}W{sub 0} calculations, which we have implemented in the modified version of the Elk full-potential LAPW code. Direct band gaps at the Γ point have been found for spinel-type nitrides γ-M{sub 3}N{sub 4} with M = Si, Ge, and Sn. The corresponding GW-corrected band gaps agree with experiment. We have also found that the GW calculations with and without the plasmon-pole approximation give very similar results, even when the system contains semi-core d electrons. These spinel-type nitrides are novel materials for potential optoelectronic applications because of their direct and tunable band gaps.

  3. Quasiparticle and Optical Properties of Solids and Nanostructures: The GW-BSE Approach

    NASA Astrophysics Data System (ADS)

    Louie, Steven G.; Rubio, Angel

    We present a review of recent progress in the first-principles study of the spectroscopic properties of solids and nanostructures employing a many-body Green's function approach based on the GW approximation to the electron self-energy. The approach has been widely used to investigate the excitedstate properties of condensed matter as probed by photoemission, tunneling, optical, and related techniques. In this article, we first give a brief overview of the theoretical foundations of the approach, then present a sample of applications to systems ranging from extended solids to surfaces to nanostructures and discuss some possible ideas for further developments.

  4. GW quasiparticle energy study of ternary tetradymite Bi{sub 2}Te{sub 2}Se and Bi{sub 2}Te{sub 2}S thin films

    SciTech Connect

    Shuaibu, Alhassan; Rahman, Md. Mahmudur; Zainuddin, Hishamuddin; Talib, Zainal Abidin; Muhida, Rifki

    2015-04-24

    In this work, we have evaluated the quasiparticle energies of ternary tetradymite Bi{sub 2}Te{sub 2}Se and Bi{sub 2}Te{sub 2}S using first-principles calculation within the G{sub 0}W{sub 0} methods. We have also performed a broad convergence tests in order to investigate the quasiparticle corrections to the structural parameters and to the semi core d electrons in both of the compounds. For each case, we have calculated the many-body corrections within a one-shot GW method of the compounds. Our results have shown that for Bi{sub 2}Te{sub 2}Se the GW corrections increase the band gap to almost 10%, and for specific atomic positions, the band structure shows a close value to the experimental one. For Bi{sub 2}Te{sub 2}S, despite increase in the band gap due to the GW corrections, possibility of bulk resistivity that can be significant for photovoltaic applications was observed.

  5. BerkeleyGW: A massively parallel computer package for the calculation of the quasiparticle and optical properties of materials and nanostructures

    NASA Astrophysics Data System (ADS)

    Deslippe, Jack; Samsonidze, Georgy; Strubbe, David A.; Jain, Manish; Cohen, Marvin L.; Louie, Steven G.

    2012-06-01

    based on density-functional theory, fail to correctly capture this physics. Solution method: We construct and solve the Dyson's equation for the quasiparticle energies and wavefunctions within the GW approximation for the electron self-energy. We additionally construct and solve the Bethe-Salpeter equation for the correlated electron-hole (exciton) wavefunctions and excitation energies. Restrictions: The material size is limited in practice by the computational resources available. Materials with up to 500 atoms per periodic cell can be studied on large HPCs. Additional comments: The distribution file for this program is approximately 110 Mbytes and therefore is not delivered directly when download or E-mail is requested. Instead a html file giving details of how the program can be obtained is sent. Running time: 1-1000 minutes (depending greatly on system size and processor number).

  6. Self-consistent triaxial models

    NASA Astrophysics Data System (ADS)

    Sanders, Jason L.; Evans, N. Wyn

    2015-11-01

    We present self-consistent triaxial stellar systems that have analytic distribution functions (DFs) expressed in terms of the actions. These provide triaxial density profiles with cores or cusps at the centre. They are the first self-consistent triaxial models with analytic DFs suitable for modelling giant ellipticals and dark haloes. Specifically, we study triaxial models that reproduce the Hernquist profile from Williams & Evans, as well as flattened isochrones of the form proposed by Binney. We explore the kinematics and orbital structure of these models in some detail. The models typically become more radially anisotropic on moving outwards, have velocity ellipsoids aligned in Cartesian coordinates in the centre and aligned in spherical polar coordinates in the outer parts. In projection, the ellipticity of the isophotes and the position angle of the major axis of our models generally changes with radius. So, a natural application is to elliptical galaxies that exhibit isophote twisting. As triaxial Stäckel models do not show isophote twists, our DFs are the first to generate mass density distributions that do exhibit this phenomenon, typically with a gradient of ≈10°/effective radius, which is comparable to the data. Triaxiality is a natural consequence of models that are susceptible to the radial orbit instability. We show how a family of spherical models with anisotropy profiles that transition from isotropic at the centre to radially anisotropic becomes unstable when the outer anisotropy is made sufficiently radial. Models with a larger outer anisotropy can be constructed but are found to be triaxial. We argue that the onset of the radial orbit instability can be identified with the transition point when adiabatic relaxation yields strongly triaxial rather than weakly spherical endpoints.

  7. G W -BSE, self-consistency, and vertex corrections applied to group IB/IIB atoms and oxide molecules

    NASA Astrophysics Data System (ADS)

    Hung, Linda; Ogut, Serdar

    2015-03-01

    Time-dependent density functional theory (TDDFT), the GW approximation, and the Bethe-Salpeter equation (BSE) are often used for the first-principles calculation of excited-state properties of materials that contain transition metals. Accuracy is improved compared to mean-field theories such as Kohn-Sham DFT or Hartree-Fock; however, predicted quasiparticle levels and optical spectra can still differ from experiment. We model Cu, Zn, Ag, and Cd atoms and their oxide molecules to assess various approximations in many-body perturbation theory methods that contribute to these differences. In particular, we examine how self-consistent iterations and/or a two-point vertex function affect the predicted excitation energies, compared to ``one-shot'' G0W0 calculations. Experimental measurements of optical spectra and ionization energies for charged and neutral atoms are widely available, and allow us to evaluate excitations from both s and d states. Differences between TDDFT and BSE spectra are also discussed. Calculations are performed with RGWBS, a software suite which uses a basis of transition space and quasiparticle wavefunctions. Supported by DOE Grant No. DE-SC0001853.

  8. GW and Bethe-Salpeter study of small water clusters

    SciTech Connect

    Blase, Xavier Boulanger, Paul; Bruneval, Fabien; Fernandez-Serra, Marivi; Duchemin, Ivan

    2016-01-21

    We study within the GW and Bethe-Salpeter many-body perturbation theories the electronic and optical properties of small (H{sub 2}O){sub n} water clusters (n = 1-6). Comparison with high-level CCSD(T) Coupled-Cluster at the Single Double (Triple) levels and ADC(3) Green’s function third order algebraic diagrammatic construction calculations indicates that the standard non-self-consistent G{sub 0}W{sub 0}@PBE or G{sub 0}W{sub 0}@PBE0 approaches significantly underestimate the ionization energy by about 1.1 eV and 0.5 eV, respectively. Consequently, the related Bethe-Salpeter lowest optical excitations are found to be located much too low in energy when building transitions from a non-self-consistent G{sub 0}W{sub 0} description of the quasiparticle spectrum. Simple self-consistent schemes, with update of the eigenvalues only, are shown to provide a weak dependence on the Kohn-Sham starting point and a much better agreement with reference calculations. The present findings rationalize the theory to experiment possible discrepancies observed in previous G{sub 0}W{sub 0} and Bethe-Salpeter studies of bulk water. The increase of the optical gap with increasing cluster size is consistent with the evolution from gas to dense ice or water phases and results from an enhanced screening of the electron-hole interaction.

  9. GW and Bethe-Salpeter study of small water clusters.

    PubMed

    Blase, Xavier; Boulanger, Paul; Bruneval, Fabien; Fernandez-Serra, Marivi; Duchemin, Ivan

    2016-01-21

    We study within the GW and Bethe-Salpeter many-body perturbation theories the electronic and optical properties of small (H2O)n water clusters (n = 1-6). Comparison with high-level CCSD(T) Coupled-Cluster at the Single Double (Triple) levels and ADC(3) Green's function third order algebraic diagrammatic construction calculations indicates that the standard non-self-consistent G0W0@PBE or G0W0@PBE0 approaches significantly underestimate the ionization energy by about 1.1 eV and 0.5 eV, respectively. Consequently, the related Bethe-Salpeter lowest optical excitations are found to be located much too low in energy when building transitions from a non-self-consistent G0W0 description of the quasiparticle spectrum. Simple self-consistent schemes, with update of the eigenvalues only, are shown to provide a weak dependence on the Kohn-Sham starting point and a much better agreement with reference calculations. The present findings rationalize the theory to experiment possible discrepancies observed in previous G0W0 and Bethe-Salpeter studies of bulk water. The increase of the optical gap with increasing cluster size is consistent with the evolution from gas to dense ice or water phases and results from an enhanced screening of the electron-hole interaction.

  10. GW and Bethe-Salpeter study of small water clusters

    NASA Astrophysics Data System (ADS)

    Blase, Xavier; Boulanger, Paul; Bruneval, Fabien; Fernandez-Serra, Marivi; Duchemin, Ivan

    2016-01-01

    We study within the GW and Bethe-Salpeter many-body perturbation theories the electronic and optical properties of small (H2O)n water clusters (n = 1-6). Comparison with high-level CCSD(T) Coupled-Cluster at the Single Double (Triple) levels and ADC(3) Green's function third order algebraic diagrammatic construction calculations indicates that the standard non-self-consistent G0W0@PBE or G0W0@PBE0 approaches significantly underestimate the ionization energy by about 1.1 eV and 0.5 eV, respectively. Consequently, the related Bethe-Salpeter lowest optical excitations are found to be located much too low in energy when building transitions from a non-self-consistent G0W0 description of the quasiparticle spectrum. Simple self-consistent schemes, with update of the eigenvalues only, are shown to provide a weak dependence on the Kohn-Sham starting point and a much better agreement with reference calculations. The present findings rationalize the theory to experiment possible discrepancies observed in previous G0W0 and Bethe-Salpeter studies of bulk water. The increase of the optical gap with increasing cluster size is consistent with the evolution from gas to dense ice or water phases and results from an enhanced screening of the electron-hole interaction.

  11. Self-consistent asset pricing models

    NASA Astrophysics Data System (ADS)

    Malevergne, Y.; Sornette, D.

    2007-08-01

    We discuss the foundations of factor or regression models in the light of the self-consistency condition that the market portfolio (and more generally the risk factors) is (are) constituted of the assets whose returns it is (they are) supposed to explain. As already reported in several articles, self-consistency implies correlations between the return disturbances. As a consequence, the alphas and betas of the factor model are unobservable. Self-consistency leads to renormalized betas with zero effective alphas, which are observable with standard OLS regressions. When the conditions derived from internal consistency are not met, the model is necessarily incomplete, which means that some sources of risk cannot be replicated (or hedged) by a portfolio of stocks traded on the market, even for infinite economies. Analytical derivations and numerical simulations show that, for arbitrary choices of the proxy which are different from the true market portfolio, a modified linear regression holds with a non-zero value αi at the origin between an asset i's return and the proxy's return. Self-consistency also introduces “orthogonality” and “normality” conditions linking the betas, alphas (as well as the residuals) and the weights of the proxy portfolio. Two diagnostics based on these orthogonality and normality conditions are implemented on a basket of 323 assets which have been components of the S&P500 in the period from January 1990 to February 2005. These two diagnostics show interesting departures from dynamical self-consistency starting about 2 years before the end of the Internet bubble. Assuming that the CAPM holds with the self-consistency condition, the OLS method automatically obeys the resulting orthogonality and normality conditions and therefore provides a simple way to self-consistently assess the parameters of the model by using proxy portfolios made only of the assets which are used in the CAPM regressions. Finally, the factor decomposition with the

  12. Transport theory with self-consistent confinement related to the lattice data

    NASA Astrophysics Data System (ADS)

    Bożek, P.; He, Y. B.; Hüfner, J.

    1998-06-01

    The space-time development of a quark-gluon plasma is calculated from a Vlasov equation for the distribution function of quasiparticles with medium dependent masses. At each space-time point the masses are calculated self-consistently from a gap equation, whose form is determined by the requirement that in thermal equilibrium and for a range of temperatures the energy density of the quasiparticle system is identical to the one from lattice calculations. The numerical solutions of the Vlasov equation display confinement. Relations to effective theories like that by Friedberg and Lee and Nambu and Jona-Lasinio are established.

  13. Self-consistent approach to beta decay and delayed neutron emission

    NASA Astrophysics Data System (ADS)

    Borzov, I. N.

    2016-11-01

    A brief overview of the recent self-consistent studies of nuclear beta decay is given including the relativistic quasi-particle random-phase approximation or QRPA and Finite Amplitude Method. The results of our self-consistent continuum QRPA model based on the density functional description of the ground states are presented. They are in a good agreement with the recent experimental beta-decay half-lives and delayed neutron emission branchings for the nuclei approaching (and beyond) the neutron closed shells N = 50 near 78Ni and N = 82 near 132Sn. A comparison with the recent calculations from relativistic QRPA model, Finite Amplitude Method and semi-microscopic finite-range droplet model is performed. An importance of the quasi-particle phonon coupling is stressed for the description of the beta decay and delayed multi-neutron emission rates. A strategy of extending our approach to the deformed nuclei and the open problems are discussed.

  14. Quasiparticle properties of Ge(111)-2 times 1 surface

    SciTech Connect

    Zhu, X.; Louie, S.G.

    1992-08-01

    We have studied from first principles the quasiparticle properties of the 2 {times} 1 reconstructed (111) surface of Ge. Quasiparticle energies are calculated using the GW expansion of the electron self energy operator. The calculations explain a spectrum of experimental results obtained from photoemission, inverse photoemission, optical absorption, scanning tunneling microscopy, etc., for this surface. We also present a quasiparticle theory for the photoelectric threshold and examine the effects of many body corrections for this quantity.

  15. Self-consistency in Capital Markets

    NASA Astrophysics Data System (ADS)

    Benbrahim, Hamid

    2013-03-01

    Capital Markets are considered, at least in theory, information engines whereby traders contribute to price formation with their diverse perspectives. Regardless whether one believes in efficient market theory on not, actions by individual traders influence prices of securities, which in turn influence actions by other traders. This influence is exerted through a number of mechanisms including portfolio balancing, margin maintenance, trend following, and sentiment. As a result market behaviors emerge from a number of mechanisms ranging from self-consistency due to wisdom of the crowds and self-fulfilling prophecies, to more chaotic behavior resulting from dynamics similar to the three body system, namely the interplay between equities, options, and futures. This talk will address questions and findings regarding the search for self-consistency in capital markets.

  16. Self-consistent structure of metallic hydrogen

    NASA Technical Reports Server (NTRS)

    Straus, D. M.; Ashcroft, N. W.

    1977-01-01

    A calculation is presented of the total energy of metallic hydrogen for a family of face-centered tetragonal lattices carried out within the self-consistent phonon approximation. The energy of proton motion is large and proper inclusion of proton dynamics alters the structural dependence of the total energy, causing isotropic lattices to become favored. For the dynamic lattice the structural dependence of terms of third and higher order in the electron-proton interaction is greatly reduced from static lattice equivalents.

  17. Equivalence between fractional exclusion statistics and self-consistent mean-field theory in interacting-particle systems in any number of dimensions.

    PubMed

    Anghel, D V; Nemnes, G A; Gulminelli, F

    2013-10-01

    We describe a mean field interacting particle system in any number of dimensions and in a generic external potential as an ideal gas with fractional exclusion statistics (FES). We define the FES quasiparticle energies, we calculate the FES parameters of the system and we deduce the equations for the equilibrium particle populations. The FES gas is "ideal," in the sense that the quasiparticle energies do not depend on the other quasiparticle levels' populations and the sum of the quasiparticle energies is equal to the total energy of the system. We prove that the FES formalism is equivalent to the semiclassical or Thomas Fermi limit of the self-consistent mean-field theory and the FES quasiparticle populations may be calculated from the Landau quasiparticle populations by making the correspondence between the FES and the Landau quasiparticle energies. The FES provides a natural semiclassical ideal gas description of the interacting particle gas.

  18. Plasma Diffusion in Self-Consistent Fluctuations

    NASA Technical Reports Server (NTRS)

    Smets, R.; Belmont, G.; Aunai, N.

    2012-01-01

    The problem of particle diffusion in position space, as a consequence ofeleclromagnetic fluctuations is addressed. Numerical results obtained with a self-consistent hybrid code are presented, and a method to calculate diffusion coefficient in the direction perpendicular to the mean magnetic field is proposed. The diffusion is estimated for two different types of fluctuations. The first type (resuiting from an agyrotropic in itiai setting)is stationary, wide band white noise, and associated to Gaussian probability distribution function for the magnetic fluctuations. The second type (result ing from a Kelvin-Helmholtz instability) is non-stationary, with a power-law spectrum, and a non-Gaussian probabi lity distribution function. The results of the study allow revisiting the question of loading particles of solar wind origin in the Earth magnetosphere.

  19. Quasiparticle energies for cubic BN, BP, and BAs

    SciTech Connect

    Surh, M.P.; Louie, S.G.; Cohen, M.L. Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720)

    1991-04-15

    Electronic excitation energies at the high-symmetry points {Gamma}, {ital X}, and {ital L} are obtained for zinc-blende-structure BN, BP, and BAs in the {ital GW} approximation using a model dielectric function. A model for the static screening matrix makes use of the {ital ab} {ital initio} ground-state charge density and either experimental values or empirical estimates for {epsilon}{sub {infinity}}, the electronic contribution to the macroscopic dielectric constant. Wave functions from an {ital ab} {ital initio} local-density-approximation calculation with norm-conserving pseudopotentials are employed along with the self-consistent quasiparticle spectrum to obtain the energy-dependent one-particle Green function {ital G}. The minimum band gaps are found to be 6.3, 1.9, and 1.6 eV for BN, BP, and BAs, respectively, in close agreement with existing measurements of 6.1 and 2.0 eV for BN and BP, respectively. The BN direct band gap is predicted to be 11.4 eV versus the experimental value of 14.5 eV, and the BP direct band gap is predicted to be 4.4 eV versus 5.0 eV from experiment.

  20. Many-body Green's function GW and Bethe-Salpeter study of the optical excitations in a paradigmatic model dipeptide.

    PubMed

    Faber, C; Boulanger, P; Duchemin, I; Attaccalite, C; Blase, X

    2013-11-21

    We study within the many-body Green's function GW and Bethe-Salpeter formalisms the excitation energies of a paradigmatic model dipeptide, focusing on the four lowest-lying local and charge-transfer excitations. Our GW calculations are performed at the self-consistent level, updating first the quasiparticle energies, and further the single-particle wavefunctions within the static Coulomb-hole plus screened-exchange approximation to the GW self-energy operator. Important level crossings, as compared to the starting Kohn-Sham LDA spectrum, are identified. Our final Bethe-Salpeter singlet excitation energies are found to agree, within 0.07 eV, with CASPT2 reference data, except for one charge-transfer state where the discrepancy can be as large as 0.5 eV. Our results agree best with LC-BLYP and CAM-B3LYP calculations with enhanced long-range exchange, with a 0.1 eV mean absolute error. This has been achieved employing a parameter-free formalism applicable to metallic or insulating extended or finite systems.

  1. Influence of quasiparticle damping on magnetic stability

    NASA Astrophysics Data System (ADS)

    Herrmann, T.; Nolting, W.

    1996-04-01

    We propose a modified alloy analogy for the single-band Hubbard model, by which we investigate the possibility of spontaneous ferromagnetism in narrow energy bands. It is shown that a proper definition of the fictitious alloy enables self-consistent magnetic solutions to be found. The existence of spontaneous magnetism is mainly influenced by the lattice structure, the effective Coulomb coupling, and the band occupation. In accordance with the simple Stoner criterion, ferromagnetism appears in strongly correlated electron systems for band occupations, which locate the chemical potential μ in regions of high quasiparticle density of states. Rather realistic Curie temperatures are found. The macroscopic magnetic properties explain themselves via temperature-dependent quasiparticle densities of states, quasiparticle band structures, and respective spectral densities. It is shown how quasiparticle damping may depress quite substantially the stability of magnetic states by broadening corresponding spectral density peaks. Correlation effects lead to the expected splitting into two quasiparticle subbands (``Hubbard bands''), and under certain conditions to an additional exchange splitting of each of these quasiparticle subbands, as well as to a spin-dependent band narrowing, the combination of which gives rise to an unconventional ``inverse'' exchange shift at certain positions of the Brillouin zone.

  2. Gravitational Wave Emission from Long-Term Self-Consistent Two-dimensional Core-Collapse Supernova Models

    NASA Astrophysics Data System (ADS)

    Ikeda, Eishin; Kotake, Kei; Nakamura, Ko

    We report gravitational-wave (GW) signatures based on two-dimensional (2D) neutrino-radiation hydrodynamics simulations of core-collapse supernovae (CCSNe). Using multiple progenitor models, we present systematic analysis of the GW emission from the self-consistent 2D models. We find that the total GW energies emitted during the simulation become higher for models with progenitors' high compactness. This is because the high compactness leads to more energetic explosions, where non-spherical hydrodynamic motions associated with neutrino-driven convection and the Standing-Accretion-Shock-Instability develop much more violently. On the other hand, we show that the GW energies become smaller for high-compactness models that fail to explode by the neutrino-driven mechanism. This is because non-spherical motions in the postbounce core get gradually weaker with the decreasing mass accretion rate to the proto-neutron star, which leads to the smaller GW amplitudes in the long postbounce evolution. We discuss the detectability of the GW signals from both the successful and unsuccessful models using the advanced GW detectors including LIGO and KAGRA.

  3. Fully converged plane-wave-based self-consistent G W calculations of periodic solids

    NASA Astrophysics Data System (ADS)

    Cao, Huawei; Yu, Zhongyuan; Lu, Pengfei; Wang, Lin-Wang

    2017-01-01

    The G W approximation is a well-known method to obtain the quasiparticle and spectral properties of systems ranging from molecules to solids. In practice, G W calculations are often employed with many different approximations and truncations. In this work, we describe the implementation of a fully self-consistent G W approach based on the solution of the Dyson equation using a plane wave basis set. Algorithmic, numerical, and technical details of the self-consistent G W approach are presented. The fully self-consistent G W calculations are performed for GaAs, ZnO, and CdS including semicores in the pseudopotentials. No further approximations and truncations apart from the truncation on the plane wave basis set are made in our implementation of the G W calculation. After adopting a special potential technique, a ˜100 Ry energy cutoff can be used without the loss of accuracy. We found that the self-consistent G W (sc-G W ) significantly overestimates the bulk band gaps, and this overestimation is likely due to the underestimation of the macroscopic dielectric constants. On the other hand, the sc-G W accurately predicts the d -state positions, most likely because the d -state screening does not sensitively depend on the macroscopic dielectric constant. Our work indicates the need to include the high-order vertex term in order for the many-body perturbation theory to accurately predict the semiconductor band gaps. It also sheds some light on why, in some cases, the G0W0 bulk calculation is more accurate than the fully self-consistent G W calculation, because the initial density-functional theory has a better dielectric constant compared to experiments.

  4. Quasiparticle energies and excitonic effects in dense solid hydrogen near metallization

    NASA Astrophysics Data System (ADS)

    Dvorak, Marc; Chen, Xiao-Jia; Wu, Zhigang

    2014-07-01

    We investigate the crucial metallization pressure of the Cmca-12 phase of solid hydrogen (H) using many-body perturbation theory within the GW approximation. We consider the effects of self-consistency, plasmon-pole models, and the vertex correction on the quasiparticle band gap (Eg). Our calculations show that self-consistency leads to an increase in Eg by 0.33 eV over the one-shot G0W0 approach. Because of error cancellation between the effects of self-consistency and the vertex correction, the simplest G0W0 method underestimates Eg by only 0.16 eV compared with the prediction of the more accurate GWΓ approach. Employing the plasmon-pole models underestimates Eg by 0.1-0.2 eV compared to the full-frequency numerical integration results. We thus predict a metallization pressure around 280 GPa, instead of 260 GPa predicted previously. Furthermore, we compute the optical absorption including the electron-hole interaction by solving the Bethe-Salpeter equation (BSE). The resulting absorption spectra demonstrate substantial redshifts and enhancement of absorption peaks compared to the calculated spectra neglecting excitonic effects. We find that the exciton binding energy decreases with increasing pressure from 66 meV at 100 GPa to 12 meV at 200 GPa due to the enhanced electronic screening as solid H approaches metallization. Because optical measurements are so important in identifying the structure of solid H, our BSE results should improve agreement between theory and experiment.

  5. First-principles GW calculations for fullerenes, porphyrins, phtalocyanine, and other molecules of interest for organic photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Blase, X.; Attaccalite, C.; Olevano, V.

    2011-03-01

    We evaluate the performances of ab initio GW calculations for the ionization energies and highest occupied molecular orbital-lowest unoccupied molecular orbital gaps of 13 gas phase molecules of interest for organic electronic and photovoltaic applications, including the C60 fullerene, pentacene, free-base porphyrins and phtalocyanine, PTCDA, and standard monomers such as thiophene, fluorene, benzothiazole, or thiadiazole. Standard G0W0 calculations, that is, starting from eigenstates obtained with local or semilocal functionals, significantly improve the ionization energy and band gap as compared to density functional theory Kohn-Sham results, but the calculated quasiparticle values remain too small as a result of overscreening. Starting from Hartree-Fock-like eigenvalues provides much better results and is equivalent to performing self-consistency on the eigenvalues, with a resulting accuracy of 2%-4% as compared to experiment. Our calculations are based on an efficient Gaussian-basis implementation of GW with explicit treatment of the dynamical screening through contour deformation techniques.

  6. Self-Consistent Dynamics of a Josephson Junction in the Presence of an Arbitrary Environment

    NASA Astrophysics Data System (ADS)

    Joyez, Philippe

    2013-05-01

    We derive microscopically the dynamics associated with the dc Josephson effect in a superconducting tunnel junction interacting with an arbitrary electromagnetic environment. To do so, we extend to superconducting junctions the so-called P(E) theory (see, e.g., Ingold and Nazarov, arXiv:cond-mat/0508728) that accurately describes the interaction of a nonsuperconducting tunnel junction with its environment. We show the dynamics of this system is described by a small set of coupled correlation functions that take into account both Cooper pair and quasiparticle tunneling. When the phase fluctuations are small the problem is fully solved self-consistently, using and providing the exact linear admittance Y(ω) of the interacting junction.

  7. Self-Consistent-Field Calculation on Lithium Hydride for Undergraduates.

    ERIC Educational Resources Information Center

    Rioux, Frank; Harriss, Donald K.

    1980-01-01

    Describes a self-consistent-field-linear combination of atomic orbitals-molecular orbital calculation on the valence electrons of lithium hydride using the method of Roothaan. This description is intended for undergraduate physics students.

  8. Self-consistent slave rotor mean-field theory for strongly correlated systems

    NASA Astrophysics Data System (ADS)

    Zhao, E.; Paramekanti, A.

    2007-11-01

    Building on the work by Florens and Georges [Phys. Rev. B 70, 035114 (2004)], we formulate and study a self-consistent slave rotor mean-field theory for strongly correlated systems. This approach views the electron, in the strong correlation regime, as a composite of a neutral spinon and a charged rotor field. We solve the coupled spinon-rotor model self-consistently using a cluster mean-field theory for the rotors and various Ansätze for the spinon ground state. We illustrate this approach with a number of examples relevant to ongoing experiments in strongly correlated electronic systems such as (i) the phase diagram of the isotropic triangular lattice organic Mott insulators, (ii) quasiparticle excitations and tunneling asymmetry in the weakly doped cuprate superconductors, and (iii) the cyclotron mass of carriers in commensurate spin-density wave and U(1) staggered flux (or d -density wave) normal states of the underdoped cuprates. We compare the estimated cyclotron mass with results from recent quantum oscillation experiments on ortho-II YBa2Cu3O6.5 by Doiron-Leyraud [Nature (London) 447, 565 (2007)] which appear to find Fermi pockets in the magnetic field induced normal state. We comment on the relation of this normal ground state to Fermi arcs seen in photoemission experiments above Tc . This slave rotor mean-field theory can be generalized to study inhomogeneous states and strongly interacting models relevant to ultracold atoms in optical lattices.

  9. Spin-Isospin Resonances: A Self-Consistent Covariant Description

    SciTech Connect

    Liang Haozhao; Nguyen Van Giai; Meng Jie

    2008-09-19

    For the first time a fully self-consistent charge-exchange relativistic RPA based on the relativistic Hartree-Fock (RHF) approach is established. The self-consistency is verified by the so-called isobaric analog state (IAS) check. The excitation properties and the nonenergy weighted sum rules of two important charge-exchange excitation modes, the Gamow-Teller resonance (GTR) and the spin-dipole resonance (SDR), are well reproduced in the doubly magic nuclei {sup 48}Ca, {sup 90}Zr and {sup 208}Pb without readjustment of the particle-hole residual interaction. The dominant contribution of the exchange diagrams is demonstrated.

  10. Final Report Fermionic Symmetries and Self consistent Shell Model

    SciTech Connect

    Larry Zamick

    2008-11-07

    In this final report in the field of theoretical nuclear physics we note important accomplishments.We were confronted with "anomoulous" magnetic moments by the experimetalists and were able to expain them. We found unexpected partial dynamical symmetries--completely unknown before, and were able to a large extent to expain them.The importance of a self consistent shell model was emphasized.

  11. SOCIAL COMPARISON, SELF-CONSISTENCY AND THE PRESENTATION OF SELF.

    ERIC Educational Resources Information Center

    MORSE, STANLEY J.; GERGEN, KENNETH J.

    TO DISCOVER HOW A PERSON'S (P) SELF-CONCEPT IS AFFECTED BY THE CHARACTERISTICS OF ANOTHER (O) WHO SUDDENLY APPEARS IN THE SAME SOCIAL ENVIRONMENT, SEVERAL QUESTIONNAIRES, INCLUDING THE GERGEN-MORSE (1967) SELF-CONSISTENCY SCALE AND HALF THE COOPERSMITH SELF-ESTEEM INVENTORY, WERE ADMINISTERED TO 78 UNDERGRADUATE MEN WHO HAD ANSWERED AN AD FOR WORK…

  12. The Self-Consistency Model of Subjective Confidence

    ERIC Educational Resources Information Center

    Koriat, Asher

    2012-01-01

    How do people monitor the correctness of their answers? A self-consistency model is proposed for the process underlying confidence judgments and their accuracy. In answering a 2-alternative question, participants are assumed to retrieve a sample of representations of the question and base their confidence on the consistency with which the chosen…

  13. GW study of the metal-insulator transition of bcc hydrogen

    SciTech Connect

    Li, Je-luen; Rignanese, G.-M.; Chang, Eric K.; Blase, Xavier; Louie, Steven G.

    2002-01-31

    We study the metal-insulator transition in a model Mott system, a bcc hydrogen solid, by performing ab initio quasiparticle band-structure calculations within the GW approximation for a wide range of lattice constants. The value of the critical electron density n-sub c is consistent with Mott's original criterion. For smaller lattice constants, our spin-polarized GW results agree well with previous variational quantum Monte Carlo calculations. For large lattice constants, the computed quasiparticle band gap corresponds to the difference between the ionization energy and electron affinity of an isolated hydrogen atom. Near the metal-insulator transition, we investigate the quality of the quasiparticle wave functions obtained from different starting approximations in density-functional theory. Finally, we gain new insight into the GW method and its applicability to spin-polarized systems, for which several refinements are introduced.

  14. The quasiparticle zoo

    NASA Astrophysics Data System (ADS)

    Venema, Liesbeth; Verberck, Bart; Georgescu, Iulia; Prando, Giacomo; Couderc, Elsa; Milana, Silvia; Maragkou, Maria; Persechini, Lina; Pacchioni, Giulia; Fleet, Luke

    2016-12-01

    Quasiparticles are an extremely useful concept that provides a more intuitive understanding of complex phenomena in many-body physics. As such, they appear in various contexts, linking ideas across different fields and supplying a common language.

  15. Quasiparticle energy studies of bulk semiconductors, surfaces and nanotubes

    SciTech Connect

    Blase, X.F.

    1994-12-01

    Effects of many-body effects on electronic excitation energies (quasiparticle band structure) of these materials are explored. GW approximation, including local field effects, for self-energy operator is used to calculate quasi-particle energies. The newly discovered carbon nanotubes are studied; structural stability and band structures are calculated. BN nanotubes are also studied, and their stability is predicted. Unexpected electronic features are predicted for both systems. Filling of carbon nanotubes with metal atoms and the doping of BN nanotubes by carbon and other impurites is also studied. The occupied surface states at H/Si(111)-(1{times}1) surface are studied; it is shown that the electronic structure requires a full quasiparticle calculation even for this simple chemisorption system. The core level shift of the Si 2p levels for atoms near the H/Si(111)-(1{times}1) surface is calculated; a simple first order perturbation theory using pseudopotential and the local density approximation gives good results for the photoemission spectra of the core electrons. The quasiparticle energies of bulk hexagonal BN and those of an isolated BN sheet are studied; this provides an understanding of the quasiparticle band structure of BN nanotubes. A nearly free electron state with a wavefunction in the interlayer or vacuum region composes the bottom of the conduction bands. A mixed-space formalism is presented for calculating the dynamical screening effects and electron self-energy operator in solids; this provides an efficient algorithm to calculate quasiparticle energies for large systems.

  16. Self-consistent pitch angle diffusion of newborn ions

    NASA Astrophysics Data System (ADS)

    Yoon, P. H.; Ziebell, L. F.; Wu, C. S.

    1991-04-01

    A self-consistent analysis of pitch angle diffusion of newborn ions by low-frequency hydromagnetic waves predominantly propagating in one direction has been carried out. It is found that in the wave frame defined in velocity space the time evolution of an ion distribution can be described as undergoing purely pitch angle diffusion. The role of the resonant versus nonresonant diffusion is discussed in detail, and it is shown that a time-asymptotic distribution of a particular form develops. It is analytically and numerically shown that the self-consistent diffusion process leads to a time-asymptotic partial shell distributions. The relevance of this finding to observations that the ion distributions in the far upstream of cometary bow shocks have a partial shell structure rather than a complete shell is pointed out.

  17. Electronic structure and metallization of cubic GdH3 under pressure: Ab initio many-body GW calculations

    NASA Astrophysics Data System (ADS)

    Kong, Bo; Zhang, Yachao

    2016-07-01

    The electronic structures of the cubic GdH3 are extensively investigated using the ab initio many-body GW calculations treating the Gd 4f electrons either in the core (4f-core) or in the valence states (4f-val). Different degrees of quasiparticle (QP) self-consistent calculations with the different starting points are used to correct the failures of the GGA/GGA + U/HSE03 calculations. In the 4f-core case, GGA + G0W0 calculations give a fundamental band gap of 1.72 eV, while GGA+ GW0 or GGA + GW calculations present a larger band gap. In the 4f-val case, the nonlocal exchange-correlation (xc) functional HSE03 can account much better for the strong localization of the 4f states than the semilocal or Hubbard U corrected xc functional in the Kohn-Sham equation. We show that the fundamental gap of the antiferromagnetic (AFM) or ferromagnetic (FM) GdH3 can be opened up by solving the QP equation with improved starting point of eigenvalues and wave functions given by HSE03. The HSE03 + G0W0 calculations present a fundamental band gap of 2.73 eV in the AFM configuration, and the results of the corresponding GW0 and GW calculations are 2.89 and 3.03 eV, respectively. In general, for the cubic structure, the fundamental gap from G0W0 calculations in the 4f-core case is the closest to the real result. By G0W0 calculations in the 4f-core case, we find that H or Gd defects can strongly affect the band structure, especially the H defects. We explain the mechanism in terms of the possible electron correlation on the hydrogen site. Under compression, the insulator-to-metal transition in the cubic GdH3 occurs around 40 GPa, which might be a satisfied prediction.

  18. The Number Self-Consistent Renormalized Random Phase Approximation

    NASA Astrophysics Data System (ADS)

    Mariano, A.

    RPA and its quasiparticle generalization (QRPA) have been widely used to study electromagnetic transitions and beta decays in medium and heavy nuclei, being the pn-QRPA charge exchange mode extensively employed in the description of single and double beta decays in vibrational nuclei. However develops a collapse, i.e. it presents imaginary eigen-values for strengths beyond a critical value of the force. Extensions called renormalized QRPA (RQRPA) do not develop any collapse going beyond the simplest quasiboson approximation, however they present several drawbacks which will be analyzed.

  19. The Number Self-Consistent Renormalized Random Phase Approximation

    NASA Astrophysics Data System (ADS)

    Mariano, A.

    RPA and its quasiparticle generalization (QRPA) have been widely used to study electromagnetic transitions and beta decays in medium and heavy nuclei, being the pn-QRPA charge exchange mode extensively employed in the description of single and double beta decays in vibrational nuclei. However develops a collapse, i.e. it presents imaginary eigenvalues for strengths beyond a critical value of the force. Extensions called renormalized QRPA (RQRPA) do not develop any collapse going beyond the simplest quasiboson approximation, however they present several drawbacks which will be analyzed.

  20. The Number Self-Consistent Renormalized Random Phase Approximation

    NASA Astrophysics Data System (ADS)

    Mariano, A.

    2006-09-01

    RPA and its quasiparticle generalization (QRPA) have been widely used to study electromagnetic transitions and beta decays in medium and heavy nuclei, being the pn-QRPA charge exchange mode extensively employed in the description of single and double beta decays in vibrational nuclei. However develops a collapse, i.e. it presents imaginary eigenvalues for strengths beyond a critical value of the force. Extensions called renormalized QRPA (RQRPA) do not develop any collapse going beyond the simplest quasiboson approximation, however they present several drawbacks which will be analyzed.

  1. The self-consistent dynamic pole tide in global oceans

    NASA Technical Reports Server (NTRS)

    Dickman, S. R.

    1985-01-01

    The dynamic pole tide is characterized in a self-consistent manner by means of introducing a single nondifferential matrix equation compatible with the Liouville equation, modelling the ocean as global and of uniform depth. The deviations of the theory from the realistic ocean, associated with the nonglobality of the latter, are also given consideration, with an inference that in realistic oceans long-period modes of resonances would be increasingly likely to exist. The analysis of the nature of the pole tide and its effects on the Chandler wobble indicate that departures of the pole tide from the equilibrium may indeed be minimal.

  2. Beta-decay rates: towards a self-consistent approach

    SciTech Connect

    Borzov, I. N.; Goriely, S.; Pearson, J. M.

    1998-02-15

    An approximation to a self-consistent model of the ground state properties and spin-isospin excitations of neutron-rich nuclides is outlined. The structure of the Gamow-Teller strength functions in stable nuclei and short-lived nuclides undergoing high-energy {beta}-decay is discussed. The results of large-scale calculations of the {beta}-decay rates for spherical and slightly deformed nuclides of relevance to the r-process are analysed and compared with the results of existing global calculations.

  3. Limitations of the number self-consistent random phase approximation

    NASA Astrophysics Data System (ADS)

    Mariano, Alejandro; Hirsch, Jorge G.

    2000-05-01

    The quasiparticle random phase approximation (QRPA) equations are solved taking into account the Pauli principle at the expectation value level, and allowing changes in the mean field occupation numbers to minimize the energy while having the correct number of particles in the correlated vacuum. The study of Fermi pn excitations in 76Ge using a realistic Hilbert space shows that the pairing energy gaps in the modified mean field are diminished up to one half of the experimental value when strong proton-neutron correlations are present. Additionally, the Ikeda sum rule for Fermi transitions is violated due to the lack of scattering terms in the phonon operators. These results call for a critical revision of the double β decay half-lives estimated using the QRPA extensions when standard QRPA calculations collapse.

  4. Self-consistent chemical model of partially ionized plasmas

    SciTech Connect

    Arkhipov, Yu. V.; Baimbetov, F. B.; Davletov, A. E.

    2011-01-15

    A simple renormalization theory of plasma particle interactions is proposed. It primarily stems from generic properties of equilibrium distribution functions and allows one to obtain the so-called generalized Poisson-Boltzmann equation for an effective interaction potential of two chosen particles in the presence of a third one. The same equation is then strictly derived from the Bogolyubov-Born-Green-Kirkwood-Yvon (BBGKY) hierarchy for equilibrium distribution functions in the pair correlation approximation. This enables one to construct a self-consistent chemical model of partially ionized plasmas, correctly accounting for the close interrelation of charged and neutral components thereof. Minimization of the system free energy provides ionization equilibrium and, thus, permits one to study the plasma composition in a wide range of its parameters. Unlike standard chemical models, the proposed one allows one to study the system correlation functions and thereby to obtain an equation of state which agrees well with exact results of quantum-mechanical activity expansions. It is shown that the plasma and neutral components are strongly interrelated, which results in the short-range order formation in the corresponding subsystem. The mathematical form of the results obtained enables one to both firmly establish this fact and to determine a characteristic length of the structure formation. Since the cornerstone of the proposed self-consistent chemical model of partially ionized plasmas is an effective pairwise interaction potential, it immediately provides quite an efficient calculation scheme not only for thermodynamical functions but for transport coefficients as well.

  5. SELF-CONSISTENT SIZE AND VELOCITY DISTRIBUTIONS OF COLLISIONAL CASCADES

    SciTech Connect

    Pan, Margaret; Schlichting, Hilke E. E-mail: hilke@ucla.edu

    2012-03-10

    The standard theoretical treatment of collisional cascades derives a steady-state size distribution assuming a single constant velocity dispersion for all bodies regardless of size. Here we relax this assumption and solve self-consistently for the bodies' steady-state size and size-dependent velocity distributions. Specifically, we account for viscous stirring, dynamical friction, and collisional damping of the bodies' random velocities in addition to the mass conservation requirement typically applied to find the size distribution in a steady-state cascade. The resulting size distributions are significantly steeper than those derived without velocity evolution. For example, accounting self-consistently for the velocities can change the standard q = 3.5 power-law index of the Dohnanyi differential size spectrum to an index as large as q = 4. Similarly, for bodies held together by their own gravity, the corresponding power-law index range 2.88 < q < 3.14 of Pan and Sari can steepen to values as large as q = 3.26. Our velocity results allow quantitative predictions of the bodies' scale heights as a function of size. Together with our predictions, observations of the scale heights for different-sized bodies for the Kuiper belt, the asteroid belt, and extrasolar debris disks may constrain the mass and number of large bodies stirring the cascade as well as the colliding bodies' internal strengths.

  6. Self-Consistent Superthermal Electron Effects on Plasmaspheric Refilling

    NASA Technical Reports Server (NTRS)

    Liemohn, M. W.; Khazanov, G. V.; Moore, T. E.; Guiter, S. M.

    1997-01-01

    The effects of self-consistently including superthermal electrons in the definition of the ambipolar electric field are investigated for the case of plasmaspheric refilling after a geomagnetic storm. By using the total electron population in the hydrodynamic equations, a method for incorporating superthermal electron parameters in the electric field and electron temperature calculation is developed. Also, the ambipolar electric field is included in the kinetic equation for the superthermal electrons through a change of variables using the total energy and the first adiabatic invariant. Calculations based on these changes are performed by coupling time-dependent models of the thermal plasma and superthermal electrons. Results from this treatment of the electric field and the self-consistent development of the solution are discussed in detail. Specifically, there is a decreased thermal electron density in the plasmasphere during the first few minutes of refilling, a slightly accelerated proton shock front, and a decreased superthermal electron flux due to the deceleration by the electric field. The timescales of plasmaspheric refilling are discussed and determined to be somewhat shorter than previously calculated for the thermal plasma and superthermal electron population due to the effects of the field-aligned potential.

  7. Self-consistent modeling of multiscale gyrokinetics and transport

    NASA Astrophysics Data System (ADS)

    Parker, Jeffrey; Lodestro, Lynda; Told, Daniel; Jenko, Frank

    2016-10-01

    In the core of tokamak plasmas, a separation of timescales between turbulence and transport makes direct simulation of both processes computationally expensive. A workable, practical method to exploit the separation of timescales will be a key component in enabling the self-consistent solution of macroscopic profiles of density and temperature. We report on progress to implement the LoDestro scheme coupled with the gyrokinetic code GENE to perform for the first time coupled turbulence and transport simulations using a global gyrokinetic code. One of the advantages of the LoDestro scheme, which is essentially a method of solving an implicitly advanced nonlinear transport problem, is that it does not use Newton iteration and hence avoids difficulties that arise from calculating Jacobians or Jacobian-vector products in the presence of noisy fluxes. Instead, the implicit timestep equation is solved with an iteration scheme by representing the turbulent flux as the sum of diffusive and convective pieces, after which Picard iteration is used to converge to the self-consistent solution. Preliminary results will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

  8. Self-consistent theory of rupture by progressive diffuse damage.

    PubMed

    Gluzman, S; Sornette, D

    2001-06-01

    We analyze a self-consistent theory of crack growth controlled by a cumulative damage variable d(t) dependent on stress history, in the quasistatic regime where the sound wave velocity is taken as infinite. Depending upon the damage exponent m, which controls the rate of damage dd/dt~sigma(m) as a function of local stress sigma, we find two regimes. For 0self-consistent theory which neglects the dependence of stress on damage, we apply the functional renormalization method of Yukalov and Gluzman and find that divergences are replaced by singularities with exponents in agreement with those found in acoustic emission experiments. For m>/=2, the rupture dynamics is not defined without the introduction of a regularizing scheme. We investigate three regularization schemes involving, respectively, a saturation of damage, a minimum distance of approach to the crack tip, and a fixed stress maximum. In the first and third schemes, the finite-time singularity is replaced by a crack dynamics defined for all times but which is controlled by either the existence of a microscopic scale at which the stress is regularized or by the maximum sustainable stress. In the second scheme, a finite-time singularity is again found. In the first two schemes within this regime m>/=2, the theory has no continuous limit.

  9. Self-consistent conversion of a viscous fluid to particles

    NASA Astrophysics Data System (ADS)

    Molnar, Denes; Wolff, Zack

    2017-02-01

    Comparison of hydrodynamic and "hybrid" hydrodynamics+transport calculations with heavy-ion data inevitably requires the conversion of the fluid to particles. For dissipative fluids the conversion is ambiguous without additional theory input complementing hydrodynamics. We obtain self-consistent shear viscous phase-space corrections from linearized Boltzmann transport theory for a gas of hadrons. These corrections depend on the particle species, and incorporating them in Cooper-Frye freeze-out affects identified particle observables. For example, with additive quark model cross sections, proton elliptic flow is larger than pion elliptic flow at moderately high pT in Au+Au collisions at the BNL Relativistic Heavy Ion Collider. This is in contrast to Cooper-Frye freeze-out with the commonly used "democratic Grad" ansatz that assumes no species dependence. Various analytic and numerical results are also presented for massless and massive two-component mixtures to better elucidate how species dependence arises. For convenient inclusion in pure hydrodynamic and hybrid calculations, Appendix G contains self-consistent viscous corrections for each species both in tabulated and parametrized form.

  10. Self-consistent perturbation theory for two dimensional twisted bilayers

    NASA Astrophysics Data System (ADS)

    Shirodkar, Sharmila N.; Tritsaris, Georgios A.; Kaxiras, Efthimios

    Theoretical modeling and ab-initio simulations of two dimensional heterostructures with arbitrary angles of rotation between layers involve unrealistically large and expensive calculations. To overcome this shortcoming, we develop a methodology for weakly interacting heterostructures that treats the effect of one layer on the other as perturbation, and restricts the calculations to their primitive cells. Thus, avoiding computationally expensive supercells. We start by approximating the interaction potential between the twisted bilayers to that of a hypothetical configuration (viz. ideally stacked untwisted layers), which produces band structures in reasonable agreement with full-scale ab-initio calculations for commensurate and twisted bilayers of graphene (Gr) and Gr/hexagonal boron nitride (h-BN) heterostructures. We then self-consistently calculate the charge density and hence, interaction potential of the heterostructures. In this work, we test our model for bilayers of various combinations of Gr, h-BN and transition metal dichalcogenides, and discuss the advantages and shortcomings of the self-consistently calculated interaction potential. Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.

  11. Self-consistent viscous heating of rapidly compressed turbulence

    NASA Astrophysics Data System (ADS)

    Campos, Alejandro; Morgan, Brandon; Olson, Britton; Greenough, Jeffrey

    2016-11-01

    Given turbulence subjected to infinitely rapid deformations, linear terms representing interactions between the mean flow and the turbulence dictate the flow evolution, whereas non-linear terms corresponding to turbulence-turbulence interactions are safely ignored. For rapidly deformed flows where the turbulence Reynolds number is not sufficiently large, viscous effects can't be neglected and tend to play a prominent role, as shown in Davidovits & Fisch (2016). For such a case, the rapid increase of viscosity in a plasma-as compared to the weaker scaling of viscosity in a fluid-leads to the sudden viscous dissipation of turbulent kinetic energy. As described in Davidovits & Fisch, increases in temperature caused by the direct compression of the plasma drive sufficiently large values of viscosity. We report on numerical simulations of turbulence where the increase in temperature is the result of both the direct compression (an inviscid mechanism) and the self-consistent viscous transfer of energy from the turbulent scales towards the thermal energy. A comparison between implicit large-eddy simulations against well-resolved direct numerical simulations is included to asses the effect of the numerical and subgrid-scale dissipation on the self-consistent viscous energy transfer. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  12. Transport across nanogaps using self-consistent boundary conditions

    NASA Astrophysics Data System (ADS)

    Biswas, D.; Kumar, R.

    2012-06-01

    Charge particle transport across nanogaps is studied theoretically within the Schrodinger-Poisson mean field framework. The determination of self-consistent boundary conditions across the gap forms the central theme in order to allow for realistic interface potentials (such as metal-vacuum) which are smooth at the boundary and do not abruptly assume a constant value at the interface. It is shown that a semiclassical expansion of the transmitted wavefunction leads to approximate but self consistent boundary conditions without assuming any specific form of the potential beyond the gap. Neglecting the exchange and correlation potentials, the quantum Child-Langmuir law is investigated. It is shown that at zero injection energy, the quantum limiting current density (Jc) is found to obey the local scaling law Jc ~ Vgα/D5-2α with the gap separation D and voltage Vg. The exponent α > 1.1 with α → 3/2 in the classical regime of small de Broglie wavelengths.

  13. Quasiparticle properties in graphene

    NASA Astrophysics Data System (ADS)

    Hwang, Euyheon

    2012-02-01

    The quasiparticle properties in both single layer and bilayer graphene are presented. We study the electron self-energy as well as the quasiparticle spectral function in graphene, taking into account electron-electron interaction in the leading order dynamically screened Coulomb coupling and electron-impurity interaction associated with quenched disorder. Our calculation of the self-energy provides the basis for calculating all one-electron properties of graphene. We provide analytical and numerical results for quasiparticle renormalization in graphene. Comparison with existing angle-resolved photoemission spectroscopy measurements shows broad qualitative and semiquantitative agreement between theory and experiment, for both the momentum-distribution and energy-distribution curves in the measured spectra. We also present the inelastic quasiparticle scattering rate and the carrier mean free path for energetic hot electrons as a function of carrier energy, density, and temperature, including both electron-electron and electron-phonon interactions. Our results are directly applicable to device structures where ballistic transport is relevant with inelastic scattering dominating over elastic scattering.[4pt] S. Das Sarma, S. Adam, E. H. Hwang, and E. Rossi, Rev. Mod. Phys. 83, 407 (2011). [0pt] E. H. Hwang, Ben Yu-Kuang Hu, and S. Das Sarma Phys. Rev. B 76, 115434 (2007). [0pt] E. H. Hwang and S. Das Sarma Phys. Rev. B 77, 081412 (2008). [0pt] Rajdeep Sensarma, E. H. Hwang, and S. Das Sarma, Phys. Rev. B 84, 041408(R) (2011).

  14. Self-consistency in Bicultural Persons: Dialectical Self-beliefs Mediate the Relation between Identity Integration and Self-consistency

    PubMed Central

    Zhang, Rui; Noels, Kimberly A.; Lalonde, Richard N.; Salas, S. J.

    2017-01-01

    Prior research differentiates dialectical (e.g., East Asian) from non-dialectical cultures (e.g., North American and Latino) and attributes cultural differences in self-concept consistency to naïve dialecticism. In this research, we explored the effects of managing two cultural identities on consistency within the bicultural self-concept via the role of dialectical beliefs. Because the challenge of integrating more than one culture within the self is common to biculturals of various heritage backgrounds, the effects of bicultural identity integration should not depend on whether the heritage culture is dialectical or not. In four studies across diverse groups of bicultural Canadians, we showed that having an integrated bicultural identity was associated with being more consistent across roles (Studies 1–3) and making less ambiguous self-evaluations (Study 4). Furthermore, dialectical self-beliefs mediated the effect of bicultural identity integration on self-consistency (Studies 2–4). Finally, Latino biculturals reported being more consistent across roles than did East Asian biculturals (Study 2), revealing the ethnic heritage difference between the two groups. We conclude that both the content of heritage culture and the process of integrating cultural identities influence the extent of self-consistency among biculturals. Thus, consistency within the bicultural self-concept can be understood, in part, to be a unique psychological product of bicultural experience. PMID:28326052

  15. Wakes in complex plasmas: A self-consistent kinetic theory.

    PubMed

    Kompaneets, Roman; Morfill, Gregor E; Ivlev, Alexei V

    2016-06-01

    In ground-based experiments with complex (dusty) plasmas, charged microparticles are levitated against gravity by an electric field, which also drives ion flow in the parent gas. Existing analytical approaches to describe the electrostatic interaction between microparticles in such conditions generally ignore the field and ion-neutral collisions, assuming free ion flow with a certain approximation for the ion velocity distribution function (usually a shifted Maxwellian). We provide a comprehensive analysis of our previously proposed self-consistent kinetic theory including the field, ion-neutral collisions, and the corresponding ion velocity distribution. We focus on various limiting cases and demonstrate how the interplay of these factors results in different forms of the shielding potential.

  16. Wakes in complex plasmas: A self-consistent kinetic theory

    NASA Astrophysics Data System (ADS)

    Kompaneets, Roman; Morfill, Gregor E.; Ivlev, Alexei V.

    2016-06-01

    In ground-based experiments with complex (dusty) plasmas, charged microparticles are levitated against gravity by an electric field, which also drives ion flow in the parent gas. Existing analytical approaches to describe the electrostatic interaction between microparticles in such conditions generally ignore the field and ion-neutral collisions, assuming free ion flow with a certain approximation for the ion velocity distribution function (usually a shifted Maxwellian). We provide a comprehensive analysis of our previously proposed self-consistent kinetic theory including the field, ion-neutral collisions, and the corresponding ion velocity distribution. We focus on various limiting cases and demonstrate how the interplay of these factors results in different forms of the shielding potential.

  17. The Brittle-Ductile Transition - A Self-Consistent Approach.

    NASA Astrophysics Data System (ADS)

    Hobbs, B.; Regenauer-Lieb, K.; Ord, A.; Yuen, D. A.

    2006-12-01

    The brittle-ductile transition (BDT) in the Earth is commonly viewed as a switch between two different constitutive behaviors, plastic and viscous, and is represented in models by various formulations. We show that thermal-mechanical coupling leads to a self consistent view where the BDT emerges naturally within one constitutive framework once a critical temperature is attained. Viscous folding occurs above this temperature and brittle fracturing below. Seismic activity is maximised at the BDT. Orogenesis emerges as a thermal-mechanical decoupling near the BDT during flexing of the lithosphere with the development of "crocodile" -like structures, fold-nappe systems and far-travelled thrust sheets. For quartz- feldspar composite materials this transition lies in a critical range of 500 K to 580 K.

  18. A self-consistent spin-diffusion model for micromagnetics.

    PubMed

    Abert, Claas; Ruggeri, Michele; Bruckner, Florian; Vogler, Christoph; Manchon, Aurelien; Praetorius, Dirk; Suess, Dieter

    2016-12-01

    We propose a three-dimensional micromagnetic model that dynamically solves the Landau-Lifshitz-Gilbert equation coupled to the full spin-diffusion equation. In contrast to previous methods, we solve for the magnetization dynamics and the electric potential in a self-consistent fashion. This treatment allows for an accurate description of magnetization dependent resistance changes. Moreover, the presented algorithm describes both spin accumulation due to smooth magnetization transitions and due to material interfaces as in multilayer structures. The model and its finite-element implementation are validated by current driven motion of a magnetic vortex structure. In a second experiment, the resistivity of a magnetic multilayer structure in dependence of the tilting angle of the magnetization in the different layers is investigated. Both examples show good agreement with reference simulations and experiments respectively.

  19. Self-Consistent Study of Conjugated Aromatic Molecular Transistors

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Liang, Yun-Ye; Chen, Hao; Wang, Peng; Note, R.; Mizuseki, H.; Kawazoe, Y.

    2010-06-01

    We study the current through conjugated aromatic molecular transistors modulated by a transverse field. The self-consistent calculation is realized with density function theory through the standard quantum chemistry software Gaussian03 and the non-equilibrium Green's function formalism. The calculated I - V curves controlled by the transverse field present the characteristics of different organic molecular transistors, the transverse field effect of which is improved by the substitutions of nitrogen atoms or fluorine atoms. On the other hand, the asymmetry of molecular configurations to the axis connecting two sulfur atoms is in favor of realizing the transverse field modulation. Suitably designed conjugated aromatic molecular transistors possess different I - V characteristics, some of them are similar to those of metal-oxide-semiconductor field-effect transistors (MOSFET). Some of the calculated molecular devices may work as elements in graphene electronics. Our results present the richness and flexibility of molecular transistors, which describe the colorful prospect of next generation devices.

  20. Self-consistent quantum kinetic theory of diatomic molecule formation.

    PubMed

    Forrey, Robert C

    2015-07-14

    A quantum kinetic theory of molecule formation is presented which includes three-body recombination and radiative association for a thermodynamically closed system which may or may not exchange energy with its surrounding at a constant temperature. The theory uses a Sturmian representation of a two-body continuum to achieve a steady-state solution of a governing master equation which is self-consistent in the sense that detailed balance between all bound and unbound states is rigorously enforced. The role of quasibound states in catalyzing the molecule formation is analyzed in complete detail. The theory is used to make three predictions which differ from conventional kinetic models. These predictions suggest significant modifications may be needed to phenomenological rate constants which are currently in wide use. Implications for models of low and high density systems are discussed.

  1. Self-consistent quantum kinetic theory of diatomic molecule formation

    SciTech Connect

    Forrey, Robert C.

    2015-07-14

    A quantum kinetic theory of molecule formation is presented which includes three-body recombination and radiative association for a thermodynamically closed system which may or may not exchange energy with its surrounding at a constant temperature. The theory uses a Sturmian representation of a two-body continuum to achieve a steady-state solution of a governing master equation which is self-consistent in the sense that detailed balance between all bound and unbound states is rigorously enforced. The role of quasibound states in catalyzing the molecule formation is analyzed in complete detail. The theory is used to make three predictions which differ from conventional kinetic models. These predictions suggest significant modifications may be needed to phenomenological rate constants which are currently in wide use. Implications for models of low and high density systems are discussed.

  2. Using Self Consistent Field Theory on Polymeric Mixtures

    NASA Astrophysics Data System (ADS)

    von Konigslow, Kier; Park, Chul; Thompson, Russell

    The ability to predict the solubility of a particular solvent in a polymer fluid is essential to the production of polymer foams. For the past 40 years, the primary model employed to this end has been an expansion of Flory-Huggins lattice fluid theory developed by Sanchez and Lacombe (S-L theory). S-L theory, while useful in the uniform limit, is limited to homogeneous systems. Self-Consistent Field Theory (SCFT), which has long been in use in polymer physics, is a mean-field theory capable of modeling the equilibrium behaviour of both homogeneous and inhomogeneous systems. We are investigating whether SCFT, applied to polymer-solvent mixtures, is in agreement with SL-theory in the homogeneous limit. Should this prove successful, we hope to use SCFT to model more general mixtures, including inhomogeneous nanocellular polymer foam systems.

  3. Self-consistent undulator radiation via Lienard-Wiechert fields

    NASA Astrophysics Data System (ADS)

    Elias, Luis R.; Tecimer, Musit; Kimel, Isidoro

    1995-09-01

    Using Lienard-Wiechert fields and the Lorentz Force relation we present self consistent 3D radiation studies of electron beams moving through periodic electromagnetic structures such as those present in synchrotrons and free-electron laser undulators. Besides providing an economical means of calculating 3D vector radiation fields, our approach yields new insights into individual electron motion as it is driven by both, the velocity fields (Coulomb Fields) and the radiation fields generated by other electrons. We present results of electron beam compression resulting from longitudinal radiation forces competing in opposition with repulsive velocity field forces. We discuss results of noiseless 3D Self Amplified Spontaneous Emission in the X-Ray region resulting from the interaction of a filamentary electron beam with a circularly polarized magnetic undulator.

  4. Membrane stress profiles from self-consistent field theory

    NASA Astrophysics Data System (ADS)

    Ting, Christina L.; Müller, Marcus

    2017-03-01

    Using self-consistent field theory (SCFT), we develop an accurate, local expression for the stress profiles in membranes and soft matter interfaces, in general. The bond stresses are expressed in terms of pre-computed chain propagators, which are used to describe the statistical weight of the molecules and therefore require minimal additional calculations. In addition, we overcome the resolution limit of the molecular bond length by including the Irving and Kirkwood bond assignment and recover a constant normal stress profile across an interface. Using this theory, we find that the membrane lateral stress profile contains repulsive (positive) stresses in the regions of the head and tail groups, and attractive (negative) stresses near the hydrophobic/hydrophilic interface. We also verify that the zeroth and first moments of the stress profile correspond to the thermodynamic tension and product of the bending modulus and the spontaneous curvature, respectively.

  5. Causal, Self-consistent Field Quantum Mass-Spacetimes

    NASA Astrophysics Data System (ADS)

    Scofield, Dillon

    2017-01-01

    An ab initio self-consistent field (SCF) description of the causal, current conserving, evolution of quantum mass-spacetime (QMST) manifolds is presented. The properties of QMSTs are shown to follow from the properties of their homogeneous, isotropic, affine tangent spaces as characterized by the Poincaré group. QMSTs with C l (4,C) Clifford algebra structure and tangent spaces are shown to be compatible with the Standard Model of elementary particle interactions. These QMSTs include the proton-electron-neutrino-neutron excitation system. Expressions for conserved Noether currents, stress-energies, and angular-momenta are shown to be corollaries of the theory. Methods to compute the quantum geometry of few-body QMSTs are discussed.

  6. Self-Consistent Ornstein-Zernike Approximation for Lattice Gases

    SciTech Connect

    Dickman, R.; Stell, G. |

    1996-08-01

    A self-consistent approximation for the structure factor of three-dimensional lattice gases yields remarkably accurate predictions (less than 3{percent} error over most of the temperature range) for the correlation length, isothermal compressibility, specific heat, and the coexistence curve. Critical temperatures agree to within 0.2{percent}, and other critical properties to within (1{endash}2){percent}, of the best numerical estimates. Until temperature and density are within 1{percent} of their critical values, the approximate {ital effective} critical exponents do not differ appreciably from their estimated exact form; they attain their limiting spherical-model values only much closer to critical. The method should prove useful for a variety of three-dimensional lattice-gas and fluid problems; it is inappropriate to two dimensions, where it predicts criticality at zero temperature. {copyright} {ital 1996 The American Physical Society.}

  7. Photoabsorption off nuclei with self-consistent vertex corrections

    SciTech Connect

    Riek, F.; Lutz, M. F. M.; Korpa, C. L.

    2009-08-15

    We study photoproduction off nuclei based on a self-consistent and covariant many-body approach for the pion and isobar propagation in infinite nuclear matter. For the first time the t-channel exchange of an in-medium pion is evaluated in the presence of vertex correction effects consistently. In particular the interference pattern with the s-channel in-medium nucleon and isobar exchange contribution is considered. Electromagnetic gauge invariance is kept as a consequence of various Ward identities obeyed by the computation. Adjusting the set of Migdal parameters to the data set we predict an attractive mass shift for the isobar of about 50 MeV at nuclear saturation density.

  8. PICACS: self-consistent modelling of galaxy cluster scaling relations

    NASA Astrophysics Data System (ADS)

    Maughan, B. J.

    2014-01-01

    In this paper, we introduce Physically motivated, Internally Consistent Analysis of Cluster Scaling (PICACS), a detailed model of scaling relations between galaxy cluster masses and their observable properties. This model can be used to constrain simultaneously the form, scatter (including its covariance) and evolution of the scaling relations, as well as the masses of the individual clusters. In this framework, scaling relations between observables (such as that between X-ray luminosity and temperature) are modelled explicitly in terms of the fundamental mass-observable scaling relations, and so are fully constrained without being fit directly. We apply the PICACS model to two observational data sets, and show that it performs as well as traditional regression methods for simply measuring individual scaling relation parameters, but reveals additional information on the processes that shape the relations while providing self-consistent mass constraints. Our analysis suggests that the observed combination of slopes of the scaling relations can be described by a deficit of gas in low-mass clusters that is compensated for by elevated gas temperatures, such that the total thermal energy of the gas in a cluster of given mass remains close to self-similar expectations. This is interpreted as the result of AGN feedback removing low entropy gas from low-mass systems, while heating the remaining gas. We deconstruct the luminosity-temperature (L-T) relation and show that its steepening compared to self-similar expectations can be explained solely by this combination of gas depletion and heating in low-mass systems, without any additional contribution from a mass dependence of the gas structure. Finally, we demonstrate that a self-consistent analysis of the scaling relations leads to an expectation of self-similar evolution of the L-T relation that is significantly weaker than is commonly assumed.

  9. Modeling self-consistent multi-class dynamic traffic flow

    NASA Astrophysics Data System (ADS)

    Cho, Hsun-Jung; Lo, Shih-Ching

    2002-09-01

    In this study, we present a systematic self-consistent multiclass multilane traffic model derived from the vehicular Boltzmann equation and the traffic dispersion model. The multilane domain is considered as a two-dimensional space and the interaction among vehicles in the domain is described by a dispersion model. The reason we consider a multilane domain as a two-dimensional space is that the driving behavior of road users may not be restricted by lanes, especially motorcyclists. The dispersion model, which is a nonlinear Poisson equation, is derived from the car-following theory and the equilibrium assumption. Under the concept that all kinds of users share the finite section, the density is distributed on a road by the dispersion model. In addition, the dynamic evolution of the traffic flow is determined by the systematic gas-kinetic model derived from the Boltzmann equation. Multiplying Boltzmann equation by the zeroth, first- and second-order moment functions, integrating both side of the equation and using chain rules, we can derive continuity, motion and variance equation, respectively. However, the second-order moment function, which is the square of the individual velocity, is employed by previous researches does not have physical meaning in traffic flow. Although the second-order expansion results in the velocity variance equation, additional terms may be generated. The velocity variance equation we propose is derived from multiplying Boltzmann equation by the individual velocity variance. It modifies the previous model and presents a new gas-kinetic traffic flow model. By coupling the gas-kinetic model and the dispersion model, a self-consistent system is presented.

  10. Binary nucleation kinetics. I. Self-consistent size distribution

    SciTech Connect

    Wilemski, G.; Wyslouzil, B.E. ||

    1995-07-15

    Using the principle of detailed balance, we derive a new self-consistency requirement, termed the kinetic product rule, relating the evaporation coefficients and equilibrium cluster distribution for a binary system. We use this result to demonstrate and resolve an inconsistency for an idealized Kelvin model of nucleation in a simple binary mixture. We next examine several common forms for the equilibrium distribution of binary clusters based on the capillarity approximation and ideal vapor behavior. We point out fundamental deficiencies for each expression. We also show that each distribution yields evaporation coefficients that formally satisfy the new kinetic product rule but are physically unsatisfactory because they depend on the monomer vapor concentrations. We then propose a new form of the binary distribution function that is free of the deficiencies of the previous functions except for its reliance on the capillarity approximation. This new self-consistent classical (SCC) size distribution for binary clusters has the following properties: It satisfies the law of mass action; it reduces to an SCC unary distribution for clusters of a single component; and it produces physically acceptable evaporation rate coefficients that also satisfy the new kinetic product rule. Since it is possible to construct other examples of similarly well-behaved distributions, our result is not unique in this respect, but it does give reasonable predictions. As an illustration, we calculate binary nucleation rates and vapor activities for the ethanol--hexanol system at 260 K using the new SCC distribution and compare them to experimental results. The theoretical rates are uniformly higher than the experimental values over the entire vapor composition range. Although the predicted activities are lower, we find good agreement between the measured and theoretical slope of the critical vapor activity curve at a constant nucleation rate of 10{sup 7} cm{sup {minus}3} s{sup {minus}2}.

  11. Optimized virtual orbital subspace for faster GW calculations in localized basis

    NASA Astrophysics Data System (ADS)

    Bruneval, Fabien

    2016-12-01

    The popularity of the GW approximation to the self-energy to access the quasiparticle energies of molecules is constantly increasing. As the other methods addressing the electronic correlation, the GW self-energy unfortunately shows a very slow convergence with respect to the basis complexity, which precludes the calculation of accurate quasiparticle energies for large molecules. Here we propose a method to mitigate this issue that relies on two steps: (i) the definition of a reduced virtual orbital subspace, thanks to a much smaller basis set; (ii) the account of the remainder through the simpler one-ring approximation to the self-energy. We assess the quality of the corrected quasiparticle energies for simple molecules, and finally we show an application to large graphene chunks to demonstrate the numerical efficiency of the scheme.

  12. Optical properties of solids within the independent-quasiparticle approximation: Dynamical effects

    NASA Astrophysics Data System (ADS)

    del Sole, R.; Girlanda, Raffaello

    1996-11-01

    The independent-quasiparticle approximation to calculating the optical properties of solids is extended to account for dynamical effects, namely, the energy dependence of the GW self-energy. We use a simple but realistic model of such energy dependence. We find that the inclusion of dynamical effects reduces considerably the calculated absorption spectrum and makes the agreement with experiment worse.

  13. Self-consistent dynamical and thermodynamical evolutions of protoplanetary disks.

    NASA Astrophysics Data System (ADS)

    Baillie, K.; Charnoz, S.; Taillifet, E.; Piau, L.

    2012-09-01

    Astronomical observations reveal the diversity of protoplanetary disk evolutions. In order to understand the global evolution of these disks from their birth, during the collapse of the molecular cloud, to their evaporation because of the stellar radiation, many processes with different timescales must be coupled: stellar evolution, thermodynamical evolution, photoevaporation, cloud collapse, viscous spreading... Simulating all these processes simultaneously is beyond the capacity of modern computers. However, by modeling the results of large scale simulations and coupling them with models of viscous evolution, we have designed a one dimension full model of disk evolution. In order to generate the most realistic protoplanetary disk, we minimize the number of input parameters and try to calculate most of them from self-consistent processes, as early as possible in the history of the disk; starting with the collapse of the molecular cloud that feeds the disk in gas. We start from the Hueso and Guillot, 2005 [2] model of disk evolution and couple the radiative transfer description of Calvet et al, 1991 [1] allowing us to handle a non-isothermal disk which midplane temperature is defined by an irradiation term form the central star and a viscous heating term depending on the optical depth of the disk. Our new model of the disk photosphere profile allows us to estimate self-consistent photosphere heights and midplane temperatures at the same time. We then follow the disk evolution using an upgrade of the viscous spreading equation from Lynden-Bell and Pringle, 1981 [3]. In particular, the molecular cloud collapse adds a time varying term to the temporal variation of the surface mass density of the disk, in the same manner that photo-evaporation introduces a density loss term. The central star itself is modeled using recent stellar evolution code described in Piau et al, 2011 [4]. Using the same temperature model in the vertical direction, we estimate 2D thermal maps of

  14. Unifying Self-Consistent Field Theory for Weak Polyelectrolytes

    NASA Astrophysics Data System (ADS)

    Witte, Kevin; Won, You-Yeon

    2008-03-01

    A self-consistent field (SCF) theory for weak polyelectrolytes has been derived from a grand canonical partition function. The formalism accounts for the location and mixing of the charged and uncharged polymer species, treating the local (spatially dependent) charge fraction as a field variable with which to minimize the total free energy. This method of the derivation gives the resulting equations, especially those governing the local charge fraction, that are identical to the results obtained by Szleifer and coworkers (J. Polym. Sci. B Polym. Phys., 2006) who built upon the mean-field ``annealed'' free energy expression proposed by Raphael and Joanny (Europhys. Lett., 1990). However, we show that these results are further identical to the ``two-state'' model of Borukhov, Andelman and Orland (Eur. Phys. J. B, 1998), namely, the potential field due to the polymer charges with which the chains interact and the local charge fraction are shown to be exactly equal. This annealed model is derived by averaging the partition function with regard to the monomer charges. The charged and uncharged states are weighted by their probabilities which is, in our notation, the bulk charge fraction and one minus the bulk charge fraction, respectively. The utility of this theory is demonstrated by comparing its predictions against various experimental results from bulk potentiometric measurements and also from polyelectrolyte brush compression studies.

  15. First principles molecular dynamics without self-consistent field optimization

    SciTech Connect

    Souvatzis, Petros; Niklasson, Anders M. N.

    2014-01-28

    We present a first principles molecular dynamics approach that is based on time-reversible extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The optimization-free dynamics keeps the computational cost to a minimum and typically provides molecular trajectories that closely follow the exact Born-Oppenheimer potential energy surface. Only one single diagonalization and Hamiltonian (or Fockian) construction are required in each integration time step. The proposed dynamics is derived for a general free-energy potential surface valid at finite electronic temperatures within hybrid density functional theory. Even in the event of irregular functional behavior that may cause a dynamical instability, the optimization-free limit represents a natural starting guess for force calculations that may require a more elaborate iterative electronic ground state optimization. Our optimization-free dynamics thus represents a flexible theoretical framework for a broad and general class of ab initio molecular dynamics simulations.

  16. A new mixed self-consistent field procedure

    NASA Astrophysics Data System (ADS)

    Alvarez-Ibarra, A.; Köster, A. M.

    2015-10-01

    A new approach for the calculation of three-centre electronic repulsion integrals (ERIs) is developed, implemented and benchmarked in the framework of auxiliary density functional theory (ADFT). The so-called mixed self-consistent field (mixed SCF) divides the computationally costly ERIs in two sets: far-field and near-field. Far-field ERIs are calculated using the newly developed double asymptotic expansion as in the direct SCF scheme. Near-field ERIs are calculated only once prior to the SCF procedure and stored in memory, as in the conventional SCF scheme. Hence the name, mixed SCF. The implementation is particularly powerful when used in parallel architectures, since all RAM available are used for near-field ERI storage. In addition, the efficient distribution algorithm performs minimal intercommunication operations between processors, avoiding a potential bottleneck. One-, two- and three-dimensional systems are used for benchmarking, showing substantial time reduction in the ERI calculation for all of them. A Born-Oppenheimer molecular dynamics calculation for the Na+55 cluster is also shown in order to demonstrate the speed-up for small systems achievable with the mixed SCF. Dedicated to Sourav Pal on the occasion of his 60th birthday.

  17. Self-consistent MPI-IO performance requirements and expectations.

    SciTech Connect

    Gropp, W. D.; Kimpe, D.; Ross, R.; Thakur, R.; Traff, J. L.; Mathematics and Computer Science; Univ. of Illinois; Katholieke Univ. Leuven; NEC Laboratories Europe

    2008-01-01

    We recently introduced the idea of self-consistent performance requirements for MPI communication. Such requirements provide a means to ensure consistent behavior of an MPI library, thereby ensuring a degree of performance portability by making it unnecessary for a user to perform implementation-dependent optimizations by hand. For the collective operations in particular, a large number of such rules could sensibly be formulated, without making hidden assumptions about the underlying communication system or otherwise constraining the MPI implementation. In this paper, we extend this idea to the realm of parallel I/O (MPI-IO), where the issues are far more subtle. In particular, it is not always possible to specify performance requirements without making assumptions about the implementation or without a priori knowledge of the I/O access pattern. For such cases, we introduce the notion of performance expectations, which specify the desired behavior for good implementations of MPI-IO. I/O performance requirements as well as expectations could be automatically checked by an appropriate benchmarking tool.

  18. Self-consistent discharge growing model of helicon plasma

    NASA Astrophysics Data System (ADS)

    Isayama, Shogo; Hada, Tohru; Shinohara, Shunjiro; Tanikawa, Takao

    2015-11-01

    Helicon plasma is a high-density and low-temperature plasma generated by the electromagnetic (Helicon) wave excited in the plasma. It is thought to be useful for various applications including electric thrusters. Physics of helicon plasma production involves such fundamental processes as the wave propagation (dispersion relation), collisional and non-collisional wave damping, plasma heating, ionization/recombination of neutral particles, and modification of the dispersion relation by newly ionized plasma. There remain a number of unsolved physical issues such as, how the Helicon and the TG modes influence the plasma density, electron temperature and their spatial profiles. While the Helicon mode is absorbed in the bulk plasma, the TG mode is mostly absorbed near the edge of the plasma. The local power deposition in the helicon plasma is mostly balanced by collisional loss. This local power balance can give rise to the inhomogeneous electron temperature profile that leads to time evolution of density profile and dispersion relation. In our study, we construct a self-consistent model of the discharge evolution that includes the wave excitation, electron heat transfer, and diffusion of charged particles.

  19. Formation of nanocavities in dielectrics: A self-consistent modeling

    SciTech Connect

    Mezel, C.; Hallo, L.; Tikhonchuk, V. T.; Chimier, B.; Schurtz, G.; Travaille, G.; Bourgeade, A.; Hebert, D.; Nkonga, B.

    2008-09-15

    Tight focusing of a subpicosecond laser pulse in transparent dielectrics is an efficient way to release laser energy and to produce plasma. A micro-explosion results in a submicrometer cavity formation if the deposited laser energy exceeds a threshold. A self-consistent model is developed that describes this process. The energy deposition is described by a full set of Maxwell's equations in the three-dimensional geometry and it accounts for nonlinear propagation phenomena in the femtosecond time scale. The calculated energy deposition is transferred to a hydrodynamic code that describes the cavity formation. Numerical simulations show that cavity size in silica depends strongly on the latent heat of sublimation. An equation of state is developed and introduced into the hydrodynamic model that takes into account the influence of such material parameters as the binding energy, the bulk modulus, and the Grueneisen coefficient. The cavity and shock-affected region sizes are compared to experimental data. This comparison suggests that laser micro-explosions might allow to tune the parameters of equations of state in the domain of phase transitions in a cold dense matter.

  20. Self-consistent electrothermal analysis of nanotube network transistors

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Pimparkar, N.; Murthy, J. Y.; Alam, M. A.

    2011-01-01

    We develop an electrothermal transport model for nanocomposite thin films based on self-consistent solution of drift-diffusion and Poisson equations for electrons coupled with diffusive transport of heat. This model is used to analyze the performance of an electronic display the pixels of which are controlled by carbon nanotube (CNT) network thin-film transistors (TFTs). The effect of electrothermal coupling on device performance and steady state temperature rise is analyzed as a function of key device parameters such as channel length, network density, tube-to-substrate thermal conductance, and tube-to-substrate thermal conductivity ratio. Our analysis suggests that device on-current Ion may reduce by 30% for a 1 μm channel length devices due to self-heating. The temperature rise in such devices can be as high as 500 K in extreme cases due to the thermally insulating substrate and the low tube-to-substrate thermal conductance. These results suggest that an appropriate combination of network density, channel length and width should be selected for CNT-TFTs to avoid device temperature rise above acceptable limits. We analyze the effectiveness of active cooling in reducing the temperature and enhancing the performance of the device. We find that the high thermal spreading resistance between the CNT device and the electronic display reduces the effectiveness of forced convective cooling, necessitating the exploration of alternative designs for viable CNT-FET based display technology.

  1. Self-Consistent and Time-Dependent Solar Wind Models

    NASA Technical Reports Server (NTRS)

    Ong, K. K.; Musielak, Z. E.; Rosner, R.; Suess, S. T.; Sulkanen, M. E.

    1997-01-01

    We describe the first results from a self-consistent study of Alfven waves for the time-dependent, single-fluid magnetohydrodynamic (MHD) solar wind equations, using a modified version of the ZEUS MHD code. The wind models we examine are radially symmetrical and magnetized; the initial outflow is described by the standard Parker wind solution. Our study focuses on the effects of Alfven waves on the outflow and is based on solving the full set of the ideal nonlinear MHD equations. In contrast to previous studies, no assumptions regarding wave linearity, wave damping, and wave-flow interaction are made; thus, the models naturally account for the back-reaction of the wind on the waves, as well as for the nonlinear interaction between different types of MHD waves. Our results clearly demonstrate when momentum deposition by Alfven waves in the solar wind can be sufficient to explain the origin of fast streams in solar coronal holes; we discuss the range of wave amplitudes required to obtained such fast stream solutions.

  2. The self consistent expansion applied to the factorial function

    NASA Astrophysics Data System (ADS)

    Cohen, Alon; Bialy, Shmuel; Schwartz, Moshe

    2016-12-01

    Most of the interesting systems in statistical physics can be described as nonlinear stochastic field theories. A common feature in the theoretical study of such systems is that ordinary perturbation theory seldom works. On the other hand, there exists a useful tool for the study of systems of that generic nature. That tool, the Self Consistent Expansion (SCE) is technically similar to the ordinary perturbation expansion, in the sense that it is an expansion around a solvable problem. The key point which distinguishes the SCE from an ordinary perturbation expansion, is that the small parameter of the expansion is adjustable and determined inherently by optimization of the expansion. Therefore, it allows the adaptive SCE to remain accurate relative to the inflexible ordinary expansion. The goal of the present paper is to present the SCE by applying it to a well-known zero dimensional problem. We choose the evaluation of the factorial function, x!, as the test case for the SCE, because the Stirling approximation for that function is one of the best known asymptotic expansions, with a very wide use in statistical physics. We show that the SCE approximation holds for small and even negative arguments of the factorial function, where the Stirling expansion fails miserably. It does so without paying any penalty at high values of the argument, where the Stirling formula is excellent. We present numerical as well as analytic SCE approximations of the factorial function.

  3. Global Completability with Applications to Self-Consistent Quantum Tomography

    NASA Astrophysics Data System (ADS)

    Stark, Cyril Jakob

    2016-11-01

    Let {{p}1,ldots, {p}N in R^D} be unknown vectors and let {Ω subseteq {1,ldots,N}2}. Assume that the inner products {{p}i^T {p}j} are fixed for all {(i,j) in Ω}. Do these inner product constraints (up to simultaneous rotation of all vectors) determine {{p}1, ldots, {p}N} uniquely? Here we derive a necessary and sufficient condition for the uniqueness of {{p}1, ldots,{p}N} (i.e., global completability) which is applicable to a large class of practically relevant sets {Ω}. Moreover, given {Ω}, we show that the condition for global completability is universal in the sense that for almost all vectors {{p}1, ldots,{p}N in RD} the completability of {{p}1, ldots,{p}N} only depends on {Ω} and not on the specific values of {{p}i^T {p}j} for {(i,j) in Ω}. This work was motivated by practical considerations, namely, matrix factorization techniques and self-consistent quantum tomography.

  4. First principles molecular dynamics without self-consistent field optimization.

    PubMed

    Souvatzis, Petros; Niklasson, Anders M N

    2014-01-28

    We present a first principles molecular dynamics approach that is based on time-reversible extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The optimization-free dynamics keeps the computational cost to a minimum and typically provides molecular trajectories that closely follow the exact Born-Oppenheimer potential energy surface. Only one single diagonalization and Hamiltonian (or Fockian) construction are required in each integration time step. The proposed dynamics is derived for a general free-energy potential surface valid at finite electronic temperatures within hybrid density functional theory. Even in the event of irregular functional behavior that may cause a dynamical instability, the optimization-free limit represents a natural starting guess for force calculations that may require a more elaborate iterative electronic ground state optimization. Our optimization-free dynamics thus represents a flexible theoretical framework for a broad and general class of ab initio molecular dynamics simulations.

  5. Self-consistent calculations of transport and magnetization dynamics

    NASA Astrophysics Data System (ADS)

    Lee, Kyung-Jin

    2010-03-01

    In layered structures like spin-valves where the current flows perpendicular to the plane, the direction and magnitude of the spin transfer torque (STT) at a point r is decided by the spin accumulation (SA) and associated spin current at the same point r. Initial STT theories commonly assumed that the dependence of SA on magnetization (M) is local and thus essentially fixed by the local M at the same point r. However, its dependence on M is inherently nonlocal because of the 3-dimensional spin diffusion [1]. In other words, when the conduction electron arrives at a point r on the ferromagnet-normal metal interface, the reflected (transmitted) electron takes the spin direction anti-parallel (parallel) to the local M at the point r, diffuses along the interface, and then transfers its spin-angular momentum to another local M at a far away point from the r. That is, SA at a point r is affected by all local M's at other points. The local assumption becomes really invalid when M is inhomogeneous. Note that micromagnetic and time-resolved imaging studies [2] have revealed excitations of incoherent spin-waves and thus inhomogeneous M due to STT. In this situation, the effect of SA on M (=STT) and the nonlocal effect of M on the SA should be treated on an equal footing. The conventional treatments, which ignore the latter part, actually deal with only half of the relevant parts. Therefore, the self-consistent feedback between inhomogenous M and STT through the nonlocal effect should be considered. In this talk, we present self-consistent calculation results that consider the feedback, which allows us to understand peculiar spin-wave modes in a single ferromagnet and a spin-valve. If time is allowed, we extend our talk to other feedback mechanisms which result in the oscillatory STT due to ballistic spin transport [3] and the damping tensor due to the spin-motive force [4] in a very narrow magnetic domain wall. These works have been done in collaboration with Hyun-Woo Lee

  6. Self-consistent formation of continents on early Earth

    NASA Astrophysics Data System (ADS)

    Noack, Lena; Van Hoolst, Tim; Breuer, Doris; Dehant, Véronique

    2013-04-01

    In our study we want to understand how Earth evolved with time and examine the initiation of plate tectonics and the possible formation of continents on Earth. Plate tectonics and continents seem to influence the likelihood of a planet to harbour life [1], and both are strongly influenced by the planetary interior (e.g. mantle temperature and rheology) and surface conditions (e.g. stabilizing effect of continents, atmospheric temperature), and may also depend on the biosphere. Earth is the only terrestrial planet (i.e. with a rocky mantle and iron core) in the solar system where long-term plate tectonics evolved. Knowing the factors that have a strong influence on the occurrence of plate tectonics allows for prognoses about plate tectonics on terrestrial exoplanets that have been detected in the past decade, and about the likelihood of these planets to harbour Earth-like life. For this purpose, planetary interior and surface processes are coupled via 'particles' as computational tracers in the 3D code GAIA [2,3]. These particles are dispersed in the mantle and crust of the modelled planet and can track the relevant rock properties (e.g. density or water content) over time. During the thermal evolution of the planet, the particles are advected due to mantle convection and along melt paths towards the surface and help to gain information about the thermo-chemical system. This way basaltic crust that is subducted into the silicate mantle is traced in our model. It is treated differently than mantle silicates when re-molten, such that granitic (felsic) crust is produced (similar to the evolution of continental crust on early Earth [4]), which is stored in the particle properties. We apply a pseudo-plastic rheology and use small friction coefficients (since an increased reference viscosity is used in our model). We obtain initiation of plate tectonics and self-consistent formation of pre-continents after a few Myr up to several Gyr - depending on the initial conditions

  7. A self-consistent dynamo model for fully convective stars

    NASA Astrophysics Data System (ADS)

    Yadav, Rakesh Kumar; Christensen, Ulrich; Morin, Julien; Gastine, Thomas; Reiners, Ansgar; Poppenhaeger, Katja; Wolk, Scott J.

    2016-01-01

    The tachocline region inside the Sun, where the rigidly rotating radiative core meets the differentially rotating convection zone, is thought to be crucial for generating the Sun's magnetic field. Low-mass fully convective stars do not possess a tachocline and were originally expected to generate only weak small-scale magnetic fields. Observations, however, have painted a different picture of magnetism in rapidly-rotating fully convective stars: (1) Zeeman broadening measurements revealed average surface field of several kiloGauss (kG), which is similar to the typical field strength found in sunspots. (2) Zeeman-Doppler-Imaging (ZDI) technique discovered large-scale magnetic fields with a morphology often similar to the Earth's dipole-dominated field. (3) Comparison of Zeeman broadening and ZDI results showed that more than 80% of the magnetic flux resides at small scales. So far, theoretical and computer simulation efforts have not been able to reproduce these features simultaneously. Here we present a self-consistent global model of magnetic field generation in low-mass fully convective stars. A distributed dynamo working in the model spontaneously produces a dipole-dominated surface magnetic field of the observed strength. The interaction of this field with the turbulent convection in outer layers shreds it, producing small-scale fields that carry most of the magnetic flux. The ZDI technique applied to synthetic spectropolarimetric data based on our model recovers most of the large-scale field. Our model simultaneously reproduces the morphology and magnitude of the large-scale field as well as the magnitude of the small-scale field observed on low-mass fully convective stars.

  8. Self-consistent Growth of Decimeter Bodies in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Teiser, Jens; Wurm, G.

    2009-09-01

    The models currently discussed for the formation of km-size planetesimals assume that in one intermediate step decimeter bodies grow in mutual collisions between different sized smaller dust aggregates. Typical collision velocities expected are up to 10 m/s. We show here that such growth indeed readily occurs. In laboratory experiment we studied the self-consistent formation of mm- to decimeter-size bodies by accreting small 100 µm particles at collision velocities of about 7.7 m/s. Growth occurs due to direct sticking and reaccretion of fragments by gas drag. The reaccretion of impact ejecta by gas drag is well accounted for by gravity in the laboratory experiments. Most earlier experiments studied collisions as single events. Here, we study the net outcome of literally millions of collisions. Growth for impact angles of up to 70° occurs. Aggregates grown have a unique volume filling of 31% close to the maximum compaction feasible by applying local pressure on the aggregate surface (33%). This value is independent of the ratio between particles directly sticking or slowly reaccreted indicating that the growth history of an evolving decimeter body is erased by succeeding compacting impacts. We conclude that for coagulation/fragmentation models only one volume filling of 31% (or 69% porosity) has to be considered for larger bodies. In detail the accretion efficiencies will depend on the disk model (gas pressure, relative velocities) as this determines the number of particles reaccreted by gas drag. Due to the direct sticking fraction growth is possible in the whole disk but due to the gas aided reaccretion it is most efficient in the inner terrestrial planet forming region. This work was funded by the DFG FOR 759.

  9. Self-consistent Modeling of Reionization in Cosmological Hydrodynamical Simulations

    NASA Astrophysics Data System (ADS)

    Oñorbe, Jose; Hennawi, Joseph F.; Lukić, Zarija

    2017-03-01

    The ultraviolet background (UVB) emitted by quasars and galaxies governs the ionization and thermal state of the intergalactic medium (IGM), regulates the formation of high-redshift galaxies, and is thus a key quantity for modeling cosmic reionization. The vast majority of cosmological hydrodynamical simulations implement the UVB via a set of spatially uniform photoionization and photoheating rates derived from UVB synthesis models. We show that simulations using canonical UVB rates reionize and, perhaps more importantly, spuriously heat the IGM, much earlier (z∼ 15) than they should. This problem arises because at z> 6, where observational constraints are nonexistent, the UVB amplitude is far too high. We introduce a new methodology to remedy this issue, and we generate self-consistent photoionization and photoheating rates to model any chosen reionization history. Following this approach, we run a suite of hydrodynamical simulations of different reionization scenarios and explore the impact of the timing of reionization and its concomitant heat injection on the thermal state of the IGM. We present a comprehensive study of the pressure smoothing scale of IGM gas, illustrating its dependence on the details of both hydrogen and helium reionization, and argue that it plays a fundamental role in interpreting Lyα forest statistics and the thermal evolution of the IGM. The premature IGM heating we have uncovered implies that previous work has likely dramatically overestimated the impact of photoionization feedback on galaxy formation, which sets the minimum halo mass able to form stars at high redshifts. We make our new UVB photoionization and photoheating rates publicly available for use in future simulations.

  10. Self-consistent theory for systems with mesoscopic fluctuations

    NASA Astrophysics Data System (ADS)

    Ciach, A.; Góźdź, W. T.

    2016-10-01

    We have developed a theory for inhomogeneous systems that allows for the incorporation of the effects of mesoscopic fluctuations. A hierarchy of equations relating the correlation and direct correlation functions for the local excess φ ≤ft(\\mathbf{r}\\right) of the volume fraction of particles ζ has been obtained, and an approximation leading to a closed set of equations for the two-point functions has been introduced for the disordered inhomogeneous phase. We have numerically solved the self-consistent equations for one-dimensional (1D) and three-dimensional (3D) models with short-range attraction and long-range repulsion. Predictions for all of the qualitative properties of the 1D model agree with the exact results, but only semi-quantitative agreement is obtained in the simplest version of the theory. The effects of fluctuations in the two 3D models considered are significantly different, despite the very similar properties of these models in the mean-field approximation. In both cases we obtain the sequence of large-small-large compressibility for increasing ζ. The very small compressibility is accompanied by the oscillatory decay of correlations with correlation lengths that are orders of magnitude larger than the size of particles. In one of the two models considered, the small compressibility becomes very small and the large compressibility becomes very large with decreasing temperature, and eventually van der Waals loops appear. Further studies are necessary in order to determine the nature of the strongly inhomogeneous phase present for intermediate volume fractions in 3D.

  11. Self-consistent Modeling of Elastic Anisotropy in Shale

    NASA Astrophysics Data System (ADS)

    Kanitpanyacharoen, W.; Wenk, H.; Matthies, S.; Vasin, R.

    2012-12-01

    Elastic anisotropy in clay-rich sedimentary rocks has increasingly received attention because of significance for prospecting of petroleum deposits, as well as seals in the context of nuclear waste and CO2 sequestration. The orientation of component minerals and pores/fractures is a critical factor that influences elastic anisotropy. In this study, we investigate lattice and shape preferred orientation (LPO and SPO) of three shales from the North Sea in UK, the Qusaiba Formation in Saudi Arabia, and the Officer Basin in Australia (referred to as N1, Qu3, and L1905, respectively) to calculate elastic properties and compare them with experimental results. Synchrotron hard X-ray diffraction and microtomography experiments were performed to quantify LPO, weight proportions, and three-dimensional SPO of constituent minerals and pores. Our preliminary results show that the degree of LPO and total amount of clays are highest in Qu3 (3.3-6.5 m.r.d and 74vol%), moderately high in N1 (2.4-5.6 m.r.d. and 70vol%), and lowest in L1905 (2.3-2.5 m.r.d. and 42vol%). In addition, porosity in Qu3 is as low as 2% while it is up to 6% in L1605 and 8% in N1, respectively. Based on this information and single crystal elastic properties of mineral components, we apply a self-consistent averaging method to calculate macroscopic elastic properties and corresponding seismic velocities for different shales. The elastic model is then compared with measured acoustic velocities on the same samples. The P-wave velocities measured from Qu3 (4.1-5.3 km/s, 26.3%Ani.) are faster than those obtained from L1905 (3.9-4.7 km/s, 18.6%Ani.) and N1 (3.6-4.3 km/s, 17.7%Ani.). By making adjustments for pore structure (aspect ratio) and single crystal elastic properties of clay minerals, a good agreement between our calculation and the ultrasonic measurement is obtained.

  12. Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules: A Benchmark of GW Methods

    NASA Astrophysics Data System (ADS)

    Marom, Noa; Knight, Joseph; Wang, Xiaopeng; Gallandi, Lukas; Dolgounitcheva, Olga; Ren, Xinguo; Ortiz, Vincent; Rinke, Patrick; Korzdorfer, Thomas

    The performance of different GW methods is assessed for a set of 24 organic acceptors. Errors are evaluated with respect to coupled cluster singles, doubles, perturbative triples [CCSD(T)] reference data for the vertical ionization potentials (IPs) and electron affinities (EAs), extrapolated to the complete basis set limit. Additional comparisons are made to experimental data, where available. We consider fully self-consistent GW (scGW), partial self-consistency in the Green's function (scGW0) , non-self-consistent G0W0 based on several mean-field starting points, and a ``beyond GW'' second order screened exchange (SOSEX) correction to G0W0. The best performers overall are G0W0 + SOSEX and G0W0 based on an IP-tuned long range corrected hybrid functional with the former being more accurate for EAs and the latter for IPs. Both provide a balanced treatment of localized vs. delocalized states and valence spectra in good agreement with photoemission spectroscopy (PES) experiments.

  13. Anomalous quasiparticle lifetime in graphite: band structure effects.

    PubMed

    Spataru, C D; Cazalilla, M A; Rubio, A; Benedict, L X; Echenique, P M; Louie, S G

    2001-12-10

    We report ab initio calculations of quasiparticle lifetimes in graphite, as determined from the imaginary part of the self-energy operator within the GW approximation. The inverse lifetime in the energy range from 0.5 to 3.5 eV above the Fermi level presents significant deviations from the quadratic behavior naively expected from Fermi liquid theory. The deviations are explained in terms of the unique features of the band structure of this material. We also discuss the experimental results from different groups and make some predictions for future experiments.

  14. Finite amplitude method for the quasiparticle random-phase approximation

    SciTech Connect

    Avogadro, Paolo; Nakatsukasa, Takashi

    2011-07-15

    We present the finite amplitude method (FAM), originally proposed in Ref. [17], for superfluid systems. A Hartree-Fock-Bogoliubov code may be transformed into a code of the quasiparticle-random-phase approximation (QRPA) with simple modifications. This technique has advantages over the conventional QRPA calculations, such as coding feasibility and computational cost. We perform the fully self-consistent linear-response calculation for the spherical neutron-rich nucleus {sup 174}Sn, modifying the hfbrad code, to demonstrate the accuracy, feasibility, and usefulness of the FAM.

  15. Quasiparticle dynamics in graphene

    NASA Astrophysics Data System (ADS)

    Bostwick, Aaron; Ohta, Taisuke; Seyller, Thomas; Horn, Karsten; Rotenberg, Eli

    2007-01-01

    The effectively massless, relativistic behaviour of graphene's charge carriers-known as Dirac fermions-is a result of its unique electronic structure, characterized by conical valence and conduction bands that meet at a single point in momentum space (at the Dirac crossing energy). The study of many-body interactions amongst the charge carriers in graphene and related systems such as carbon nanotubes, fullerenes and graphite is of interest owing to their contribution to superconductivity and other exotic ground states in these systems. Here we show, using angle-resolved photoemission spectroscopy, that electron-plasmon coupling plays an unusually strong role in renormalizing the bands around the Dirac crossing energy-analogous to mass renormalization by electron-boson coupling in ordinary metals. Our results show that electron-electron, electron-plasmon and electron-phonon coupling must be considered on an equal footing in attempts to understand the dynamics of quasiparticles in graphene and related systems.

  16. Excitation spectra of aromatic molecules within a real-space G W -BSE formalism: Role of self-consistency and vertex corrections

    NASA Astrophysics Data System (ADS)

    Hung, Linda; da Jornada, Felipe H.; Souto-Casares, Jaime; Chelikowsky, James R.; Louie, Steven G.; Ã-ǧüt, Serdar

    2016-08-01

    We present first-principles calculations on the vertical ionization potentials (IPs), electron affinities (EAs), and singlet excitation energies on an aromatic-molecule test set (benzene, thiophene, 1,2,5-thiadiazole, naphthalene, benzothiazole, and tetrathiafulvalene) within the G W and Bethe-Salpeter equation (BSE) formalisms. Our computational framework, which employs a real-space basis for ground-state and a transition-space basis for excited-state calculations, is well suited for high-accuracy calculations on molecules, as we show by comparing against G0W0 calculations within a plane-wave-basis formalism. We then generalize our framework to test variants of the G W approximation that include a local density approximation (LDA)-derived vertex function (ΓLDA) and quasiparticle-self-consistent (QS) iterations. We find that ΓLDA and quasiparticle self-consistency shift IPs and EAs by roughly the same magnitude, but with opposite sign for IPs and the same sign for EAs. G0W0 and QS G W ΓLDA are more accurate for IPs, while G0W0ΓLDA and QS G W are best for EAs. For optical excitations, we find that perturbative G W -BSE underestimates the singlet excitation energy, while self-consistent G W -BSE results in good agreement with previous best-estimate values for both valence and Rydberg excitations. Finally, our work suggests that a hybrid approach, in which G0W0 energies are used for occupied orbitals and G0W0ΓLDA for unoccupied orbitals, also yields optical excitation energies in good agreement with experiment but at a smaller computational cost.

  17. Self-consistent Pauli corrections in Brueckner-Hartree-Fock calculations

    NASA Technical Reports Server (NTRS)

    Braley, R. C.; Ford, W. F.

    1972-01-01

    A scheme is introduced which makes it feasible to make completely self-consistent Brueckner-Hartree-Fock (BHF) and renormalized BHF calculations for spherical, closed-shell and axially-symmetric deformed nuclei. The usual requirement or orbital self-consistency has been imposed, as well as self-consistency in the starting energies and occupation probabilities. Previously, only approximate forms were used for the Pauli operator. This approximation is removed and a method for making the necessary Pauli corrections to the reaction matrix during the approach to self-consistency is presented. A discussion of the symmetries which reduce the problem to one of manageable proportions is included.

  18. GW-BSE approach on S1 vertical transition energy of large charge transfer compounds: A performance assessment.

    PubMed

    Ziaei, Vafa; Bredow, Thomas

    2016-11-07

    In this work, we apply many-body perturbation theory (MBPT) on large critical charge transfer (CT) complexes to assess its performance on the S1 excitation energy. Since the S1 energy of CT compounds is heavily dependent on the Hartree-Fock (HF) exchange fraction in the reference density functional, MBPT opens a new way for reliable prediction of CT S1 energy without explicit knowledge of suitable amount of HF-exchange, in contrary to the time-dependent density functional theory (TD-DFT), where depending on various functionals, large errors can arise. Thus, simply by starting from a (semi-)local reference functional and performing update of Kohn-Sham (KS) energies in the Green's function G while keeping dynamical screened interaction (W(ω)) frozen to the mean-field level, we obtain impressingly highly accurate S1 energy at slightly higher computational cost in comparison to TD-DFT. However, this energy-only updating mechanism in G fails to work if the initial guess contains a fraction or 100% HF-exchange, and hence considerably inaccurate S1 energy is predicted. Furthermore, eigenvalue updating both in G and W(ω) overshoots the S1 energy due to enhanced underscreening of W(ω), independent of the (hybrid-)DFT starting orbitals. A full energy-update on top of HF orbitals even further overestimates the S1 energy. An additional update of KS wave functions within the Quasi-Particle Self-Consistent GW (QSGW) deteriorates results, in stark contrast to the good results obtained from QSGW for periodic systems. For the sake of transferability, we further present data of small critical non-charge transfer systems, confirming the outcomes of the CT-systems.

  19. GW-BSE approach on S1 vertical transition energy of large charge transfer compounds: A performance assessment

    NASA Astrophysics Data System (ADS)

    Ziaei, Vafa; Bredow, Thomas

    2016-11-01

    In this work, we apply many-body perturbation theory (MBPT) on large critical charge transfer (CT) complexes to assess its performance on the S1 excitation energy. Since the S1 energy of CT compounds is heavily dependent on the Hartree-Fock (HF) exchange fraction in the reference density functional, MBPT opens a new way for reliable prediction of CT S1 energy without explicit knowledge of suitable amount of HF-exchange, in contrary to the time-dependent density functional theory (TD-DFT), where depending on various functionals, large errors can arise. Thus, simply by starting from a (semi-)local reference functional and performing update of Kohn-Sham (KS) energies in the Green's function G while keeping dynamical screened interaction (W(ω)) frozen to the mean-field level, we obtain impressingly highly accurate S1 energy at slightly higher computational cost in comparison to TD-DFT. However, this energy-only updating mechanism in G fails to work if the initial guess contains a fraction or 100% HF-exchange, and hence considerably inaccurate S1 energy is predicted. Furthermore, eigenvalue updating both in G and W(ω) overshoots the S1 energy due to enhanced underscreening of W(ω), independent of the (hybrid-)DFT starting orbitals. A full energy-update on top of HF orbitals even further overestimates the S1 energy. An additional update of KS wave functions within the Quasi-Particle Self-Consistent GW (QSGW) deteriorates results, in stark contrast to the good results obtained from QSGW for periodic systems. For the sake of transferability, we further present data of small critical non-charge transfer systems, confirming the outcomes of the CT-systems.

  20. 0{nu}{beta}{beta}-decay nuclear matrix elements with self-consistent short-range correlations

    SciTech Connect

    Simkovic, Fedor; Faessler, Amand; Muether, Herbert; Rodin, Vadim; Stauf, Markus

    2009-05-15

    A self-consistent calculation of nuclear matrix elements of the neutrinoless double-beta decays (0{nu}{beta}{beta}) of {sup 76}Ge, {sup 82}Se, {sup 96}Zr, {sup 100}Mo, {sup 116}Cd, {sup 128}Te, {sup 130}Te, and {sup 136}Xe is presented in the framework of the renormalized quasiparticle random phase approximation (RQRPA) and the standard QRPA. The pairing and residual interactions as well as the two-nucleon short-range correlations are for the first time derived from the same modern realistic nucleon-nucleon potentials, namely, from the charge-dependent Bonn potential (CD-Bonn) and the Argonne V18 potential. In a comparison with the traditional approach of using the Miller-Spencer Jastrow correlations, matrix elements for the 0{nu}{beta}{beta} decay are obtained that are larger in magnitude. We analyze the differences among various two-nucleon correlations including those of the unitary correlation operator method (UCOM) and quantify the uncertainties in the calculated 0{nu}{beta}{beta}-decay matrix elements.

  1. Quasi-particles and effective mean field in strongly interacting matter

    NASA Astrophysics Data System (ADS)

    Lévai, P.; Ko, C. M.

    2010-03-01

    We introduce a quasi-particle model of strongly interacting quark-gluon matter and explore the possible connection to an effective field theoretical description consisting of a scalar σ field by introducing a dynamically generated mass, M(σ), and a self-consistently determined interaction term, B(σ). We display a possible connection between the two types of effective description, using the Friedberg-Lee model.

  2. Probing Extreme Gravity with GW150914 and GW151226

    NASA Astrophysics Data System (ADS)

    Yagi, Kent; Yunes, Nicolas; Pretorius, Frans

    2017-01-01

    Advanced LIGO's recent discovery of the direct detection of gravitational waves from binary black hole coalescences allow us to probe gravity, for the first time, in extreme gravity regime where the field is both strong and dynamical. In this talk, I will describe how well GW150914 and GW151226 probe fundamental pillars of General Relativity, such as the equivalence principle, Lorentz invariance and massless graviton. I will then compare such new bounds to the existing bounds from Solar System experiments and binary pulsar observations. I will finally explain current limitations of probing extreme gravity with gravitational wave observations and discuss what needs to be done in future.

  3. Quasiparticle band structures and optical properties of magnesium fluoride.

    PubMed

    Yi, Zhijun; Jia, Ran

    2012-02-29

    The quasiparticle and optical properties of magnesium fluoride (MgF(2)) are computed within the GW approximation based on many-body perturbation theory (MBPT). The many-body effects appearing in self-energy and electron-hole interactions have an important influence on the electronic and optical properties. The DFT-LDA calculation shows a 6.78 eV band gap. Two methods are employed to evaluate the self-energy within the GW approximation in the present work. The generalized plasmon pole model (GPP) provides a band gap of 12.17 eV, which agrees well with the experimental value of 12.4 eV (Thomas et al 1973 Phys. Status Solidi b 56 163). Another band gap value of 11.30 eV is obtained by using a full frequency-dependent self-energy, which is also not far from the experimental value and is much better than the result from the LDA calculation. The calculated optical spectrum within DFT is significantly different from the experiment. Although the calculated optical absorption threshold within the GW method is close to the experiment, the overall shape of the spectrum is still similar to the case of DFT. However, the overall shape of the spectrum via the Bethe-Salpeter equation (BSE) method agrees well with the experiment.

  4. Microscopic model of quasiparticle wave packets in superfluids, superconductors, and paired Hall states.

    PubMed

    Parameswaran, S A; Kivelson, S A; Shankar, R; Sondhi, S L; Spivak, B Z

    2012-12-07

    We study the structure of Bogoliubov quasiparticles, bogolons, the fermionic excitations of paired superfluids that arise from fermion (BCS) pairing, including neutral superfluids, superconductors, and paired quantum Hall states. The naive construction of a stationary quasiparticle in which the deformation of the pair field is neglected leads to a contradiction: it carries a net electrical current even though it does not move. However, treating the pair field self-consistently resolves this problem: in a neutral superfluid, a dipolar current pattern is associated with the quasiparticle for which the total current vanishes. When Maxwell electrodynamics is included, as appropriate to a superconductor, this pattern is confined over a penetration depth. For paired quantum Hall states of composite fermions, the Maxwell term is replaced by a Chern-Simons term, which leads to a dipolar charge distribution and consequently to a dipolar current pattern.

  5. Ab initio quasiparticle bandstructure of ABA and ABC-stacked graphene trilayers

    NASA Astrophysics Data System (ADS)

    Menezes, Marcos; Capaz, Rodrigo; Louie, Steven

    2013-03-01

    We obtain the quasiparticle band structure of ABA and ABC-stacked graphene trilayers through ab initio density functional theory (DFT) and many-body quasiparticle calculations within the GW approximation. To interpret our results, we fit the DFT and GW π bands to a low energy tight-binding model, which is found to reproduce very well the observed features near the K point. The values of the extracted hopping parameters are reported and compared with available theoretical and experimental data. For both stackings, the quasiparticle corrections lead to a renormalization of the Fermi velocity, an effect also observed in previous calculations on monolayer graphene. They also increase the separation between the higher energy bands, which is proportional to the nearest neighbor interlayer hopping parameter γ1. Both features are brought to closer agreement with experiment through the quasiparticle corrections. Finally, other effects, such as trigonal warping, electron-hole assymetry and energy gaps are discussed in terms of the associated parameters. This work was supported by the Brazilian funding agencies: CAPES, CNPq, FAPERJ and INCT-Nanomateriais de Carbono. It was also supported by NSF grant No. DMR10-1006184 and U.S. DOE under Contract No. DE-AC02-05CH11231.

  6. The Progenitor of GW150914

    NASA Astrophysics Data System (ADS)

    Woosley, S. E.

    2016-06-01

    The spectacular detection of gravitational waves (GWs) from GW150914 and its reported association with a gamma-ray burst (GRB) offer new insights into the evolution of massive stars. Here, it is shown that no single star of any mass and credible metallicity is likely to produce the observed GW signal. Stars with helium cores in the mass range 35-133 M ⊙ encounter the pair instability and either explode or pulse until the core mass is less than 45 M ⊙, smaller than the combined mass of the observed black holes. The rotation of more massive helium cores is either braked by interaction with a slowly rotating hydrogen envelope, if one is present, or by mass loss, if one is not. The very short interval between the GW signal and the observed onset of the putative GRB in GW150914 is also too short to have come from a single star. A more probable model for making the gravitational radiation is the delayed merger of two black holes made by 70 and 90 M ⊙ stars in a binary system. The more massive component was a pulsational-pair instability supernova before making the first black hole.

  7. Importance of semicore states in GW calculations for simulating accurately the photoemission spectra of metal phthalocyanine molecules

    NASA Astrophysics Data System (ADS)

    Umari, P.; Fabris, S.

    2012-05-01

    The quasi-particle energy levels of the Zn-Phthalocyanine (ZnPc) molecule calculated with the GW approximation are shown to depend sensitively on the explicit description of the metal-center semicore states. We find that the calculated GW energy levels are in good agreement with the measured experimental photoemission spectra only when explicitly including the Zn 3s and 3p semicore states in the valence. The main origin of this effect is traced back to the exchange term in the self-energy GW approximation. Based on this finding, we propose a simplified approach for correcting GW calculations of metal phthalocyanine molecules that avoids the time-consuming explicit treatment of the metal semicore states. Our method allows for speeding up the calculations without compromising the accuracy of the computed spectra.

  8. Self-consistent Bogoliubov-de Gennes theory of the vortex lattice state in a two-dimensional strongly type-II superconductor at high magnetic fields

    NASA Astrophysics Data System (ADS)

    Zhuravlev, Vladimir; Duan, Wenye; Maniv, Tsofar

    2017-01-01

    A self-consistent Bogoliubov-de Gennes theory of the vortex lattice state in a 2D strong type-II superconductor at high magnetic fields reveals a novel quantum mixed state around the semiclassical Hc 2, characterized by a well-defined Landau-Bloch band structure in the quasiparticle spectrum and suppressed order-parameter amplitude, which sharply crossover into the well-known semiclassical (Helfand-Werthamer) results upon decreasing magnetic field. Application to the 2D superconducting state observed recently on the surface of the topological insulator Sb2Te3 accounts well for the experimental data, revealing a strong type-II superconductor, with unusually low carrier density and very small cyclotron mass, which can be realized only in the strong coupling superconductor limit.

  9. Formation and stability of self-consistent double layer structures in plasma

    SciTech Connect

    Sanduloviciu, M.

    1995-12-31

    The presence of critical values in the current versus voltage characteristic of an electrode immersed in a plasma is used as an argument for the existence of self-consistent (autoorganized) double layers in collisional and collisionless presumed plasmas.

  10. Self-consistent one-gluon exchange in soliton bag models

    NASA Astrophysics Data System (ADS)

    Dodd, L. R.; Williams, A. G.

    1988-08-01

    The treatment of soliton bag models as two-point boundary value problems is extended to include self-consistent one-gluon exchange interactions. The colour-magnetic contribution to the nucleon-delta mass splitting is calculated self-consistently in the mean-field, one-gluon-exchange approximation for the Friedberg-Lee and Nielsen-Patkos models. Small glueball mass parameters (mGB~500 MeV) are favoured. Comparisons with previous calculations are made.

  11. Nonadiabatic semiclassical scattering: Atom-diatom collisions in self-consistent matrix propagator formalism

    NASA Astrophysics Data System (ADS)

    Herman, Michael F.; Freed, Karl F.

    1983-05-01

    The self-consistent matrix propagator method of Laing and Freed is extended to treat semiclassical nonadiabatic scattering in the collinear atom-diatom system. Applications are made to a model system in which diabatic surfaces are parallel, so the nonadiabatic transitions are not well localized in space, thereby introducing difficulties in some previous nonadiabatic semiclassical methods. In the self-consistent matrix propagator method nonadiabatic transitions occur at the boundaries of Magnus regions, and the relative phases, associated with trajectories undergoing transitions at different boundaries, must accurately be determined. This necessitates the determination of the absolute phases of the uniformized classical S matrix, a phase which is unnecessary in single potential surface semiclassical scattering. Semiclassical calculations are compared with full close coupled quantum calculations of Schmalz. The agreement is very good even at relatively low energies. The largest errors enter, as anticipated, for highly classically forbidden transitions whose overall probabilities are, however, rather small. The self-consistent matrix propagator method becomes simpler to apply and more accurate as the total energy increases, i.e., as the fully quantum calculations become prohibitively large. The method has the physical appeal that the self-consistent trajectories follow essentially adiabatic surfaces in strongly interacting regions and diabatic surfaces in weakly interacting regions, with a self-consistent interpolation between these regions.

  12. Continuous surface switching: An improved time-dependent self-consistent-field method for nonadiabatic dynamics

    NASA Astrophysics Data System (ADS)

    Volobuev, Yuri L.; Hack, Michael D.; Topaler, Maria S.; Truhlar, Donald G.

    2000-06-01

    We present a new semiclassical method for electronically nonadiabatic collisions. The method is a variant of the time-dependent self-consistent-field method and is called continuous surface switching. The algorithm involves a self-consistent potential trajectory surface switching approach that is designed to combine the advantages of the trajectory surface hopping approach and the Ehrenfest classical path self-consistent potential approach without their relative disadvantages. Viewed from the self-consistent perspective, it corresponds to "on-the-fly histogramming" of the Ehrenfest method by a natural decay of mixing; viewed from the surface hopping perspective, it corresponds to replacing discontinuous surface hops by continuous surface switching. In this article we present the method and illustrate it for three multidimensional cases. Accurate quantum mechanical scattering calculations are carried out for these three cases by a linear algebraic variational method, and the accurate values of reactive probabilities, quenching probabilities, and moments of final vibrational and rotational distributions are compared to the results of continuous surface switching, the trajectory surface hopping method in two representations, the time-dependent self-consistent-field method, and the Miller-Meyer classical electron method to place the results of the semiclassical methods in perspective.

  13. An overview of self-consistent methods for fiber-reinforced composites

    NASA Technical Reports Server (NTRS)

    Gramoll, Kurt C.; Freed, Alan D.; Walker, Kevin P.

    1991-01-01

    The Walker et al. (1989) self-consistent method to predict both the elastic and the inelastic effective material properties of composites is examined and compared with the results of other self-consistent and elastically based solutions. The elastic part of their method is shown to be identical to other self-consistent methods for non-dilute reinforced composite materials; they are the Hill (1965), Budiansky (1965), and Nemat-Nasser et al. (1982) derivations. A simplified form of the non-dilute self-consistent method is also derived. The predicted, elastic, effective material properties for fiber reinforced material using the Walker method was found to deviate from the elasticity solution for the v sub 31, K sub 12, and mu sub 31 material properties (fiber is in the 3 direction) especially at the larger volume fractions. Also, the prediction for the transverse shear modulus, mu sub 12, exceeds one of the accepted Hashin bounds. Only the longitudinal elastic modulus E sub 33 agrees with the elasticity solution. The differences between the Walker and the elasticity solutions are primarily due to the assumption used in the derivation of the self-consistent method, i.e., the strain fields in the inclusions and the matrix are assumed to remain constant, which is not a correct assumption for a high concentration of inclusions.

  14. Using Hartree-Fock pseudopotentials in GW calculations

    NASA Astrophysics Data System (ADS)

    Hamann, D. R.; Vanderbilt, David

    2010-03-01

    The issue of including shallow ``semi-core'' states as valence has recently resurfaced in the context of self-consistent GW calculations.footnotetextF. Bruneval et al., Phys. Rev. Lett. 97, 267601 (2006). Supposing that semi-core-valence exchange is the dominant process necessitating the inclusion of semi-cores, we have investigated whether the use Hartree-Fock pseudopotentialsfootnotetextW. A. Al-Saidi, E. J. Walter, and A. M. Rappe, Phys. Rev. B 77, 075122 (2008). instead of density-functional psp's might obviate the need for semi-cores. The answers to this question appear to be ``yes'' for the case of CuCl (filled d shell), and ``semi-cores don't matter anyway'' for ScN (empty d shell). Opportunity permitting, additional examples will be discussed.

  15. Recent Progress in GW-based Methods for Excited-State Calculations of Reduced Dimensional Systems

    NASA Astrophysics Data System (ADS)

    da Jornada, Felipe H.

    2015-03-01

    Ab initio calculations of excited-state phenomena within the GW and GW-Bethe-Salpeter equation (GW-BSE) approaches allow one to accurately study the electronic and optical properties of various materials, including systems with reduced dimensionality. However, several challenges arise when dealing with complicated nanostructures where the electronic screening is strongly spatially and directionally dependent. In this talk, we discuss some recent developments to address these issues. First, we turn to the slow convergence of quasiparticle energies and exciton binding energies with respect to k-point sampling. This is very effectively dealt with using a new hybrid sampling scheme, which results in savings of several orders of magnitude in computation time. A new ab initio method is also developed to incorporate substrate screening into GW and GW-BSE calculations. These two methods have been applied to mono- and few-layer MoSe2, and yielded strong environmental dependent behaviors in good agreement with experiment. Other issues that arise in confined systems and materials with reduced dimensionality, such as the effect of the Tamm-Dancoff approximation to GW-BSE, and the calculation of non-radiative exciton lifetime, are also addressed. These developments have been efficiently implemented and successfully applied to real systems in an ab initio framework using the BerkeleyGW package. I would like to acknowledge collaborations with Diana Y. Qiu, Steven G. Louie, Meiyue Shao, Chao Yang, and the experimental groups of M. Crommie and F. Wang. This work was supported by Department of Energy under Contract No. DE-AC02-05CH11231 and by National Science Foundation under Grant No. DMR10-1006184.

  16. Quantum thermal transport through anharmonic systems: A self-consistent approach

    NASA Astrophysics Data System (ADS)

    He, Dahai; Thingna, Juzar; Wang, Jian-Sheng; Li, Baowen

    2016-10-01

    We propose a feasible and effective approach to study quantum thermal transport through anharmonic systems. The main idea is to obtain an effective harmonic Hamiltonian for the anharmonic system by applying the self-consistent phonon theory. By using the effective harmonic Hamiltonian, we study thermal transport within the framework of the nonequilibrium Green's function method using the celebrated Caroli formula. We corroborate our quantum self-consistent approach by using the quantum master equation that can deal with anharmonicity exactly, but is limited to the weak system-bath coupling regime. Finally, in order to demonstrate its strength, we apply the quantum self-consistent approach to study thermal rectification in a weakly coupled two-segment anharmonic system.

  17. MultiSIMNRA: A computational tool for self-consistent ion beam analysis using SIMNRA

    NASA Astrophysics Data System (ADS)

    Silva, T. F.; Rodrigues, C. L.; Mayer, M.; Moro, M. V.; Trindade, G. F.; Aguirre, F. R.; Added, N.; Rizzutto, M. A.; Tabacniks, M. H.

    2016-03-01

    SIMNRA is widely adopted by the scientific community of ion beam analysis for the simulation and interpretation of nuclear scattering techniques for material characterization. Taking advantage of its recognized reliability and quality of the simulations, we developed a computer program that uses multiple parallel sessions of SIMNRA to perform self-consistent analysis of data obtained by different ion beam techniques or in different experimental conditions of a given sample. In this paper, we present a result using MultiSIMNRA for a self-consistent multi-elemental analysis of a thin film produced by magnetron sputtering. The results demonstrate the potentialities of the self-consistent analysis and its feasibility using MultiSIMNRA.

  18. Self-consistent electrostatic potential due to trapped plasma in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Miller, Ronald H.; Khazanov, George V.

    1993-01-01

    A steady state solution for the self-consistent electrostatic potential due to a plasma confined in a magnetic flux tube is considered. A steady state distribution function is constructed for the trapped particles from the constants of the motion, in the absence of waves and collisions. Using Liouville's theorem, the particle density along the geomagnetic field is determined and found to depend on the local magnetic field, self-consistent electric potential, and the equatorial plasma distribution function. A hot anisotropic magnetospheric plasma in steady state is modeled by a bi-Maxwellian at the equator. The self-consistent electric potential along the magnetic field is calculated assuming quasineutrality, and the potential drop is found to be approximately equal to the average kinetic energy of the equatorially trapped plasma. The potential is compared with that obtained by Alfven and Faelthammar (1963).

  19. Effective dipole moment for the mode coupling instability: Mapping of self-consistent wake models

    SciTech Connect

    Roecker, T. B.; Zhdanov, S. K.; Ivlev, A. V.; Morfill, G. E.; Lampe, M.; Joyce, G.

    2012-07-15

    The theory of the mode coupling instability operating in two-dimensional plasma crystals is generalized, by employing the linear plasma response formalism to describe the interparticle interactions self-consistently. In this approach, the underlying ion distribution function is calculated from first principles. Subthermal and suprathermal regimes of the ion flow are considered. A mapping procedure is proposed, which relates the self-consistent coupling coefficients to the effective dipole moment of the wake-the parameter which characterizes the mode coupling in the framework of the conventionally used Yukawa/point-wake model. The importance of the self-consistent approach is demonstrated by comparing the theoretically obtained dipole moments with the values deduced from experiments.

  20. Efficient self-consistent treatment of electron correlation within the random phase approximation

    NASA Astrophysics Data System (ADS)

    Bleiziffer, Patrick; Heßelmann, Andreas; Görling, Andreas

    2013-08-01

    A self-consistent Kohn-Sham (KS) method is presented that treats correlation on the basis of the adiabatic-connection dissipation-fluctuation theorem employing the direct random phase approximation (dRPA), i.e., taking into account only the Coulomb kernel while neglecting the exchange-correlation kernel in the calculation of the Kohn-Sham correlation energy and potential. The method, denoted self-consistent dRPA method, furthermore treats exactly the exchange energy and the local multiplicative KS exchange potential. It uses Gaussian basis sets, is reasonably efficient, exhibiting a scaling of the computational effort with the forth power of the system size, and thus is generally applicable to molecules. The resulting dRPA correlation potentials in contrast to common approximate correlation potentials are in good agreement with exact reference potentials. The negatives of the eigenvalues of the highest occupied molecular orbitals are found to be in good agreement with experimental ionization potentials. Total energies from self-consistent dRPA calculations, as expected, are even poorer than non-self-consistent dRPA total energies and dRPA reaction and non-covalent binding energies do not significantly benefit from self-consistency. On the other hand, energies obtained with a recently introduced adiabatic-connection dissipation-fluctuation approach (EXXRPA+, exact-exchange random phase approximation) that takes into account, besides the Coulomb kernel, also the exact frequency-dependent exchange kernel are significantly improved if evaluated with orbitals obtained from a self-consistent dRPA calculation instead of an exact exchange-only calculation. Total energies, reaction energies, and noncovalent binding energies obtained in this way are of the same quality as those of high-level quantum chemistry methods, like the coupled cluster singles doubles method which is computationally more demanding.

  1. Temperature dependence of self-consistent full matrix material constants of lead zirconate titanate ceramics

    PubMed Central

    Cao, Wenwu

    2015-01-01

    Up to date, there are no self-consistent data in the literature on the temperature dependence of full matrix material properties for piezoelectric materials because they are extremely difficult to determine. Using only one sample, we have measured the temperature dependence of full matrix constants of lead zirconate titanate (PZT-4) from room temperature to 120 °C by resonant ultrasound spectroscopy. Self-consistency is guaranteed here because all data at different temperatures come from one sample. Such temperature dependence data would make it a reality to accurately predict device performance at high temperatures using computer simulations. PMID:25713470

  2. Periodic Pulay method for robust and efficient convergence acceleration of self-consistent field iterations

    DOE PAGES

    Banerjee, Amartya S.; Suryanarayana, Phanish; Pask, John E.

    2016-01-21

    Pulay's Direct Inversion in the Iterative Subspace (DIIS) method is one of the most widely used mixing schemes for accelerating the self-consistent solution of electronic structure problems. In this work, we propose a simple generalization of DIIS in which Pulay extrapolation is performed at periodic intervals rather than on every self-consistent field iteration, and linear mixing is performed on all other iterations. Lastly, we demonstrate through numerical tests on a wide variety of materials systems in the framework of density functional theory that the proposed generalization of Pulay's method significantly improves its robustness and efficiency.

  3. Self-consistent Goedel cosmology with spin-density in Riemann-Cartan spacetime

    NASA Technical Reports Server (NTRS)

    Smalley, L. L.

    1986-01-01

    It is shown that the Goedel metric (GM) for a rotating cosmology is compatible with the self-consistent formulation of the Einstein-Cartan (EC) metric-torsion theory for a spinning fluid. The proposed calculation shows, within the context of an EC theory, how to self-consistently incorporate a perfect fluid with spin density into the GM without changing the metric. It is found that the only changes produced in the GM parameters in connection with a spinning fluid are that the cosmological constant becomes slightly more negative and the sense of rotation is flipped 180 deg.

  4. Thermodynamically self-consistent non-stochastic micromagnetic model for the ferromagnetic state

    SciTech Connect

    Dvornik, Mykola Vansteenkiste, Arne; Van Waeyenberge, Bartel

    2014-10-20

    In this work, a self-consistent thermodynamic approach to micromagnetism is presented. The magnetic degrees of freedom are modeled using the Landau-Lifshitz-Baryakhtar theory, which separates the different contributions to the magnetic damping, and thereby allows them to be coupled to the electron and phonon systems in a self-consistent way. We show that this model can quantitatively reproduce ultrafast magnetization dynamics in Nickel suggesting that in ferromagnetic metals the ultrafast angular momentum transfer happens via the relativistic spin-electron scattering.

  5. Characterisation of gunshot residue particles using self-consistent ion beam analysis

    NASA Astrophysics Data System (ADS)

    Bailey, M. J.; Jeynes, C.

    2009-06-01

    Individual particles of gunshot residue were studied with particle-induced X-ray emission and backscattering spectrometry using a 2.5 MeV H + beam focussed to ˜4 μm and self-consistent fitting of the data. The geometry of these spherical particles was considered in order to accurately fit the corresponding particle spectrum and therefore to quantify the trace element composition of these particles. The demonstrable self-consistency of this method allows the compositions of most residue particles to be determined unambiguously and with a higher sensitivity to trace elements than conventional methods.

  6. Symplectic multiparticle tracking model for self-consistent space-charge simulation

    NASA Astrophysics Data System (ADS)

    Qiang, Ji

    2017-01-01

    Symplectic tracking is important in accelerator beam dynamics simulation. So far, to the best of our knowledge, there is no self-consistent symplectic space-charge tracking model available in the accelerator community. In this paper, we present a two-dimensional and a three-dimensional symplectic multiparticle spectral model for space-charge tracking simulation. This model includes both the effect from external fields and the effect of self-consistent space-charge fields using a split-operator method. Such a model preserves the phase space structure and shows much less numerical emittance growth than the particle-in-cell model in the illustrative examples.

  7. A self-consistent theory of collective alpha particle losses induced by Alfvenic turbulence

    SciTech Connect

    Biglari, H. . Plasma Physics Lab.); Diamond, P.H. . Dept. of Physics)

    1992-01-01

    The nonlinear dynamics of kinetic Alfven waves, resonantly excited by energetic ions/alpha particles, is investigated. It is shown that {alpha}-particles govern both linear instability and nonlinear saturation dynamics, while the background MHD turbulence results only in a nonlinear real frequency shift. The most efficient saturation mechanism is found to be self-induced profile modification. Expressions for the fluctuation amplitudes and the {alpha}-particle radial flux are self-consistently derived. The work represents the first self-consistent, turbulent treatment of collective {alpha}-particle losses by Alfvenic fluctuations.

  8. Enriching Elementary Quantum Mechanics with the Computer: Self-Consistent Field Problems in One Dimension

    ERIC Educational Resources Information Center

    Bolemon, Jay S.; Etzold, David J.

    1974-01-01

    Discusses the use of a small computer to solve self-consistent field problems of one-dimensional systems of two or more interacting particles in an elementary quantum mechanics course. Indicates that the calculation can serve as a useful introduction to the iterative technique. (CC)

  9. Self-Consistent Non-Stationary Theory of Multipactor in DLA Structures

    SciTech Connect

    Sinitsyn, O. V.; Nusinovich, G. S.; Antonsen, T. M.; Kishek, R.

    2009-01-22

    In this paper a non-stationary self-consistent theoretical model of multipactor in dielectric loaded accelerator structures is proposed. In comparison with our previous work, the effects of the cylindricity are included. The corresponding numerical implementation of the model is described and some simulation results are shown.

  10. Self-consistent Purcell factor and spontaneous topological transition in hyperbolic metamaterials

    NASA Astrophysics Data System (ADS)

    Krasikov, Sergey; Iorsh, Ivan V.

    2016-10-01

    In this work we develop a self-consistent approach for calculation of the Purcell factor and Lamb shift in highly dispersive hyperbolic metamaterial accounting for the effective dipole frequency shift. Also we theoretically predict the possibility of spontaneous topological transition, which occurs not due to the external change of the system parameters but only due to the Lamb shift.

  11. Integrable motion of curves in self-consistent potentials: Relation to spin systems and soliton equations

    NASA Astrophysics Data System (ADS)

    Myrzakulov, R.; Mamyrbekova, G. K.; Nugmanova, G. N.; Yesmakhanova, K. R.; Lakshmanan, M.

    2014-06-01

    Motion of curves and surfaces in R3 lead to nonlinear evolution equations which are often integrable. They are also intimately connected to the dynamics of spin chains in the continuum limit and integrable soliton systems through geometric and gauge symmetric connections/equivalence. Here we point out the fact that a more general situation in which the curves evolve in the presence of additional self-consistent vector potentials can lead to interesting generalized spin systems with self-consistent potentials or soliton equations with self-consistent potentials. We obtain the general form of the evolution equations of underlying curves and report specific examples of generalized spin chains and soliton equations. These include principal chiral model and various Myrzakulov spin equations in (1+1) dimensions and their geometrically equivalent generalized nonlinear Schrödinger (NLS) family of equations, including Hirota-Maxwell-Bloch equations, all in the presence of self-consistent potential fields. The associated gauge equivalent Lax pairs are also presented to confirm their integrability.

  12. Subjective Confidence in Perceptual Judgments: A Test of the Self-Consistency Model

    ERIC Educational Resources Information Center

    Koriat, Asher

    2011-01-01

    Two questions about subjective confidence in perceptual judgments are examined: the bases for these judgments and the reasons for their accuracy. Confidence in perceptual judgments has been claimed to rest on qualitatively different processes than confidence in memory tasks. However, predictions from a self-consistency model (SCM), which had been…

  13. Quasiparticle corrections for the calculation of optical properties: SiC and GaN

    NASA Astrophysics Data System (ADS)

    Aulbur, Wilfried G.; Wilkins, John W.

    1996-03-01

    We study quasiparticle corrections to linear and nonlinear optical response functions of SiC and GaN, two technologically important wide-band-gap semiconductors. In contrast to earlier work that included quasiparticle corrections via a constant shift Δ of the conduction band energies, we explicitly take into account the dispersion of the band gap correction throughout the Brillouin zone: Δ arrow Δ (k). We implemented a parallel version of a quasiparticle calculation in the so-called GW approximation which allows the determination of Δ (k). In this approximation, the self-energy of the quasiparticles is given by the product of the dressed propagator, G, and the screened interaction, W. The screened interaction is calculated via a plasmon pole model which can also be used to determine plasmon bands. We present plasmon bandstructures for SiC and GaN. Our code is coarse-grain parallel and runs on the 128-node CRAY-T3D of the Ohio Supercomputer Center. It is written in an object-oriented way using C++ and interfaces heavily and efficiently with existing Fortran codes. Supported by DOE, NSF, the Ohio Supercomputer Center, and the 0.3truecm Cornell Theory Center.

  14. Majorana quasiparticles of an inhomogeneous Rashba chain

    NASA Astrophysics Data System (ADS)

    Maśka, Maciej M.; Gorczyca-Goraj, Anna; Tworzydło, Jakub; Domański, Tadeusz

    2017-01-01

    We investigate the inhomogeneous Rashba chain coupled to a superconducting substrate, hosting the Majorana quasiparticles near its edges. We discuss its subgap spectrum and study how robust the zero-energy quasiparticles are against the diagonal and off-diagonal disorder. Studying the Z2 topological invariant we show that disorder-induced transition from the topologically nontrivial to trivial phases is manifested by characteristic features in the spatially resolved quasiparticle spectrum at zero energy. We provide evidence for the nonlocal nature of the zero-energy Majorana quasiparticles that are well preserved upon partitioning the chain into separate pieces. Even though the Majorana quasiparticles are not completely immune to inhomogeneity, we show that they can spread onto other (normal) nanoscopic objects via the proximity effect.

  15. Self-Consistent Sources for Integrable Equations Via Deformations of Binary Darboux Transformations

    NASA Astrophysics Data System (ADS)

    Chvartatskyi, Oleksandr; Dimakis, Aristophanes; Müller-Hoissen, Folkert

    2016-08-01

    We reveal the origin and structure of self-consistent source extensions of integrable equations from the perspective of binary Darboux transformations. They arise via a deformation of the potential that is central in this method. As examples, we obtain in particular matrix versions of self-consistent source extensions of the KdV, Boussinesq, sine-Gordon, nonlinear Schrödinger, KP, Davey-Stewartson, two-dimensional Toda lattice and discrete KP equation. We also recover a (2+1)-dimensional version of the Yajima-Oikawa system from a deformation of the pKP hierarchy. By construction, these systems are accompanied by a hetero binary Darboux transformation, which generates solutions of such a system from a solution of the source-free system and additionally solutions of an associated linear system and its adjoint. The essence of all this is encoded in universal equations in the framework of bidifferential calculus.

  16. Self-consistent simulation of radio frequency multipactor on micro-grooved dielectric surface

    SciTech Connect

    Cai, Libing; Wang, Jianguo; Cheng, Guoxin; Zhu, Xiangqin; Xia, Hongfu

    2015-02-07

    The multipactor plays a key role in the surface breakdown on the feed dielectric window irradiated by high power microwave. To study the suppression of multipactor, a 2D electrostatic PIC-MCC simulation code was developed. The space charge field, including surface deposited charge and multipactor electron charge field, is obtained by solving 2D Poisson's equation in time. Therefore, the simulation is self-consistent and does not require presetting a fixed space charge field. By using this code, the self-consistent simulation of the RF multipactor on the periodic micro-grooved dielectric surface is realized. The 2D space distributions of the multipactor electrons and space charge field are presented. From the simulation results, it can be found that only half slopes have multipactor discharge when the slope angle exceeds a certain value, and the groove presents a pronounced suppression effect on the multipactor.

  17. Thermodynamic approach to the interpretation of self-consistent pressure profiles in a tokamak

    SciTech Connect

    Dyabilin, K. S.; Razumova, K. A.

    2015-09-15

    The phenomenon of invariable pressure profiles in tokamaks is interpreted in the framework of the thermodynamic approach suggesting that invariable self-consistent states correspond to the minimum of free energy. Solutions qualitatively consistent with the experiment are obtained under the assumption that the mechanism for the formation of self-consistent profiles is directly related to equilibrium diamagnetic currents. The dynamics of the system and specific transport phenomena, such as energy and particle pinching and a decrease in the local density under auxiliary electron cyclotron resonance heating (density pump-out), are analyzed in the vicinity of an equilibrium state characterized by a stable pressure profile. The scaling for the energy confinement time deduced from the transport model agrees qualitatively with the ITER scaling based on the analysis of experimental data obtained in many tokamaks. The possibility of using generalized Tsallis statistics to analyze pressure profiles is considered.

  18. Integrated fusion simulation with self-consistent core-pedestal coupling

    NASA Astrophysics Data System (ADS)

    Meneghini, O.; Snyder, P. B.; Smith, S. P.; Candy, J.; Staebler, G. M.; Belli, E. A.; Lao, L. L.; Park, J. M.; Green, D. L.; Elwasif, W.; Grierson, B. A.; Holland, C.

    2016-04-01

    Accurate prediction of fusion performance in present and future tokamaks requires taking into account the strong interplay between core transport, pedestal structure, current profile, and plasma equilibrium. An integrated modeling workflow capable of calculating the steady-state self-consistent solution to this strongly coupled problem has been developed. The workflow leverages state-of-the-art components for collisional and turbulent core transport, equilibrium and pedestal stability. Testing against a DIII-D discharge shows that the workflow is capable of robustly predicting the kinetic profiles (electron and ion temperature and electron density) from the axis to the separatrix in a good agreement with the experiments. An example application is presented, showing self-consistent optimization for the fusion performance of the 15 MA D-T ITER baseline scenario as functions of the pedestal density and ion effective charge Zeff .

  19. Integrated fusion simulation with self-consistent core-pedestal coupling

    SciTech Connect

    Meneghini, O.; Snyder, P. B.; Smith, S. P.; Candy, J.; Staebler, G. M.; Belli, E. A.; Lao, L. L.; Park, J. M.; Green, D. L.; Elwasif, W.; Grierson, B. A.; Holland, C.

    2016-04-20

    In this study, accurate prediction of fusion performance in present and future tokamaks requires taking into account the strong interplay between core transport, pedestal structure, current profile and plasma equilibrium. An integrated modeling workflow capable of calculating the steady-state self- consistent solution to this strongly-coupled problem has been developed. The workflow leverages state-of-the-art components for collisional and turbulent core transport, equilibrium and pedestal stability. Validation against DIII-D discharges shows that the workflow is capable of robustly pre- dicting the kinetic profiles (electron and ion temperature and electron density) from the axis to the separatrix in good agreement with the experiments. An example application is presented, showing self-consistent optimization for the fusion performance of the 15 MA D-T ITER baseline scenario as functions of the pedestal density and ion effective charge Zeff.

  20. Integrated fusion simulation with self-consistent core-pedestal coupling

    DOE PAGES

    Meneghini, O.; Snyder, P. B.; Smith, S. P.; ...

    2016-04-20

    In this study, accurate prediction of fusion performance in present and future tokamaks requires taking into account the strong interplay between core transport, pedestal structure, current profile and plasma equilibrium. An integrated modeling workflow capable of calculating the steady-state self- consistent solution to this strongly-coupled problem has been developed. The workflow leverages state-of-the-art components for collisional and turbulent core transport, equilibrium and pedestal stability. Validation against DIII-D discharges shows that the workflow is capable of robustly pre- dicting the kinetic profiles (electron and ion temperature and electron density) from the axis to the separatrix in good agreement with the experiments.more » An example application is presented, showing self-consistent optimization for the fusion performance of the 15 MA D-T ITER baseline scenario as functions of the pedestal density and ion effective charge Zeff.« less

  1. Self-consistent magnetization dynamics of a ferromagnetic quantum dot driven by a spin bias

    NASA Astrophysics Data System (ADS)

    Siu, Z. B.; Jalil, M. B. A.; Tan, S. G.

    2012-04-01

    We present an iterative scheme which combines the non-equilibrium Green's function (NEGF) for evaluating the quantum spin transport in a ferromagnetic quantum dot device and the Landau-Lifshitz (LL) equation for modeling the magnetization dynamics of the dot. For a given initial magnetization, the spin polarization of current and the resulting spin torque in the dot are calculated using the NEGF formalism. The torque acts on the magnetic moment of the dot, and the resultant magnetization dynamics is obtained from the LL equation. The new value of the dot's magnetization is then used as an input for the next round of NEGF calculation, and the whole process is repeated iteratively. The spin torque is thus calculated self-consistently with the dynamics of the magnetic moment of the dot. We apply this self-consistent iterative scheme to study the magnetization dynamics in an exemplary quantum dot system with an induced spin bias in the leads under varying damping conditions.

  2. Self-consistent waveforms from a scalar charge in orbit around a Schwarzschild blak hole

    NASA Astrophysics Data System (ADS)

    Diener, Peter; Vega, Ian; Wardell, Barry; Detweiler, Steven

    2012-03-01

    Extreme Mass Ratio In-spirals of compact objects into super massive black holes are expected to be a very important source of gravitational waves for future space based gravitational wave detectors. For the detection and analysis of gravitational waves from such events, it is necessary to know the waveforms to exquisite precision. Here we report on recent progress on using the effective source approach to the self-force problem to perform self-consistent evolutions of a scalar charge in orbit around a Schwarzschild black hole. The effective source approach allow us to cheaply extract the self-force acting on the scalar charge at every timestep and thereby evolve both the scalar field produced by the particle and the orbit of the particle at the same time in a self-consistent manner. We present the first waveforms generated using this method.

  3. Self-consistent approach to the Wigner-Seitz treatment of soliton matter

    NASA Astrophysics Data System (ADS)

    Weber, Urban; McGovern, Judith A.

    1998-06-01

    We propose a self-consistent approach to the treatment of nuclear matter as a crystal of solitons in the Wigner-Seitz approximation. Specifically, we use a Bloch-like boundary condition on the quarks at the edge of a spherical cell which allows the dispersion relation for a given radius to be calculated self-consistently along with the meson fields; in previous work some ansatz for the dispersion relation has always been an input. Results in all models are very sensitive to the form of the dispersion relation, and so our approach represents a significant advance. We apply the method to both the Friedberg-Lee model and the chiral quark-meson model of Birse and Banerjee. Only the latter shows short-range repulsion; in the former the transition to a quark plasma occurs at unrealistically low densities.

  4. Gauge transformations of constrained discrete modified KP systems with self-consistent sources

    NASA Astrophysics Data System (ADS)

    Huang, Ran; Song, Tao; Li, Chuanzhong

    In this paper, we firstly recall some basic facts about the discrete KP(d-KP) and discrete modified KP(d-mKP) hierarchies, and then we find that d-KP hierarchy and d-mKP hierarchy are linked by a gauge transformation. What’s more, we give three gauge transformation operators of the d-mKP hierarchy and give their successive applications. We further construct the ghost symmetry and use this symmetry to give the definition the d-mKP hierarchy with self-consistent sources. We also give gauge transformations of a newly defined constrained d-mKP(cd-mKP) hierarchy and the constrained d-mKP hierarchy with self-consistent sources(cd-mKPHSCSs).

  5. Self-consistent solution for proximity effect and Josephson current in ballistic graphene SNS Josephson junctions

    SciTech Connect

    Black-Schaffer, Annica M.

    2010-04-06

    We use a tight-binding Bogoliubov-de Gennes (BdG) formalism to self-consistently calculate the proximity effect, Josephson current, and local density of states in ballistic graphene SNS Josephson junctions. Both short and long junctions, with respect to the superconducting coherence length, are considered, as well as different doping levels of the graphene. We show that self-consistency does not notably change the current-phase relationship derived earlier for short junctions using the non-selfconsistent Dirac-BdG formalism but predict a significantly increased critical current with a stronger junction length dependence. In addition, we show that in junctions with no Fermi level mismatch between the N and S regions superconductivity persists even in the longest junctions we can investigate, indicating a diverging Ginzburg-Landau superconducting coherence length in the normal region.

  6. Formation and stability of the self-consistent one-dimensional tail current sheet

    NASA Technical Reports Server (NTRS)

    Pritchett, P. L.; Coroniti, F. V.

    1992-01-01

    The paper investigates the formation, the structure, and the stability of self-consistent one-dimensional current sheets in which the ions carry most of the current and momentum (the occurrence of which was suggested by observations of Mitchell et al., 1990; and Sergeev et al., 1990). Results of the analysis showed that, for the case of a cold current sheet, the characteristic thickness lamba equals to about (Bz/B0) exp 4/3 c/omega(p0), where Bz is the normal field component, B0 is the asymptotic magnitude of the reversing field, and c/omega(p0)is the collisionless ion skin depth based on lobe density. A two-dimensional self-consistent dynamical simulation model is developed, which demonstrates that these idealized current sheets are unstable to kink perturbations driven by the anisotropic pressure distribution produced by the chaotic nature of the particle orbits in a field-reversal region.

  7. Quasiparticle energies, excitons, and optical spectra of few-layer black phosphorus

    NASA Astrophysics Data System (ADS)

    Tran, Vy; Fei, Ruixiang; Yang, Li

    2015-12-01

    We report first-principles GW-Bethe-Salpeter-equation (BSE) studies of excited-state properties of few-layer black phosphorus (BP) (phosphorene). With improved GW computational methods, we obtained converged quasiparticle band gaps and optical absorption spectra by the single-shot (G0W0) procedure. Moreover, we reveal fine structures of anisotropic excitons, including the series of one-dimensional like wave functions, spin singlet-triplet splitting, and electron-hole binding energy spectra by solving BSE. An effective-mass model is employed to describe these electron-hole pairs, shedding light on estimating the exciton binding energy of anisotropic two-dimensional semiconductors without expensive ab initio simulations. Finally, the anisotropic optical response of BP is explained by using optical selection rules based on the projected single-particle density of states at band edges.

  8. Self-consistent Bohmian description of strong field-driven electron dynamics

    SciTech Connect

    Botheron, P.; Pons, B.

    2010-08-15

    Drawing from the Bohmian formulation of the time-dependent Schroedinger equation, we present a self-consistent hydrodynamical method to describe electron dynamics in strong field light-matter interactions. Prototypical implementation is made for one-dimensional H atom embedded in short and intense laser pulses. The method provides very accurate electron densities and yields quantum trajectories that shed light on the electron dynamics, beyond the strong-field approximation.

  9. Self consistent MHD modeling of the solar wind from coronal holes with distinct geometries

    NASA Technical Reports Server (NTRS)

    Stewart, G. A.; Bravo, S.

    1995-01-01

    Utilizing an iterative scheme, a self-consistent axisymmetric MHD model for the solar wind has been developed. We use this model to evaluate the properties of the solar wind issuing from the open polar coronal hole regions of the Sun, during solar minimum. We explore the variation of solar wind parameters across the extent of the hole and we investigate how these variations are affected by the geometry of the hole and the strength of the field at the coronal base.

  10. A self-consistent theory of localization in nonlinear random media

    NASA Astrophysics Data System (ADS)

    Cherroret, Nicolas

    2017-01-01

    The self-consistent theory of localization is generalized to account for a weak quadratic nonlinear potential in the wave equation. For spreading wave packets, the theory predicts the destruction of Anderson localization by the nonlinearity and its replacement by algebraic subdiffusion, while classical diffusion remains unaffected. In 3D, this leads to the emergence of a subdiffusion-diffusion transition in place of the Anderson transition. The accuracy and the limitations of the theory are discussed.

  11. Towards a Self Consistent Model of the Thermal Structure of the Venus Atmosphere

    NASA Astrophysics Data System (ADS)

    Limaye, S. S.

    2014-04-01

    An International Team has been formed under the International Space Science Institute (ISSI), Bern, Switzerland to consider results on the thermal structure of the Venus atmosphere obtained from space missions and ground based observations since the Venus International Reference Atmosphere was developed [1] and to arrive at a self consistent model of the atmospheric structure - temperature and density with altitude/pressure from the available results.

  12. Generalized Volterra lattices: Binary Darboux transformations and self-consistent sources

    NASA Astrophysics Data System (ADS)

    Müller-Hoissen, F.; Chvartatskyi, O.; Toda, K.

    2017-03-01

    We study two families of matrix versions of generalized Volterra (or Bogoyavlensky) lattice equations. For each family, the equations arise as reductions of a partial differential-difference equation in one continuous and two discrete variables, which is a realization of a general integrable equation in bidifferential calculus. This allows to derive a binary Darboux transformation and also self-consistent source extensions via general results of bidifferential calculus. Exact solutions are constructed from the simplest seed solutions.

  13. Self-consistent models for Coulomb heated X-ray pulsar atmospheres

    NASA Technical Reports Server (NTRS)

    Harding, A.; Meszaros, S. P.; Kirk, J.; Galloway, D.

    1983-01-01

    Calculations of accreting magnetized neutron star atmospheres heated by the gradual deceleration of protons via Coulomb collisions are presented. Self consistent determinations of the temperature and density structure for different accretion rates are made by assuming hydrostatic equilibrium and energy balance, coupled with radiative transfer. The full radiative transfer in two polarizations, using magnetic cross sections but with cyclotron resonance effects treated approximately, is carried out in the inhomogeneous atmospheres.

  14. Self-consistent modeling of the electrohydrodynamics of a conductive meniscus

    SciTech Connect

    Wright, G.S.; Krein, P.T.; Chato, J.C.

    1995-07-01

    A complete self-consistent model has been developed for the motion of a conductive liquid surface on a capillary orifice, under an applied electric field. The model uses a quasi-one-dimensional hydrodynamic formulation and a two-dimensional axisymmetric boundary element solution for electric field. The model permits simulation of meniscus behavior with time-varying electric excitation or pressure. Results for resonance behavior and drop emission are presented, with experimental results for comparison.

  15. Self-Consistent Chaotic Transport in a High-Dimensional Mean-Field Hamiltonian Map Model

    DOE PAGES

    Martínez-del-Río, D.; del-Castillo-Negrete, D.; Olvera, A.; ...

    2015-10-30

    We studied the self-consistent chaotic transport in a Hamiltonian mean-field model. This model provides a simplified description of transport in marginally stable systems including vorticity mixing in strong shear flows and electron dynamics in plasmas. Self-consistency is incorporated through a mean-field that couples all the degrees-of-freedom. The model is formulated as a large set of N coupled standard-like area-preserving twist maps in which the amplitude and phase of the perturbation, rather than being constant like in the standard map, are dynamical variables. Of particular interest is the study of the impact of periodic orbits on the chaotic transport and coherentmore » structures. Furthermore, numerical simulations show that self-consistency leads to the formation of a coherent macro-particle trapped around the elliptic fixed point of the system that appears together with an asymptotic periodic behavior of the mean field. To model this asymptotic state, we introduced a non-autonomous map that allows a detailed study of the onset of global transport. A turnstile-type transport mechanism that allows transport across instantaneous KAM invariant circles in non-autonomous systems is discussed. As a first step to understand transport, we study a special type of orbits referred to as sequential periodic orbits. Using symmetry properties we show that, through replication, high-dimensional sequential periodic orbits can be generated starting from low-dimensional periodic orbits. We show that sequential periodic orbits in the self-consistent map can be continued from trivial (uncoupled) periodic orbits of standard-like maps using numerical and asymptotic methods. Normal forms are used to describe these orbits and to find the values of the map parameters that guarantee their existence. Numerical simulations are used to verify the prediction from the asymptotic methods.« less

  16. Self-Consistent Chaotic Transport in a High-Dimensional Mean-Field Hamiltonian Map Model

    SciTech Connect

    Martínez-del-Río, D.; del-Castillo-Negrete, D.; Olvera, A.; Calleja, R.

    2015-10-30

    We studied the self-consistent chaotic transport in a Hamiltonian mean-field model. This model provides a simplified description of transport in marginally stable systems including vorticity mixing in strong shear flows and electron dynamics in plasmas. Self-consistency is incorporated through a mean-field that couples all the degrees-of-freedom. The model is formulated as a large set of N coupled standard-like area-preserving twist maps in which the amplitude and phase of the perturbation, rather than being constant like in the standard map, are dynamical variables. Of particular interest is the study of the impact of periodic orbits on the chaotic transport and coherent structures. Furthermore, numerical simulations show that self-consistency leads to the formation of a coherent macro-particle trapped around the elliptic fixed point of the system that appears together with an asymptotic periodic behavior of the mean field. To model this asymptotic state, we introduced a non-autonomous map that allows a detailed study of the onset of global transport. A turnstile-type transport mechanism that allows transport across instantaneous KAM invariant circles in non-autonomous systems is discussed. As a first step to understand transport, we study a special type of orbits referred to as sequential periodic orbits. Using symmetry properties we show that, through replication, high-dimensional sequential periodic orbits can be generated starting from low-dimensional periodic orbits. We show that sequential periodic orbits in the self-consistent map can be continued from trivial (uncoupled) periodic orbits of standard-like maps using numerical and asymptotic methods. Normal forms are used to describe these orbits and to find the values of the map parameters that guarantee their existence. Numerical simulations are used to verify the prediction from the asymptotic methods.

  17. Self-consistent solitons for vacuum decay in radiatively generated potentials

    NASA Astrophysics Data System (ADS)

    Garbrecht, Björn; Millington, Peter

    2015-12-01

    We use a Green's function approach in order to develop a method for calculating the tunneling rate between radiatively generated nondegenerate vacua. We apply this to a model that exhibits spontaneous symmetry breaking via the Coleman-Weinberg mechanism, where we determine the self-consistent tunneling configuration and illustrate the impact of gradient effects that arise from accounting for the underlying space-time inhomogeneity.

  18. A self-consistent determination of the RVB and SC gaps in the YRZ ansatz

    NASA Astrophysics Data System (ADS)

    Rao, Zi-Ye; Wang, Xiao-Min; Jiang, Hong-Min

    2017-03-01

    A correct understanding of the origin of the pseudogap in high temperature (high-T c) cuprate superconductors is considered to be a peripheral breakthrough in the understanding of the microscopic mechanism of the high-T c superconductivity. Yang-Rice-Zhang (YRZ) ansatz is an important phenomenological theory to describe the phenomenon of pseudogap. However, in the framework of YRZ, the pseudogap (resonant valence bond (RVB) gap) and the superconducting (SC) gap are unable to have a self-consistent determination at different doping concentrations, and this severely limits the application of the YRZ ansatz. Based on the YRZ ansatz, this study develops a technical method to determine the RVB and SC gaps in a self-consistent manner. It is revealed that the self-consistent calculations of the doping dependence of RVB, SC gaps and spectral function are not only consistent with the empirical gap formula in the YRZ framework, but also consistent with the doping evolution of the Fermi surface observed in the angle-resolved photoemission spectroscopy (ARPES) experiments. Our method will greatly extend the applications of the YRZ ansatz, and will deepen our understanding of the origin of pseudogap as well as the mechanism of high-T c superconductivity.

  19. From Observations to Self-consistent Modelling of the ISM in Galaxies

    NASA Astrophysics Data System (ADS)

    de Avillez, M.; Breitschwerdt, D.

    Since we are on the verge of studying the ISM in great detail due to immensely improved observational facilities and techniques in all wavelength ranges and similar progress on the computer hard- and software side, a major goal of this symposium will be to stimulate an intense discussion between observers and theoreticians on a self-consistent picture of the ISM. Observers should tell us WHAT we see on ALL scales of the ISM, near and far, and what boundary conditions would be appropriate for realistic models, and theoreticians should point out what assumptions and simplifications their codes need, and WHAT future observations could test their models. Thus, the workshop will start with sessions on ISM observations: Bubbles, superbubbles, stellar winds, chimneys, galactic fountains, HVCs, X-ray halos, diffuse ionized gas in galaxies, formation of molecular clouds, magnetic fields and the dynamo mechanism in the Galaxy, and turbulence in the ISM. All these subjects are of great importance for the task at hand. Followed on the last day with a session on the self consistent picture of the ISM where observations that give us information of the self-consistent picture will discussed as well as the numerical modeling and techniques.

  20. Two-way self-consistent coupling of HEIDI in SWMF

    NASA Astrophysics Data System (ADS)

    Ilie, R.; Liemohn, M. W.; Toth, G.

    2013-12-01

    In this study we present results from the two-way coupling between the kinetic Hot Electron and Ion Drift Integrator (HEIDI) model and the Space Weather Modeling Framework (SWMF). HEIDI solves the time dependent, gyration and bounced averaged kinetic equation for the phase space density of different ring current species and computes full pitch angle distributions for all local times and radial distances. This model was generalized to accommodate an arbitrary magnetic field and, through the coupling with SWMF, it obtains the magnetic field description along with the plasma distribution at the model boundaries from the Block Adaptive Tree Solar Wind Roe Upwind Scheme (BATS-R-US) magnetohydrodynamics (MHD) model within the SWMF. Electric field self-consistency is assured by the passing of convection potentials from the Ridley Ionosphere Model (RIM) within SWMF. Our study tests the various levels of coupling between the 3 models, highlighting the roles that the magnetic field, plasma sheet conditions and the cross polar cap potential play in the formation and evolution of the ring current. The results of the self-consistent coupling between HEIDI, BATSRUS and RIM during disturbed conditions emphasize the importance of a kinetic self-consistent approach to the description of the geospace.

  1. A self-consistent determination of the RVB and SC gaps in the YRZ ansatz.

    PubMed

    Rao, Zi-Ye; Wang, Xiao-Min; Jiang, Hong-Min

    2017-03-01

    A correct understanding of the origin of the pseudogap in high temperature (high-T c) cuprate superconductors is considered to be a peripheral breakthrough in the understanding of the microscopic mechanism of the high-T c superconductivity. Yang-Rice-Zhang (YRZ) ansatz is an important phenomenological theory to describe the phenomenon of pseudogap. However, in the framework of YRZ, the pseudogap (resonant valence bond (RVB) gap) and the superconducting (SC) gap are unable to have a self-consistent determination at different doping concentrations, and this severely limits the application of the YRZ ansatz. Based on the YRZ ansatz, this study develops a technical method to determine the RVB and SC gaps in a self-consistent manner. It is revealed that the self-consistent calculations of the doping dependence of RVB, SC gaps and spectral function are not only consistent with the empirical gap formula in the YRZ framework, but also consistent with the doping evolution of the Fermi surface observed in the angle-resolved photoemission spectroscopy (ARPES) experiments. Our method will greatly extend the applications of the YRZ ansatz, and will deepen our understanding of the origin of pseudogap as well as the mechanism of high-T c superconductivity.

  2. Two-particle irreducible effective actions versus resummation: Analytic properties and self-consistency

    NASA Astrophysics Data System (ADS)

    Brown, Michael; Whittingham, Ian

    2015-11-01

    Approximations based on two-particle irreducible (2PI) effective actions (also known as Φ-derivable, Cornwall-Jackiw-Tomboulis or Luttinger-Ward functionals depending on context) have been widely used in condensed matter and non-equilibrium quantum/statistical field theory because this formalism gives a robust, self-consistent, non-perturbative and systematically improvable approach which avoids problems with secular time evolution. The strengths of 2PI approximations are often described in terms of a selective resummation of Feynman diagrams to infinite order. However, the Feynman diagram series is asymptotic and summation is at best a dangerous procedure. Here we show that, at least in the context of a toy model where exact results are available, the true strength of 2PI approximations derives from their self-consistency rather than any resummation. This self-consistency allows truncated 2PI approximations to capture the branch points of physical amplitudes where adjustments of coupling constants can trigger an instability of the vacuum. This, in effect, turns Dyson's argument for the failure of perturbation theory on its head. As a result we find that 2PI approximations perform better than Padé approximation and are competitive with Borel-Padé resummation. Finally, we introduce a hybrid 2PI-Padé method.

  3. Self-consistent models for triaxial galaxies with flat rotation curves - The disk case

    NASA Technical Reports Server (NTRS)

    Kuijken, Konrad

    1993-01-01

    We examine the possibility of constructing scale-free triaxial logarithmic potentials self-consistently, using Schwarzschild's linear programing method. In particular, we explore the limit of nonaxisymmetric disks. In this case it is possible to reduce the problem to the self-consistent reconstruction of the disk surface density on the unit circle, a considerably simpler problem than the usual 2D or 3D one. Models with surface densities of the form Sigma = (x exp n + (y/q) exp n) exp - 1/n with n = 2 or 4 are investigated. We show that the complicated shapes of the 'boxlet' orbit families (which replace the box orbit family found in potentials with smooth cores) limit the possibility of building self-consistent models, though elliptical disks of axis ratio above 0.7 and a restricted range of boxier models can be constructed. This result relies on using sufficiently fine bins, smaller than the 10 deg bins commonly used in 2D or 3D investigations. It also indicates the need for caution in interpreting N-body models of triaxial halos in which the core of the potential is numerically smoothed.

  4. Some exploitations of the self-consistent QRPA approach with the Gogny force

    SciTech Connect

    Peru, S.; Martini, M.; Dupuis, M.

    2012-10-20

    Fully consistent axially-symmetric-deformed quasiparticle random phase approximation calculations have been performed with the D1S Gogny force. Giant resonances in exotic nuclei as well as in deformed Mg and Si isotopes have been studied. Dipole responses have been calculated in Ne isotopes and N=16 isotones to study the existence of soft dipole modes in exotic nuclei. The same formalism has been used to describe multipole responses up to octupole in the deformed and heavy nucleus {sup 238}U. Low energy spectroscopy of nickel isotopes has been studied, revealing 0{sup +} states which display a particular structure.

  5. Self-consistent calculations of optical properties of type I and type II quantum heterostructures

    NASA Astrophysics Data System (ADS)

    Shuvayev, Vladimir A.

    In this Thesis the self-consistent computational methods are applied to the study of the optical properties of semiconductor nanostructures with one- and two-dimensional quantum confinements. At first, the self-consistent Schrodinger-Poisson system of equations is applied to the cylindrical core-shell structure with type II band alignment without direct Coulomb interaction between carriers. The electron and hole states and confining potential are obtained from a numerical solution of this system. The photoluminescence kinetics is theoretically analyzed, with the nanostructure size dispersion taken into account. The results are applied to the radiative recombination in the system of ZnTe/ZnSe stacked quantum dots. A good agreement with both continuous wave and time-resolved experimental observations is found. It is shown that size distribution results in the photoluminescence decay that has essentially non-exponential behavior even at the tail of the decay where the carrier lifetime is almost the same due to slowly changing overlap of the electron and hole wavefunctions. Also, a model situation applicable to colloidal core-shell nanowires is investigated and discussed. With respect to the excitons in type I quantum wells, a new computationally efficient and flexible approach of calculating the characteristics of excitons, based on a self-consistent variational treatment of the electron-hole Coulomb interaction, is developed. In this approach, a system of self-consistent equations describing the motion of an electron-hole pair is derived. The motion in the growth direction of the quantum well is separated from the in-plane motion, but each of them occurs in modified potentials found self-consistently. This approach is applied to a shallow quantum well with the delta-potential profile, for which analytical expressions for the exciton binding energy and the ground state eigenfunctions are obtained, and to the quantum well with the square potential profile with several

  6. Post-GW energies from an extended Bethe-Salpeter scheme

    NASA Astrophysics Data System (ADS)

    Maggio, Emanuele; Kresse, Georg

    Hedin's breakthrough in many-body physics is a computationally manageable scheme to implicitly account for many-body effects thanks to the introduction of a self-energy, whose expression is known but in practice approximated by truncation at some order in the inter-particle interaction. Hedin's scheme allows the computation of quasi-particle addition and removal energies. The introduction of an added particle (or hole) to the system will trigger the formation of higher order neutral excitations (particle/hole pairs formation). The widespread GW approximation only partially accounts for these effects by replacing the bare interparticle interaction with a dressed one. Other effects are contained in the vertex function and are typically disregarded.In the present work, we move beyond the GW level by including vertex effects in the self-energy. This is implemented by expressing the self-energy in terms of the reducible two-particle scattering amplitude. The latter is related to the kernel of the Bethe-Salpeter equation and to the corresponding polarisation propagator. The proposed implementation allows us to evaluate the quality of quasi-particle spectra for a range of realistic solids and molecular systems.

  7. Accurate description of the electronic structure of organic semiconductors by GW methods

    NASA Astrophysics Data System (ADS)

    Marom, Noa

    2017-03-01

    Electronic properties associated with charged excitations, such as the ionization potential (IP), the electron affinity (EA), and the energy level alignment at interfaces, are critical parameters for the performance of organic electronic devices. To computationally design organic semiconductors and functional interfaces with tailored properties for target applications it is necessary to accurately predict these properties from first principles. Many-body perturbation theory is often used for this purpose within the GW approximation, where G is the one particle Green’s function and W is the dynamically screened Coulomb interaction. Here, the formalism of GW methods at different levels of self-consistency is briefly introduced and some recent applications to organic semiconductors and interfaces are reviewed.

  8. Self-consistent generalized Langevin-equation theory for liquids of nonspherically interacting particles.

    PubMed

    Elizondo-Aguilera, L F; Zubieta Rico, P F; Ruiz-Estrada, H; Alarcón-Waess, O

    2014-11-01

    A self-consistent generalized Langevin-equation theory is proposed to describe the self- and collective dynamics of a liquid of linear Brownian particles. The equations of motion for the spherical harmonics projections of the collective and self-intermediate-scattering functions, F_{lm,lm}(k,t) and F_{lm,lm}^{S}(k,t), are derived as a contraction of the description involving the stochastic equations of the corresponding tensorial one-particle density n_{lm}(k,t) and the translational (α=T) and rotational (α=R) current densities j_{lm}^{α}(k,t). Similar to the spherical case, these dynamic equations require as an external input the equilibrium structural properties of the system contained in the projections of the static structure factor, denoted by S_{lm,lm}(k). Complementing these exact equations with simple (Vineyard-like) approximate relations for the collective and the self-memory functions we propose a closed self-consistent set of equations for the dynamic properties involved. In the long-time asymptotic limit, these equations become the so-called bifurcation equations, whose solutions (the nonergodicity parameters) can be written, extending the spherical case, in terms of one translational and one orientational scalar dynamic order parameter, γ_{T} and γ_{R}, which characterize the possible dynamical arrest transitions of the system. As a concrete illustrative application of this theory we determine the dynamic arrest diagram of the dipolar hard-sphere fluid. In qualitative agreement with mode coupling theory, the present self-consistent equations also predict three different regions in the state space spanned by the macroscopic control parameters η (volume fraction) and T* (scaled temperature): a region of fully ergodic states, a region of mixed states, in which the translational degrees of freedom become arrested while the orientational degrees of freedom remain ergodic, and a region of fully nonergodic states.

  9. Self-consistent mode-coupling approach to one-dimensional heat transport

    NASA Astrophysics Data System (ADS)

    Delfini, Luca; Lepri, Stefano; Livi, Roberto; Politi, Antonio

    2006-06-01

    In the present Rapid Communication we present an analytical and numerical solution of the self-consistent mode-coupling equations for the problem of heat conductivity in one-dimensional systems. Such a solution leads us to propose a different scenario to accommodate the known results obtained so far for this problem. More precisely, we conjecture that the universality class is determined by the leading order of the nonlinear interaction potential. Moreover, our analysis allows us to determine the memory kernel, whose expression puts on a more firm basis the previously conjectured connection between anomalous heat conductivity and anomalous diffusion.

  10. Size-consistent self-consistent configuration interaction from a complete active space

    NASA Astrophysics Data System (ADS)

    Ben Amor, Nadia; Maynau, Daniel

    1998-04-01

    The size-consistent self-consistent (SC) 2 method is based on intermediate Hamiltonians and ensures size-extensivity of any configuration interaction (CI) by correcting its diagonal elements. In this work, an (SC) 2 dressing is proposed on a complete active space SDCI. This approach yields a more efficient code which can treat larger multireference problems. Tests are proposed on the potential energy curve of F 2, the bond stretching of water and the inclusion of an Be atom in the H 2 molecule. Comparisons with approximate methods such as average quadratic coupled cluster (AQCC) are presented. AQCC appears as a good approximation to (SC) 2.

  11. Strain distribution due to surface domains: a self-consistent approach with respect to surface elasticity

    PubMed Central

    Fuhr, Javier

    2015-01-01

    Summary Elastically mediated interactions between surface domains are classically described in terms of point forces. Such point forces lead to local strain divergences that are usually avoided by introducing a poorly defined cut-off length. In this work, we develop a self-consistent approach in which the strain field induced by the surface domains is expressed as the solution of an integral equation that contains surface elastic constants, S ij. For surfaces with positive S ij the new approach avoids the introduction of a cut-off length. The classical and the new approaches are compared in case of 1-D periodic ribbons. PMID:25821670

  12. Premixed Combustion Simulations with a Self-Consistent Plasma Model for Initiation

    SciTech Connect

    Sitaraman, Hariswaran; Grout, Ray

    2016-01-08

    Combustion simulations of H2-O2 ignition are presented here, with a self-consistent plasma fluid model for ignition initiation. The plasma fluid equations for a nanosecond pulsed discharge are solved and coupled with the governing equations of combustion. The discharge operates with the propagation of cathode directed streamer, with radical species produced at streamer heads. These radical species play an important role in the ignition process. The streamer propagation speeds and radical production rates were found to be sensitive to gas temperature and fuel-oxidizer equivalence ratio. The oxygen radical production rates strongly depend on equivalence ratio and subsequently results in faster ignition of leaner mixtures.

  13. Self-consistent study of the alpha particle driven TAE mode

    SciTech Connect

    Wu, Y.; White, R.B.

    1994-04-01

    The interaction of high energy particles with an Alfven eigenmode is investigated self-consistently by using a realistic kinetic dispersion relation. All important poloidal mode numbers and their radial mode profiles as calculated with the NOVA-K code are included. A Hamiltonian guiding center code is used to simulate the alpha particle motion. The numerical simulations include particle orbit width, nonlinear particle dynamics and the effects of the modes on the particles. Modification of the particle distribution leading to mode saturation is observed. Particle loss is limited to devices in which the alpha particle gyro radius is a significant fraction of the minor radius.

  14. A self-consistent quasistatic equilibrium for non-neutral diamagnetic electron vortices

    SciTech Connect

    Church, B.W.; Sudan, R.N.

    1995-06-01

    A self-consistent quasistatic equilibrium for a non-neutral cylindrical electron vortex has been found using the two-dimensional relativistic electron fluid equations. While other work on electron vortices considered a regime where the vortex radius is much smaller than the collisionless skin depth {lambda}={ital c}/{omega}{sub {ital p}}, this equilibrium is valid for large-radius, diamagnetic vortices and predicts a maximum radius of 2{sup 3/2}{lambda} for a highly relativistic electron vortex. The vortex model shows good agreement with observations of diamagnetic electron vortices in two-dimensional electromagnetic particle-in-cell simulations of magnetically insulated transmission lines.

  15. Vibrational self-consistent field calculations for spectroscopy of biological molecules: new algorithmic developments and applications.

    PubMed

    Roy, Tapta Kanchan; Gerber, R Benny

    2013-06-28

    This review describes the vibrational self-consistent field (VSCF) method and its other variants for computing anharmonic vibrational spectroscopy of biological molecules. The superiority and limitations of this algorithm are discussed with examples. The spectroscopic accuracy of the VSCF method is compared with experimental results and other available state-of-the-art algorithms for various biologically important systems. For large biological molecules with many vibrational modes, the scaling of computational effort is investigated. The accuracy of the vibrational spectra of biological molecules using the VSCF approach for different electronic structure methods is also assessed. Finally, a few open problems and challenges in this field are discussed.

  16. Self-consistent relativistic random-phase approximation with vacuum polarization

    SciTech Connect

    Haga, A.; Toki, H.; Tamenaga, S.; Horikawa, Y.; Yadav, H.L.

    2005-09-01

    We present a theoretical formulation for the description of nuclear excitations within the framework of a relativistic random-phase approximation whereby the vacuum polarization arising from nucleon-antinucleon fields is duly accounted for. The vacuum contribution to the Lagrangian is explicitly described as extra new terms of interacting mesons by means of the derivative expansion of the effective action. It is shown that the self-consistent calculation yields zero eigenvalue for the spurious isoscalar-dipole state and also conserves the vector-current density.

  17. Self-consistent high-Reynolds-number asymptotics for zero-pressure-gradient turbulent boundary layers

    NASA Astrophysics Data System (ADS)

    Monkewitz, Peter A.; Chauhan, Kapil A.; Nagib, Hassan M.

    2007-11-01

    The asymptotic behavior of mean velocity and integral parameters in flat plate turbulent boundary layers under zero pressure gradient are studied for Reynolds numbers approaching infinity. Using the classical two-layer approach of Millikan, Rotta, and Clauser with a logarithmic velocity profile in the overlap region between "inner" and "outer" layers, a fully self-consistent leading-order description of the mean velocity profile and all integral parameters is developed. It is shown that this description fits most high Reynolds number data, and in particular their Reynolds number dependence, exceedingly well; i.e., within experimental errors.

  18. Self-consistent linear response for the spin-orbit interaction related properties

    NASA Astrophysics Data System (ADS)

    Solovyev, I. V.

    2014-07-01

    In many cases, the relativistic spin-orbit (SO) interaction can be regarded as a small perturbation to the electronic structure of solids and treated using regular perturbation theory. The major obstacle on this route comes from the fact that the SO interaction can also polarize the electron system and produce some additional contributions to the perturbation theory expansion, which arise from the electron-electron interactions in the same order of the SO coupling. In electronic structure calculations, it may even lead to the necessity of abandoning the perturbation theory and returning to the original self-consistent solution of Kohn-Sham-like equations with the effective potential v̂, incorporating simultaneously the effects of the electron-electron interactions and the SO coupling, even though the latter is small. In this work, we present the theory of self-consistent linear response (SCLR), which allows us to get rid of numerical self-consistency and formulate the last step fully analytically in the first order of the SO coupling. This strategy is applied to the unrestricted Hartree-Fock solution of an effective Hubbard-type model, derived from the first-principles electronic structure calculations in the basis of Wannier functions for the magnetically active states. We show that by using v̂, obtained in SCLR, one can successfully reproduce results of ordinary self-consistent calculations for the orbital magnetization and other properties, which emerge in the first order of the SO coupling. Particularly, SCLR appears to be an extremely useful approach for calculations of antisymmetric Dzyaloshinskii-Moriya (DM) interactions based on the magnetic force theorem, where only by using the total perturbation one can make a reliable estimate for the DM parameters. Furthermore, due to the powerful 2n+1 theorem, the SCLR theory allows us to obtain the total energy change up to the third order of the SO coupling, which can be used in calculations of magnetic anisotropy

  19. VCSEL modeling with self-consistent models: From simple approximations to comprehensive numerical analysis

    NASA Astrophysics Data System (ADS)

    Dems, Maciej; Beling, Piotr; Gebski, Marcin; Piskorski, Łukasz; Walczak, Jarosław; Kuc, Maciej; Frasunkiewicz, Leszek; Wasiak, Michał; Sarzała, Robert; Czyszanowski, Tomasz

    2015-03-01

    In the talk we show the process of modeling complete physical properties of VCSELs and we present a step-by-step development of its complete multi-physics model, gradually improving its accuracy. Then we introduce high contrast gratings to the VCSEL design, which strongly complicates its optical modeling, making the comprehensive multi-physics VCSEL simulation a challenging task. We show, however, that a proper choice of a self-consistent simulation algorithm can still make such a simulation a feasible one, which is necessary for an efficient optimization of the laser prior to its costly manufacturing.

  20. Self-Consistent Orbital Evolution of a Particle around a Schwarzschild Black Hole

    NASA Astrophysics Data System (ADS)

    Diener, Peter; Vega, Ian; Wardell, Barry; Detweiler, Steven

    2012-05-01

    The motion of a charged particle is influenced by the self-force arising from the particle’s interaction with its own field. In a curved spacetime, this self-force depends on the entire past history of the particle and is difficult to evaluate. As a result, all existing self-force evaluations in curved spacetime are for particles moving along a fixed trajectory. Here, for the first time, we overcome this long-standing limitation and present fully self-consistent orbits and waveforms of a scalar charged particle around a Schwarzschild black hole.

  1. Self-consistent collective coordinate for reaction path and inertial mass

    NASA Astrophysics Data System (ADS)

    Wen, Kai; Nakatsukasa, Takashi

    2016-11-01

    We propose a numerical method to determine the optimal collective reaction path for a nucleus-nucleus collision, based on the adiabatic self-consistent collective coordinate (ASCC) method. We use an iterative method, combining the imaginary-time evolution and the finite amplitude method, for the solution of the ASCC coupled equations. It is applied to the simplest case, α -α scattering. We determine the collective path, the potential, and the inertial mass. The results are compared with other methods, such as the constrained Hartree-Fock method, Inglis's cranking formula, and the adiabatic time-dependent Hartree-Fock (ATDHF) method.

  2. Variational Geminal-augmented Multireference Self-consistent Field Theory: Two-electron Systems

    SciTech Connect

    Varganov, Sergey

    2010-06-18

    We introduce a geminal-augmented multiconfigurational self-consistent field method for describing electron correlation effects. The approach is based on variational optimization of a MCSCF-type wave function augmented by a single geminal. This wave function is able to account for some dynamic correlation without explicit excitations to virtual molecular orbitals. Test calculations on two-electron systems demonstrate the ability of the proposed method to describe ionic and covalent electronic states in a balanced way, i.e., including the effects of both static and dynamic correlation simultaneously. Extension of the theory to larger systems will potentially provide an alternative to standard multireference methods.

  3. General variational many-body theory with complete self-consistency for trapped bosonic systems

    SciTech Connect

    Streltsov, Alexej I.; Alon, Ofir E.; Cederbaum, Lorenz S.

    2006-06-15

    In this work we develop a complete variational many-body theory for a system of N trapped bosons interacting via a general two-body potential. The many-body solution of this system is expanded over orthogonal many-body basis functions (configurations). In this theory both the many-body basis functions and the respective expansion coefficients are treated as variational parameters. The optimal variational parameters are obtained self-consistently by solving a coupled system of noneigenvalue--generally integro-differential--equations to get the one-particle functions and by diagonalizing the secular matrix problem to find the expansion coefficients. We call this theory multiconfigurational Hartree theory for bosons or MCHB(M), where M specifies explicitly the number of one-particle functions used to construct the configurations. General rules for evaluating the matrix elements of one- and two-particle operators are derived and applied to construct the secular Hamiltonian matrix. We discuss properties of the derived equations. We show that in the limiting cases of one configuration the theory boils down to the well-known Gross-Pitaevskii and the recently developed multi-orbital mean fields. The invariance of the complete solution with respect to unitary transformations of the one-particle functions is utilized to find the solution with the minimal number of contributing configurations. In the second part of our work we implement and apply the developed theory. It is demonstrated that for any practical computation where the configurational space is restricted, the description of trapped bosonic systems strongly depends on the choice of the many-body basis set used, i.e., self-consistency is of great relevance. As illustrative examples we consider bosonic systems trapped in one- and two-dimensional symmetric and asymmetric double well potentials. We demonstrate that self-consistency has great impact on the predicted physical properties of the ground and excited states

  4. Properties of hadronic systems according to the non-extensive self-consistent thermodynamics

    SciTech Connect

    Deppman, A.

    2014-11-11

    The non-extensive self-consistent theory describing the thermodynamics of hadronic systems at high temperatures is used to derive some thermodynamical quantities, as pressure, entropy, speed of sound and trace-anomaly. The calculations are free of fitting parameters, and the results are compared to lattice QCD calculations, showing a good agreement between theory and data up to temperatures around 175 MeV. Above this temperature the effects of a singularity in the partition function at T{sub o} = 192 MeV results in a divergent behaviour in respect with the lattice calculation.

  5. Self-Consistent Field Approach for Cross-Linked Copolymer Materials

    NASA Astrophysics Data System (ADS)

    Schmid, Friederike

    2013-07-01

    A generalized self-consistent field approach for polymer networks with a fixed topology is developed. It is shown that the theory reproduces the localization of cross-links, which is characteristic for gels. The theory is then used to study the order-disorder transition in regular networks of end-linked diblock copolymers. Compared to diblock copolymer melts, the transition is shifted towards lower values of the incompatibility parameter χ (the Flory- Huggins parameter). Moreover, the transition becomes strongly first order already at the mean-field level. If stress is applied, the transition is further shifted and finally vanishes in a critical point.

  6. Self-consistent theory of electronic states in topological broken-gap quantum wells

    NASA Astrophysics Data System (ADS)

    Winkler, R.

    Recently broken-gap quantum wells made of InAs/GaSb/AlSb have raised great interest as they may show a gate-tunable phase transition from a trivial phase to a topologically protected quantum spin Hall phase. We present a quantitative self-consistent theory of electronic states in such systems taking into account the charge transfer between different layers which can substantially modify the level structure including the phase boundary between the inverted and non-inverted regime. We also discuss spin effects and the unusual Landau fans in a quantizing magnetic field. Work supported by the NSF Grant DMR-1310199.

  7. Problems in the self-consistent profile approach to the theory of laser mode-locking

    NASA Astrophysics Data System (ADS)

    New, G. H. C.; Catherall, J. M.

    1984-05-01

    The 'self-consistent profile' approach to mode-locking theory, in the case of a laser medium with a short recovery time is studied. Taking the case of mode-locking by synchronous pumping as a specific example, steady-state profiles derived from a commonly-used approximate method are compared with those generated by an essentially exact numerical technique. Substantial discrepancies in the solutions are shown to arise from invalid assumptions in the standard approach, suggesting that results predicted by this method in other areas of mode-locking theory should be treated with caution.

  8. Solvent effects in time-dependent self-consistent field methods. I. Optical response calculations

    DOE PAGES

    Bjorgaard, J. A.; Kuzmenko, V.; Velizhanin, K. A.; ...

    2015-01-22

    In this study, we implement and examine three excited state solvent models in time-dependent self-consistent field methods using a consistent formalism which unambiguously shows their relationship. These are the linear response, state specific, and vertical excitation solvent models. Their effects on energies calculated with the equivalent of COSMO/CIS/AM1 are given for a set of test molecules with varying excited state charge transfer character. The resulting solvent effects are explained qualitatively using a dipole approximation. It is shown that the fundamental differences between these solvent models are reflected by the character of the calculated excitations.

  9. Self-consistent Hartree-Fock approach for interacting bosons in optical lattices

    NASA Astrophysics Data System (ADS)

    Lü, Qin-Qin; Patton, Kelly R.; Sheehy, Daniel E.

    2014-12-01

    A theoretical study of interacting bosons in a periodic optical lattice is presented. Instead of the commonly used tight-binding approach (applicable near the Mott-insulating regime of the phase diagram), the present work starts from the exact single-particle states of bosons in a cubic optical lattice, satisfying the Mathieu equation, an approach that can be particularly useful at large boson fillings. The effects of short-range interactions are incorporated using a self-consistent Hartree-Fock approximation, and predictions for experimental observables such as the superfluid transition temperature, condensate fraction, and boson momentum distribution are presented.

  10. Pressure tensor in the presence of velocity shear: Stationary solutions and self-consistent equilibria

    SciTech Connect

    Cerri, S. S.; Pegoraro, F.; Califano, F.; Jenko, F.

    2014-11-15

    Observations and numerical simulations of laboratory and space plasmas in almost collisionless regimes reveal anisotropic and non-gyrotropic particle distribution functions. We investigate how such states can persist in the presence of a sheared flow. We focus our attention on the pressure tensor equation in a magnetized plasma and derive analytical self-consistent plasma equilibria which exhibit a novel asymmetry with respect to the magnetic field direction. These results are relevant for investigating, within fluid models that retain the full pressure tensor dynamics, plasma configurations where a background shear flow is present.

  11. A Self Consistent Multiprocessor Space Charge Algorithm that is Almost Embarrassingly Parallel

    SciTech Connect

    Edward Nissen, B. Erdelyi, S.L. Manikonda

    2012-07-01

    We present a space charge code that is self consistent, massively parallelizeable, and requires very little communication between computer nodes; making the calculation almost embarrassingly parallel. This method is implemented in the code COSY Infinity where the differential algebras used in this code are important to the algorithm's proper functioning. The method works by calculating the self consistent space charge distribution using the statistical moments of the test particles, and converting them into polynomial series coefficients. These coefficients are combined with differential algebraic integrals to form the potential, and electric fields. The result is a map which contains the effects of space charge. This method allows for massive parallelization since its statistics based solver doesn't require any binning of particles, and only requires a vector containing the partial sums of the statistical moments for the different nodes to be passed. All other calculations are done independently. The resulting maps can be used to analyze the system using normal form analysis, as well as advance particles in numbers and at speeds that were previously impossible.

  12. Calculating gravitationally self-consistent sea level changes driven by dynamic topography

    NASA Astrophysics Data System (ADS)

    Austermann, J.; Mitrovica, J. X.

    2015-12-01

    We present a generalized formalism for computing gravitationally self-consistent sea level changes driven by the combined effects of dynamic topography, geoid perturbations due to mantle convection, ice mass fluctuations and sediment redistribution on a deforming Earth. Our mathematical treatment conserves mass of the surface (ice plus ocean) load and the solid Earth. Moreover, it takes precise account of shoreline migration and the associated ocean loading. The new formalism avoids a variety of approximations adopted in previous models of sea level change driven by dynamic topography, including the assumption that a spatially fixed isostatic amplification of `air-loaded' dynamic topography accurately accounts for ocean loading effects. While our approach is valid for Earth models of arbitrary complexity, we present numerical results for a set of simple cases in which a pattern of dynamic topography is imposed, the response to surface mass loading assumes that Earth structure varies only with depth and that isostatic equilibrium is maintained at all times. These calculations, involving fluid Love number theory, indicate that the largest errors in previous predictions of sea level change driven by dynamic topography occur in regions of shoreline migration, and thus in the vicinity of most geological markers of ancient sea level. We conclude that a gravitationally self-consistent treatment of long-term sea level change is necessary in any effort to use such geological markers to estimate ancient ice volumes.

  13. Fractional charge and spin errors in self-consistent Green’s function theory

    SciTech Connect

    Phillips, Jordan J. Kananenka, Alexei A.; Zgid, Dominika

    2015-05-21

    We examine fractional charge and spin errors in self-consistent Green’s function theory within a second-order approximation (GF2). For GF2, it is known that the summation of diagrams resulting from the self-consistent solution of the Dyson equation removes the divergences pathological to second-order Møller-Plesset (MP2) theory for strong correlations. In the language often used in density functional theory contexts, this means GF2 has a greatly reduced fractional spin error relative to MP2. The natural question then is what effect, if any, does the Dyson summation have on the fractional charge error in GF2? To this end, we generalize our previous implementation of GF2 to open-shell systems and analyze its fractional spin and charge errors. We find that like MP2, GF2 possesses only a very small fractional charge error, and consequently minimal many electron self-interaction error. This shows that GF2 improves on the critical failings of MP2, but without altering the positive features that make it desirable. Furthermore, we find that GF2 has both less fractional charge and fractional spin errors than typical hybrid density functionals as well as random phase approximation with exchange.

  14. Radio-frequency sheaths physics: Experimental characterization on Tore Supra and related self-consistent modeling

    NASA Astrophysics Data System (ADS)

    Jacquot, Jonathan; Milanesio, Daniele; Colas, Laurent; Corre, Yann; Goniche, Marc; Gunn, Jamie; Heuraux, Stéphane; Kubic, Martin

    2014-02-01

    During the 2011 experimental campaign, one of the three ion cyclotron resonance heating (ICRH) antennas in the Tore Supra (TS) tokamak was equipped with a new type of Faraday screen (FS). The new design aimed at minimizing RF sheaths as well as increasing the heat exhaust capability of the actively cooled screen. It proved to be inefficient for attenuating the RF-sheaths on the screen itself on the contrary to the heat exhaust concept that allowed operation despite higher heat fluxes on the antenna. In parallel, a new approach has been proposed to model self-consistently RF sheaths: the SSWICH (Self-consistent Sheaths and Waves for IC Heating) code. Simulations results from SSWICH coupled with the TOPICA antenna code were able to reproduce the difference between the two FS designs and part of the spatial pattern of heat loads and floating potential. The poloidal pattern is a reliable result that mainly depends on the electrical design of the antenna while the radial pattern is on the contrary highly sensitive to loosely constrained parameters such as perpendicular conductivity that generates a DC current circulation from the the private region inside the antenna limiters to the free SOL outside these limiters. Moreover the cantilevered bars seem to be the element in the design of the new screen that enhanced RF sheaths.

  15. Radio-frequency sheaths physics: Experimental characterization on Tore Supra and related self-consistent modeling

    NASA Astrophysics Data System (ADS)

    Jacquot, Jonathan; Milanesio, Daniele; Colas, Laurent; Corre, Yann; Goniche, Marc; Gunn, Jamie; Heuraux, Stéphane; Kubič, Martin

    2014-06-01

    During the 2011 experimental campaign, one of the three ion cyclotron resonance heating (ICRH) antennas in the Tore Supra tokamak was equipped with a new type of Faraday screen (FS). The new design aimed at minimizing the integrated parallel electric field over long field lines as well as increasing the heat exhaust capability of the actively cooled screen. It proved to be inefficient for attenuating the radio-frequency (RF)-sheaths on the screen itself on the contrary to the heat exhaust concept that allowed operation despite higher heat fluxes on the antenna. In parallel, a new approach has been proposed to model self-consistently RF sheaths: the SSWICH (Self-consistent Sheaths and Waves for IC Heating) code. Simulations results from SSWICH coupled with the TOPICA antenna code were able to reproduce the difference between the two FS designs and part of the spatial pattern of heat loads and Langmuir probe floating potential. The poloidal pattern is a reliable result that mainly depends on the electrical design of the antenna while the radial pattern is on the contrary highly sensitive to loosely constrained parameters such as perpendicular conductivity that generates a DC current circulation from the private region inside the antenna limiters to the free scrape off layer outside these limiters. Moreover, the cantilevered bars seem to be the element in the screen design that enhanced the plasma potential.

  16. Self-consistent field model for strong electrostatic correlations and inhomogeneous dielectric media

    SciTech Connect

    Ma, Manman Xu, Zhenli

    2014-12-28

    Electrostatic correlations and variable permittivity of electrolytes are essential for exploring many chemical and physical properties of interfaces in aqueous solutions. We propose a continuum electrostatic model for the treatment of these effects in the framework of the self-consistent field theory. The model incorporates a space- or field-dependent dielectric permittivity and an excluded ion-size effect for the correlation energy. This results in a self-energy modified Poisson-Nernst-Planck or Poisson-Boltzmann equation together with state equations for the self energy and the dielectric function. We show that the ionic size is of significant importance in predicting a finite self energy for an ion in an inhomogeneous medium. Asymptotic approximation is proposed for the solution of a generalized Debye-Hückel equation, which has been shown to capture the ionic correlation and dielectric self energy. Through simulating ionic distribution surrounding a macroion, the modified self-consistent field model is shown to agree with particle-based Monte Carlo simulations. Numerical results for symmetric and asymmetric electrolytes demonstrate that the model is able to predict the charge inversion at high correlation regime in the presence of multivalent interfacial ions which is beyond the mean-field theory and also show strong effect to double layer structure due to the space- or field-dependent dielectric permittivity.

  17. Ring current Atmosphere interactions Model with Self-Consistent Magnetic field

    SciTech Connect

    Jordanova, Vania; Jeffery, Christopher; Welling, Daniel

    2016-09-09

    The Ring current Atmosphere interactions Model with Self-Consistent magnetic field (B) is a unique code that combines a kinetic model of ring current plasma with a three dimensional force-balanced model of the terrestrial magnetic field. The kinetic portion, RAM, solves the kinetic equation to yield the bounce-averaged distribution function as a function of azimuth, radial distance, energy and pitch angle for three ion species (H+, He+, and O+) and, optionally, electrons. The domain is a circle in the Solar-Magnetic (SM) equatorial plane with a radial span of 2 to 6.5 RE. It has an energy range of approximately 100 eV to 500 KeV. The 3-D force balanced magnetic field model, SCB, balances the JxB force with the divergence of the general pressure tensor to calculate the magnetic field configuration within its domain. The domain ranges from near the Earth’s surface, where the field is assumed dipolar, to the shell created by field lines passing through the SM equatorial plane at a radial distance of 6.5 RE. The two codes work in tandem, with RAM providing anisotropic pressure to SCB and SCB returning the self-consistent magnetic field through which RAM plasma is advected.

  18. Wave solutions of ion cyclotron heated plasmas with self-consistent velocity distributions in a tokamak

    NASA Astrophysics Data System (ADS)

    Lee, Jungpyo; Wright, John; Bonoli, Paul; Harvey, Robert

    2015-11-01

    We describe a numerical model for the propagation and absorption of ion cyclotron waves in a tokamak with a non-Maxwellian velocity space distribution function. The non-Maxwellian distribution is calculated by solving Maxwell's equations and the Fokker-Plank equation self-consistently. This approach will be useful to interpret measurements of minority hydrogen tail formation during ICRF heating experiments in Alcator C-Mod. To couple the Maxwell equation solver with Fokker-Plank equation solver, the quasilinear diffusion coefficients for the fundamental ion cyclotron absorption and the first harmonic absorption are calculated. In a previous study, the all-orders spectral algorithm wave solver (AORSA) was coupled with the Fokker-Plank code (CQL3D) to find the self-consistent non-Maxwellian distribution. We derive the modified quasilinear diffusion coefficients for the finite Larmor radius (FLR) approximation using a significantly faster wave solver (TORIC) following the approach by Jaeger. The coupled TORIC-CQL3D model will be compared against results from AORSA-CQL3D in order to verify the accuracy of the reduced FLR physics in TORIC. Work supported by US Department of Energy Contract No. DE-FC02-01ER54648.

  19. Self-Consistent Hybrid Functional Calculations: Implications for Structural, Electronic, and Optical Properties of Oxide Semiconductors

    NASA Astrophysics Data System (ADS)

    Fritsch, Daniel; Morgan, Benjamin J.; Walsh, Aron

    2017-01-01

    The development of new exchange-correlation functionals within density functional theory means that increasingly accurate information is accessible at moderate computational cost. Recently, a newly developed self-consistent hybrid functional has been proposed (Skone et al., Phys. Rev. B 89:195112, 2014), which allows for a reliable and accurate calculation of material properties using a fully ab initio procedure. Here, we apply this new functional to wurtzite ZnO, rutile SnO2, and rocksalt MgO. We present calculated structural, electronic, and optical properties, which we compare to results obtained with the PBE and PBE0 functionals. For all semiconductors considered here, the self-consistent hybrid approach gives improved agreement with experimental structural data relative to the PBE0 hybrid functional for a moderate increase in computational cost, while avoiding the empiricism common to conventional hybrid functionals. The electronic properties are improved for ZnO and MgO, whereas for SnO2 the PBE0 hybrid functional gives the best agreement with experimental data.

  20. Self-consistent order-{ital N} density-functional calculations for very large systems

    SciTech Connect

    Ordejon, P.; Artacho, E.; Soler, J.M.

    1996-04-01

    We present a method to perform fully self-consistent density-functional calculations that scales linearly with the system size and which is well suited for very large systems. It uses strictly localized pseudoatomic orbitals as basis functions. The sparse Hamiltonian and overlap matrices are calculated with an {ital O}({ital N}) effort. The long-range self-consistent potential and its matrix elements are computed in a real-space grid. The other matrix elements are directly calculated and tabulated as a function of the interatomic distances. The computation of the total energy and atomic forces is also done in {ital O}({ital N}) operations using truncated, Wannier-like localized functions to describe the occupied states, and a band-energy functional which is iteratively minimized with no orthogonality constraints. We illustrate the method with several examples, including carbon and silicon supercells with up to 1000 Si atoms and supercells of {beta}-C{sub 3}N{sub 4}. We apply the method to solve the existing controversy about the faceting of large icosahedral fullerenes by performing dynamical simulations on C{sub 60}, C{sub 240}, and C{sub 540}. {copyright} {ital 1996 The American Physical Society.}

  1. Monte Carlo simulation and self-consistent integral equation theory for polymers in quenched random media.

    PubMed

    Sung, Bong June; Yethiraj, Arun

    2005-08-15

    The conformational properties and static structure of freely jointed hard-sphere chains in matrices composed of stationary hard spheres are studied using Monte Carlo simulations and integral equation theory. The simulations show that the chain size is a nonmonotonic function of the matrix density when the matrix spheres are the same size as the monomers. When the matrix spheres are of the order of the chain size the chain size decreases monotonically with increasing matrix volume fraction. The simulations are used to test the replica-symmetric polymer reference interaction site model (RSP) integral equation theory. When the simulation results for the intramolecular correlation functions are input into the theory, the agreement between theoretical predictions and simulation results for the pair-correlation functions is quantitative only at the highest fluid volume fractions and for small matrix sphere sizes. The RSP theory is also implemented in a self-consistent fashion, i.e., the intramolecular and intermolecular correlation functions are calculated self-consistently by combining a field theory with the integral equations. The theory captures qualitative trends observed in the simulations, such as the nonmonotonic dependence of the chain size on media fraction.

  2. A Self-Consistent Plasma-Sheath Model for the Inductively Coupled Plasma Reactor

    NASA Technical Reports Server (NTRS)

    Bose, Deepak; Govindam, T. R.; Meyyappan, M.

    2000-01-01

    Accurate determination of ion flux on a wafer requires a self-consistent, multidimensional modeling of plasma reactor that adequately resolves the sheath region adjoining the wafer. This level of modeling is difficult to achieve since non-collisional sheath lengths are usually 3-4 orders of magnitude smaller than the reactor scale. Also, the drift-diffusion equations used for ion transport becomes invalid in the sheath since the ion frictional force is no longer in equilibrium with drift and diffusion forces. The alternative is to use a full momentum equation for each ionic species. In this work we will present results from a self-consistent reactor scale-sheath scale model for 2D inductively coupled plasmas. The goal of this study is to improve the modeling capabilities and assess the importance of additional physics in determining important reactor performance features, such as the ion flux uniformity, coil frequency and configuration effects, etc. Effect of numerical dissipation on the solution quality will also be discussed.

  3. New Class of Self-Consistent Current Sheets and Filaments in Collisionless Plasma

    NASA Astrophysics Data System (ADS)

    Derishev, E. V.; Kocharovsky, V. V.; Kocharovsky, Vl. V.; Martyanov, V. Yu.

    2006-08-01

    A continuous set of stationary current sheets and filaments in collisionless multi-component plasma is found analytically using integrals of two-dimensional motion of particles in the self-consistent magnetic field. In our solutions, which are relativistic in general, the magnetic energy density can be comparable to that of particles, and the spatial scale can be arbitrary compared to typical gyroradius of the particles. We consider the properties of newly found stationary solutions and their possible applications to analysis of magnetic field configurations emerging in various astrophysical plasmas, including coronal structures, shocks and jets. The results are used for interpretation of recent observations and numerical simulations. By choosing particular dependence of particle distribution function on the integrals of motion we are able to obtain various profiles of magnetic field and self-consistent current, including non-monotone. The obtained solutions describe much more general class of equilibrium configurations as compared to known generalizations of Harris current sheets. On this basis, we suggest a way to describe slow dynamics and filamentation of collisionless current configurations in coronal plasma and in Active Galactic Nuclei, Gamma-Ray Bursts, and microquasars.

  4. Self-consistent evolution of accreting low-mass stars and brown dwarfs

    NASA Astrophysics Data System (ADS)

    Baraffe, I.; Elbakyan, V. G.; Vorobyov, E. I.; Chabrier, G.

    2017-01-01

    We present self-consistent calculations coupling numerical hydrodynamics simulations of collapsing pre-stellar cores and stellar evolution models of accreting objects. We analyse the main impact of consistent accretion history on the evolution and lithium depletion of young low-mass stars and brown dwarfs. These consistent models confirm the generation of a luminosity spread in Herzsprung-Russell diagrams at ages 1-10 Myr. They also confirm that early accretion can produce objects with abnormal Li depletion, as found in a previous study that was based on arbitrary accretion rates. The results strengthen that objects with anomalously high level of Li depletion in young clusters should be extremely rare. We also find that early phases of burst accretion can produce coeval models of similar mass with a range of different Li surface abundances, and in particular with Li-excess compared to the predictions of non-accreting counterparts. This result is due to a subtle competition between the effect of burst accretion and its impact on the central stellar temperature, the growth of the stellar radiative core and the accretion of fresh Li from the accretion disk. Only consistent models could reveal such a subtle combination of effects. This new result could explain the recent, puzzling observations of Li-excess of fast rotators in the young cluster NGC 2264. Present self-consistent accreting models are available in electronic form.

  5. Self-consistent theory of nanodomain formation on non-polar surfaces of ferroelectrics

    DOE PAGES

    Morozovska, Anna N.; Obukhovskii, Vyacheslav; Fomichov, Evhen; ...

    2016-04-28

    We propose a self-consistent theoretical approach capable of describing the features of the anisotropic nanodomain formation induced by a strongly inhomogeneous electric field of a charged scanning probe microscopy tip on nonpolar cuts of ferroelectrics. We obtained that a threshold field, previously regarded as an isotropic parameter, is an anisotropic function that is specified from the polar properties and lattice pinning anisotropy of a given ferroelectric in a self-consistent way. The proposed method for the calculation of the anisotropic threshold field is not material specific, thus the field should be anisotropic in all ferroelectrics with the spontaneous polarization anisotropy alongmore » the main crystallographic directions. The most evident examples are uniaxial ferroelectrics, layered ferroelectric perovskites, and low-symmetry incommensurate ferroelectrics. Obtained results quantitatively describe the differences at several times in the nanodomain length experimentally observed on X and Y cuts of LiNbO3 and can give insight into the anisotropic dynamics of nanoscale polarization reversal in strongly inhomogeneous electric fields.« less

  6. Self-consistent theory of nanodomain formation on non-polar surfaces of ferroelectrics

    SciTech Connect

    Morozovska, Anna N.; Obukhovskii, Vyacheslav; Fomichov, Evhen; Varenyk, O. V.; Shur, Vladimir Ya.; Kalinin, Sergei V.; Eliseev, E. A.

    2016-04-28

    We propose a self-consistent theoretical approach capable of describing the features of the anisotropic nanodomain formation induced by a strongly inhomogeneous electric field of a charged scanning probe microscopy tip on nonpolar cuts of ferroelectrics. We obtained that a threshold field, previously regarded as an isotropic parameter, is an anisotropic function that is specified from the polar properties and lattice pinning anisotropy of a given ferroelectric in a self-consistent way. The proposed method for the calculation of the anisotropic threshold field is not material specific, thus the field should be anisotropic in all ferroelectrics with the spontaneous polarization anisotropy along the main crystallographic directions. The most evident examples are uniaxial ferroelectrics, layered ferroelectric perovskites, and low-symmetry incommensurate ferroelectrics. Obtained results quantitatively describe the differences at several times in the nanodomain length experimentally observed on X and Y cuts of LiNbO3 and can give insight into the anisotropic dynamics of nanoscale polarization reversal in strongly inhomogeneous electric fields.

  7. Microwave air plasmas in capillaries at low pressure I. Self-consistent modeling

    NASA Astrophysics Data System (ADS)

    Coche, P.; Guerra, V.; Alves, L. L.

    2016-06-01

    This work presents the self-consistent modeling of micro-plasmas generated in dry air using microwaves (2.45 GHz excitation frequency), within capillaries (<1 mm inner radius) at low pressure (300 Pa). The model couples the system of rate balance equations for the most relevant neutral and charged species of the plasma to the homogeneous electron Boltzmann equation. The maintenance electric field is self-consistently calculated adopting a transport theory for low to intermediate pressures, taking into account the presence of O- ions in addition to several positive ions, the dominant species being O{}2+ , NO+ and O+ . The low-pressure small-radius conditions considered yield very-intense reduced electric fields (˜600-1500 Td), coherent with species losses controlled by transport and wall recombination, and kinetic mechanisms strongly dependent on electron-impact collisions. The charged-particle transport losses are strongly influenced by the presence of the negative ion, despite its low-density (˜10% of the electron density). For electron densities in the range (1-≤ft. 4\\right)× {{10}12} cm-3, the system exhibits high dissociation degrees for O2 (˜20-70%, depending on the working conditions, in contrast with the  ˜0.1% dissociation obtained for N2), a high concentration of O2(a) (˜1014 cm-3) and NO(X) (5× {{10}14} cm-3) and low ozone production (<{{10}-3}% ).

  8. "Hairy" Nanoparticles in Block Copolymers and Homopolymers: Modeling using Hybrid Self-Consistent Field Theory

    NASA Astrophysics Data System (ADS)

    Ginzburg, Valeriy

    2011-03-01

    Today, dispersed nanoparticles play important role in various applications (toughened plastics, healthcare, personal care, etc.) Mesoscale simulations and theory are important in understanding what governs the morphology of nanoparticles under various conditions. In particular, for nanoparticle/block copolymer mixtures, two popular simulation methods are Self-Consistent Field/Density Functional Theory (SCF-DFT) (Thompson, Ginzburg, Matsen, and Balazs, Science 292, 2469 [2001]), and Hybrid Self-Consistent Field Theory (HSCFT) (Sides et al., Phys Rev Lett 96, 250601 [2006]). The two methods are shown to be very similar in their assumptions and end-results; the choice of the method to be used can depend on the specific problem. Here, we use modified HSCFT to explicitly account for the complicated role of short-chain ligands grafted onto nanoparticles to promote dispersion. In particular, we discuss the phase diagrams of such ``hairy'' nanoparticles in diblock copolymers as function of diblock composition, nanoparticle volume fraction, and ligand length. Depending on the particle size and ligand coverage, particles could segregate into favorable domain, stay close to the interface, or phase-separate from the block copolymer altogether. We also consider the dispersion of ``hairy'' nanoparticles in a homopolymer and analyze the morphologies of particle clusters as function of ligand length. The results could have interesting implications for the design of new nanocomposite materials.

  9. Self-consistent theory of finite Fermi systems and Skyrme-Hartree-Fock method

    NASA Astrophysics Data System (ADS)

    Saperstein, E. E.; Tolokonnikov, S. V.

    2016-11-01

    Recent results obtained on the basis of the self-consistent theory of finite Fermi systems by employing the energy density functional proposed by Fayans and his coauthors are surveyed. These results are compared with the predictions of Skyrme-Hartree-Fock theory involving several popular versions of the Skyrme energy density functional. Spherical nuclei are predominantly considered. The charge radii of even and odd nuclei and features of low-lying 2+ excitations in semimagic nuclei are discussed briefly. The single-particle energies ofmagic nuclei are examined inmore detail with allowance for corrections to mean-field theory that are induced by particle coupling to low-lying collective surface excitations (phonons). The importance of taking into account, in this problem, nonpole (tadpole) diagrams, which are usually disregarded, is emphasized. The spectroscopic factors of magic and semimagic nuclei are also considered. In this problem, only the surface term stemming from the energy dependence induced in the mass operator by the exchange of surface phonons is usually taken into account. The volume contribution associated with the energy dependence initially present in the mass operator within the self-consistent theory of finite Fermi systems because of the exchange of high-lying particle-hole excitations is also included in the spectroscopic factor. The results of the first studies that employed the Fayans energy density functional for deformed nuclei are also presented.

  10. Self-Consistent Conversion of a Viscous Fluid to Particles and Heavy-Ion Physics Applications

    NASA Astrophysics Data System (ADS)

    Wolff, Zack J.

    The most widely used theoretical framework to model the early stages of a heavy-ion collision is viscous hydrodynamics. Comparing hydrodynamic simulations to heavy-ion data inevitably requires the conversion of the fluid to particles. This conversion, typically done in the Cooper-Frye formalism, is ambiguous for viscous fluids. In this thesis work, self-consistent phase space corrections are calculated by solving the linearized Boltzmann equation. These species-dependent solutions are contrasted with those obtained using the ad-hoc ''democratic Grad'' ansatz typically employed in the literature in which coefficients are independent of particle dynamics. Solutions are calculated analytically for a massless gas and numerically for the general case of a hadron resonance gas. For example, it is found that for a gas of massless particles interacting via isotropic, energy-independent 2 → 2 scatterings, the shear viscous corrections variationally prefer a momentum dependence close to p3/2 rather than the quadratic dependence assumed in the Grad ansatz. The self-consistent phase space distributions are then used to calculate transverse momentum spectra and differential flow coefficients, v n(pT), to study the effects on heavy-ion identified particle observables. Using additive quark model cross sections, it is found that proton flow coefficients are higher than those for pions at moderately high pT in Pb + Pb collisions at LHC, especially for the coefficients v 4 and v6.

  11. Fractional charge and spin errors in self-consistent Green's function theory

    NASA Astrophysics Data System (ADS)

    Phillips, Jordan J.; Kananenka, Alexei A.; Zgid, Dominika

    2015-05-01

    We examine fractional charge and spin errors in self-consistent Green's function theory within a second-order approximation (GF2). For GF2, it is known that the summation of diagrams resulting from the self-consistent solution of the Dyson equation removes the divergences pathological to second-order Møller-Plesset (MP2) theory for strong correlations. In the language often used in density functional theory contexts, this means GF2 has a greatly reduced fractional spin error relative to MP2. The natural question then is what effect, if any, does the Dyson summation have on the fractional charge error in GF2? To this end, we generalize our previous implementation of GF2 to open-shell systems and analyze its fractional spin and charge errors. We find that like MP2, GF2 possesses only a very small fractional charge error, and consequently minimal many electron self-interaction error. This shows that GF2 improves on the critical failings of MP2, but without altering the positive features that make it desirable. Furthermore, we find that GF2 has both less fractional charge and fractional spin errors than typical hybrid density functionals as well as random phase approximation with exchange.

  12. Self-Consistent Monte Carlo Study of the Coulomb Interaction under Nano-Scale Device Structures

    NASA Astrophysics Data System (ADS)

    Sano, Nobuyuki

    2011-03-01

    It has been pointed that the Coulomb interaction between the electrons is expected to be of crucial importance to predict reliable device characteristics. In particular, the device performance is greatly degraded due to the plasmon excitation represented by dynamical potential fluctuations in high-doped source and drain regions by the channel electrons. We employ the self-consistent 3D Monte Carlo (MC) simulations, which could reproduce both the correct mobility under various electron concentrations and the collective plasma waves, to study the physical impact of dynamical potential fluctuations on device performance under the Double-gate MOSFETs. The average force experienced by an electron due to the Coulomb interaction inside the device is evaluated by performing the self-consistent MC simulations and the fixed-potential MC simulations without the Coulomb interaction. Also, the band-tailing associated with the local potential fluctuations in high-doped source region is quantitatively evaluated and it is found that the band-tailing becomes strongly dependent of position in real space even inside the uniform source region. This work was partially supported by Grants-in-Aid for Scientific Research B (No. 2160160) from the Ministry of Education, Culture, Sports, Science and Technology in Japan.

  13. Radio-frequency sheaths physics: Experimental characterization on Tore Supra and related self-consistent modeling

    SciTech Connect

    Jacquot, Jonathan; Colas, Laurent Corre, Yann; Goniche, Marc; Gunn, Jamie; Kubič, Martin; Milanesio, Daniele; Heuraux, Stéphane

    2014-06-15

    During the 2011 experimental campaign, one of the three ion cyclotron resonance heating (ICRH) antennas in the Tore Supra tokamak was equipped with a new type of Faraday screen (FS). The new design aimed at minimizing the integrated parallel electric field over long field lines as well as increasing the heat exhaust capability of the actively cooled screen. It proved to be inefficient for attenuating the radio-frequency (RF)-sheaths on the screen itself on the contrary to the heat exhaust concept that allowed operation despite higher heat fluxes on the antenna. In parallel, a new approach has been proposed to model self-consistently RF sheaths: the SSWICH (Self-consistent Sheaths and Waves for IC Heating) code. Simulations results from SSWICH coupled with the TOPICA antenna code were able to reproduce the difference between the two FS designs and part of the spatial pattern of heat loads and Langmuir probe floating potential. The poloidal pattern is a reliable result that mainly depends on the electrical design of the antenna while the radial pattern is on the contrary highly sensitive to loosely constrained parameters such as perpendicular conductivity that generates a DC current circulation from the private region inside the antenna limiters to the free scrape off layer outside these limiters. Moreover, the cantilevered bars seem to be the element in the screen design that enhanced the plasma potential.

  14. The multi-configuration self-consistent field method within a polarizable embedded framework

    NASA Astrophysics Data System (ADS)

    Hedegârd, Erik Donovan; List, Nanna H.; Jensen, Hans Jørgen Aagaard; Kongsted, Jacob

    2013-07-01

    We present a detailed derivation of Multi-Configuration Self-Consistent Field (MCSCF) optimization and linear response equations within the polarizable embedding scheme: PE-MCSCF. The MCSCF model enables a proper description of multiconfigurational effects in reaction paths, spin systems, excited states, and other properties which cannot be described adequately with current implementations of polarizable embedding in density functional or coupled cluster theories. In the PE-MCSCF scheme the environment surrounding the central quantum mechanical system is represented by distributed multipole moments and anisotropic dipole-dipole polarizabilities. The PE-MCSCF model has been implemented in DALTON. As a preliminary application, the low lying valence states of acetone and uracil in water has been calculated using Complete Active Space Self-Consistent Field (CASSCF) wave functions. The dynamics of the water environment have been simulated using a series of snapshots generated from classical Molecular Dynamics. The calculated shifts from gas-phase to water display between good and excellent correlation with experiment and previous calculations. As an illustration of another area of potential applications we present calculations of electronic transitions in the transition metal complex, [Fe(NO)(CN)5]2 - in a micro-solvated environment. This system is highly multiconfigurational and the influence of solvation is significant.

  15. Application of self-consistent field theory to self-assembled bilayer membranes

    NASA Astrophysics Data System (ADS)

    Zhang, Ping-Wen; Shi, An-Chang

    2015-12-01

    Bilayer membranes self-assembled from amphiphilic molecules such as lipids, surfactants, and block copolymers are ubiquitous in biological and physiochemical systems. The shape and structure of bilayer membranes depend crucially on their mechanical properties such as surface tension, bending moduli, and line tension. Understanding how the molecular properties of the amphiphiles determine the structure and mechanics of the self-assembled bilayers requires a molecularly detailed theoretical framework. The self-consistent field theory provides such a theoretical framework, which is capable of accurately predicting the mechanical parameters of self-assembled bilayer membranes. In this mini review we summarize the formulation of the self-consistent field theory, as exemplified by a model system composed of flexible amphiphilic chains dissolved in hydrophilic polymeric solvents, and its application to the study of self-assembled bilayer membranes. Project supported by the National Natural Science Foundation of China (Grant Nos. 11421101 and 21274005) and the Natural Sciences and Engineering Research Council (NSERC) of Canada.

  16. Quantum-classical path integral with self-consistent solvent-driven reference propagators.

    PubMed

    Banerjee, Tuseeta; Makri, Nancy

    2013-10-24

    Efficient procedures for evaluating the quantum-classical path integral (QCPI) [J. Chem. Phys. 2013, 137, 22A552] are described. The main idea is to identify a trajectory-specific reference Hamiltonian that captures the dominant effects of the classical "solvent" degrees of freedom on the dynamics of the quantum "system". This time-dependent reference is used to construct a system propagator that is valid for large time increments. Residual "quantum memory" interactions are included via the path integral representation of the density matrix, which converges with large time steps. Two physically motivated reference schemes are considered. The first involves the dynamics of the solvent unperturbed by the system, which forms the basis for the "classical path" approximation. The second is based on solvent trajectories determined self-consistently with the evolution of the system, according to the time-dependent self-consistent field or Ehrenfest model. Application to dissipative two-level systems indicates that both reference schemes allow a substantial increase of the path integral time step, leading to rapid convergence of the path sum. In addition, the time-dependent reference propagators automatically weigh state-to-state coupling against solvent reorganization in the determination of transition probabilities, further enhancing the convergence of the path integral.

  17. Convergence of the Breit interaction in self-consistent and configuration-interaction approaches

    NASA Astrophysics Data System (ADS)

    Chantler, C. T.; Nguyen, T. V. B.; Lowe, J. A.; Grant, I. P.

    2014-12-01

    Much discussion in relativistic atomic physics and quantum optics has related to the interaction of gauge and perturbation of the Hamiltonian or Dirac operator. It has been commented that Lorentz and gauge independence requires different forms of the perturbation operator in shifting from one gauge to another. Equally, it has been commented that gauge convergence is not possible without different operator forms in different bases and without the operator being embedded within the self-consistent kernel. We explore the logic and self-consistency of these arguments, applied to the well-known Breit operator in an area of continuing discussion. We find that convergence is now possible to a remarkable degree including a Breit interaction operator in a form consistent with the gauge for length and velocity relativistic forms of the multipole operator, implemented at the configuration-interaction level. Excellent convergence is obtained for Breit interaction energies, interaction mixing coefficients, interaction transition probabilities and eigenenergies and transition probabilities in complex open shells (transition metal K α transitions and shake satellites), and forbidden transitions.

  18. Holographic maps of quasiparticle interference

    NASA Astrophysics Data System (ADS)

    Dalla Torre, Emanuele G.; He, Yang; Demler, Eugene

    2016-11-01

    The analysis of Fourier-transformed scanning tunnelling microscopy images with subatomic resolution is a common tool for studying the properties of quasiparticle excitations in strongly correlated materials. Although Fourier amplitudes are generally complex valued, earlier analysis primarily focused on their absolute values. Their complex phases were often deemed random, and thus irrelevant, due to the unknown positions of the impurities in the sample. Here we show how to factor out these random phases by analysing overlaps between Fourier amplitudes that differ by reciprocal lattice vectors. The resulting holographic maps provide important and previously unknown information about the electronic structures. When applied to superconducting cuprates, our method solves a long-standing puzzle of the dichotomy between equivalent wavevectors. We show that d-wave Wannier functions of the conduction band provide a natural explanation for experimental results that were interpreted as evidence for competing unconventional charge modulations. Our work opens a new pathway to identify the nature of electronic states in scanning tunnelling microscopy.

  19. Self-consistent nonspherical isothermal halos embedding zero-thickness disks

    NASA Astrophysics Data System (ADS)

    Amorisco, N. C.; Bertin, G.

    2010-09-01

    Context. That the rotation curves of spiral galaxies are generally flat in the outer regions is commonly considered an indication that galaxy disks are embedded in quasi-isothermal halos. In practice, disk-halo decompositions of galaxy rotation curves are performed in a parametric way by modeling the halo force contribution by means of expressions that approximately describe the properties of the regular isothermal sphere or other spherical density distributions suggested by cosmological simulations. Aims: In this paper we construct self-consistent models of nonspherical isothermal halos embedding a zero-thickness disk, by assuming that the halo distribution function is a Maxwellian. The general method developed here can also be used to study the properties of other physically-based choices for the halo distribution function and to the case of a disk accompanied by a bulge. Methods: The construction was performed by means of an iterative procedure that generalizes a method introduced in the past to construct spheroidal models of rotating elliptical galaxies. In a preliminary investigation, which set the empirical framework to study the self-consistent models developed in this paper, we note the existence of a fine tuning between the scalelengths RΩ and h, respectively characterizing the rise of the rotation curve and the luminosity profile of the disk, which surprisingly applies to both high surface brightness and low surface brightness galaxies in similar ways. We show that this empirical correlation identifies a much stronger conspiracy than the one required by the smoothness and flatness of the rotation curve and often referred to as disk-halo conspiracy. Results: As a natural property, the self-consistent models presented in this paper are found to be characterized by smooth and flat rotation curves for very different disk-to-halo mass ratios, hence suggesting that conspiracy is not as dramatic as often imagined. For a typical, observed rotation curve, with

  20. GW-501516 GlaxoSmithKline/Ligand.

    PubMed

    Pelton, Patricia

    2006-04-01

    GlaxoSmithKline and Ligand are developing GW-501516, a peroxisome proliferator-activator receptor-delta agonist for the potential treatment of dyslipidemia. Phase II clinical trials of this compound are ongoing.

  1. Large-scale GW software development

    NASA Astrophysics Data System (ADS)

    Kim, Minjung; Mandal, Subhasish; Mikida, Eric; Jindal, Prateek; Bohm, Eric; Jain, Nikhil; Kale, Laxmikant; Martyna, Glenn; Ismail-Beigi, Sohrab

    Electronic excitations are important in understanding and designing many functional materials. In terms of ab initio methods, the GW and Bethe-Saltpeter Equation (GW-BSE) beyond DFT methods have proved successful in describing excited states in many materials. However, the heavy computational loads and large memory requirements have hindered their routine applicability by the materials physics community. We summarize some of our collaborative efforts to develop a new software framework designed for GW calculations on massively parallel supercomputers. Our GW code is interfaced with the plane-wave pseudopotential ab initio molecular dynamics software ``OpenAtom'' which is based on the Charm++ parallel library. The computation of the electronic polarizability is one of the most expensive parts of any GW calculation. We describe our strategy that uses a real-space representation to avoid the large number of fast Fourier transforms (FFTs) common to most GW methods. We also describe an eigendecomposition of the plasmon modes from the resulting dielectric matrix that enhances efficiency. This work is supported by NSF through Grant ACI-1339804.

  2. Quantitative analysis of valence photoemission spectra and quasiparticle excitations at chromophore-semiconductor interfaces

    NASA Astrophysics Data System (ADS)

    Patrick, Christopher; Giustino, Feliciano

    2013-03-01

    Understanding electron energetics at interfaces between solids and molecules is a key challenge in many areas of nanotechnology research. Here we develop a quantitative theory of quasiparticle excitations at these interfaces and apply it to the prototypical dye-sensitized solar cell interface of N3 dye molecules adsorbed on the anatase TiO2 (101) surface.[2] Our approach combines density-functional calculations on large interface models, bulk GW calculations,[3] image charge renormalization, thermal broadening and configurational disorder to obtain a quasiparticle spectrum in good agreement with experimental photoemission data. Our calculations clarify the atomistic origin of the chromophore peak at low binding energy, and illustrate the dual role played by the TiO2 substrate in screening the quasiparticle states of the N3 molecule through both long-range image-charge effects and direct charge transfer via the covalently-bonded anchor groups. Work funded by the UK EPSRC and the ERC under the EU FP7/ERC Grant No. 239578. Calculations were performed at the Oxford Supercomputing Centre.

  3. Self-consistent Model of Magnetospheric Electric Field, RC and EMIC Waves

    NASA Technical Reports Server (NTRS)

    Gamayunov, K. V.; Khazanov, G. V.; Liemohn, M. W.; Fok, M.-C.

    2007-01-01

    Electromagnetic ion cyclotron (EMIC) waves are an important magnetospheric emission, which is excited near the magnetic equator with frequencies below the proton gyro-frequency. The source of bee energy for wave growth is provided by temperature anisotropy of ring current (RC) ions, which develops naturally during inward convection from the plasma sheet These waves strongly affect the dynamic s of resonant RC ions, thermal electrons and ions, and the outer radiation belt relativistic electrons, leading to non-adiabatic particle heating and/or pitch-angle scattering and loss to the atmosphere. The rate of ion and electron scattering/heating is strongly controlled by the Wave power spectral and spatial distributions, but unfortunately, the currently available observational information regarding EMIC wave power spectral density is poor. So combinations of reliable data and theoretical models should be utilized in order to obtain the power spectral density of EMIC waves over the entire magnetosphere throughout the different storm phases. In this study, we present the simulation results, which are based on two coupled RC models that our group has developed. The first model deals with the large-scale magnetosphere-ionosphere electrodynamic coupling, and provides a self-consistent description of RC ions/electrons and the magnetospheric electric field. The second model is based on a coupled system of two kinetic equations, one equation describes the RC ion dynamics and another equation describes the power spectral density evolution of EMIC waves, and self-consistently treats a micro-scale electrodynamic coupling of RC and EMIC waves. So far, these two models have been applied independently. However, the large-scale magnetosphere-ionosphere electrodynamics controls the convective patterns of both the RC ions and plasmasphere altering conditions for EMIC wave-particle interaction. In turn, the wave induced RC precipitation Changes the local field-aligned current

  4. Self-consistent hybrid neoclassical-magnetohydrodynamic simulations of axisymmetric plasmas

    NASA Astrophysics Data System (ADS)

    Lyons, Brendan Carrick

    Neoclassical effects (e.g., conductivity reduction and bootstrap currents) have a profound impact on many magnetohydrodynamic (MHD) instabilities in toroidally-confined plasmas, including tearing modes, edge-localized modes, and resistive wall modes. High-fidelity simulations of such phenomena require a multiphysics code that self-consistently couples the kinetic and fluid models. We review a hybrid formulation from the recent literatureAB that is appropriate for such studies. In particular, the formulation uses a set of time-dependent drift-kinetic equations (DKEs) to advance the non-Maxwellian part of the electron and ion distribution functions (fNM) with linearized Fokker-Planck-Landau collision operators. The form of the DKEs used were derived in a Chapman-Enskog-like fashion, ensuring that fNM carries no density, momentum, or temperature. Rather, these quantities are contained within the background Maxwellian and are evolved by a set of MHD equations which are closed by moments of fNM . We then present two DKE solvers based upon this formulation in axisymmetric toroidal geometries. The Neoclassical Ion-Electron Solver (NIES) solves the steady-state DKEs in the low-collisionality limit. Convergence and benchmark studies are discussed, providing a proof-of-principle that this new formulation can accurately reproduce results from the literature in the limit considered. We then present the DK4D code which evolves the finite-collisionality DKEs time-dependently. Computational methods used and successful benchmarks to other neoclassical models and codes are discussed. Furthermore, we couple DK4D to a reduced, transport-timescale MHD code. The resulting hybrid code is used to simulate the evolution of the current density in a large-aspect-ratio plasma in the presence of several different time-dependent pressure profiles. These simulations demonstrate the self-consistent, dynamic formation of the ohmic and bootstrap currents. In the slowly-evolving plasmas considered

  5. Electric dipole response of neutron-rich calcium isotopes in relativistic quasiparticle time blocking approximation

    NASA Astrophysics Data System (ADS)

    Egorova, Irina A.; Litvinova, Elena

    2016-09-01

    New results for electric dipole strength in the chain of even-even calcium isotopes with the mass numbers A =40 -54 are presented. Starting from the covariant Lagrangian of quantum hadrodynamics, spectra of collective vibrations (phonons) and phonon-nucleon coupling vertices for J ≤6 and natural parity were computed in a self-consistent relativistic quasiparticle random-phase approximation (RQRPA). These vibrations coupled to Bogoliubov two-quasiparticle configurations (2 q ⊗phonon ) formed the model space for the calculations of the dipole response function in the relativistic quasiparticle time blocking approximation. The calculations in the latter approach were performed for the giant dipole resonance (GDR) and compared to those obtained with the RQRPA and to available data. The evolution of the dipole strength with the neutron number is investigated for both high-frequency GDRs and low-lying strengths. The development of a pygmy resonant structure on the low-energy shoulder of the GDR is traced and analyzed in terms of transition densities. A dependence of the pygmy dipole strength on the isospin asymmetry parameter is extracted.

  6. Energy level alignment at hybridized organic-metal interfaces from a GW projection approach

    NASA Astrophysics Data System (ADS)

    Chen, Yifeng; Tamblyn, Isaac; Quek, Su Ying

    Energy level alignments at organic-metal interfaces are of profound importance in numerous (opto)electronic applications. Standard density functional theory (DFT) calculations generally give incorrect energy level alignments and missing long-range polarization effects. Previous efforts to address this problem using the many-electron GW method have focused on physisorbed systems where hybridization effects are insignificant. Here, we use state-of-the-art GW methods to predict the level alignment at the amine-Au interface, where molecular levels do hybridize with metallic states. This non-trivial hybridization implies that DFT result is a poor approximation to the quasiparticle states. However, we find that the self-energy operator is approximately diagonal in the molecular basis, allowing us to use a projection approach to predict the level alignments. Our results indicate that the metallic substrate reduces the HOMO-LUMO gap by 3.5 4.0 eV, depending on the molecular coverage/presence of Au adatoms. Our GW results are further compared with those of a simple image charge model that describes the level alignment in physisorbed systems. Syq and YC acknowledge Grant NRF-NRFF2013-07 and the medium-sized centre program from the National Research Foundation, Singapore.

  7. Analysis of Bidirectional Associative Memory using Self-consistent Signal to Noise Analysis and Statistical Neurodynamics

    NASA Astrophysics Data System (ADS)

    Shouno, Hayaru; Kido, Shoji; Okada, Masato

    2004-09-01

    Bidirectional associative memory (BAM) is a kind of an artificial neural network used to memorize and retrieve heterogeneous pattern pairs. Many efforts have been made to improve BAM from the the viewpoint of computer application, and few theoretical studies have been done. We investigated the theoretical characteristics of BAM using a framework of statistical-mechanical analysis. To investigate the equilibrium state of BAM, we applied self-consistent signal to noise analysis (SCSNA) and obtained a macroscopic parameter equations and relative capacity. Moreover, to investigate not only the equilibrium state but also the retrieval process of reaching the equilibrium state, we applied statistical neurodynamics to the update rule of BAM and obtained evolution equations for the macroscopic parameters. These evolution equations are consistent with the results of SCSNA in the equilibrium state.

  8. Accelerating self-consistent field convergence with the augmented Roothaan–Hall energy function

    PubMed Central

    Hu, Xiangqian; Yang, Weitao

    2010-01-01

    Based on Pulay’s direct inversion iterative subspace (DIIS) approach, we present a method to accelerate self-consistent field (SCF) convergence. In this method, the quadratic augmented Roothaan–Hall (ARH) energy function, proposed recently by Høst and co-workers [J. Chem. Phys. 129, 124106 (2008)], is used as the object of minimization for obtaining the linear coefficients of Fock matrices within DIIS. This differs from the traditional DIIS of Pulay, which uses an object function derived from the commutator of the density and Fock matrices. Our results show that the present algorithm, abbreviated ADIIS, is more robust and efficient than the energy-DIIS (EDIIS) approach. In particular, several examples demonstrate that the combination of ADIIS and DIIS (“ADIIS+DIIS”) is highly reliable and efficient in accelerating SCF convergence. PMID:20136307

  9. Sea level changes from seismic dislocations: a self-consistent approach

    NASA Astrophysics Data System (ADS)

    Piersanti, A.; Melini, D.; Spada, G.

    2009-12-01

    Large earthquakes are a potentially important source of relative sea level variations, since they can drive global deformations and simultaneously perturb the gravity field of the Earth. We obtained a gravitationally self-consistent, integral sea level equation suitable for earthquakes, in which, for the first time, we are able to account both for direct effects by the seismic dislocation and for the feedback from water loading associated with sea level changes. The seismic sealevel equation can be solved numerically within the well-estabilisthed theoretical framework of glacio-isostatic adjustment modeling. Through a set of numerical benchmarks we demonstrate the effectiveness of the numerical implementation. As an application, we model sea level signals following the 2004 Sumatra-Andaman earthquake, showing that surface loading from ocean water redistribution (so far ignored in post-seismic deformation modeling) may account for a significant fraction of the total computed sea level variation.

  10. Improved master equation approach to quantum transport: from Born to self-consistent Born approximation.

    PubMed

    Jin, Jinshuang; Li, Jun; Liu, Yu; Li, Xin-Qi; Yan, YiJing

    2014-06-28

    Beyond the second-order Born approximation, we propose an improved master equation approach to quantum transport under self-consistent Born approximation. The basic idea is to replace the free Green's function in the tunneling self-energy diagram by an effective reduced propagator under the Born approximation. This simple modification has remarkable consequences. It not only recovers the exact results for quantum transport through noninteracting systems under arbitrary voltages, but also predicts the challenging nonequilibrium Kondo effect. Compared to the nonequilibrium Green's function technique that formulates the calculation of specific correlation functions, the master equation approach contains richer dynamical information to allow more efficient studies for such as the shot noise and full counting statistics.

  11. Coarse-Grained Force field for the Nucleosome from Self-Consistent Multiscaling

    SciTech Connect

    Voltz, Karine; Trylska, Joanna; Tozzini, Valentina; Kurkal-Siebert, V; Smith, Jeremy C; Langowski, Jorg

    2008-02-01

    A coarse-grained simulation model for the nucleosome is developed, using a methodology modified from previous work on the ribosome. Protein residues and DNA nucleotides are represented as beads, interacting through harmonic (for neighboring) or Morse (for nonbonded) potentials. Force-field parameters were estimated by Boltzmann inversion of the corresponding radial distribution functions obtained from a 5-ns all-atom molecular dynamics (MD) simulation, and were refined to produce agreement with the all-atom MD simulation. This self-consistent multiscale approach yields a coarse-grained model that is capable of reproducing equilibrium structural properties calculated from a 50-ns all-atom MD simulation. This coarse-grained model speeds up nucleosome simulations by a factor of 10{sup 3} and is expected to be useful in examining biologically relevant dynamical nucleosome phenomena on the microsecond timescale and beyond.

  12. Raychaudhuri equation in the self-consistent Einstein-Cartan theory with spin-density

    NASA Technical Reports Server (NTRS)

    Fennelly, A. J.; Krisch, Jean P.; Ray, John R.; Smalley, Larry L.

    1988-01-01

    The physical implications of the Raychaudhuri equation for a spinning fluid in a Riemann-Cartan spacetime is developed and discussed using the self-consistent Lagrangian based formulation for the Einstein-Cartan theory. It was found that the spin-squared terms contribute to expansion (inflation) at early times and may lead to a bounce in the final collapse. The relationship between the fluid's vorticity and spin angular velocity is clarified and the effect of the interaction terms between the spin angular velocity and the spin in the Raychaudhuri equation investigated. These results should prove useful for studies of systems with an intrinsic spin angular momentum in extreme astrophysical or cosmological problems.

  13. Similarities between Prescott Lecky's theory of self-consistency and Carl Rogers' self-theory.

    PubMed

    Merenda, Peter F

    2010-10-01

    The teachings of Prescott Lecky on the self-concept at Columbia University in the 1920s and 1930s and the posthumous publications of his book on self-consistency beginning in 1945 are compared with the many publications of Carl Rogers on the self-concept beginning in the early 1940s. Given that Rogers was a graduate student at Columbia in the 1920s and 1930s, the striking similarities between these two theorists, as well as claims attributed to Rogers by Rogers' biographers and writers who have quoted Rogers on his works relating to self-theory, strongly suggest that Rogers borrowed from Lecky without giving him the proper credit. Much of Rogers' writings on the self-concept included not only terms and concepts which were original with Lecky, but at times these were actually identical.

  14. Self consistent theories of superfluid density and collective modes in BCS-BEC

    NASA Astrophysics Data System (ADS)

    Boyack, Rufus; Anderson, Brandon; Wu, Chien-Te; Levin, Kathryn

    Establishing fully self consistent and sum rule compatible response functions in strongly correlated Fermi superfluids has been a historically challenging subject. In this talk, we present recent progress pertaining to response functions in many-body Fermi systems. We note that even in strict BCS theory, the textbook derivation of density and current response functions in the gradient expansion breaks certain conservation laws such as the compressibility sum rule. To include additional contributions that preserve all expected conservation laws, we show how to exploit Ward identities within two different t-matrix schemes. In this way we address the density-density response (including collective modes) and the superfluid density. Finally, we characterize approximations made in the literature where some consistency requirements have been dropped.

  15. Self-consistent simulation of CdTe solar cells with active defects

    DOE PAGES

    Brinkman, Daniel; Guo, Da; Akis, Richard; ...

    2015-07-21

    We demonstrate a self-consistent numerical scheme for simulating an electronic device which contains active defects. As a specific case, we consider copper defects in cadmium telluride solar cells. The presence of copper has been shown experimentally to play a crucial role in predicting device performance. The primary source of this copper is migration away from the back contact during annealing, which likely occurs predominantly along grain boundaries. We introduce a mathematical scheme for simulating this effect in 2D and explain the numerical implementation of the system. Lastly, we will give numerical results comparing our results to known 1D simulations tomore » demonstrate the accuracy of the solver and then show results unique to the 2D case.« less

  16. Beyond Poisson-Boltzmann: fluctuations and fluid structure in a self-consistent theory

    NASA Astrophysics Data System (ADS)

    Buyukdagli, S.; Blossey, R.

    2016-09-01

    Poisson-Boltzmann (PB) theory is the classic approach to soft matter electrostatics and has been applied to numerous physical chemistry and biophysics problems. Its essential limitations are in its neglect of correlation effects and fluid structure. Recently, several theoretical insights have allowed the formulation of approaches that go beyond PB theory in a systematic way. In this topical review, we provide an update on the developments achieved in the self-consistent formulations of correlation-corrected Poisson-Boltzmann theory. We introduce a corresponding system of coupled non-linear equations for both continuum electrostatics with a uniform dielectric constant, and a structured solvent—a dipolar Coulomb fluid—including non-local effects. While the approach is only approximate and also limited to corrections in the so-called weak fluctuation regime, it allows us to include physically relevant effects, as we show for a range of applications of these equations.

  17. Self-consistent implementation of ensemble density functional theory method for multiple strongly correlated electron pairs

    NASA Astrophysics Data System (ADS)

    Filatov, Michael; Liu, Fang; Kim, Kwang S.; Martínez, Todd J.

    2016-12-01

    The spin-restricted ensemble-referenced Kohn-Sham (REKS) method is based on an ensemble representation of the density and is capable of correctly describing the non-dynamic electron correlation stemming from (near-)degeneracy of several electronic configurations. The existing REKS methodology describes systems with two electrons in two fractionally occupied orbitals. In this work, the REKS methodology is extended to treat systems with four fractionally occupied orbitals accommodating four electrons and self-consistent implementation of the REKS(4,4) method with simultaneous optimization of the orbitals and their fractional occupation numbers is reported. The new method is applied to a number of molecular systems where simultaneous dissociation of several chemical bonds takes place, as well as to the singlet ground states of organic tetraradicals 2,4-didehydrometaxylylene and 1,4,6,9-spiro[4.4]nonatetrayl.

  18. Self-consistent field theory simulations of block copolymer assembly on a sphere

    NASA Astrophysics Data System (ADS)

    Chantawansri, T. L.; Bosse, A. W.; Hexemer, A.; Ceniceros, H. D.; Garcia-Cervera, C. J.; Kramer, E. J.; Fredrickson, G. H.

    2007-03-01

    Using a self-consistent field theory (SCFT) framework, we explore the topic of self-assembly in a thin AB diblock copolymer melt confined to the surface of the sphere. This model is numerically simulated by spectral collocation with a spherical harmonic basis. The method allows us to investigate the lamellar and cylindrical phases on the surface of a sphere as a function of sphere radius. For thin cylinder-forming films, with uniform radial composition, we have found that the number of microdomains in the ground state configuration is determined by a delicate competition between chain stretching and topological constraints. Notably, our SCFT simulations have shown the absence of configurations with 11 and 13 domains in the ground state. For thin lamellar films, we examined the stability of three lamellar configurations: spiral, hedgehog, and quasi-baseball phases. The spiral and hedgehog morphologies are found to alternate in stability over a range of sphere radii.

  19. Self-consistent spectrophotometric basicity scale in acetonitrile covering the range between pyridine and DBU

    PubMed

    Kaljurand; Rodima; Leito; Koppel; Schwesinger

    2000-09-22

    A self-consistent spectrophotometric basicity scale in acetonitrile, including DBU, ten (arylimino)tris(1-pyrrolidinyl)phosphoranes, two (arylimino)tris(dimethylamino)phosphoranes, 2-phenyl-1,1,3, 3-tetramethylguanidine, 1-(2-tolyl)biguanide, benzylamine, two substituted benzimidazoles, pyridine, and ten substituted pyridines, has been created. The span of the scale is almost 12 pK(a) units. Altogether, 29 different bases were studied and 53 independent equilibrium constant measurements were carried out, each describing the relative basicity of two bases. The scale is anchored to the pK(a) value of pyridine of 12.33 that has been measured by Coetzee et al. Comparison of the basicity data of phenyliminophosphoranes and phenyltetramethylguanidines implies that the P=N bond in the (arylimino)tris(1-pyrrolidinyl)phosphoranes involves contribution from the ylidic (zwitterionic) structure analogous to that found in phosphorus ylides.

  20. Representation independent algorithms for molecular response calculations in time-dependent self-consistent field theories

    SciTech Connect

    Tretiak, Sergei

    2008-01-01

    Four different numerical algorithms suitable for a linear scaling implementation of time-dependent Hartree-Fock and Kohn-Sham self-consistent field theories are examined. We compare the performance of modified Lanczos, Arooldi, Davidson, and Rayleigh quotient iterative procedures to solve the random-phase approximation (RPA) (non-Hermitian) and Tamm-Dancoff approximation (TDA) (Hermitian) eigenvalue equations in the molecular orbital-free framework. Semiempirical Hamiltonian models are used to numerically benchmark algorithms for the computation of excited states of realistic molecular systems (conjugated polymers and carbon nanotubes). Convergence behavior and stability are tested with respect to a numerical noise imposed to simulate linear scaling conditions. The results single out the most suitable procedures for linear scaling large-scale time-dependent perturbation theory calculations of electronic excitations.

  1. Representation independent algorithms for molecular response calculations in time-dependent self-consistent field theories

    NASA Astrophysics Data System (ADS)

    Tretiak, Sergei; Isborn, Christine M.; Niklasson, Anders M. N.; Challacombe, Matt

    2009-02-01

    Four different numerical algorithms suitable for a linear scaling implementation of time-dependent Hartree-Fock and Kohn-Sham self-consistent field theories are examined. We compare the performance of modified Lanczos, Arooldi, Davidson, and Rayleigh quotient iterative procedures to solve the random-phase approximation (RPA) (non-Hermitian) and Tamm-Dancoff approximation (TDA) (Hermitian) eigenvalue equations in the molecular orbital-free framework. Semiempirical Hamiltonian models are used to numerically benchmark algorithms for the computation of excited states of realistic molecular systems (conjugated polymers and carbon nanotubes). Convergence behavior and stability are tested with respect to a numerical noise imposed to simulate linear scaling conditions. The results single out the most suitable procedures for linear scaling large-scale time-dependent perturbation theory calculations of electronic excitations.

  2. Multifractality and quantum diffusion from self-consistent theory of localization

    SciTech Connect

    Suslov, I. M.

    2015-11-15

    Multifractal properties of wave functions in a disordered system can be derived from self-consistent theory of localization by Vollhardt and Wölfle. A diagrammatic interpretation of results allows to obtain all scaling relations used in numerical experiments. The arguments are given that the one-loop Wegner result for a space dimension d = 2 + ϵ is exact, so the multifractal spectrum is strictly parabolical. The σ-models are shown to be deficient at the four-loop level and the possible reasons of that are discussed. The extremely slow convergence to the thermodynamic limit is demonstrated. The open question on the relation between multifractality and a spatial dispersion of the diffusion coefficient D(ω, q) is resolved in the compromise manner due to ambiguity of the D(ω, q) definition. Comparison is made with the extensive numerical material.

  3. Simultaneous determination of electron beam profile and material response using self-consistent iterative method

    NASA Astrophysics Data System (ADS)

    Kandel, Yudhishthir; Denbeaux, Gregory

    2016-08-01

    We develop a novel iterative method to accurately measure electron beam shape (current density distribution) and monotonic material response as a function of position. A common method is to scan an electron beam across a knife edge along many angles to give an approximate measure of the beam profile, however such scans are not easy to obtain in all systems. The present work uses only an electron beam and multiple exposed regions of a thin film of photoresist to measure the complete beam profile for any beam shape, where the material response is characterized externally. This simplifies the setup of new experimental tools. We solve for self-consistent photoresist thickness loss response to dose and the electron beam profile simultaneously by optimizing a novel functional iteratively. We also show the successful implementation of the method in a real world data set corrupted by noise and other experimental variabilities.

  4. Onsets of hierarchy truncation and self-consistent Born approximation with quantum mechanics prescriptions invariance.

    PubMed

    Zhang, Hou-Dao; Yan, YiJing

    2015-12-07

    The issue of efficient hierarchy truncation is related to many approximate theories. In this paper, we revisit this issue from both the numerical efficiency and quantum mechanics prescription invariance aspects. The latter requires that the truncation approximation made in Schrödinger picture, such as the quantum master equations and their self-consistent-Born-approximation improvements, should be transferable to their Heisenberg-picture correspondences, without further approximations. We address this issue with the dissipaton equation of motion (DEOM), which is a unique theory for the dynamics of not only reduced systems but also hybrid bath environments. We also highlight the DEOM theory is not only about how its dynamical variables evolve in time, but also the underlying dissipaton algebra. We demonstrate this unique feature of DEOM with model systems and report some intriguing nonlinear Fano interferences characteristics that are experimentally measurable.

  5. Self-Consistent Calculation of Half-Harmonic Emission with an Electromagnetic Zakharov Model

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Myatt, J. F.; Maximov, A. V.; Short, R. W.; Dubois, D. F.; Russell, D. A.; Vu, H. X.

    2015-11-01

    Half-harmonic emission has been regarded as a signal of two-plasmon decay or stimulated Raman scattering (SRS). Experimental observations at the Omega Laser Facility show both blue and red shifts of half-harmonic light. The red shift might be a powerful diagnostic tool to measure electron temperature near quarter-critical density. However, the interpretation of the half-harmonics spectrum is difficult because of its complicated generation mechanism. To resolve this problem, a self-consistent electromagnetic Zakharov code that is able to calculate half harmonics emission has been developed, including all the possible generation mechanisms such as absolute SRS, Thomson down-scattering, linear mode conversion, and nonlinear mode conversion. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  6. Thermochemistry of solvation: A self-consistent three-dimensional reference interaction site model approach

    NASA Astrophysics Data System (ADS)

    Kovalenko, Andriy; Truong, Thanh N.

    2000-11-01

    We developed a self-consistent three-dimensional reference interaction site model integral equation theory with the molecular hypernetted chain closure (SC-3D-RISM/HNC) for studying thermochemistry of solvation of ionic solutes in a polar molecular solvent. It is free from the inconsistency in the positions of the ion-solvent site distribution peaks, peculiar to the conventional RISM/HNC approach and improves the predictions for the solvation thermodynamics. The SC-3D-RISM treatment can be readily generalized to the case of finite ionic concentrations, including the consistent dielectric corrections to provide a consistent description of the dielectric properties of ion-molecular solution. The proposed theory is tested for hydration of the Na+ and Cl- ions in ambient water at infinite dilution. An improved agreement of the ion hydration structure and thermodynamics with molecular simulation results is found as compared to the conventional RISM/HNC treatment.

  7. Equilibrium statistical mechanics of self-consistent wave-particle system

    NASA Astrophysics Data System (ADS)

    Elskens, Yves

    2005-10-01

    The equilibrium distribution of N particles and M waves (e.g. Langmuir) is analysed in the weak-coupling limit for the self-consistent hamiltonian model H = ∑rpr^2 /(2m) + ∑jφjIj+ ɛ∑r,j(βj/ kj) (kjxr- θj) [1]. In the canonical ensemble, with temperature T and reservoir velocity v < jφj/kj, the wave intensities are almost independent and exponentially distributed, with expectation = kBT / (φj- kjv). These equilibrium predictions are in agreement with Monte Carlo samplings [2] and with direct simulations of the dynamics, indicating equivalence between canonical and microcanonical ensembles. [1] Y. Elskens and D.F. Escande, Microscopic dynamics of plasmas and chaos (IoP publishing, Bristol, 2003). [2] M-C. Firpo and F. Leyvraz, 30th EPS conf. contr. fusion and plasma phys., P-2.8 (2003).

  8. Optimization of nanowire DNA sensor sensitivity using self-consistent simulation.

    PubMed

    Baumgartner, S; Vasicek, M; Bulyha, A; Heitzinger, C

    2011-10-21

    In order to facilitate the rational design and the characterization of nanowire field-effect sensors, we have developed a model based on self-consistent charge-transport equations combined with interface conditions for the description of the biofunctionalized surface layer at the semiconductor/electrolyte interface. Crucial processes at the interface, such as the screening of the partial charges of the DNA strands and the influence of the angle of the DNA strands with respect to the nanowire, are computed by a Metropolis Monte Carlo algorithm for charged molecules at interfaces. In order to investigate the sensing mechanism of the device, we have computed the current–voltage characteristics, the electrostatic potential and the concentrations of electrons and holes. Very good agreement with measurements has been found and optimal device parameters have been identified. Our approach provides the capability to study the device sensitivity, which is of fundamental importance for reliable sensing.

  9. A new constraint DFT technique for self-consistent determination of U values

    NASA Astrophysics Data System (ADS)

    Hamada, Tomoyuki; Ohno, Takahisa

    A new constraint density functional (DFT) technique workable in combination with the projector augmented wave (PAW) and pseudoptential (PP) methods was developed. This technique calculates the effective on-site-interaction parameter, Ueff , of correlated electrons of materials, self-consistently, by using the DFT +U method. The Ueff determined by this technique has a clear physical meaning in that it determines the electronic structures of strongly correlated electronic systems (SCESs) andvice versa. The technique was used to determine the Ueff of correlated electrons of hexagonal neodymium sesquioxide (h-Nd2O3) and orthorhombic iron oxide (o-FeO) in the antiferromagnetic states, and it was shown to be effective for this purpose. The newly developed constraint DFT technique enables first principles DFT +U PAW and PP calculations of SCESs free from any empirical parameters, which are more reliable than the DFT +U PAW and PP calculations of them using empirical Ueffs. Hatoyama, Saitama, 350-0395, Japan.

  10. Nilsson-SU3 self-consistency in heavy N =Z nuclei

    NASA Astrophysics Data System (ADS)

    Zuker, A. P.; Poves, A.; Nowacki, F.; Lenzi, S. M.

    2015-08-01

    It is argued that there exist natural shell-model spaces optimally adapted to the operation of two variants of Elliott's SU3 symmetry that provide accurate predictions of quadrupole moments of deformed states. A self-consistent Nilsson-like calculation describes the competition between the realistic quadrupole force and the central field, indicating a remarkable stability of the quadrupole moments—which remain close to their quasi- and pseudo-SU3 values—as the single-particle splittings increase. A detailed study of the N =Z even nuclei from 56Ni to 96Cd reveals that the region of prolate deformation is bounded by a pair of transitional nuclei 72Kr and 84Mo in which prolate ground-state bands are predicted to dominate, though coexisting with oblate ones.

  11. Self-consistent Cooper-Frye freeze-out of a viscous fluid to particles

    NASA Astrophysics Data System (ADS)

    Wolff, Zack; Molnar, Denes

    2014-09-01

    Comparing hydrodynamic simulations to heavy-ion data inevitably requires the conversion of the fluid to particles. This conversion, typically done in the Cooper-Frye formalism, is ambiguous for viscous fluids. We compute self-consistent phase space corrections by solving the linearized Boltzmann equation and contrast the solutions to those obtained using the ad-hoc "democratic Grad" ansatz typically employed in the literature where coefficients are independent of particle dynamics. Solutions are calculated analytically for a massless gas and numerically for both a pion-nucleon gas and for the general case of a hadron resonance gas. We find that the momentum dependence of the corrections in all systems investigated is best fit by a power close to 3/2 rather than the typically used quadratic ansatz. The effects on harmonic flow coefficients v2 and v4 are substantial, and should be taken into account when extracting medium properties from experimental data.

  12. Phase diagram of rod-coil diblock copolymer melts by self-consistent field theory

    NASA Astrophysics Data System (ADS)

    Yan, Dadong; Tang, Jiuzhou; Jiang, Ying; Zhang, Xinghua; Chen, Jeff

    A unified phase diagram is presented for rod-coil diblock copolymer melts in the isotropic phase regime as a function of the asymmetric parameter. The study is based on free-energy calculation, which incorporates three-dimensional spatial variations of the volume fraction with angular dependence. The wormlike-chain model is used in a self-consistent field treatment. Body-centered cubic, A15, hexagonal, gyroid, and lamellar structures where the rod segments are packed inside the convex rod-coil interface are found stable. As the conformational asymmetric parameter increases, the A15 phase region expands and the gyroid phase region reduces. The stability of the structures is analyzed by concepts such as packing frustration, spinodal limit, and interfacial curvature.

  13. Self-consistent simulation of CdTe solar cells with active defects

    SciTech Connect

    Brinkman, Daniel; Guo, Da; Akis, Richard; Ringhofer, Christian; Sankin, Igor; Fang, Tian; Vasileska, Dragica

    2015-07-21

    We demonstrate a self-consistent numerical scheme for simulating an electronic device which contains active defects. As a specific case, we consider copper defects in cadmium telluride solar cells. The presence of copper has been shown experimentally to play a crucial role in predicting device performance. The primary source of this copper is migration away from the back contact during annealing, which likely occurs predominantly along grain boundaries. We introduce a mathematical scheme for simulating this effect in 2D and explain the numerical implementation of the system. Lastly, we will give numerical results comparing our results to known 1D simulations to demonstrate the accuracy of the solver and then show results unique to the 2D case.

  14. Second-Order Perturbation Theory for Generalized Active Space Self-Consistent-Field Wave Functions.

    PubMed

    Ma, Dongxia; Li Manni, Giovanni; Olsen, Jeppe; Gagliardi, Laura

    2016-07-12

    A multireference second-order perturbation theory approach based on the generalized active space self-consistent-field (GASSCF) wave function is presented. Compared with the complete active space (CAS) and restricted active space (RAS) wave functions, GAS wave functions are more flexible and can employ larger active spaces and/or different truncations of the configuration interaction expansion. With GASSCF, one can explore chemical systems that are not affordable with either CASSCF or RASSCF. Perturbation theory to second order on top of GAS wave functions (GASPT2) has been implemented to recover the remaining electron correlation. The method has been benchmarked by computing the chromium dimer ground-state potential energy curve. These calculations show that GASPT2 gives results similar to CASPT2 even with a configuration interaction expansion much smaller than the corresponding CAS expansion.

  15. Covariant and self-consistent vertex corrections for pions and isobars in nuclear matter

    SciTech Connect

    Korpa, C. L.; Lutz, M. F. M.; Riek, F.

    2009-08-15

    We evaluate the pion and isobar propagators in cold nuclear matter self-consistently applying a covariant form of the isobar-hole model. Migdal's vertex correction effects are considered systematically in the absence of phenomenological soft form factors. Saturated nuclear matter is modeled by scalar and vector mean fields for the nucleon. It is shown that the short-range dressing of the {pi}N{delta} vertex has a significant effect on the pion and isobar properties. Using realistic parameters sets we predict a downward shift of about 50 MeV for the {delta} resonance at nuclear saturation density. The pionic soft modes are much less pronounced than in previous studies.

  16. The self-consistent multiparticle-multihole configuration mixing. Motivations, state of the art and perspectives

    NASA Astrophysics Data System (ADS)

    Pillet, N.; Robin, C.; Dupuis, M.; Hupin, G.; Berger, J.-F.

    2017-03-01

    The main objective of this paper is to review the state of the art of the multiparticle-multihole configuration mixing approach which was proposed and implemented using the Gogny interaction ˜ 10 years ago. Various theoretical aspects are re-analyzed when a Hamiltonian description is chosen: the link with exact many-body theories, the impact of truncations in the multiconfigurational space, the importance of defining single-particle orbitals which are consistent with the correlations introduced in the many-body wave function, the role of the self-consistency, and more practically the numerical convergence algorithm. Several applications done with the phenomenological effective Gogny interaction are discussed. Finally, future directions to extend and generalize the method are discussed.

  17. Self-Consistent Multiscale Theory of Internal Wave, Mean-Flow Interactions

    SciTech Connect

    Holm, D.D.; Aceves, A.; Allen, J.S.; Alber, M.; Camassa, R.; Cendra, H.; Chen, S.; Duan, J.; Fabijonas, B.; Foias, C.; Fringer, O.; Gent, P.R.; Jordan, R.; Kouranbaeva, S.; Kovacic, G.; Levermore, C.D.; Lythe, G.; Lifschitz, A.; Marsden, J.E.; Margolin, L.; Newberger, P.; Olson, E.; Ratiu, T.; Shkoller, S.; Timofeyev, I.; Titi, E.S.; Wynn, S.

    1999-06-03

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The research reported here produced new effective ways to solve multiscale problems in nonlinear fluid dynamics, such as turbulent flow and global ocean circulation. This was accomplished by first developing new methods for averaging over random or rapidly varying phases in nonlinear systems at multiple scales. We then used these methods to derive new equations for analyzing the mean behavior of fluctuation processes coupled self consistently to nonlinear fluid dynamics. This project extends a technology base relevant to a variety of multiscale problems in fluid dynamics of interest to the Laboratory and applies this technology to those problems. The project's theoretical and mathematical developments also help advance our understanding of the scientific principles underlying the control of complex behavior in fluid dynamical systems with strong spatial and temporal internal variability.

  18. Self-consistent simulation of CdTe solar cells with active defects

    SciTech Connect

    Brinkman, Daniel; Ringhofer, Christian; Guo, Da; Akis, Richard; Vasileska, Dragica; Sankin, Igor; Fang, Tian

    2015-07-21

    We demonstrate a self-consistent numerical scheme for simulating an electronic device which contains active defects. As a specific case, we consider copper defects in cadmium telluride solar cells. The presence of copper has been shown experimentally to play a crucial role in predicting device performance. The primary source of this copper is migration away from the back contact during annealing, which likely occurs predominantly along grain boundaries. We introduce a mathematical scheme for simulating this effect in 2D and explain the numerical implementation of the system. Finally, we will give numerical results comparing our results to known 1D simulations to demonstrate the accuracy of the solver and then show results unique to the 2D case.

  19. Self-consistent van der Waals density functional study of benzene adsorption on Si(100)

    NASA Astrophysics Data System (ADS)

    Hamamoto, Yuji; Hamada, Ikutaro; Inagaki, Kouji; Morikawa, Yoshitada

    2016-06-01

    The adsorption of benzene on the Si(100) surface is studied theoretically using the self-consistent van der Waals density functional (vdW-DF) method. The adsorption energies of two competing adsorption structures, butterfly (BF) and tight-bridge (TB) structures, are calculated with several vdW-DFs at saturation coverage. Our results show that recently proposed vdW-DFs with high accuracy all prefer TB to BF, in accord with more accurate calculations based on exact exchange and correlation within the random-phase approximation. Detailed analyses reveal the important roles played by the molecule-surface interaction and molecular deformation upon adsorption, and we suggest that their precise description is a prerequisite for accurate prediction of the most stable adsorption structure of organic molecules on semiconductor surfaces.

  20. Self-consistent description of electrokinetic phenomena in particle-based simulations.

    PubMed

    Hernández-Ortiz, Juan P; de Pablo, Juan J

    2015-07-07

    A new computational method is presented for study suspensions of charged particles undergoing fluctuating hydrodynamic and electrostatic interactions. The proposed model is appropriate for polymers, proteins, and porous particles embedded in a continuum electrolyte. A self-consistent Langevin description of the particles is adopted in which hydrodynamic and electrostatic interactions are included through a Green's function formalism. An Ewald-like split is adopted in order to satisfy arbitrary boundary conditions for the Stokeslet and Poisson Green functions, thereby providing a formalism that is applicable to any geometry and that can be extended to deformable objects. The convection-diffusion equation for the continuum ions is solved simultaneously considering Nernst-Planck diffusion. The method can be applied to systems at equilibrium and far from equilibrium. Its applicability is demonstrated in the context of electrokinetic motion, where it is shown that the ionic clouds associated with individual particles can be severely altered by the flow and concentration, leading to intriguing cooperative effects.

  1. Self-consistent description of spin-phonon dynamics in ferromagnets

    NASA Astrophysics Data System (ADS)

    Nieves, P.; Serantes, D.; Chubykalo-Fesenko, O.

    2016-07-01

    Several recently reported exciting phenomena such as spin caloritronics or ultrafast laser-induced spin dynamics involve the action of temperature on spin dynamics. However, the inverse effect of magnetization dynamics on temperature change is very frequently ignored. Based on the density matrix approach, in this work we derive a self-consistent model for describing the magnetization and phonon temperature dynamics in ferromagnets in the framework of the quantum Landau-Lifshitz-Bloch equation. We explore potential applicability of our approach for two cases, inspired by magnetocaloric effect and magnetic fluid hyperthermia. In the first case, the spin-phonon dynamics is governed by the longitudinal relaxation in bulk systems close to the Curie temperature; while in the second case it is described by the transverse relaxation during the hysteresis cycle of individual nanoparticles well below the Curie temperature.

  2. Self-consistent inclusion of classical large-angle Coulomb collisions in plasma Monte Carlo simulations

    SciTech Connect

    Turrell, A.E. Sherlock, M.; Rose, S.J.

    2015-10-15

    Large-angle Coulomb collisions allow for the exchange of a significant proportion of the energy of a particle in a single collision, but are not included in models of plasmas based on fluids, the Vlasov–Fokker–Planck equation, or currently available plasma Monte Carlo techniques. Their unique effects include the creation of fast ‘knock-on’ ions, which may be more likely to undergo certain reactions, and distortions to ion distribution functions relative to what is predicted by small-angle collision only theories. We present a computational method which uses Monte Carlo techniques to include the effects of large-angle Coulomb collisions in plasmas and which self-consistently evolves distribution functions according to the creation of knock-on ions of any generation. The method is used to demonstrate ion distribution function distortions in an inertial confinement fusion (ICF) relevant scenario of the slowing of fusion products.

  3. Self-consistent current sheet structures in the quiet-time magnetotail

    NASA Technical Reports Server (NTRS)

    Holland, Daniel L.; Chen, James

    1993-01-01

    The structure of the quiet-time magnetotail is studied using a test particle simulation. Vlasov equilibria are obtained in the regime where v(D) = E(y) c/B(z) is much less than the ion thermal velocity and are self-consistent in that the current and magnetic field satisfy Ampere's law. Force balance between the plasma and magnetic field is satisfied everywhere. The global structure of the current sheet is found to be critically dependent on the source distribution function. The pressure tensor is nondiagonal in the current sheet with anisotropic temperature. A kinetic mechanism is proposed whereby changes in the source distribution results in a thinning of the current sheet.

  4. SELF-CONSISTENT LANGEVIN SIMULATION OF COULOMB COLLISIONS IN CHARGED-PARTICLE BEAMS

    SciTech Connect

    J. QIANG; R. RYNE; S. HABIB

    2000-05-01

    In many plasma physics and charged-particle beam dynamics problems, Coulomb collisions are modeled by a Fokker-Planck equation. In order to incorporate these collisions, we present a three-dimensional parallel Langevin simulation method using a Particle-In-Cell (PIC) approach implemented on high-performance parallel computers. We perform, for the first time, a fully self-consistent simulation, in which the friction and diffusion coefficients are computed from first principles. We employ a two-dimensional domain decomposition approach within a message passing programming paradigm along with dynamic load balancing. Object oriented programming is used to encapsulate details of the communication syntax as well as to enhance reusability and extensibility. Performance tests on the SGI Origin 2000 and the Cray T3E-900 have demonstrated good scalability. Work is in progress to apply our technique to intrabeam scattering in accelerators.

  5. Self-consistent radiation-based simulation of electric arcs: II. Application to gas circuit breakers

    NASA Astrophysics Data System (ADS)

    Iordanidis, A. A.; Franck, C. M.

    2008-07-01

    An accurate and robust method for radiative heat transfer simulation for arc applications was presented in the previous paper (part I). In this paper a self-consistent mathematical model based on computational fluid dynamics and a rigorous radiative heat transfer model is described. The model is applied to simulate switching arcs in high voltage gas circuit breakers. The accuracy of the model is proven by comparison with experimental data for all arc modes. The ablation-controlled arc model is used to simulate high current PTFE arcs burning in cylindrical tubes. Model accuracy for the lower current arcs is evaluated using experimental data on the axially blown SF6 arc in steady state and arc resistance measurements close to current zero. The complete switching process with the arc going through all three phases is also simulated and compared with the experimental data from an industrial circuit breaker switching test.

  6. Nonlocal thermodynamic equilibrium self-consistent average-atom model for plasma physics.

    PubMed

    Faussurier, G; Blancard, C; Berthier, E

    2001-02-01

    A time-dependent collisional-radiative average-atom model is presented to study statistical properties of highly charged ion plasmas in off-equilibrium conditions. The time evolution of electron populations and the electron covariance matrix is obtained as approximate solutions of a master equation. Atomic structure is described either with a screened-hydrogenic model including l splitting, or by calculating one-electron states in a self-consistent average-atom potential. Collisional and radiative excitation/deexcitation and ionization/recombination rates, as well as autoionization and dielectronic recombination rates, are formulated within the average-configuration framework. Local thermodynamic equilibrium is obtained as a specific steady-state solution. The influence of atomic structure and the role of autoionization and dielectronic recombination processes are studied by calculating steady-state average ionization and ionization variance of hot plasmas with or without radiation field.

  7. Theory for self-consistent interplay between light and nanomaterials strongly modified by metallic nanostructures.

    PubMed

    Ishikawa, Akira; Osono, Katsuya; Nobuhiro, Atsushi; Mizumoto, Yoshihiko; Torimoto, Tsukasa; Ishihara, Hajime

    2013-03-28

    The design of the interplay between light and nanomaterials by the effect of localized-surface-plasmon resonance in metallic nanostructures is a fascinating subject, and recently, a lot of research has been carried out from both fundamental and applicational points of view. In this paper, we demonstrate the theories for describing the self-consistent interplay between the electronic states in the nanomaterials, the localized surface plasmons in the metallic nanostructures, and the light field, which provides insight into how the photoexcitation processes are modified through microscopic energy exchanges. As examples of such demonstrations, we show two cases, i.e., the interaction between a single metallic nanosphere and a quantum dot, and that between metallic nanostructures forming a nanogap and dimer molecules, where a peculiar dependence of photoexcitation processes on the distance between the metallic nanostructure and the absorbers arises depending on the respective characteristics of their interplay.

  8. From Observations to Self-Consistent Modelling of the ISM in Galaxies

    NASA Astrophysics Data System (ADS)

    de Avillez, M. A.; Breitschwerdt, D.

    2004-03-01

    Research of the interstellar medium (ISM) has been advancing rapidly during the last 10 years, mainly due to immensely improved observational facilities and techniques in all wavelength ranges. We are now able to investigate the ISM in external galaxies and even the intergalactic and intracluster medium in great detail. Increased spatial and spectral resolution have provided us with a great deal of information on the interstellar gas in its various phases, the magnetic field and the cosmic rays, and of course, also the stellar component, which is the driving agent of the interstellar matter cycle. Since only fairly recently, a sufficient amount of computing power has become available to tackle these problems with some prospect of obtaining a self-consistent picture of the ISM, a major goal of this workshop was to bring together observers and theoreticians sufficiently close, so that intense discussions about the necessities and desiderata of modelling the ISM could be stimulated. Observers have shown in great detail on this conference of what is seen on all scales of the ISM, near and far, and what boundary conditions would be appropriate for realistic models, and theoreticians pointed out what assumptions and simplifications their codes need, and how future observations could test their models. As a first step towards this goal, some self-consistent numerical simulations with a minimum number of relevant physical processes were also presented on this meeting. There was wide agreement, that this approach - to keep observers and theoreticians in close contact and also in sometimes quite controversial discussions - will bear fruitful results in the near future. Link: http://www.wkap.nl/prod/b/1-4020-1939-4

  9. Towards self-consistent modelling of the Sgr A* accretion flow: linking theory and observation

    NASA Astrophysics Data System (ADS)

    Roberts, Shawn R.; Jiang, Yan-Fei; Wang, Q. Daniel; Ostriker, Jeremiah P.

    2017-04-01

    The interplay between supermassive black holes (SMBHs) and their environments is believed to command an essential role in galaxy evolution. The majority of these SMBHs are in the radiative inefficient accretion phase where this interplay remains elusive, but suggestively important, due to few observational constraints. To remedy this, we directly fit 2D hydrodynamic simulations to Chandra observations of Sgr A* with Markov chain Monte Carlo sampling, self-consistently modelling the 2D inflow-outflow solution for the first time. We find the temperature and density at flow onset are consistent with the origin of the gas in the stellar winds of massive stars in the vicinity of Sgr A*. We place the first observational constraints on the angular momentum of the gas and estimate the centrifugal radius, rc ≈ 0.056 rb ≈ 8 × 10-3 pc, where rb is the Bondi radius. Less than 1 per cent of the inflowing gas accretes on to the SMBH, the remainder being ejected in a polar outflow. We decouple the quiescent point-like emission from the spatially extended flow. We find this point-like emission, accounting for ∼4 per cent of the quiescent flux, is spectrally too steep to be explained by unresolved flares, nor bremsstrahlung, but is likely a combination of a relatively steep synchrotron power law and the high-energy tail of inverse-Compton emission. With this self-consistent model of the accretion flow structure, we make predictions for the flow dynamics and discuss how future X-ray spectroscopic observations can further our understanding of the Sgr A* accretion flow.

  10. Self-consistent evolution of tissue damage under stress wave propagation

    SciTech Connect

    Amendt, P; Glinsky, M; Kaufman, Y; London, R A; Sapir, M; Strauss, M

    1999-01-14

    Laser-initiated stress waves are reflected from tissue boundaries, thereby inducing tensile stresses, which are responsible for tissue damage. A self-consistent model of tissue failure evolution induced by stress wave propagation is considered. The failed tissue is represented by an ensemble of spherical voids and includes the effect of nucleation, growth and coalescence of voids under stress wave tension. Voids nucleate around impurities and grow according to an extended Rayleigh model that includes the effects of surface tension, viscosity and acoustic emission at void collapse. The damage model is coupled self-consistently to a one-dimensional planar hydrodynamic model of stress waves generated by a short pulse laser. We considered the problem of a bipolar wave generated by a short pulse laser absorbed on a free boundary of an aqueous system. The propagating wave includes a tensile component, which interacts with the impurities of exponential distribution in dimension, impurity density ({approximately}10{sup 8} cm{sup -3}) void and an ensemble of voids is generated. For moderate growth reduces the tensile wave component and causes the pressure to oscillate between tension and compression. For low impurity density ({approximately}10{sup 6} cm{sup -3} ) the bubbles grow on a long time scale (5-10 {micro}sec) relative to the wave interaction time ({approximately}100 nsec). At later times the growing bubbles interact with each other causing pressure oscillations and delay the system from reaching the 1 bar ambient compression pressure. This effect increases considerably the bubble lifetime consistent with experiments. At the collapse stage small bubbles collapse earlier and induce pressures, which reduce the collapse time of the larger bubbles.

  11. Self-Consistent Magnetosphere-Ionosphere Coupling and Associated Plasma Energization Processes

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Six, N. Frank (Technical Monitor)

    2002-01-01

    Magnetosphere-Ionosphere (MI) coupling and associated with this process electron and ion energization processes have interested scientists for decades and, in spite of experimental and theoretical research efforts, are still ones of the least well known dynamic processes in space plasma physics. The reason for this is that the numerous physical processes associated with MI coupling occur over multiple spatial lengths and temporal scales. One typical example of MI coupling is large scale ring current (RC) electrodynamic coupling that includes calculation of the magnetospheric electric field that is consistent with the ring current (RC) distribution. A general scheme for numerical simulation of such large-scale magnetosphere-ionosphere coupling processes has been presented earlier in many works. The mathematical formulation of these models are based on "modified frozen-in flux theorem" for an ensemble of adiabatically drifting particles in the magnetosphere. By tracking the flow of particles through the inner magnetosphere, the bounce-averaged phase space density of the hot ions and electrons can be reconstructed and the magnetospheric electric field can be calculated such that it is consistent with the particle distribution in the magnetosphere. The new a self-consistent ring current model has been developed that couples electron and ion magnetospheric dynamics with calculation of electric field. Two new features were taken into account in addition to the RC ions, we solve an electron kinetic equation in our model, self-consistently including these results in the solution. Second, using different analytical relationships, we calculate the height integrated ionospheric conductances as the function of precipitated high energy magnetospheric electrons and ions as produced by our model. This results in fundamental changes to the electric potential pattern in the inner magnetosphere, with a smaller Alfven boundary than previous potential formulations would predict but

  12. A full, self-consistent treatment of thermal wind balance on oblate fluid planets

    NASA Astrophysics Data System (ADS)

    Galanti, Eli; Kaspi, Yohai; Tziperman, Eli

    2017-01-01

    The nature of the flow below the cloud level on Jupiter and Saturn is still unknown. Relating the flow on these planets to perturbations in their density field is key to the analysis of the gravity measurements expected from both the Juno (Jupiter) and Cassini (Saturn) spacecrafts during 2016-17. Both missions will provide latitude-dependent gravity fields, which in principle could be inverted to calculate the vertical structure of the observed cloud-level zonal flow on these planets. Theories to date connecting the gravity field and the flow structure have been limited to potential theories under a barotropic assumption, or estimates based on thermal wind balance that allow analyzing baroclinic wind structures, but have made simplifying assumptions. Those include the effects of the deviations from spherical symmetry, the centrifugal force due to density perturbations, and self-gravitational effects of the density perturbations. Recent studies attempted to include some effects but not in a self-consistent manner. The present study introduces such a self-consistent perturbation approach to the thermal wind balance that incorporates all physical effects, and applies it to several example wind structures, both barotropic and baroclinic. The contribution of each term is analyzed, and the results are compared in the barotropic limit to those of potential theory. It is found that the dominant balance involves the original simplified thermal wind approach. This balance produces a good order-of-magnitude estimate of the gravitational moments, and is able, therefore, to address the order one question of how deep the flows are given measurements of gravitational moments. The additional terms are significantly smaller and none of these terms is dominant, so any approximation attempting to improve over the simplified thermal wind approach needs to include all other terms.

  13. A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood

    NASA Astrophysics Data System (ADS)

    Bell, Cameron P. M.; Mamajek, Eric E.; Naylor, Tim

    2015-11-01

    We present a self-consistent, absolute isochronal age scale for young ( ≲ 200 Myr), nearby ( ≲ 100 pc) moving groups in the solar neighbourhood based on homogeneous fitting of semi-empirical pre-main-sequence model isochrones using the τ2 maximum-likelihood fitting statistic of Naylor & Jeffries in the MV, V - J colour-magnitude diagram. The final adopted ages for the groups are as follows: 149^{+51}_{-19} {Myr} for the AB Dor moving group, 24 ± 3 Myr for the β Pic moving group (BPMG), 45^{+11}_{-7} {Myr} for the Carina association, 42^{+6}_{-4} {Myr} for the Columba association, 11 ± 3 Myr for the η Cha cluster, 45 ± 4 Myr for the Tucana-Horologium moving group (Tuc-Hor), 10 ± 3 Myr for the TW Hya association and 22^{+4}_{-3} {Myr} for the 32 Ori group. At this stage we are uncomfortable assigning a final, unambiguous age to the Argus association as our membership list for the association appears to suffer from a high level of contamination, and therefore it remains unclear whether these stars represent a single population of coeval stars. Our isochronal ages for both the BPMG and Tuc-Hor are consistent with recent lithium depletion boundary (LDB) ages, which unlike isochronal ages, are relatively insensitive to the choice of low-mass evolutionary models. This consistency between the isochronal and LDB ages instils confidence that our self-consistent, absolute age scale for young, nearby moving groups is robust, and hence we suggest that these ages be adopted for future studies of these groups. Software implementing the methods described in this study is available from http://www.astro.ex.ac.uk/people/timn/tau-squared/.

  14. [Detection of SOS response inhibitor with E. coli GW1104 and GW1107 and its mechanism].

    PubMed

    Qian, J; Jin, Z C

    1994-03-01

    E. coli GW1104 and GW1107 are temperature-sensitive strains carrying a fusion gene umu:: Mud(Ap,lac) with genotypes recA441 (tif-1) and recA441 (tif-1),lexA (Def) (spr), respectively. SOS response can be produced spontaneously at 32 degrees C in E. coli GW1107, and induced at 42 degrees C in both E. coli GW1107 and GW1104. To detect SOS response inhibitor and to study its mechanism, a quick-test-system was established based on their genetic characteristics of the two strains. It was found some kinds of Chinese herbal medicine, vegetables, and chemicals could inhibit SOS response in the strains to different extent with varied mechanisms. Shell of water chestnut could inhibit temperature-induced SOS response at 42 degrees C in E. coli GW1104, and spontaneously-produced one at 32 degrees C in E.coli GW1107. Chinese chives can only inhibit temperature-induced SOS response in E. coli GW1104. It suggested the former's inhibition effect on SOS response occurred at lexA gene or on the pathway of SOS response before lexA gene, and so did the latter's on the pathway after lexA gene.

  15. Understanding the LIGO GW150914 event

    NASA Astrophysics Data System (ADS)

    Naselsky, Pavel; Jackson, Andrew D.; Liu, Hao

    2016-08-01

    We present a simplified method for the extraction of meaningful signals from Hanford and Livingston 32 second data for the GW150914 event made publicly available by the LIGO collaboration, and demonstrate its ability to reproduce the LIGO collaboration's own results quantitatively given the assumption that all narrow peaks in the power spectrum are a consequence of physically uninteresting signals and can be removed. After the clipping of these peaks and return to the time domain, the GW150914 event is readily distinguished from broadband background noise. This simple technique allows us to identify the GW150914 event without any assumption regarding its physical origin and with minimal assumptions regarding its shape. We also confirm that the LIGO GW150914 event is uniquely correlated in the Hanford and Livingston detectors for the full 4096 second data at the level of 6-7 σ with a temporal displacement of τ = 6.9 ± 0.4 ms. We have also identified a few events that are morphologically close to GW150914 but less strongly cross correlated with it.

  16. Self-Consistent Model of Magnetospheric Electric Field, Ring Current, Plasmasphere, and Electromagnetic Ion Cyclotron Waves: Initial Results

    NASA Technical Reports Server (NTRS)

    Gamayunov, K. V.; Khazanov, G. V.; Liemohn, M. W.; Fok, M.-C.; Ridley, A. J.

    2009-01-01

    Further development of our self-consistent model of interacting ring current (RC) ions and electromagnetic ion cyclotron (EMIC) waves is presented. This model incorporates large scale magnetosphere-ionosphere coupling and treats self-consistently not only EMIC waves and RC ions, but also the magnetospheric electric field, RC, and plasmasphere. Initial simulations indicate that the region beyond geostationary orbit should be included in the simulation of the magnetosphere-ionosphere coupling. Additionally, a self-consistent description, based on first principles, of the ionospheric conductance is required. These initial simulations further show that in order to model the EMIC wave distribution and wave spectral properties accurately, the plasmasphere should also be simulated self-consistently, since its fine structure requires as much care as that of the RC. Finally, an effect of the finite time needed to reestablish a new potential pattern throughout the ionosphere and to communicate between the ionosphere and the equatorial magnetosphere cannot be ignored.

  17. All-electron first-principles GW+Bethe-Salpeter calculation for optical absorption spectra of sodium clusters

    SciTech Connect

    Noguchi, Yoshifumi; Ohno, Kaoru

    2010-04-15

    The optical absorption spectra of sodium clusters (Na{sub 2n}, n{<=} 4) are calculated by using an all-electron first-principles GW+Bethe-Salpeter method with the mixed-basis approach within the Tamm-Dancoff approximation. In these small systems, the excitonic effect strongly affects the optical properties due to the confinement of exciton in the small system size. The present state-of-the-art method treats the electron-hole two-particle Green's function by incorporating the ladder diagrams up to the infinite order and therefore takes into account the excitonic effect in a good approximation. We check the accuracy of the present method by comparing the resulting spectra with experiments. In addition, the effect of delocalization in particular in the lowest unoccupied molecular orbital in the GW quasiparticle wave function is also discussed by rediagonalizing the Dyson equation.

  18. Third minima in thorium and uranium isotopes in a self-consistent theory

    NASA Astrophysics Data System (ADS)

    McDonnell, J. D.; Nazarewicz, W.; Sheikh, J. A.

    2013-05-01

    Background: Well-developed third minima, corresponding to strongly elongated and reflection-asymmetric shapes associated with dimolecular configurations, have been predicted in some non-self-consistent models to impact fission pathways of thorium and uranium isotopes. These predictions have guided the interpretation of resonances seen experimentally. On the other hand, self-consistent calculations consistently predict very shallow potential-energy surfaces in the third minimum region.Purpose: We investigate the interpretation of third-minimum configurations in terms of dimolecular (cluster) states. We study the isentropic potential-energy surfaces of selected even-even thorium and uranium isotopes at several excitation energies. In order to understand the driving effects behind the presence of third minima, we study the interplay between pairing and shell effects.Methods: We use the finite-temperature superfluid nuclear density functional theory. We consider two Skyrme energy density functionals: a traditional functional SkM* and a recent functional UNEDF1 optimized for fission studies.Results: We predict very shallow or no third minima in the potential-energy surfaces of 232Th and 232U. In the lighter Th and U isotopes with N=136 and 138, the third minima are better developed. We show that the reflection-asymmetric configurations around the third minimum can be associated with dimolecular states involving the spherical doubly magic 132Sn and a lighter deformed Zr or Mo fragment. The potential-energy surfaces for 228,232Th and 232U at several excitation energies are presented. We also study isotopic chains to demonstrate the evolution of the depth of the third minimum with neutron number.Conclusions: We show that the neutron shell effect that governs the existence of the dimolecular states around the third minimum is consistent with the spherical-to-deformed shape transition in the Zr and Mo isotopes around N=58. We demonstrate that the depth of the third minimum

  19. Self-consistent particle-in-cell simulations of fundamental and harmonic plasma radio emission mechanisms

    NASA Astrophysics Data System (ADS)

    Thurgood, J. O.; Tsiklauri, D.

    2015-12-01

    Aims: The simulation of three-wave interaction based plasma emission, thought to be the underlying mechanism for Type III solar radio bursts, is a challenging task requiring fully-kinetic, multi-dimensional models. This paper aims to resolve a contradiction in past attempts, whereby some studies indicate that no such processes occur. Methods: We self-consistently simulate three-wave based plasma emission through all stages by using 2D, fully kinetic, electromagnetic particle-in-cell simulations of relaxing electron beams using the EPOCH2D code. Results: Here we present the results of two simulations; Run 1 (nb/n0 = 0.0057, vb/ Δvb = vb/Ve = 16) and Run 2 (nb/n0 = 0.05, vb/ Δvb = vb/Ve = 8), which we find to permit and prohibit plasma emission respectively. We show that the possibility of plasma emission is contingent upon the frequency of the initial electrostatic waves generated by the bump-in-tail instability, and that these waves may be prohibited from participating in the necessary three-wave interactions due to frequency conservation requirements. In resolving this apparent contradiction through a comprehensive analysis, in this paper we present the first self-consistent demonstration of fundamental and harmonic plasma emission from a single-beam system via fully kinetic numerical simulation. We caution against simulating astrophysical radio bursts using unrealistically dense beams (a common approach which reduces run time), as the resulting non-Langmuir characteristics of the initial wave modes significantly suppresses emission. Comparison of our results also indicates that, contrary to the suggestions of previous authors, an alternative plasma emission mechanism based on two counter-propagating beams is unnecessary in an astrophysical context. Finally, we also consider the action of the Weibel instability which generates an electromagnetic beam mode. As this provides a stronger contribution to electromagnetic energy than the emission, we stress that

  20. A finite element approach to self-consistent field theory calculations of multiblock polymers

    NASA Astrophysics Data System (ADS)

    Ackerman, David M.; Delaney, Kris; Fredrickson, Glenn H.; Ganapathysubramanian, Baskar

    2017-02-01

    Self-consistent field theory (SCFT) has proven to be a powerful tool for modeling equilibrium microstructures of soft materials, particularly for multiblock polymers. A very successful approach to numerically solving the SCFT set of equations is based on using a spectral approach. While widely successful, this approach has limitations especially in the context of current technologically relevant applications. These limitations include non-trivial approaches for modeling complex geometries, difficulties in extending to non-periodic domains, as well as non-trivial extensions for spatial adaptivity. As a viable alternative to spectral schemes, we develop a finite element formulation of the SCFT paradigm for calculating equilibrium polymer morphologies. We discuss the formulation and address implementation challenges that ensure accuracy and efficiency. We explore higher order chain contour steppers that are efficiently implemented with Richardson Extrapolation. This approach is highly scalable and suitable for systems with arbitrary shapes. We show spatial and temporal convergence and illustrate scaling on up to 2048 cores. Finally, we illustrate confinement effects for selected complex geometries. This has implications for materials design for nanoscale applications where dimensions are such that equilibrium morphologies dramatically differ from the bulk phases.

  1. Self-consistent calculation of the nuclear composition in hot and dense stellar matter

    NASA Astrophysics Data System (ADS)

    Furusawa, Shun; Mishustin, Igor

    2017-03-01

    We investigate the mass fractions and in-medium properties of heavy nuclei in stellar matter at characteristic densities and temperatures for supernova (SN) explosions. The individual nuclei are described within the compressible liquid-drop model taking into account modifications of bulk, surface, and Coulomb energies. The equilibrium properties of nuclei and the full ensemble of heavy nuclei are calculated self-consistently. It is found that heavy nuclei in the ensemble are either compressed or decompressed depending on the isospin asymmetry of the system. The compression or decompression has a little influence on the binding energies, total mass fractions, and average mass numbers of heavy nuclei, although the equilibrium densities of individual nuclei themselves are changed appreciably above one-hundredth of normal nuclear density. We find that nuclear structure in the single-nucleus approximation deviates from the actual one obtained in the multinucleus description, since the density of free nucleons is different between these two descriptions. This study indicates that a multinucleus description is required to realistically account for in-medium effects on the nuclear structure in supernova matter.

  2. Self-consistent Model Of Debris Discs Coupling Dynamics And Collisions

    NASA Astrophysics Data System (ADS)

    Kral, Quentin; Thebault, P.; Charnoz, S.

    2012-10-01

    I will present the first attempt at developing a fully self-consistent code coupling dynamics and collisions to study debris discs. So far, these two crucial mechanisms were studied separately, with N-body and statistical codes respectively, because of stringent computational constraints. In particular, incorporating collisional effects (especially destructive collisions) into an N-body scheme was deemed an impossible task because of the exponential increase of particles it would imply. We present here an alternative approach, based on the LIDT code developed by Charnoz et al.(2012) for protoplanetary discs, and strongly upgraded to account for the complexity of debris disc physics (high velocity collisions, radiation-pressure affected orbits, etc.). In this 3D Lagrangian-Eulerian code, grains of given size at a given location in a disc are grouped into "super-particles" (SPs), whose orbits are tracked with an N-body code and whose mutual collisions are treated using a particle-in-a-box scheme. To keep the number of super-particles from diverging, a reassignment routine reallocates redundant SPs to regions where they are needed. Our code is under development but already working for simple astrophysical cases. I will present some preliminary results for simple disc configurations, as well as some perspectives for the close-future.

  3. Self-consistent model of a solid for the description of lattice and magnetic properties

    NASA Astrophysics Data System (ADS)

    Balcerzak, T.; Szałowski, K.; Jaščur, M.

    2017-03-01

    In the paper a self-consistent theoretical description of the lattice and magnetic properties of a model system with magnetoelastic interaction is presented. The dependence of magnetic exchange integrals on the distance between interacting spins is assumed, which couples the magnetic and the lattice subsystem. The framework is based on summation of the Gibbs free energies for the lattice subsystem and magnetic subsystem. On the basis of minimization principle for the Gibbs energy, a set of equations of state for the system is derived. These equations of state combine the parameters describing the elastic properties (relative volume deformation) and the magnetic properties (magnetization changes). The formalism is extensively illustrated with the numerical calculations performed for a system of ferromagnetically coupled spins S=1/2 localized at the sites of simple cubic lattice. In particular, the significant influence of the magnetic subsystem on the elastic properties is demonstrated. It manifests itself in significant modification of such quantities as the relative volume deformation, thermal expansion coefficient or isothermal compressibility, in particular, in the vicinity of the magnetic phase transition. On the other hand, the influence of lattice subsystem on the magnetic one is also evident. It takes, for example, the form of dependence of the critical (Curie) temperature and magnetization itself on the external pressure, which is thoroughly investigated.

  4. Neural-network accelerated fusion simulation with self-consistent core-pedestal coupling

    NASA Astrophysics Data System (ADS)

    Meneghini, O.; Candy, J.; Snyder, P. B.; Staebler, G.; Belli, E.

    2016-10-01

    Practical fusion Whole Device Modeling (WDM) simulations require the ability to perform predictions that are fast, but yet account for the sensitivity of the fusion performance to the boundary constraint that is imposed by the pedestal structure of H-mode plasmas due to the stiff core transport models. This poster presents the development of a set of neural-network (NN) models for the pedestal structure (as predicted by the EPED model), and the neoclassical and turbulent transport fluxes (as predicted by the NEO and TGLF codes, respectively), and their self-consistent coupling within the TGYRO transport code. The results are benchmarked with the ones obtained via the coupling scheme described in [Meneghini PoP 2016]. By substituting the most demanding codes with their NN-accelerated versions, the solution can be found at a fraction of the computation cost of the original coupling scheme, thereby combining the accuracy of a high-fidelity model with the fast turnaround time of a reduced model. Work supported by U.S. DOE DE-FC02-04ER54698 and DE-FG02-95ER54309.

  5. Why protein R-factors are so large: a self-consistent analysis.

    PubMed

    Vitkup, Dennis; Ringe, Dagmar; Karplus, Martin; Petsko, Gregory A

    2002-03-01

    The R-factor and R-free are commonly used to measure the quality of protein models obtained in X-ray crystallography. Well-refined protein structures usually have R-factors in the range of 20-25%, whereas intrinsic errors in the experimental data are usually around 5%. We use molecular dynamics simulations to perform a self-consistent analysis by which we determine the major factors contributing to large values of protein R-factors. The analysis shows that significant R-factor values can arise from the use of isotropic B-factors to model anisotropic protein motions and from coordinate errors. Even in the absence of coordinate errors, the use of isotropic B-factors can cause the R-factors to be around 10%; for coordinate errors smaller than 0.2 A, the two errors types make similar contributions. The inaccuracy of the energy function used and multistate protein dynamics are unlikely to make significant contributions to the large R-factors.

  6. A control-oriented self-consistent model of an inductively-coupled plasma

    NASA Astrophysics Data System (ADS)

    Keville, Bernard; Turner, Miles

    2009-10-01

    An essential first step in the design of real time control algorithms for plasma processes is to determine dynamical relationships between actuator quantities such as gas flow rate set points and plasma states such electron density. An ideal first principles-based, control-oriented model should exhibit the simplicity and computational requirements of an empirical model and, in addition, despite sacrificing first principles detail, capture enough of the essential physics and chemistry of the process in order to provide reasonably accurate qualitative predictions. This presentation describes a control-oriented model of a cylindrical low pressure planar inductive discharge with a stove top antenna. The model consists of equivalent circuit coupled to a global model of the plasma chemistry to produce a self-consistent zero-dimensional model of the discharge. The non-local plasma conductivity and the fields in the plasma are determined from the wave equation and the two-term solution of the Boltzmann equation. Expressions for the antenna impedance and the parameters of the transformer equivalent circuit in terms of the isotropic electron distribution and the geometry of the chamber are presented.

  7. Photoelectron Effects on the Self-Consistent Potential in the Collisionless Polar Wind

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Liemohn, M. W.; Moore, T. E.

    1997-01-01

    The presence of unthermalized photoelectrons in the sunlit polar cap leads to an enhanced ambipolar potential drop and enhanced upward ion acceleration. Observations in the topside ionosphere have led to the conclusion that large-scale electrostatic potential drops exist above the spacecraft along polar magnetic field lines connected to regions of photoelectron production. A kinetic approach is used for the O(+), H(+), and photoelectron (p) distributions, while a fluid approach is used to describe the thermal electrons (e) and self-consistent electric field (E(sub II)) electrons are allowed to carry a flux that compensates for photoelectron escape, a critical assumption. Collisional processes are excluded, leading to easier escape of polar wind particles and therefore to the formation of the largest potential drop consistent with this general approach. We compute the steady state electric field enhancement and net potential drop expected in the polar wind due to the presence of photoelectrons as a function of the fractional photoelectron content and the thermal plasma characteristics. For a set of low-altitude boundary conditions typical of the polar wind ionosphere, including 0.1% photoelectron content, we found a potential drop from 500 km to 5 R(sub E) of 6.5 V and a maximum thermal electron temperature of 8800 K. The reasonable agreement of our results with the observed polar wind suggests that the assumptions of this approach are valid.

  8. Self-consistent second-order Green’s function perturbation theory for periodic systems

    SciTech Connect

    Rusakov, Alexander A. Zgid, Dominika

    2016-02-07

    Despite recent advances, systematic quantitative treatment of the electron correlation problem in extended systems remains a formidable task. Systematically improvable Green’s function methods capable of quantitatively describing weak and at least qualitatively strong correlations appear as promising candidates for computational treatment of periodic systems. We present a periodic implementation of temperature-dependent self-consistent 2nd-order Green’s function (GF2) method, where the self-energy is evaluated in the basis of atomic orbitals. Evaluating the real-space self-energy in atomic orbitals and solving the Dyson equation in k-space are the key components of a computationally feasible algorithm. We apply this technique to the one-dimensional hydrogen lattice — a prototypical crystalline system with a realistic Hamiltonian. By analyzing the behavior of the spectral functions, natural occupations, and self-energies, we claim that GF2 is able to recover metallic, band insulating, and at least qualitatively Mott regimes. We observe that the iterative nature of GF2 is essential to the emergence of the metallic and Mott phases.

  9. Self-consistent Keldysh approach to quenches in the weakly interacting Bose-Hubbard model

    NASA Astrophysics Data System (ADS)

    Lo Gullo, N.; Dell'Anna, L.

    2016-11-01

    We present a nonequilibrium Green's-functional approach to study the dynamics following a quench in weakly interacting Bose-Hubbard model (BHM). The technique is based on the self-consistent solution of a set of equations which represents a particular case of the most general set of Hedin's equations for the interacting single-particle Green's function. We use the ladder approximation as a skeleton diagram for the two-particle scattering amplitude useful, through the self-energy in the Dyson equation, for finding the interacting single-particle Green's function. This scheme is then implemented numerically by a parallelized code. We exploit this approach to study the correlation propagation after a quench in the interaction parameter, for one and two dimensions. In particular, we show how our approach is able to recover the crossover from the ballistic to the diffusive regime by increasing the boson-boson interaction. Finally we also discuss the role of a thermal initial state on the dynamics both for one- and two-dimensional BHMs, finding that, surprisingly, at high temperature a ballistic evolution is restored.

  10. Self-consistent field for fragmented quantum mechanical model of large molecular systems.

    PubMed

    Jin, Yingdi; Su, Neil Qiang; Xu, Xin; Hu, Hao

    2016-01-30

    Fragment-based linear scaling quantum chemistry methods are a promising tool for the accurate simulation of chemical and biomolecular systems. Because of the coupled inter-fragment electrostatic interactions, a dual-layer iterative scheme is often employed to compute the fragment electronic structure and the total energy. In the dual-layer scheme, the self-consistent field (SCF) of the electronic structure of a fragment must be solved first, then followed by the updating of the inter-fragment electrostatic interactions. The two steps are sequentially carried out and repeated; as such a significant total number of fragment SCF iterations is required to converge the total energy and becomes the computational bottleneck in many fragment quantum chemistry methods. To reduce the number of fragment SCF iterations and speed up the convergence of the total energy, we develop here a new SCF scheme in which the inter-fragment interactions can be updated concurrently without converging the fragment electronic structure. By constructing the global, block-wise Fock matrix and density matrix, we prove that the commutation between the two global matrices guarantees the commutation of the corresponding matrices in each fragment. Therefore, many highly efficient numerical techniques such as the direct inversion of the iterative subspace method can be employed to converge simultaneously the electronic structure of all fragments, reducing significantly the computational cost. Numerical examples for water clusters of different sizes suggest that the method shall be very useful in improving the scalability of fragment quantum chemistry methods.

  11. Self-consistent modeling of jet formation process in the nanosecond laser pulse regime

    NASA Astrophysics Data System (ADS)

    Mézel, C.; Hallo, L.; Souquet, A.; Breil, J.; Hébert, D.; Guillemot, F.

    2009-12-01

    Laser induced forward transfer (LIFT) is a direct printing technique. Because of its high application potential, interest continues to increase. LIFT is routinely used in printing, spray generation and thermal-spike sputtering. Biological material such as cells and proteins have already been transferred successfully for the creation of biological microarrays. Recently, modeling has been used to explain parts of the ejection transfer process. No global modeling strategy is currently available. In this paper, a hydrodynamic code is utilized to model the jet formation process and estimate the constraints obeyed by the bioelements during the transfer. A self-consistent model that includes laser energy absorption, plasma formation via ablation, and hydrodynamic processes is proposed and confirmed with experimental results. Fundamental physical mechanisms via one-dimensional modeling are presented. Two-dimensional (2D) simplified solutions of the jet formation model equations are proposed. Predicted results of the model are jet existence and its velocity. The 2D simulation results are in good agreement with a simple model presented by a previous investigator.

  12. Replica Ornstein-Zernike self-consistent theory for mixtures in random pores.

    PubMed

    Pellicane, G; Caccamo, C; Wilson, D S; Lee, L L

    2004-06-01

    We present a self-consistent integral equation theory for a binary liquid in equilibrium with a disordered medium, based on the formalism of the replica Ornstein-Zernike (ROZ) equations. Specifically, we derive direct formulas for the chemical potentials and the zero-separation theorems (the latter provide a connection between the chemical potentials and the fluid cavity distribution functions). Next we solve a modified-Verlet closure to ROZ equations, which has built-in parameters that can be adjusted to satisfy the zero-separation theorems. The degree of thermodynamic consistency of the theory is also kept under control. We model the binary fluid in random pores as a symmetrical binary mixture of nonadditive hard spheres in a disordered hard-sphere matrix and consider two different values of the nonadditivity parameter and of the quenched matrix packing fraction, at different mixture concentrations. We compare the theoretical structural properties as obtained through the present approach with Percus-Yevick and Martinov-Sarkisov integral equation theories, and assess both structural and thermodynamic properties by performing canonical standard and biased grand canonical Monte Carlo simulations. Our theory appears superior to the other integral equation schemes here examined and provides reliable estimates of the chemical potentials. This feature should be useful in studying the fluid phase behavior of model adsorbates in random pores in general.

  13. A self-consistent model for estimating the critical current of superconducting devices

    NASA Astrophysics Data System (ADS)

    Zermeño, V.; Sirois, F.; Takayasu, M.; Vojenciak, M.; Kario, A.; Grilli, F.

    2015-08-01

    Nowadays, there is growing interest in using superconducting wires or tapes for the design and manufacture of devices such as cables, coils, rotating machinery, transformers, and fault current limiters, among others. Their high current capacity has made them the candidates of choice for manufacturing compact and light cables and coils that can be used in the large-scale power applications described above. However, the performance of these cables and coils is limited by their critical current, which is determined by several factors, including the conductor’s material properties and the geometric layout of the device itself. In this work we present a self-consistent model for estimating the critical current of superconducting devices. This is of large importance when the operating conditions are such that the self-field produced by the current is a significant fraction of the total field. The model is based on the asymptotic limit when time approaches infinity of Faraday’s equation written in terms of the magnetic vector potential. It uses a continuous E-J relationship and takes the angular dependence of the critical current density on the magnetic flux density into account. The proposed model is used to estimate the critical current of superconducting devices such as cables, coils, and coils made of transposed cables with very high accuracy. The high computing speed of this model makes it an ideal candidate for design optimization.

  14. Nonlinear coupling of tearing modes with self-consistent resistivity evolution in tokamaks

    SciTech Connect

    Carreras, B.; Hicks, H.R.; Holmes, J.A.; Waddell, B.V.

    1980-02-01

    The nonlinear interaction of tearing modes of different helicity is studied for realistic values of the tokamak parameters of resistivity and parallel heat conduction. The self-consistent evolution of the resistivity is taken into account through the electron heat conduction equation. For equilibrium q profiles inferred from electron temperature profile measured before a tokamak disruption, the essential result is that the (m = 2; n = 1) model nonlinearly destabilizes other modes on a rapid time scale. Because of the development of magnetic islands of different helicity, the toroidal current density is severely deformed. These islands overlap and field lines become stochastic in a sizable plasma volume, flattening the temperature profile in this region through parallel heat transport. The deformation of the toroidal current produces a rapid decrease in the self-inductance of the plasma, and the voltage at the limiter decreases, becoming increasingly negative. An extensive survey of equilibria and initial conditions has been conducted, and a simple prescription for their nonlinear stability properties is given.

  15. TOPICA/TORIC integration for self-consistent antenna and plasma analysis

    NASA Astrophysics Data System (ADS)

    Maggiora, Riccardo; Lancellotti, Vito; Milanesio, Daniele; Kyrytsya, Volodymyr; Vecchi, Giuseppe; Bonoli, Paul T.; Wright, John C.

    2006-10-01

    TOPICA [1] is a numerical suite conceived for prediction and analysis of plasma-facing antennas. It can handle real-life 3D antenna geometries (with housing, Faraday screen, etc.) as well as a realistic plasma model, including measured density and temperature profiles. TORIC [2] solves the finite Larmor radius wave equations in the ICRF regime in arbitrary axisymmetric toroidal plasmas. Due to the approach followed in developing TOPICA (i.e. the formal splitting of the problem in the vacuum region around the antenna and the plasma region inside the toroidal chamber), the code lends itself to handle toroidal plasmas, provided TORIC is run independently to yield the plasma surface admittance tensorsY (m,m',n). The latter enter directly into the integral equations solved by TOPICA, thus allowing a far more accurate plasma description that accounts for curvature effects. TOPICA outputs comprise, among others, the EM fields in front of the plasma: these can in turn be input to TORIC, in order to self-consistently determine the EM field propagation in the plasma. In this work, we report on the theory underlying the TOPICA/TORIC integration and the ongoing evolution of the two codes. [1] V. Lancellotti et al., Nucl. Fusion, 46 (2006) S476 [2] M. Brambilla, Plasma Phys. Contr. Fusion (1999) 41 1

  16. A self-consistent first-principle based approach to model carrier mobility in organic materials

    NASA Astrophysics Data System (ADS)

    Meded, Velimir; Friederich, Pascal; Symalla, Franz; Neumann, Tobias; Danilov, Denis; Wenzel, Wolfgang

    2015-12-01

    Transport through thin organic amorphous films, utilized in OLEDs and OPVs, has been a challenge to model by using ab-initio methods. Charge carrier mobility depends strongly on the disorder strength and reorganization energy, both of which are significantly affected by the details in environment of each molecule. Here we present a multi-scale approach to describe carrier mobility in which the materials morphology is generated using DEPOSIT, a Monte Carlo based atomistic simulation approach, or, alternatively by molecular dynamics calculations performed with GROMACS. From this morphology we extract the material specific hopping rates, as well as the on-site energies using a fully self-consistent embedding approach to compute the electronic structure parameters, which are then used in an analytic expression for the carrier mobility. We apply this strategy to compute the carrier mobility for a set of widely studied molecules and obtain good agreement between experiment and theory varying over several orders of magnitude in the mobility without any freely adjustable parameters. The work focuses on the quantum mechanical step of the multi-scale workflow, explains the concept along with the recently published workflow optimization, which combines density functional with semi-empirical tight binding approaches. This is followed by discussion on the analytic formula and its agreement with established percolation fits as well as kinetic Monte Carlo numerical approaches. Finally, we skatch an unified multi-disciplinary approach that integrates materials science simulation and high performance computing, developed within EU project MMM@HPC.

  17. Self-Consistent Simulation of Turbulence and Transport in Tokamak Edge Plasmas

    SciTech Connect

    Rognlien, T D; Umansky, M V; Xu, X Q; Cohen, R H

    2003-09-03

    The status of coupling the fluid 3D turbulence code BOUT and the fluid plasma/neutral 2D transport code UEDGE is reported, where both codes simulate the edge region of diverted tokamaks from several cm inside the magnetic separatrix to the far scrape-off layer (SOL), thereby including the magnetic X-point. Because the characteristic time scale of the turbulence is short ({approx} 10{sup -5}-10{sup -4}s) and the profile evolution time scale can be long ({approx} 10{sup -2}-10{sup -1} s owing to recycling), an iterative scheme is used that relaxes the turbulent fluxes passed from BOUT to UEDGE and the profiles from UEDGE to BOUT over many coupling steps. Each code is run on its own characteristic time scale, yielding a statistically averaged steady state. For this initial study, the ion and neutral densities and parallel velocities are evolved, while the temperature profiles are stationary. Here the turbulence code is run in the electrostatic approximation. For this example of self-consistent coupling with strong L-mode-like turbulence, the ion flux to the main-chamber exceeds that to the divertor plates.

  18. Self-consistent modeling of terahertz waveguide and cavity with frequency-dependent conductivity

    NASA Astrophysics Data System (ADS)

    Huang, Y. J.; Chu, K. R.; Thumm, M.

    2015-01-01

    The surface resistance of metals, and hence the Ohmic dissipation per unit area, scales with the square root of the frequency of an incident electromagnetic wave. As is well recognized, this can lead to excessive wall losses at terahertz (THz) frequencies. On the other hand, high-frequency oscillatory motion of conduction electrons tends to mitigate the collisional damping. As a result, the classical theory predicts that metals behave more like a transparent medium at frequencies above the ultraviolet. Such a behavior difference is inherent in the AC conductivity, a frequency-dependent complex quantity commonly used to treat electromagnetics of metals at optical frequencies. The THz region falls in the gap between microwave and optical frequencies. However, metals are still commonly modeled by the DC conductivity in currently active vacuum electronics research aimed at the development of high-power THz sources (notably the gyrotron), although a small reduction of the DC conductivity due to surface roughness is sometimes included. In this study, we present a self-consistent modeling of the gyrotron interaction structures (a metallic waveguide or cavity) with the AC conductivity. The resulting waveguide attenuation constants and cavity quality factors are compared with those of the DC-conductivity model. The reduction in Ohmic losses under the AC-conductivity model is shown to be increasingly significant as the frequency reaches deeper into the THz region. Such effects are of considerable importance to THz gyrotrons for which the minimization of Ohmic losses constitutes a major design consideration.

  19. Voigt, Reuss, Hill, and self-consistent techniques for modeling ultrasonic scattering

    NASA Astrophysics Data System (ADS)

    Kube, Christopher M.; Turner, Joseph A.

    2015-03-01

    An elastic wave propagating in a metal loses a portion of its energy from scattering caused by acoustic impedance differences existing at the boundaries of anisotropic grains. Theoretical scattering models capture this phenomena by assuming the incoming wave is described by an average elastic moduli tensor Cijkl0(x) that is perturbed by a grain with elasticity Cijkl(x') where the scattering event occurs when x = x'. Previous models have assumed that Cijkl0(x) is the Voigt average of the single-crystal elastic moduli tensor. However, this assumption may be incorrect because the Voigt average overestimates the wave's phase velocity. Thus, the use of alternate definitions of Cijkl0(x) to describe the incoming wave is posed. Voigt, Reuss, Hill, and self-consistent definitions of Cijkl0(x) are derived in the context of ultrasonic scattering models. The scattering-based models describing ultrasonic backscatter, attenuation, and diffusion are shown to be highly dependent on the definition of Cijkl0(x) .

  20. Fully-Explicit and Self-Consistent Algebraic Reynolds Stress Models

    NASA Technical Reports Server (NTRS)

    Girimaji, Sharath S.

    1995-01-01

    A fully-explicit, self-consistent algebraic expression for the Reynolds stress, which is the exact solution to the Reynolds stress transport equation in the 'weak equilibrium' limit for two-dimensional mean flows for all linear and some quasi-linear pressure-strain models, is derived. Current explicit algebraic Reynolds stress models derived by employing the 'weak equilibrium' assumption treat the production-to-dissipation (P/epsilon) ratio implicitly, resulting in an effective viscosity that can be singular away from the equilibrium limit. In the present paper, the set of simultaneous algebraic Reynolds stress equations are solved in the full non-linear form and the eddy viscosity is found to be non-singular. Preliminary tests indicate that the model performs adequately, even for three dimensional mean flow cases. Due to the explicit and non-singular nature of the effective viscosity, this model should mitigate many of the difficulties encountered in computing complex turbulent flows with the algebraic Reynolds stress models.

  1. Accelerating self consistent field convergence by rubber sheeting of initial electronic wave functions.

    NASA Astrophysics Data System (ADS)

    Matthews, G. Eric; Holzwarth, N. A. W.; Martin, George; Keeling, Briana; Agopsowicz, Douglas

    2007-03-01

    We develop an algorithm for generating better initial electronic wave function estimates for density functional theory calculations following atomic movement. First principles molecular dynamics and atomic relaxation calculations involve successive movements of atoms followed by self consistent field (SCF) solutions for electronic wave functions. The SCF solutions converge most rapidly when starting from reasonably good estimates. Often estimates are generated directly from the wave functions of the previous atomic positions without adjustments for effects of position changes. Such estimates result in fast convergence to the correct wave function for small atomic movements, but for larger movements, convergence may be much slower. We present a method for improving the estimates of the new wave functions by using information from the movement of the atoms. Our algorithm is based on the ``rubber-sheeting'' method used in overlaying satellite imagery on geographic maps. A warping function is calculated that stretches and shrinks different regions of the wave function so that regions near nuclei are dragged along with the atoms. These estimates yield faster convergence for cases studied thus far.

  2. Self consistent solution of the tJ model in the overdoped regime

    NASA Astrophysics Data System (ADS)

    Shastry, B. Sriram; Hansen, Daniel

    2013-03-01

    Detailed results from a recent microscopic theory of extremely correlated Fermi liquids, applied to the t-J model in two dimensions, are presented. The theory is to second order in a parameter λ, and is valid in the overdoped regime of the tJ model. The solution reported here is from Ref, where relevant equations given in Ref are self consistently solved for the square lattice. Thermodynamic variables and the resistivity are displayed at various densities and T for two sets of band parameters. The momentum distribution function and the renormalized electronic dispersion, its width and asymmetry are reported along principal directions of the zone. The optical conductivity is calculated. The electronic spectral function A (k , ω) probed in ARPES, is detailed with different elastic scattering parameters to account for the distinction between LASER and synchrotron ARPES. A high (binding) energy waterfall feature, sensitively dependent on the band hopping parameter t' is noted. This work was supported by DOE under Grant No. FG02-06ER46319.

  3. SELF-CONSISTENT ORBITS AND PHYSICAL PROPERTIES FOR EIGHT SINGLE-LINED SPECTROSCOPIC BINARIES

    SciTech Connect

    Wang, Xiaoli; Ren, Shulin; Fu, Yanning E-mail: rensl@pmo.ac.cn

    2015-10-15

    For single-lined spectroscopic binaries (SB1s), self-consistent orbits can be determined via a simultaneous fit including both radial velocity data and the Hipparcos Intermediate Astrometric Data. Using the ratio λ of the semimajor axes of the photocenter to the primary orbits, the present paper develops an iterative fitting method. First, an initial orbit of an SB1 is determined with the assumption that λ equals 1. On the basis of this orbit, we use a stellar evolutionary model to distribute the total mass and luminosity to the primary and the secondary and update λ from the component mass and luminosity ratios. Then the orbit is updated using the updated value of λ, which completes a step of the iterative process. If this process is convergent, the resulting orbit is compatible with the physical properties of component stars. By using this method, the orbital solutions of eight SB1s as well as the physical properties are determined. We find that the component magnitude differences of these systems are very large, except for HIP 7143 and 45333. This suggests that only the secondaries of the two systems can be resolved with the present-day observational techniques, which is in agreement with recent observations.

  4. Average intragranular misorientation trends in polycrystalline materials predicted by a viscoplastic self-consistent approach

    SciTech Connect

    Lebensohn, Ricardo A.; Zecevic, Miroslav; Knezevic, Marko; McCabe, Rodney J.

    2015-12-15

    Here, this work presents estimations of average intragranular fluctuations of lattice rotation rates in polycrystalline materials, obtained by means of the viscoplastic self-consistent (VPSC) model. These fluctuations give a tensorial measure of the trend of misorientation developing inside each single crystal grain representing a polycrystalline aggregate. We first report details of the algorithm implemented in the VPSC code to estimate these fluctuations, which are then validated by comparison with corresponding full-field calculations. Next, we present predictions of average intragranular fluctuations of lattice rotation rates for cubic aggregates, which are rationalized by comparison with experimental evidence on annealing textures of fcc and bcc polycrystals deformed in tension and compression, respectively, as well as with measured intragranular misorientation distributions in a Cu polycrystal deformed in tension. The orientation-dependent and micromechanically-based estimations of intragranular misorientations that can be derived from the present implementation are necessary to formulate sound sub-models for the prediction of quantitatively accurate deformation textures, grain fragmentation, and recrystallization textures using the VPSC approach.

  5. Diffusion-induced growth of nanowires: Generalized boundary conditions and self-consistent kinetic equation

    NASA Astrophysics Data System (ADS)

    Dubrovskii, V. G.; Hervieu, Yu. Yu.

    2014-09-01

    In this work, we present a theoretical analysis of the diffusion-induced growth of "vapor-liquid-solid" nanowires, based on the stationary equations with generalized boundary conditions. We discuss why and how the earlier results are modified when the adatom chemical potential is discontinuous at the nanowire base. Several simplified models for the adatom diffusion flux are discussed, yielding the 1 /Rp radius dependence of the length, with p ranging from 0.5 to 2. The self-consistent approach is used to couple the diffusion transport with the kinetics of 2D nucleation under the droplet. This leads to a new growth equation that contains only two dimensional parameters and the power exponents p and q, where q=1 or 2 depends on the nucleus position. We show that this equation describes the size-dependent depression of the growth rate of narrow nanowires much better than the Gibbs-Thomson correction in several important cases. Overall, our equation fits very well the experimental data on the length-radius correlations of III-V and group IV nanowires obtained by different epitaxy techniques.

  6. INFLOW-OUTFLOW MODEL WITH CONDUCTION AND SELF-CONSISTENT FEEDING FOR Sgr A*

    SciTech Connect

    Shcherbakov, Roman V.; Baganoff, Frederick K.

    2010-06-10

    We propose a two-temperature radial inflow-outflow model near Sgr A* with self-consistent feeding and conduction. Stellar winds from individual stars are considered to find the rates of mass injection and energy injection. These source terms help to partially eliminate the boundary conditions on the inflow. Electron thermal conduction is crucial for inhibiting the accretion. Energy diffuses out from several gravitational radii, unbinding more gas at several arcseconds and limiting the accretion rate to <1% of Bondi rate. We successfully fit the X-ray surface brightness profile found from the extensive Chandra observations and reveal the X-ray point source in the center. The super-resolution technique allows us to infer the presence and estimate the unabsorbed luminosity L {approx} 4 x 10{sup 32} erg s{sup -1} of the point source. The employed relativistic heat capacity and direct heating of electrons naturally lead to low electron temperature T{sub e} {approx} 4 x 10{sup 10} K near the black hole. Within the same model, we fit 86 GHz optically thick emission and obtain the order of magnitude agreement of Faraday rotation measure, thus achieving a single accretion model suitable at all radii.

  7. Elastic plastic self-consistent (EPSC) modeling of plastic deformation in fayalite olivine

    DOE PAGES

    Burnley, Pamela C

    2015-07-01

    Elastic plastic self-consistent (EPSC) simulations are used to model synchrotron X-ray diffraction observations from deformation experiments on fayalite olivine using the deformation DIA apparatus. Consistent with results from other in situ diffraction studies of monomineralic polycrystals, the results show substantial variations in stress levels among grain populations. Rather than averaging the lattice reflection stresses or choosing a single reflection to determine the macroscopic stress supported by the specimen, an EPSC simulation is used to forward model diffraction data and determine a macroscopic stress that is consistent with lattice strains of all measured diffraction lines. The EPSC simulation presented here includesmore » kink band formation among the plastic deformation mechanisms in the simulation. The inclusion of kink band formation is critical to the success of the models. This study demonstrates the importance of kink band formation as an accommodation mechanism during plastic deformation of olivine as well as the utility of using EPSC models to interpret diffraction from in situ deformation experiments.« less

  8. Elastic plastic self-consistent (EPSC) modeling of plastic deformation in fayalite olivine

    SciTech Connect

    Burnley, Pamela C

    2015-07-01

    Elastic plastic self-consistent (EPSC) simulations are used to model synchrotron X-ray diffraction observations from deformation experiments on fayalite olivine using the deformation DIA apparatus. Consistent with results from other in situ diffraction studies of monomineralic polycrystals, the results show substantial variations in stress levels among grain populations. Rather than averaging the lattice reflection stresses or choosing a single reflection to determine the macroscopic stress supported by the specimen, an EPSC simulation is used to forward model diffraction data and determine a macroscopic stress that is consistent with lattice strains of all measured diffraction lines. The EPSC simulation presented here includes kink band formation among the plastic deformation mechanisms in the simulation. The inclusion of kink band formation is critical to the success of the models. This study demonstrates the importance of kink band formation as an accommodation mechanism during plastic deformation of olivine as well as the utility of using EPSC models to interpret diffraction from in situ deformation experiments.

  9. A priori complete active space self consistent field localized orbitals: an application on linear polyenes

    NASA Astrophysics Data System (ADS)

    Angeli, Celestino; Sparta, Manuel; Cimiraglia, Renzo

    2006-03-01

    A recently proposed a priori localization technique is used to exploit the possibility to reduce the number of active orbitals in a Complete Active Space Self Consistent Field calculation. The work relies on the fact that the new approach allows a strict control on the nature of the active orbitals and therefore makes it possible to include in the active space only the relevant orbitals. The idea is tested on the calculation of the energy barrier for rigid rotation of linear polyenes. In order to obtain a relevant set of data, a number of possible rotations around double bonds have been considered in the ethylene, butadiene, hexatriene, octatetraene, decapentaene, dodecahexaene molecules. The possibility to reduce the dimension of the active space has been investigated, considering for each possible rotation different active spaces ranging from the minimal dimension of 2 electrons in 2 π orbitals to the π-complete space. The results show that the rigid isomerization in the polyene molecules can be described with a negligible loss in accuracy with active spaces no larger than ten orbitals and ten electrons. In the special case of the rotation around the terminal double bond, the space can be further reduced to six orbitals and six electrons with a large decrease of the computational cost. An interesting summation rule has been found and verified for the stabilization of the energy barriers as a function of the dimension of the conjugated lateral chains and of the dimension of the active space.

  10. How important is self-consistency for the dDsC density dependent dispersion correction?

    SciTech Connect

    Brémond, Éric; Corminboeuf, Clémence; Golubev, Nikolay; Steinmann, Stephan N.

    2014-05-14

    The treatment of dispersion interactions is ubiquitous but computationally demanding for seamless ab initio approaches. A highly popular and simple remedy consists in correcting for the missing interactions a posteriori by adding an attractive energy term summed over all atom pairs to standard density functional approximations. These corrections were originally based on atom pairwise parameters and, hence, had a strong touch of empiricism. To overcome such limitations, we recently proposed a robust system-dependent dispersion correction, dDsC, that is computed from the electron density and that provides a balanced description of both weak inter- and intramolecular interactions. From the theoretical point of view and for the sake of increasing reliability, we here verify if the self-consistent implementation of dDsC impacts ground-state properties such as interaction energies, electron density, dipole moments, geometries, and harmonic frequencies. In addition, we investigate the suitability of the a posteriori scheme for molecular dynamics simulations, for which the analysis of the energy conservation constitutes a challenging tests. Our study demonstrates that the post-SCF approach in an excellent approximation.

  11. A self-consistent first-principle based approach to model carrier mobility in organic materials

    SciTech Connect

    Meded, Velimir; Friederich, Pascal; Symalla, Franz; Neumann, Tobias; Danilov, Denis; Wenzel, Wolfgang

    2015-12-31

    Transport through thin organic amorphous films, utilized in OLEDs and OPVs, has been a challenge to model by using ab-initio methods. Charge carrier mobility depends strongly on the disorder strength and reorganization energy, both of which are significantly affected by the details in environment of each molecule. Here we present a multi-scale approach to describe carrier mobility in which the materials morphology is generated using DEPOSIT, a Monte Carlo based atomistic simulation approach, or, alternatively by molecular dynamics calculations performed with GROMACS. From this morphology we extract the material specific hopping rates, as well as the on-site energies using a fully self-consistent embedding approach to compute the electronic structure parameters, which are then used in an analytic expression for the carrier mobility. We apply this strategy to compute the carrier mobility for a set of widely studied molecules and obtain good agreement between experiment and theory varying over several orders of magnitude in the mobility without any freely adjustable parameters. The work focuses on the quantum mechanical step of the multi-scale workflow, explains the concept along with the recently published workflow optimization, which combines density functional with semi-empirical tight binding approaches. This is followed by discussion on the analytic formula and its agreement with established percolation fits as well as kinetic Monte Carlo numerical approaches. Finally, we skatch an unified multi-disciplinary approach that integrates materials science simulation and high performance computing, developed within EU project MMM@HPC.

  12. Self-consistent field tight-binding model for neutral and (multi-) charged carbon clusters

    NASA Astrophysics Data System (ADS)

    Montagnon, Laurent; Spiegelman, Fernand

    2007-08-01

    A semiempirical model for carbon clusters modeling is presented, along with structural and dynamical applications. The model is a tight-binding scheme with additional one- and two-center distance-dependent electrostatic interactions treated self-consistently. This approach, which explicitly accounts for charge relaxation, allows us to treat neutral and (multi-) charged clusters not only at equilibrium but also in dissociative regions. The equilibrium properties, geometries, harmonic spectra, and relative stabilities of the stable isomers of neutral and singly charged clusters in the range n =1-14, for C20 and C60, are found to reproduce the results of ab initio calculations. The model is also shown to be successful in describing the stability and fragmentation energies of dictations in the range n =2-10 and allows the determination of their Coulomb barriers, as examplified for the smallest sizes (C22+,C32+,C42+). We also present time-dependent mean-field and linear response optical spectra for the C8 and C60 clusters and discuss their relevance with respect to existing calculations.

  13. Self-consistent approach to the description of relaxation processes in classical multiparticle systems

    NASA Astrophysics Data System (ADS)

    Mokshin, A. V.

    2015-04-01

    The concept of time correlation functions is a very convenient theoretical tool in describing relaxation processes in multiparticle systems because, on one hand, correlation functions are directly related to experimentally measured quantities (for example, intensities in spectroscopic studies and kinetic coefficients via the Kubo-Green relation) and, on the other hand, the concept is also applicable beyond the equilibrium case. We show that the formalism of memory functions and the method of recurrence relations allow formulating a self-consistent approach for describing relaxation processes in classical multiparticle systems without needing a priori approximations of time correlation functions by model dependences and with the satisfaction of sum rules and other physical conditions guaranteed. We also demonstrate that the approach can be used to treat the simplest relaxation scenarios and to develop microscopic theories of transport phenomena in liquids, the propagation of density fluctuations in equilibrium simple liquids, and structure relaxation in supercooled liquids. This approach generalizes the mode-coupling approximation in the Götze-Leutheusser realization and the Yulmetyev-Shurygin correlation approximations.

  14. Astrometric Monitoring of the HR 8799 Planets: Orbit Constraints from Self-consistent Measurements

    NASA Astrophysics Data System (ADS)

    Konopacky, Q. M.; Marois, C.; Macintosh, B. A.; Galicher, R.; Barman, T. S.; Metchev, S. A.; Zuckerman, B.

    2016-08-01

    We present new astrometric measurements from our ongoing monitoring campaign of the HR 8799 directly imaged planetary system. These new data points were obtained with NIRC2 on the W.M. Keck II 10 m telescope between 2009 and 2014. In addition, we present updated astrometry from previously published observations in 2007 and 2008. All data were reduced using the SOSIE algorithm, which accounts for systematic biases present in previously published observations. This allows us to construct a self-consistent data set derived entirely from NIRC2 data alone. From this data set, we detect acceleration for two of the planets (HR 8799b and e) at >3σ. We also assess possible orbital parameters for each of the four planets independently. We find no statistically significant difference in the allowed inclinations of the planets. Fitting the astrometry while forcing coplanarity also returns χ 2 consistent to within 1σ of the best fit values, suggesting that if inclination offsets of ≲20° are present, they are not detectable with current data. Our orbital fits also favor low eccentricities, consistent with predictions from dynamical modeling. We also find period distributions consistent to within 1σ with a 1:2:4:8 resonance between all planets. This analysis demonstrates the importance of minimizing astrometric systematics when fitting for solutions to highly undersampled orbits.

  15. Growing discharge trees with self-consistent charge transport: the collective dynamics of streamers

    NASA Astrophysics Data System (ADS)

    Luque, Alejandro; Ebert, Ute

    2014-01-01

    We introduce the generic structure of a growth model for branched discharge trees that consistently combines a finite channel conductivity with the physical law of charge conservation. It is applicable, e.g., to streamer coronas near tip or wire electrodes and ahead of lightning leaders, to leaders themselves and to the complex breakdown structures of sprite discharges high above thunderclouds. Then we implement and solve the simplest model for positive streamers in ambient air with self-consistent charge transport. We demonstrate that charge conservation contradicts the common assumption of dielectric breakdown models that the electric fields inside all streamers are equal to the so-called stability field and we even find cases of local field inversion. We also find that, counter-intuitively, the inner branches of a positive-streamer tree are negatively charged, which provides a natural explanation for the observed reconnections of streamers in laboratory experiments and in sprites. Our simulations show the structure of an overall ‘streamer of streamers’ that we name collective streamer front, and predict effective streamer branching angles, the charge structure within streamer trees and streamer reconnection.

  16. Developing a self-consistent description of Titan's upper atmosphere without hydrodynamic escape

    NASA Astrophysics Data System (ADS)

    Bell, Jared M.; Hunter Waite, J.; Westlake, Joseph H.; Bougher, Stephen W.; Ridley, Aaron J.; Perryman, Rebecca; Mandt, Kathleen

    2014-06-01

    In this study, we develop a best fit description of Titan's upper atmosphere between 500 km and 1500 km, using a one-dimensional (1-D) version of the three-dimensional (3-D) Titan Global Ionosphere-Thermosphere Model. For this modeling, we use constraints from several lower atmospheric Cassini-Huygens investigations and validate our simulation results against in situ Cassini Ion-Neutral Mass Spectrometer (INMS) measurements of N2, CH4, H2, 40Ar, HCN, and the major stable isotopic ratios of 14N/15N in N2. We focus our investigation on aspects of Titan's upper atmosphere that determine the amount of atmospheric escape required to match the INMS measurements: the amount of turbulence, the inclusion of chemistry, and the effects of including a self-consistent thermal balance. We systematically examine both hydrodynamic escape scenarios for methane and scenarios with significantly reduced atmospheric escape. Our results show that the optimum configuration of Titan's upper atmosphere is one with a methane homopause near 1000 km and atmospheric escape rates of 1.41-1.47 ×1011 CH4 m-2 s-1 and 1.08 ×1014 H2 m-2 s-1 (scaled relative to the surface). We also demonstrate that simulations consistent with hydrodynamic escape of methane systematically produce inferior fits to the multiple validation points presented here.

  17. Self-consistent calculation of the coupling constant in the Gross-Pitaevskii equation

    SciTech Connect

    Cherny, A.Yu.; Brand, J.

    2004-10-01

    A method is proposed for a self-consistent evaluation of the coupling constant in the Gross-Pitaevskii equation without involving a pseudopotential replacement. A renormalization of the coupling constant occurs due to medium effects and the trapping potential, e.g., in quasi-1D or quasi-2D systems. It is shown that a simplified version of the Hartree-Fock-Bogoliubov approximation leads to a variational problem for both the condensate and a two-body wave function describing the behavior of a pair of bosons in the Bose-Einstein condensate. The resulting coupled equations are free of unphysical divergences. Particular cases of this scheme that admit analytical estimations are considered and compared to the literature. In addition to the well-known cases of low-dimensional trapping, crossover regimes can be studied. The values of the kinetic, interaction, external, and release energies in low dimensions are also evaluated and contributions due to short-range correlations are found to be substantial.

  18. Linear elasticity and phase behavior of block copolymer melts by self consistent field theory

    NASA Astrophysics Data System (ADS)

    Tyler, Christopher Austin

    Self Consistent Field Theory (SCFT) is a well established theory for describing the thermodynamics of block copolymer melts and blends. Although the theory is approximate, it has been quite successful in describing the phase behavior of diblock copolymers. We have applied SCFT to study the linear elastic behavior and the phase behavior of block copolymer melts. First, we calculate the linear elastic response of block copolymer melts ordered on a cubic lattice, with either body-centered or gyroid symmetry. We compare our results to experiments. A large, low-frequency plateau in the elastic storage modulus, corresponding to approximately 0.2kT per polymer chain, has been experimentally observed. By calculating the free energy of block copolymer melts on deformed lattices, we find that SOFT correctly predicts the elastic behavior of these three-dimensionally-ordered structures. We also investigate the phase behavior of triblock copolymer melts. Recent experimental work has identified a new, non-cubic, three-dimensional network phase, termed the O70 phase, in ABC triblock copolymers. We investigate the phase behavior of ABC triblock copolymer melts by calculating the free energy of several candidate phases, including the O70 phase. We find that O 70 is an equilibrium structure in triblock copolymer melts and that the SCFT and experimentally observed phase boundaries agree qualitatively. We also find that O70 is an equilibrium phase in diblock copolymer melts.

  19. Spatial Structure of Regular and Chaotic Orbits in A Self-Consistent Triaxial Stellar System

    NASA Astrophysics Data System (ADS)

    Muzzio, J. C.; Carpintero, D. D.; Wachlin, F. C.

    2005-01-01

    We created a triaxial stellar system through the cold dissipationless collapse of 100,000 particles whose evolution was followed with a multipolar code. Once an equilibrium system had been obtained, the multipolar expansion was freezed and smoothed in order to get a stationary smooth potential. The resulting model was self-consistent and the orbits and Lyapunov exponents could then be computed for a randomly selected sample of 3472 of the bodies that make up the system. More than half of the orbits (52.7 % ) turned out to be chaotic. Regular orbits were then classified using the frequency analysis automatic code of Carpintero and Aguilar (1998, MNRAS 298(1), 1 21). We present plots of the distributions of the different kinds of orbits projected on the symmetry planes of the system. We distinguish chaotic orbits with only one non-zero Lyapunov exponent from those with two non-zero exponents and show that their spatial distributions differ, that of the former being more similar to the one of the regular orbits. Most of the regular orbits are boxes and boxlets, but the minor axis tubes play an important role filling in the wasp waists of the boxes and helping to give a lentil shape to the system. We see no problem in building stable triaxial models with substantial amounts of chaotic orbits; the difficulties found by other authors may be due not to a physical cause but to a limitation of Schwarzschild’s method.

  20. Optical Pattern Formation in Spatially Bunched Atoms: A Self-Consistent Model and Experiment

    NASA Astrophysics Data System (ADS)

    Schmittberger, Bonnie L.; Gauthier, Daniel J.

    2014-05-01

    The nonlinear optics and optomechanical physics communities use different theoretical models to describe how optical fields interact with a sample of atoms. There does not yet exist a model that is valid for finite atomic temperatures but that also produces the zero temperature results that are generally assumed in optomechanical systems. We present a self-consistent model that is valid for all atomic temperatures and accounts for the back-action of the atoms on the optical fields. Our model provides new insights into the competing effects of the bunching-induced nonlinearity and the saturable nonlinearity. We show that it is crucial to keep the fifth and seventh-order nonlinearities that arise when there exists atomic bunching, even at very low optical field intensities. We go on to apply this model to the results of our experimental system where we observe spontaneous, multimode, transverse optical pattern formation at ultra-low light levels. We show that our model accurately predicts our experimentally observed threshold for optical pattern formation, which is the lowest threshold ever reported for pattern formation. We gratefully acknowledge the financial support of the NSF through Grant #PHY-1206040.

  1. Self-consistent stationary MHD shear flows in the solar atmosphere as electric field generators

    NASA Astrophysics Data System (ADS)

    Nickeler, D. H.; Karlický, M.; Wiegelmann, T.; Kraus, M.

    2014-09-01

    Context. Magnetic fields and flows in coronal structures, for example, in gradual phases in flares, can be described by 2D and 3D magnetohydrostatic (MHS) and steady magnetohydrodynamic (MHD) equilibria. Aims: Within a physically simplified, but exact mathematical model, we study the electric currents and corresponding electric fields generated by shear flows. Methods: Starting from exact and analytically calculated magnetic potential fields, we solved the nonlinear MHD equations self-consistently. By applying a magnetic shear flow and assuming a nonideal MHD environment, we calculated an electric field via Faraday's law. The formal solution for the electromagnetic field allowed us to compute an expression of an effective resistivity similar to the collisionless Speiser resistivity. Results: We find that the electric field can be highly spatially structured, or in other words, filamented. The electric field component parallel to the magnetic field is the dominant component and is high where the resistivity has a maximum. The electric field is a potential field, therefore, the highest energy gain of the particles can be directly derived from the corresponding voltage. In our example of a coronal post-flare scenario we obtain electron energies of tens of keV, which are on the same order of magnitude as found observationally. This energy serves as a source for heating and acceleration of particles.

  2. Self-Consistent Synchrotron Spectra from Trans-Relativistic Electron Acceleration

    NASA Astrophysics Data System (ADS)

    Becker, Peter A.

    2015-01-01

    Most existing analytical models describing the second-order Fermi acceleration of relativistic electrons due to collisions with MHD waves assume that the injected seed particles are already highly relativistic, despite the fact that the most prevalent source of particles is usually the non-relativistic thermal background gas. This presents a problem because the momentum dependence of the momentum diffusion coefficient describing the interaction between the electrons and the MHD waves is qualitatively different in the non-relativistic and highly relativistic limits. The lack of an analytical model has forced workers to rely on numerical simulations to obtain particle spectra describing the trans-relativistic case. In this work, we present the first analytical solution to the global, trans-relativistic problem of electron acceleration, obtained by using a hybrid form for the momentum diffusion coefficient, given by the sum of the two asymptotic forms. We refer to this process as "quasi hard-sphere scattering." The model also incorporates the appropriate momentum dependence for the particle escape timescale, and the effect of synchrotron and inverse-Compton losses, which are critical for establishing the location of the high-energy cutoff in the particle spectrum. Since synchrotron and inverse-Compton losses are included in the transport equation, the resulting radiation spectra are computed self-consistently. The results can be used to model the acceleration of radiating electrons in AGN and solar environments, applications of both types are discussed.

  3. Quantum self-consistency of AdS×Σ brane models

    NASA Astrophysics Data System (ADS)

    Flachi, Antonino; Pujolàs, Oriol

    2003-07-01

    Continuing our previous work, we consider a class of higher dimensional brane models with the topology of AdSD1+1×Σ, where Σ is a one-parameter compact manifold and two branes of codimension one are located at the orbifold fixed points. We consider a setup where such a solution arises from Einstein-Yang-Mills theory and evaluate the one-loop effective potential induced by gauge fields and by a generic bulk scalar field. We show that this type of brane model resolves the gauge hierarchy between the Planck and electroweak scales through redshift effects due to the warp factor a=e-πkr. The value of a is then fixed by minimizing the effective potential. We find that, as in the Randall-Sundrum case, the gauge field contribution to the effective potential stabilizes the hierarchy without fine-tuning as long as the Laplacian ΔΣ on Σ has a zero eigenvalue. Scalar fields can stabilize the hierarchy depending on the mass and the nonminimal coupling. We also address the quantum self-consistency of the solution, showing that the classical brane solution is not spoiled by quantum effects.

  4. Self-Consistent Solutions for the Scattering State with Two Free Electrons

    NASA Astrophysics Data System (ADS)

    Hahn, Y. K.; Gau, J. N.; Zerrad, E.

    2013-11-01

    Wave functions for the scattering states with two free electrons in the field of an ion core are explicitly calculated by the self-consistent, continuum Hartree-Fock (CHF) theory. Typically, such states are associated with the three-body recombination, collisional ionization and photo-double ionization, but have never been directly studied previously. The calculated continuum orbitals are found to be predominantly of the plane-wave forms, as though the system is translation invariant, in the context of many-body HF theory. The symmetry is mildly broken by the presence of the core ion, at about fifteen-percents level, indicating that the orbitals are largely delocalized and the effect of the core potential is an important but minor perturbation. The properties of channel orthogonality and completeness are preserved by the nearly plane wave forms. To test the validity of this finding and the CHF, the continuum orbitals are used to evaluate the amplitudes for the electron impact ionization, and the amputation procedure, that is crucial in the theory, is also critically re-examined.

  5. Emission-Line Star-Forming Dwarf Galaxies: Self-Consistent Evolutionary Models

    NASA Astrophysics Data System (ADS)

    Martin-Manjon, M. L.

    2009-05-01

    We have computed a series of realistic and self-consistent models able to reproduce the observable characteristics of HII galaxies in a star bursting scenario. Our models combine different codes of chemical evolution, evolutionary population synthesis and photoionization. The emitted spectrum of HII galaxies is calculated by means of the photoionization code CLOUDY, using as ionizing spectrum the spectral energy distribution (SED) of the modelled HII galaxy. These SED have been computed using new and updated stellar population models, obtained according to the star formation and the metal enrichment histories given by a chemical evolution model. Each model is characterized by three parameters which determine the evolution of a given galaxy: the initial efficiency of star formation, the attenuation or strenght of these bursts, and the elapsed time between them. Our model technique gives results that reproduce the observed abundances, diagnostic diagrams and equivalent width vs colour relations for local HII galaxies in every evolutionary stage, and can be extrapolated to other objects under different assumed star formation scenarios.

  6. Secondary electron emission and self-consistent charge transport in semi-insulating samples

    SciTech Connect

    Fitting, H.-J.; Touzin, M.

    2011-08-15

    Electron beam induced self-consistent charge transport and secondary electron emission (SEE) in insulators are described by means of an electron-hole flight-drift model (FDM) now extended by a certain intrinsic conductivity (c) and are implemented by an iterative computer simulation. Ballistic secondary electrons (SE) and holes, their attenuation to drifting charge carriers, and their recombination, trapping, and field- and temperature-dependent detrapping are included. As a main result the time dependent ''true'' secondary electron emission rate {delta}(t) released from the target material and based on ballistic electrons and the spatial distributions of currents j(x,t), charges {rho}(x,t), field F(x,t), and potential V(x,t) are obtained where V{sub 0} = V(0,t) presents the surface potential. The intrinsic electronic conductivity limits the charging process and leads to a conduction sample current to the support. In that case the steady-state total SE yield will be fixed below the unit: i.e., {sigma} {eta} + {delta} < 1.

  7. Self-Consistent Simulations of Heavy-Ion Beams Interacting with Electron-Clouds

    SciTech Connect

    Vay, J; Furman, M A; Seidl, P A; Cohen, R H; Friedman, A; Grote, D P; Covo, M K; Molvik, A W; Stoltz, P H; Veitzer, S; Verboncoeur, J P

    2006-08-04

    Electron-clouds and rising desorbed gas pressure limit the performance of many existing accelerators and, potentially, that of future accelerators including heavy-ion warm-dense matter and fusion drivers. For the latter, self-consistent simulation of the interaction of the heavy-ion beam(s) with the electron-cloud is necessary. To this end, we have merged the two codes WARP (HIF accelerator code) and POSINST (high-energy e-cloud build-up code), and added modules for neutral gas molecule generation, gas ionization, and electron tracking algorithms in magnetic fields with large time steps. The new tool is being benchmarked against the High-Current Experiment (HCX) and good agreement has been achieved. The simulations have also aided diagnostic interpretation and have identified unanticipated physical processes. We present the ''roadmap'' describing the different modules and their interconnections, along with detailed comparisons with HCX experimental results, as well as a preliminary application to the modeling of electron clouds in the Large Hadron Collider.

  8. Filling in the Roadmap for Self-Consistent Electron Cloud and Gas Modeling

    SciTech Connect

    Vay, J; Furman, M A; Seidl, P A; Cohen, R H; Friedman, A; Grote, D P; Covo, M K; Molvik, A W; Stoltz, P H; Veitzer, S; Verboncoeur, J

    2005-10-11

    Electron clouds and gas pressure rise limit the performance of many major accelerators. A multi-laboratory effort to understand the underlying physics via the combined application of experiment, theory, and simulation is underway. We present here the status of the simulation capability development, based on a merge of the three-dimensional parallel Particle-In-Cell (PIC) accelerator code WARP and the electron cloud code POSINST, with additional functionalities. The development of the new capability follows a ''roadmap'' describing the different functional modules, and their inter-relationships, that are ultimately needed to reach self-consistency. Newly developed functionalities include a novel particle mover bridging the time scales between electron and ion motion, a module to generate neutrals desorbed by beam ion impacts at the wall, and a module to track impact ionization of the gas by beam ions or electrons. Example applications of the new capability to the modeling of electron effects in the High Current Experiment (HCX) are given.

  9. Average intragranular misorientation trends in polycrystalline materials predicted by a viscoplastic self-consistent approach

    DOE PAGES

    Lebensohn, Ricardo A.; Zecevic, Miroslav; Knezevic, Marko; ...

    2015-12-15

    Here, this work presents estimations of average intragranular fluctuations of lattice rotation rates in polycrystalline materials, obtained by means of the viscoplastic self-consistent (VPSC) model. These fluctuations give a tensorial measure of the trend of misorientation developing inside each single crystal grain representing a polycrystalline aggregate. We first report details of the algorithm implemented in the VPSC code to estimate these fluctuations, which are then validated by comparison with corresponding full-field calculations. Next, we present predictions of average intragranular fluctuations of lattice rotation rates for cubic aggregates, which are rationalized by comparison with experimental evidence on annealing textures of fccmore » and bcc polycrystals deformed in tension and compression, respectively, as well as with measured intragranular misorientation distributions in a Cu polycrystal deformed in tension. The orientation-dependent and micromechanically-based estimations of intragranular misorientations that can be derived from the present implementation are necessary to formulate sound sub-models for the prediction of quantitatively accurate deformation textures, grain fragmentation, and recrystallization textures using the VPSC approach.« less

  10. Self-consistent nonlocal feedback theory for electrocatalytic swimmers with heterogeneous surface chemical kinetics

    NASA Astrophysics Data System (ADS)

    Nourhani, Amir; Crespi, Vincent H.; Lammert, Paul E.

    2015-06-01

    We present a self-consistent nonlocal feedback theory for the phoretic propulsion mechanisms of electrocatalytic micromotors or nanomotors. These swimmers, such as bimetallic platinum and gold rods catalyzing decomposition of hydrogen peroxide in aqueous solution, have received considerable theoretical attention. In contrast, the heterogeneous electrochemical processes with nonlocal feedback that are the actual "engines" of such motors are relatively neglected. We present a flexible approach to these processes using bias potential as a control parameter field and a locally-open-circuit reference state, carried through in detail for a spherical motor. While the phenomenological flavor makes meaningful contact with experiment easier, required inputs can also conceivably come from, e.g., Frumkin-Butler-Volmer kinetics. Previously obtained results are recovered in the weak-heterogeneity limit and improved small-basis approximations tailored to structural heterogeneity are presented. Under the assumption of weak inhomogeneity, a scaling form is deduced for motor speed as a function of fuel concentration and swimmer size. We argue that this form should be robust and demonstrate a good fit to experimental data.

  11. Construction of A Self-consistent Landscape for Multistable Gene Regulatory Circuits

    NASA Astrophysics Data System (ADS)

    Lu, Mingyang; Onuchic, Jose; Ben-Jacob, Eshel

    2014-03-01

    Cell fate decisions during embryonic development and tumorigenesis pose a major research challenge in modern developmental and cancer biology. Cell fate decisions between different phenotypes are regulated by multistable gene circuits that give rise to the coexistence of several stable states. Internal and external noise play crucial role in determining the transitions between and the relative stability of the coexisting phenotypes. The deterministic dynamics of these circuits is not derivable from a potential. Yet, motivated by Waddington Epigenetic Landscape, many rely on the notion of effective potential to describe cell fate determination in the presence of noise. Here, we present a construction of a self-consistent landscape (effective potential, W ≡ -ln(probability)), utilizing the Eikonal equation approach (WKB approximation of the corresponding Fokker Planck equation) for the cases of white noise and shot noise. The approach is based on utilizing the method of characteristics in a special way. We also devised a numerical method to efficiently calculate the contour of the potential and the optimal path for the transitions from one stable state to another. We tested the method on the bistable and tristable double inhibition circuits, and we showed that the constructed landscape agrees very well with the numerical simulation of the stochastic equations. We expect this method to be valuable to a wide range of multistable gene circuits.

  12. A Self-consistent Simulation of KSTAR Reverse-shear Operation Mode using ASTRA Code

    NASA Astrophysics Data System (ADS)

    Kim, J. Y.; Jhang, Hogun

    2001-10-01

    A simulation study is presented on the reverse-shear operation mode of KSTAR (Korea Superconducting Tokamak Advanced Research) device, using the ASTRA (Automatic System of TRansport Analysis in a tokamak) code. The heat deposition and the current profile evolution are modeled self-consistently from the ASTRA code into which several heating and current-drive modules of NBI, ICRH/FWCD, and LHCD have been implemented. The anomalous transport is modeled more elaborately by using the theory-based models, such as IFS/PPPL one, rather than conventional empirical or artificial formulas. The effect of equilibrium flow shear and its time evolution are also included in the modeling for a more realistic description of the formation of ITB and its spatial and temporal evolution. Finally, based on the simulation results we will discuss the possible way to get an AT mode plasma with high-beta and high bootstrap current fraction, avoiding a steep pressure gradient and related local MHD instabilities.

  13. Thermal effusivity measurements for liquids: a self-consistent photoacoustic methodology.

    PubMed

    Balderas-López, J A

    2007-06-01

    A self-consistent photoacoustic methodology for the measurement of the thermal effusivity for liquids is presented. This methodology makes use of the analytical solution for the one-dimensional heat diffusion problem for a single layer, assuming a harmonic heat source in the surface absorption limit. The analytical treatment involves fitting procedures over normalized amplitudes and phases, obtained as the ratio of photoacoustic signals in the front configuration with and without the liquid sample, as functions of the modulation frequency. Two values of thermal effusivity for each liquid sample are obtained, one from the analysis of the normalized amplitudes and the other one from the normalized phases. The comparison between the experimental and theoretical phases allows the description of a simple criterion for deciding on the appropriate modulation frequency range for the analysis in each case. This methodology was applied for measuring the thermal effusivity of some pure liquids; a very good agreement between the thermal effusivity values obtained by this methodology and the corresponding ones reported in the literature was obtained.

  14. An Extended Self-Consistent Viscoplastic Polycrystal Formulation: Application to Polycrystals with Voids

    SciTech Connect

    Lebensohn, Ricardo A.; Tomé, Carlos N.; Maudlin, Paul J.

    2003-08-01

    In this work we consider the presence of ellipsoidal voids inside polycrystals submitted to large strain deformation. For this purpose, the originally incompressible viscoplastic self-consistent (VPSC) formulation of Lebensohn and Tomé (1993) has been extended to compressible polycrystals. In doing this, both the deviatoric and the spherical components of strain rate and stress are accounted for. Such an extended model allows us to account for the presence of voids and for porosity evolution, while preserving the anisotropy and crystallographic capabilities of the VPSC model. The formulation is adjusted to match Gurson model in the limit of rateindependent isotropic media and spherical voids. We present several applications of this extended VPSC model that address the coupling between texture, plastic anisotropy, void shape, triaxiality, and porosity evolution. This report contains a detailed and comprehensive derivation of the VPSC polycrystal model and of the equations associated with the theory. Such description is meant to serve as a general reference source for the VPSC formulation and is not limited to the particular case of voided polycrystals.

  15. Self-Consistent Solution for the Annihilation-Diffusion Problem with Long-Range Interactions

    NASA Astrophysics Data System (ADS)

    Ginzburg, Valeriy V.

    1996-03-01

    We study the kinetics of the two-species annihilation A + B arrow 0. It is known that in the absense of long-range forces, particle density decays with time as t^-ν, with ν = d/4, d < 4, and ν = 1, d > 4 footnote D. Toussaint and F. Wilczek, J. Chem. Phys. 78, 2642 (1983). In the presence of long-range power-law forces, annihilation kinetics becomes more complicated, and exact solution is not known. Scaling theories of such systems were proposed recently, in which decay exponent was calculated based on the motion of an individual particle footnote V. Ginzburg, P. Beale, and N. A. Clark, Phys. Rev. E 52, 2583 (1995) footnote Y. Ispolatov, P. Krapivsky, Phys. Rev. E, in press. Here we derive hydrodynamic equations of evolution for a system with arbitrary power-law interaction and find self-consistent asymptotic solutions for the limit of large t. For the first time, all three factors - annihilation, diffusion and long-range forces - are accounted for. The solution is consistent with Toussaint-Wilczek and Ispolatov-Krapivsky results for non-interacting and Coulombic systems, respectively; it agrees with earlier speculations that! for Coulombic systems, mean-field annihilation exponent 1 is valid for any system dimensionality d > 1. To judge the validity of the obtained solution for intermediate power-laws, more computational data is required.

  16. Analytic models of regularly branched polymer brushes using the self-consistent mean field theory

    NASA Astrophysics Data System (ADS)

    LeSher, Daniel

    2015-10-01

    Polymer brushes consist of multiple monomers connected together with one of the polymer chain's ends attached to a surface. Polymer brushes have shown great promise for a wide variety of applications including drug delivery dendrimer systems and as tunable brushes that can change their shape and physical properties in response to changes in their environment. Regularly branched polymer brushes which are structured as a function of their chemical indices are investigated here using the self-consistent mean field theory for electrically neutral polymers. The brushes were described using weighting functions, f(n), were n was the fewest number of monomers from a specified location to a free end. Brushes with weighting functions of the form f(n)=nb, f(n)=ebn, as well as f(n)=dan when d 2 and alpha > 2 were found to match the parabolic free chain end profile expected, while it was determined that polymer brushes described using f(n)=n b must be very small in order to remain in equilibrium. However, brushes described by f(n)=2G(N-n) N and f(n)2n were found to be unstable for real, positive values of the potential of the system.

  17. Petascale self-consistent electromagnetic computations using scalable and accurate algorithms for complex structures

    NASA Astrophysics Data System (ADS)

    Cary, John R.; Abell, D.; Amundson, J.; Bruhwiler, D. L.; Busby, R.; Carlsson, J. A.; Dimitrov, D. A.; Kashdan, E.; Messmer, P.; Nieter, C.; Smithe, D. N.; Spentzouris, P.; Stoltz, P.; Trines, R. M.; Wang, H.; Werner, G. R.

    2006-09-01

    As the size and cost of particle accelerators escalate, high-performance computing plays an increasingly important role; optimization through accurate, detailed computermodeling increases performance and reduces costs. But consequently, computer simulations face enormous challenges. Early approximation methods, such as expansions in distance from the design orbit, were unable to supply detailed accurate results, such as in the computation of wake fields in complex cavities. Since the advent of message-passing supercomputers with thousands of processors, earlier approximations are no longer necessary, and it is now possible to compute wake fields, the effects of dampers, and self-consistent dynamics in cavities accurately. In this environment, the focus has shifted towards the development and implementation of algorithms that scale to large numbers of processors. So-called charge-conserving algorithms evolve the electromagnetic fields without the need for any global solves (which are difficult to scale up to many processors). Using cut-cell (or embedded) boundaries, these algorithms can simulate the fields in complex accelerator cavities with curved walls. New implicit algorithms, which are stable for any time-step, conserve charge as well, allowing faster simulation of structures with details small compared to the characteristic wavelength. These algorithmic and computational advances have been implemented in the VORPAL7 Framework, a flexible, object-oriented, massively parallel computational application that allows run-time assembly of algorithms and objects, thus composing an application on the fly.

  18. A self-consistent linear-mode model of stellar convection

    NASA Technical Reports Server (NTRS)

    Macauslan, J.

    1985-01-01

    A normal-mode expansion of the linearized fluid equations in terms of small subset of spherical harmonics can provide a foundation for a physically motivated, self-consistent description of a solar-type convection zone. In the absence of dissipation, a second-order differential equation governs the radial dependence of the modes, so that interpretation of the effects on convection quantities of the normal-form 'potential well' is straightforward. The philosophy is quite different from the more recent work of Narasimha and Antia (1982): all envelopes presented here differ substantially from MLT envelopes, and therefore, from theirs, which are constructed to be consistent with MLT. The amplitude of all modes is set by a Kelvin-Helmholtz-('shear'-) instability argument unrelated to solar observations, with the result that the convection description may be considered to arise from 'first-hueristic-principles'. The thermodynamics modelled vaguely resemble the sun's, and more vigorously convective envelopes show some phenomena qualitatively like solar observations (e.g., atmospheric velocity spectra).

  19. Self-consistent Simulations of Plasma-Neutral in a Partially Ionized Astrophysical Turbulent Plasma

    NASA Astrophysics Data System (ADS)

    Shaikh, Dastgeer; Zank, G. P.

    2010-03-01

    A local turbulence model is developed to study energy cascades in the heliosheath and outer heliosphere (OH) based on self-consistent two-dimensional fluid simulations. The model describes a partially ionized magnetofluid OH that couples a neutral hydrogen fluid with a plasma primarily through charge-exchange interactions. Charge-exchange interactions are ubiquitous in warm heliospheric plasma, and the strength of the interaction depends largely on the relative speed between the plasma and the neutral fluid. Unlike small-length scale linear collisional dissipation in a single fluid, charge-exchange processes introduce channels that can be effective on a variety of length scales that depend on the neutral and plasma densities, temperature, relative velocities, charge-exchange cross section, and the characteristic length scales. We find, from scaling arguments and nonlinear coupled fluid simulations, that charge-exchange interactions modify spectral transfer associated with large-scale energy-containing eddies. Consequently, the turbulent cascade rate prolongs spectral transfer among inertial range turbulent modes. Turbulent spectra associated with the neutral and plasma fluids are therefore steeper than those predicted by Kolmogorov's phenomenology. Our work is important in the context of the global heliospheric interaction, the energization and transport of cosmic rays, gamma-ray bursts, interstellar density spectra, etc. Furthermore, the plasma-neutral coupling is crucial in understanding the energy dissipation mechanism in molecular clouds and star formation processes.

  20. A New Self-Consistent Field Model of Polymer/Nanoparticle Mixture

    PubMed Central

    Chen, Kang; Li, Hui-shu; Zhang, Bo-kai; Li, Jian; Tian, Wen-de

    2016-01-01

    Field-theoretical method is efficient in predicting assembling structures of polymeric systems. However, it’s challenging to generalize this method to study the polymer/nanoparticle mixture due to its multi-scale nature. Here, we develop a new field-based model which unifies the nanoparticle description with the polymer field within the self-consistent field theory. Instead of being “ensemble-averaged” continuous distribution, the particle density in the final morphology can represent individual particles located at preferred positions. The discreteness of particle density allows our model to properly address the polymer-particle interface and the excluded-volume interaction. We use this model to study the simplest system of nanoparticles immersed in the dense homopolymer solution. The flexibility of tuning the interfacial details allows our model to capture the rich phenomena such as bridging aggregation and depletion attraction. Insights are obtained on the enthalpic and/or entropic origin of the structural variation due to the competition between depletion and interfacial interaction. This approach is readily extendable to the study of more complex polymer-based nanocomposites or biology-related systems, such as dendrimer/drug encapsulation and membrane/particle assembly. PMID:26829174

  1. Description of quasiparticle and satellite properties via cumulant expansions of the retarded one-particle Green's function

    DOE PAGES

    Mayers, Matthew Z.; Hybertsen, Mark S.; Reichman, David R.

    2016-08-22

    A cumulant-based GW approximation for the retarded one-particle Green's function is proposed, motivated by an exact relation between the improper Dyson self-energy and the cumulant generating function. We explore qualitative aspects of this method within a simple one-electron independent phonon model, where it is seen that the method preserves the energy moment of the spectral weight while also reproducing the exact Green's function in the weak-coupling limit. For the three-dimensional electron gas, this method predicts multiple satellites at the bottom of the band, albeit with inaccurate peak spacing. But, its quasiparticle properties and correlation energies are more accurate than bothmore » previous cumulant methods and standard G0W0. These results point to features that may be exploited within the framework of cumulant-based methods and suggest promising directions for future exploration and improvements of cumulant-based GW approaches.« less

  2. Description of quasiparticle and satellite properties via cumulant expansions of the retarded one-particle Green's function

    SciTech Connect

    Mayers, Matthew Z.; Hybertsen, Mark S.; Reichman, David R.

    2016-08-22

    A cumulant-based GW approximation for the retarded one-particle Green's function is proposed, motivated by an exact relation between the improper Dyson self-energy and the cumulant generating function. We explore qualitative aspects of this method within a simple one-electron independent phonon model, where it is seen that the method preserves the energy moment of the spectral weight while also reproducing the exact Green's function in the weak-coupling limit. For the three-dimensional electron gas, this method predicts multiple satellites at the bottom of the band, albeit with inaccurate peak spacing. But, its quasiparticle properties and correlation energies are more accurate than both previous cumulant methods and standard G0W0. These results point to features that may be exploited within the framework of cumulant-based methods and suggest promising directions for future exploration and improvements of cumulant-based GW approaches.

  3. Quasiparticle anisotropic hydrodynamics for central collisions

    NASA Astrophysics Data System (ADS)

    Alqahtani, Mubarak; Nopoush, Mohammad; Strickland, Michael

    2017-03-01

    We use quasiparticle anisotropic hydrodynamics to study an azimuthally symmetric boost-invariant quark-gluon plasma including the effects of both shear and bulk viscosities. In quasiparticle anisotropic hydrodynamics, a single finite-temperature quasiparticle mass is introduced and fit to the lattice data in order to implement a realistic equation of state (EoS). We compare results obtained by using the quasiparticle method with the standard method of imposing the EoS in anisotropic hydrodynamics and viscous hydrodynamics. Using these three methods, we extract the primordial particle spectra, total number of charged particles, and average transverse momentum for various values of the shear viscosity to entropy density ratio η /s . We find that the three methods agree well for small shear viscosity to entropy density ratio η /s , but differ at large η /s , with the standard anisotropic EoS method showing suppressed production at low transverse-momentum compared with the other two methods considered. Finally, we demonstrate explicitly that, when using standard viscous hydrodynamics, the bulk-viscous correction can drive the primordial particle spectra negative at large pT. Such behavior is not seen in either anisotropic hydrodynamics approach, irrespective of the value of η /s .

  4. Using Quasiparticle Poisoning To Detect Photons

    NASA Technical Reports Server (NTRS)

    Echternach, Pierre; Day, Peter

    2006-01-01

    According to a proposal, a phenomenon associated with excitation of quasiparticles in certain superconducting quantum devices would be exploited as a means of detecting photons with exquisite sensitivity. The phenomenon could also be exploited to perform medium-resolution spectroscopy. The proposal was inspired by the observation that Coulomb blockade devices upon which some quantum logic gates are based are extremely sensitive to quasiparticles excited above the superconducting gaps in their leads. The presence of quasiparticles in the leads can be easily detected via the charge states. If quasiparticles could be generated in the leads by absorption of photons, then the devices could be used as very sensitive detectors of electromagnetic radiation over the spectral range from x-rays to submillimeter waves. The devices in question are single-Cooper-pair boxes (SCBs), which are mesoscopic superconducting devices developed for quantum computing. An SCB consists of a small superconducting island connected to a reservoir via a small tunnel junction and connected to a voltage source through a gate capacitor. An SCB is an artificial two-level quantum system, the Hamiltonian of which can be controlled by the gate voltage. One measures the expected value of the charge of the eigenvectors of this quantum system by use of a radio-frequency single-electron transistor. A plot of this expected value of charge as a function of gate voltage resembles a staircase that, in the ideal case, consists of steps of height 2 e (where e is the charge of one electron). Experiments have shown that depending on the parameters of the device, quasiparticles in the form of "broken" Cooper pairs present in the reservoir can tunnel to the island, giving rise to steps of 1 e. This effect is sometimes called "poisoning." Simulations have shown that an extremely small average number of quasiparticles can generate a 1-e periodic signal. In a device according to the proposal, this poisoning would be

  5. Quantum Limits in Interferometric GW Antennas

    NASA Technical Reports Server (NTRS)

    Romano, R.; Barone, F.; Maddalena, P.; Solimeno, S.; Zaccaria, F.; Manko, M. A.; Manko, V. I.

    1996-01-01

    We discuss a model for interferometric GW antennas illuminated by a laser beam and a vacuum squeezed field. The sensitivity of the antenna will depend on the properties of the radiation entering the two ports and on the optical characteristics of the interferometer components, e.g. mirrors, beam-splitter, lenses.

  6. Self-consistent orogenic wedge formation and shear zone propagation due to thermal softening

    NASA Astrophysics Data System (ADS)

    Jaquet, Yoann; Duretz, Thibault; Schmalholz, Stefan M.

    2016-04-01

    We present two dimensional numerical simulations of orogenic wedge formation for a viscoelastoplastic lithosphere under compression. The thermo-mechanical model is based on the principle of energy conservation and includes temperature-dependent rheologies. With this approach, shear zones caused by thermal softening develop spontaneously in the absence of strain softening. The initial locus of shear localization is controlled by either lateral temperature variations (100°C) at the model base or by lateral variations in crustal thickness. The first episode of strain localization occurs after 15% bulk shortening. With ongoing strain, a series of shear zones arise and propagate towards the foreland leading to the self-consistent formation of an orogenic wedge. We investigate the impact of bulk shortening rates, erosion and rheology on the dynamics of wedge formation, the associated topography and uplift rates. The maximum topography reaches up to 10 km and the surface morphology evolves according to shear zone activation and deactivation. Uplift rates are transient and peak values are maintained only on very short time scales. A running average of the uplift rate versus time curves with a time-window of 4 My provides average uplift rates in the order of a few millimeters per year. Erosion is an important parameter for the formation and the evolution of the wedge (e.g. can control the spacing of shear zones by modifying crustal thickness). Rheological parameters, such as the friction angle or the upper crustal viscosity, control the occurrence of strain localization. Bulk shortening rates between 10-15 and 10-16 s-1 do not have a major impact on the resulting wedge structure.

  7. Nonuniqueness and Structural Stability of Self-Consistent Models of Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Siopis, Christos

    Schwarzschild's method was used to construct equilibrium solutions to the collisionless Boltzmann equation corresponding to a Plummer sphere. These solutions were compared with analytical results to test the robustness of the numerical method and its efficiency in probing the degeneracy of the solution space. The method was then used to construct genuinely triaxial stellar equilibria, for which no analytical solutions are known, and to study their nonuniqueness. The particular model that was studied is a three-dimensional generalization of Dehnen's spherical potential, which contains a central density cusp and admits both regular and chaotic orbits. It was found that, for a model with a weak density cusp, self-consistent models do not exist if the chaotic orbits are assumed to be completely mixed so as to yield a time-independent building-block: only the innermost 65% of the mass can be mixed. In these inner regions, it is possible to obtain alternative solutions that contain significantly different numbers of chaotic orbits, yet yield (at least approximately) the same mass density distribution. However, it is not clear whether these solutions are truly time-independent, since the ``unmixed'' chaotic orbits in the outer regions, which do not sample an invariant measure, can cause secular evolution. When using Schwarzschild's method, one must be very careful to sample accessible phase-space as comprehensively and as densely as possible, while at the same time ensuring that each orbit is a truly time-independent building block. Some of the numerical equilibria were sampled to generate initial conditions for N-body simulations, with the aim of testing the structural stability of the models. Preliminary work showed that no catastrophic evolution takes place, but there is a weak tendency for the configuration to become more nearly axisymmetric over a period of several dynamical times. It is not presently clear whether this tendency is real or a numerical artifact.

  8. Self-consistent modeling of DEMOs with 1.5D BALDUR integrated predictive modeling code

    NASA Astrophysics Data System (ADS)

    Wisitsorasak, A.; Somjinda, B.; Promping, J.; Onjun, T.

    2017-02-01

    Self-consistent simulations of four DEMO designs proposed by teams from China, Europe, India, and Korea are carried out using the BALDUR integrated predictive modeling code in which theory-based models are used, for both core transport and boundary conditions. In these simulations, a combination of the NCLASS neoclassical transport and multimode (MMM95) anomalous transport model is used to compute a core transport. The boundary is taken to be at the top of the pedestal, where the pedestal values are described using a pedestal temperature model based on a combination of magnetic and flow shear stabilization, pedestal width scaling and an infinite- n ballooning pressure gradient model and a pedestal density model based on a line average density. Even though an optimistic scenario is considered, the simulation results suggest that, with the exclusion of ELMs, the fusion gain Q obtained for these reactors is pessimistic compared to their original designs, i.e. 52% for the Chinese design, 63% for the European design, 22% for the Korean design, and 26% for the Indian design. In addition, the predicted bootstrap current fractions are also found to be lower than their original designs, as fractions of their original designs, i.e. 0.49 (China), 0.66 (Europe), and 0.58 (India). Furthermore, in relation to sensitivity, it is found that increasing values of the auxiliary heating power and the electron line average density from their design values yield an enhancement of fusion performance. In addition, inclusion of sawtooth oscillation effects demonstrate positive impacts on the plasma and fusion performance in European, Indian and Korean DEMOs, but degrade the performance in the Chinese DEMO.

  9. A Self-Consistent Radiative Transfer Model for Simulating Active and Passive Observations of Precipitation

    NASA Astrophysics Data System (ADS)

    Adams, I. S.

    2015-12-01

    Current generation sensors suites such as those included on the Global Precipitation Measurement (GPM) mission, Aquarius, and Soil Moisture Active / Passive (SMAP) exploit a combination to provide a greater understanding of geophysical phenomena. While "operationalized" retrieval algorithms require fast forward models, the ability to perform higher fidelity simulations is necessary for understanding the physics of remote sensing problems to test assumptions and to develop parameterizations for the fast models. To ensure proper synergy between active and passive modeling, forward models must be consistent between the two sensor types. This work presents a self-consistent active and passive radiative transfer model for simulating radar and radiometer responses to precipitation. To accomplish this, we extend the Atmospheric Radiative Transfer Simulator (ARTS) version 2.3 to solve the radiative transfer equation for radar under multiple scattering conditions using Monte Carlo integration. Early versions of ARTS (1.1 and later) included a passive Monte Carlo solver, and ARTS is capable of handling atmospheres of up to three dimensions with ellipsoidal planetary geometries. The modular nature of ARTS facilitates extensibility, and the well-developed ray-tracing tools are suited for implementation of Monte Carlo algorithms. Finally, since ARTS handles the full Stokes vector, co- and cross-polarized reflectivity products are possible for scenarios that include nonspherical particles, with or without preferential alignment. The accuracy of the forward model will be demonstrated, and the effects of multiple scattering will be detailed. The three-dimensional nature of the radiative transfer model will be useful for understanding the effects of nonuniform beamfill and multiple scattering for spatially heterogeneous precipitation events. This targets of this forward model are GPM (the Dual-wavelength Precipitation Radar (DPR) and GPM Microwave Imager (GMI)) and airborne sensors

  10. Self-Consistent, 2D Magneto-Hydrodynamic Simulations of Magnetically Driven Flyer Plates

    NASA Astrophysics Data System (ADS)

    Lemke, Raymond W.

    2002-11-01

    The intense magnetic field generated in the 20 MA Z-machine is used to accelerate flyer plates to high velocity for equation of state experiments. A peak magnetic drive pressure on the order of 2 Mbar can be generated, which accelerates an approximately 0.2 g aluminum disc to 21 km/s [1]. We have used 2D magneto-hydrodynamic (MHD) simulation to investigate the physics of accelerating flyer plates using multi-megabar magnetic drive pressures. A typical shock physics load is formed by a rectangular slab cathode enclosed by a hollow rectangular duct (the anode). The anode and cathode are connected (shorted) at one end. The electrodes are highly compressible at multi-megabar pressures. Electrode deformation that occurs during the rise time of the current pulse causes significant inductance increase, which reduces the peak current (drive pressure) relative to a static geometry. This important dynamic effect is modeled self-consistently by driving the MHD simulation with a circuit model of Z. Comparison of simulation results with highly accurate velocity interferometry measurements shows that the drive pressure waveform is affected by current losses and short circuiting in the machine, in conjunction with time varying load inductance. The understanding gained from these comparisons has allowed us to optimize shock physics loads using simulation. In this way a load was designed to produce a flyer velocity of 28 km/s, which was achieved experimentally on Z. We have identified paths to producing a flyer velocity of 40 km/s and peak isentropic pressure of 10 Mbar on the refurbished Z-machine [2]. Details of the modeling, the physics and comparisons with experiment are presented. [1] M. D. Knudson et al., Phys. Rev. Letters 87 (22), 22550-1 (2002). [2] R. W. Lemke et al., to be published in Proc. of the Int. Conf. on High Power Particle Beams and Dense Z-Pinches, Albuquerque, NM, June 23-28, 2002.

  11. Self-consistent modeling of electrochemical strain microscopy of solid electrolytes

    DOE PAGES

    Tselev, Alexander; Morozovska, Anna N.; Udod, Alexei; ...

    2014-10-10

    Electrochemical strain microscopy (ESM) employs a strong electromechanical coupling in solid ionic conductors to map ionic transport and electrochemical processes with nanometer-scale spatial resolution. To elucidate the mechanisms of the ESM image formation, we performed self-consistent numerical modeling of the electromechanical response in solid electrolytes under the probe tip in a linear, small-signal regime using the Boltzmann–Planck–Nernst–Einstein theory and Vegard's law while taking account of the electromigration and diffusion. We identified the characteristic time scales involved in the formation of the ESM response and found that the dynamics of the charge carriers in the tip-electrolyte system with blocking interfaces canmore » be described as charging of the diffuse layer at the tip-electrolyte interface through the tip contact spreading resistance. At the high frequencies used in the detection regime, the distribution of the charge carriers under the tip is governed by evanescent concentration waves generated at the tip-electrolyte interface. The ion drift length in the electric field produced by the tip determines the ESM response at high frequencies, which follows a 1/f asymptotic law. The electronic conductivity, as well as the electron transport through the electrode-electrolyte interface, do not have a significant effect on the ESM signal in the detection regime. The results indicate, however, that for typical solid electrolytes at room temperature, the ESM response originates at and contains information about the very surface layer of a sample, and the properties of the one-unit-cell-thick surface layer may significantly contribute to the ESM response, implying a high surface sensitivity and a high lateral resolution of the technique. On the other hand, it follows that a rigorous analysis of the ESM signals requires techniques that account for the discrete nature of a solid.« less

  12. A self-consistent two-fluid model of a magnetized plasma-wall transition

    SciTech Connect

    Gyergyek, T.; Kovačič, J.

    2015-09-15

    A self-consistent one-dimensional two-fluid model of the magnetized plasma-wall transition is presented. The model includes magnetic field, elastic collisions between ions and electrons, and creation/annihilation of charged particles. Two systems of differential equations are derived. The first system describes the whole magnetized plasma-wall transition region, which consists of the pre-sheath, the magnetized pre-sheath (Chodura layer), and the sheath, which is not neutral, but contains a positive space charge. The second system of equations describes only the neutral part of the plasma-wall transition region—this means only the pre-sheath and the Chodura layer, but not also the sheath. Both systems are solved numerically. The first system of equations has two singularities. The first occurs when ion velocity in the direction perpendicularly to the wall drops below the ion thermal velocity. The second occurs when the electron velocity in the direction perpendicularly to the wall exceeds the electron thermal velocity. The second system of differential equations only has one singularity, which has also been derived analytically. For finite electron to ion mass ratio, the integration of the second system always breaks down before the Bohm criterion is fulfilled. Some properties of the first system of equations are examined. It is shown that the increased collision frequency demagnetizes the plasma. On the other hand, if the magnetic field is so strong that the ion Larmor radius and the Debye length are comparable, the electron velocity in the direction perpendicularly to the wall reaches the electron thermal velocity before the ion velocity in the direction perpendicularly to the wall reaches the ion sound velocity. In this case, the integration of the model equations breaks down before the Bohm criterion is fulfilled and the sheath is formed.

  13. A Self-consistent and Spatially Dependent Model of the Multiband Emission of Pulsar Wind Nebulae

    NASA Astrophysics Data System (ADS)

    Lu, Fang-Wu; Gao, Quan-Gui; Zhang, Li

    2017-01-01

    A self-consistent and spatially dependent model is presented to investigate the multiband emission of pulsar wind nebulae (PWNe). In this model, a spherically symmetric system is assumed and the dynamical evolution of the PWN is included. The processes of convection, diffusion, adiabatic loss, radiative loss, and photon–photon pair production are taken into account in the electron’s evolution equation, and the processes of synchrotron radiation, inverse Compton scattering, synchrotron self-absorption, and pair production are included for the photon’s evolution equation. Both coupled equations are simultaneously solved. The model is applied to explain observed results of the PWN in MSH 15–52. Our results show that the spectral energy distributions (SEDs) of both electrons and photons are all a function of distance. The observed photon SED of MSH 15–52 can be well reproduced in this model. With the parameters obtained by fitting the observed SED, the spatial variations of photon index and surface brightness observed in the X-ray band can also be well reproduced. Moreover, it can be derived that the present-day diffusion coefficient of MSH 15–52 at the termination shock is {κ }0=6.6× {10}24 {{cm}}2 {{{s}}}-1, the spatial average has a value of \\bar{κ }=1.4× {10}25 {{cm}}2 {{{s}}}-1, and the present-day magnetic field at the termination shock has a value of {B}0=26.6 μ {{G}} and the spatial averaged magnetic field is \\bar{B}=14.9 μ {{G}}. The spatial changes of the spectral index and surface brightness at different bands are predicted.

  14. Self-consistent modeling of electrochemical strain microscopy of solid electrolytes

    SciTech Connect

    Tselev, Alexander; Morozovska, Anna N.; Udod, Alexei; Eliseev, Eugene A.; Kalinin, Sergei V.

    2014-10-10

    Electrochemical strain microscopy (ESM) employs a strong electromechanical coupling in solid ionic conductors to map ionic transport and electrochemical processes with nanometer-scale spatial resolution. To elucidate the mechanisms of the ESM image formation, we performed self-consistent numerical modeling of the electromechanical response in solid electrolytes under the probe tip in a linear, small-signal regime using the Boltzmann–Planck–Nernst–Einstein theory and Vegard's law while taking account of the electromigration and diffusion. We identified the characteristic time scales involved in the formation of the ESM response and found that the dynamics of the charge carriers in the tip-electrolyte system with blocking interfaces can be described as charging of the diffuse layer at the tip-electrolyte interface through the tip contact spreading resistance. At the high frequencies used in the detection regime, the distribution of the charge carriers under the tip is governed by evanescent concentration waves generated at the tip-electrolyte interface. The ion drift length in the electric field produced by the tip determines the ESM response at high frequencies, which follows a 1/f asymptotic law. The electronic conductivity, as well as the electron transport through the electrode-electrolyte interface, do not have a significant effect on the ESM signal in the detection regime. The results indicate, however, that for typical solid electrolytes at room temperature, the ESM response originates at and contains information about the very surface layer of a sample, and the properties of the one-unit-cell-thick surface layer may significantly contribute to the ESM response, implying a high surface sensitivity and a high lateral resolution of the technique. On the other hand, it follows that a rigorous analysis of the ESM signals requires techniques that account for the discrete nature of a solid.

  15. Microscopic Self-consistent Study of Neon Halos with Resonant Contributions

    SciTech Connect

    Zhang, Shisheng; Smith, Michael Scott; Kang, Zhong-Shu; Zhao, Jie

    2014-01-01

    Recent reaction measurements have been interpreted as evidence of a halo structure in the exotic neutron-rich isotopes 29,31Ne. While theoretical studies of 31Ne generally agree on its halo nature, they differ significantly in their predictions of its properties and underlying cause (e.g., that 31Ne lies in an "island of inversion'"). We have made a systematic theoretical analysis of possible Neon halo signatures -- the first using a fully microscopic, relativistic mean field approach that properly treats positive energy orbitals (such as the valence neutron in 31Ne) self-consistently with bound levels, and that includes the pairing effect that keeps the nucleus loosely bound with negative Fermi energy. Our model is the analytical continuation of the coupling constant (ACCC) method based on a relativistic mean field (RMF) theory with Bardeen-Cooper-Schrieffer (BCS) pairing approximation. We calculate neutron- and matter-radii, one-neutron separation energies, p- and f-orbital energies and occupation probabilities, and neutron densities for single-particle resonant orbitals in 27-31Ne. We analyze these results for evidence of neutron halo formation in 29,31Ne. Our model predicts a p-orbit 1n halo structure for 31Ne, based on a radius increase from 30Ne that is 7 - 8 times larger than the increase from 29Ne to 30Ne, as well as a decrease in the neutron separation energy by a factor of ~ 10 compared to that of 27-30Ne. In contrast to other studies, our inclusion of resonances yields an inverted ordering of p and f orbitals for small deformations. Furthermore, we find no evidence of an s-orbit 1n halo in 29Ne as recently claimed in the literature.

  16. Time-dependent restricted-active-space self-consistent-field theory with space partition

    NASA Astrophysics Data System (ADS)

    Miyagi, Haruhide; Madsen, Lars Bojer

    2017-02-01

    Aiming at efficient numerical analysis of time-dependent (TD) many-electron dynamics of atoms involving multielectron continua, the TD restricted-active-space self-consistent-field theory with space partition (TD-RASSCF-SP) is presented. The TD-RASSCF-SP wave function is expanded in terms of TD configuration-interaction coefficients with Slater determinants composed of two kinds of TD orbitals: M ̂ orbitals are defined to be nonvanishing in the inner region (V ̂), a small volume around the atomic nucleus, and M ˇ orbitals are nonvanishing in the large outer region (V ˇ). For detailed discussion of the SP strategy, the equations of motion are derived by two different formalisms for comparison. To ensure continuous differentiability of the wave function across the two regions, one of the formalisms makes use of the property of the finite-element discrete-variable-representation (FEDVR) functions and introduces additional time-independent orbitals. The other formalism is more general and is based on the Bloch operator as in the R -matrix theory, but turns out to be less practical for numerical applications. Hence, using the FEDVR-based formalism, the numerical performance is tested by computing double-ionization dynamics of atomic beryllium in intense light fields. To achieve high accuracy, M ̂ should be set large to take into account the strong many-electron correlation around the nucleus. On the other hand, M ˇ can be set much smaller than M ̂ for capturing the weaker correlation between the two outgoing photoelectrons. As a result, compared with more accurate multiconfigurational TD Hartree-Fock (MCTDHF) method, the TD-RASSCF-SP method may achieve comparable accuracy in the description of the double-ionization dynamics. There are, however, difficulties related to the stiffness of the equations of motion of the TD-RASSCF-SP method, which makes the required time step for this method smaller than the one needed for the MCTDHF approach.

  17. Self-consistent calculations of rare-gas-transition-metal interaction potentials

    NASA Astrophysics Data System (ADS)

    Drakova, D.; Doyen, G.; v. Trentini, F.

    1985-11-01

    A model Hamiltonian is used to calculate potential-energy surfaces for He and Ne on the (110) faces of Ni, Cu, Pd, and Ag. The calculations are nonperturbative, self-consistent, and contain no parameters which are fittable with respect to the gas-solid interaction. Static image-force effects are included. The theory represents the first quantum-mechanical approach to rare-gas-transition-metal potentials which includes the interaction of the rare-gas orbitals with the d electrons in a consistent way. Corrugation is found to be approximately proportional to the d-electron charge density. The sp band is represented by a Sommerfeld model with hybridization gap, which does not contribute to the corrugation. Part of the potential arises through the hybridization of the rare-gas orbitals with the unoccupied metal states. This interference energy is roughly a factor of 2 larger for neon than for helium, leading to larger corrugations of the neon potentials as compared with the helium potentials. This is in agreement with recent experiments, but in contrast to earlier theoretical predictions. The theoretically calculated corrugations and well depths compare reasonably to the experimental data where available. The computed values of corrugation for He increase in the order Ni, Cu, Ag, and Pd. This agrees with experiments where soft potentials have been fitted to the scattering data, although the predicted He/Ni(110) corrugation is overly large by more than a factor of 2. With increasing energy, the He corrugation increases slightly in the calculations. The dependence is nearly constant for Ni and strongest for Pd. For Ne/Ni(110) and Ne/Pd(110) corrugation decreases with energy. Image-force effects are found to be important for the corrugation and softness of the neon potentials.

  18. Cost-driven self-consistent fabrication and assembly tolerance classes

    NASA Astrophysics Data System (ADS)

    Thompson, Kevin P.; Rolland, Jannick P.

    2015-10-01

    At the 1994 International Optics Design Conference, a paper was presented by the author that proposed that optics costs are often driven by the fabrication and assembly tolerances. In addition, that these tolerances fall into groups (classes) that for any given shop are set typically by the capital investment in measurement equipment that the shop has access to. The premise is then that it is essential that the optical system tolerances on fabrication, e.g. radii, element thickness, wedge, surface figure, and surface finish and on assembly e.g. component tilt and decenter and spacer thickness and wedge that are assigned by the optical designer be self-consistent with the capabilities of the shops that are solicited to provide a quotation. In the 1994 paper, five classes of optical fabricators were identified; catalog, regular, select, premium, and ultimate (lithography). For each of these classes, representative minimum tolerances were published along with estimates of the cost increment. An important concept is that if any one tolerance falls into a tighter class, then the optical system must be built in a shop capitalized to provide that one minimum tolerance and as a result all the other tolerances can typically be moved to the tighter class with little cost impact. The primary cost impact then is driven by the class of shop dictated by the minimum tolerance. In this talk, a primary purpose is to revisit the tolerances associated with a given class of shop and update the numbers to reflect advances in the intervening two decades.

  19. A Fully Self-consistent Multi-layered Model of Jupiter

    NASA Astrophysics Data System (ADS)

    Kong, Dali; Zhang, Keke; Schubert, Gerald

    2016-08-01

    We construct a three-dimensional, fully self-consistent, multi-layered, non-spheroidal model of Jupiter consisting of an inner core, a metallic electrically conducting dynamo region, and an outer molecular electrically insulating envelope. We assume that the Jovian zonal winds are on cylinders parallel to the rotation axis but, due to the effect of magnetic braking, are confined within the outer molecular envelope. We also assume that the location of the molecular-metallic interface is characterized by its equatorial radius {{HR}}e, where R e is the equatorial radius of Jupiter at the 1 bar pressure level and H is treated as a parameter of the model. We solve the relevant mathematical problem via a perturbation approach. The leading-order problem determines the density, size, and shape of the inner core, the irregular shape of the 1 bar pressure level, and the internal structure of Jupiter that accounts for the full effect of rotational distortion, but without the influence of the zonal winds; the next-order problem determines the variation of the gravitational field solely caused by the effect of the zonal winds on the rotationally distorted non-spheroidal Jupiter. The leading-order solution produces the known mass, the known equatorial and polar radii, and the known zonal gravitational coefficient J 2 of Jupiter within their error bars; it also yields the coefficients J 4 and J 6 within about 5% accuracy, the core equatorial radius 0.09{R}e and the core density {ρ }c=2.0× {10}4 {{kg}} {{{m}}}-3 corresponding to 3.73 Earth masses; the next-order solution yields the wind-induced variation of the zonal gravitational coefficients of Jupiter.

  20. Self-consistent nonlinear kinetic simulations of the anomalous Doppler instability of suprathermal electrons in plasmas

    SciTech Connect

    Lai, W. N.; Chapman, S. C.; Dendy, R. O.

    2013-10-15

    Suprathermal tails in the distributions of electron velocities parallel to the magnetic field are found in many areas of plasma physics, from magnetic confinement fusion to solar system plasmas. Parallel electron kinetic energy can be transferred into plasma waves and perpendicular gyration energy of particles through the anomalous Doppler instability (ADI), provided that energetic electrons with parallel velocities v{sub ||}≥(ω+Ω{sub ce})/k{sub ||} are present; here Ω{sub ce} denotes electron cyclotron frequency, ω the wave angular frequency, and k{sub ||} the component of wavenumber parallel to the magnetic field. This phenomenon is widely observed in tokamak plasmas. Here, we present the first fully self-consistent relativistic particle-in-cell simulations of the ADI, spanning the linear and nonlinear regimes of the ADI. We test the robustness of the analytical theory in the linear regime and follow the ADI through to the steady state. By directly evaluating the parallel and perpendicular dynamical contributions to j·E in the simulations, we follow the energy transfer between the excited waves and the bulk and tail electron populations for the first time. We find that the ratio Ω{sub ce}/(ω{sub pe}+Ω{sub ce}) of energy transfer between parallel and perpendicular, obtained from linear analysis, does not apply when damping is fully included, when we find it to be ω{sub pe}/(ω{sub pe}+Ω{sub ce}); here ω{sub pe} denotes the electron plasma frequency. We also find that the ADI can arise beyond the previously expected range of plasma parameters, in particular when Ω{sub ce}>ω{sub pe}. The simulations also exhibit a spectral feature which may correspond to the observations of suprathermal narrowband emission at ω{sub pe} detected from low density tokamak plasmas.

  1. Size-extensive vibrational self-consistent field methods with anharmonic geometry corrections

    NASA Astrophysics Data System (ADS)

    Hermes, Matthew R.; Keçeli, Murat; Hirata, So

    2012-06-01

    In the size-extensive vibrational self-consistent field (XVSCF) method introduced earlier [M. Keçeli and S. Hirata, J. Chem. Phys. 135, 134108 (2011)], 10.1063/1.3644895, only a small subset of even-order force constants that can form connected diagrams were used to compute extensive total energies and intensive transition frequencies. The mean-field potentials of XVSCF formed with these force constants have been shown to be effectively harmonic, making basis functions, quadrature, or matrix diagonalization in the conventional VSCF method unnecessary. We introduce two size-consistent VSCF methods, XVSCF(n) and XVSCF[n], for vibrationally averaged geometries in addition to energies and frequencies including anharmonic effects caused by up to the nth-order force constants. The methods are based on our observations that a small number of odd-order force constants of certain types can form open, connected diagrams isomorphic to the diagram of the mean-field potential gradients and that these nonzero gradients shift the potential minima by intensive amounts, which are interpreted as anharmonic geometry corrections. XVSCF(n) evaluates these mean-field gradients and force constants at the equilibrium geometry and estimates this shift accurately, but approximately, neglecting the coupling between these two quantities. XVSCF[n] solves the coupled equations for geometry corrections and frequencies with an iterative algorithm, giving results that should be identical to those of VSCF when applied to an infinite system. We present the diagrammatic and algebraic definitions, algorithms, and initial implementations as well as numerical results of these two methods. The results show that XVSCF(n) and XVSCF[n] reproduce the vibrationally averaged geometries of VSCF for naphthalene and anthracene in their ground and excited vibrational states accurately at fractions of the computational cost.

  2. Self-Consistent Field Model Spectra and Images for the Rapid Rotator α Cephei

    NASA Astrophysics Data System (ADS)

    Aufdenberg, Jason P.; MacGregor, K.; Sola, M.

    2012-05-01

    Non-LTE synthetic radiation fields have been coupled to Self-Consistent Field (SCF) rotating star models to predict images, interferometric observables (visibilities and closure phases), spectral energy distributions (SEDs), and high-resolution spectra for comparison with rapid rotater alpha Cephei (Alderamin). SCF models include differential rotation from the interior to the surface and differ from Roche models that assume a point-mass approximation of the gravitational potential and axially symmetric uniform rotation. SCF models are parametrized by a mass, the ratio of the axial rotation rate to the critical rate, and the degree and kind (solar or anti-solar) of differential rotation. Model spectra have been computed using a parallel interpolation algorithm (coded in Fortran90 with openMPI) which maps a radiation field database onto the rotationally distorted model star. The SCF model describes the surface shape and gravitational field from the pole to the equator. The luminosity and the von Zeipel exponent specify the variation in effective temperature with stellar latitude. The radiation field is interpolated at each point on the star for each wavelength, emergent angle, local effective, and local surface gravity. Model images are compared to the reconstructed images of Alderamin (Zhao et al. 2009) from the Michigan InfraRed Combiner (MIRC) at the CHARA Array. Model SEDs are compared to ultraviolet, visual and near-IR spectrophotometry. High-resolution model spectra are compared Alderamin's Mg II 4481 A line from the ELODIE spectral archive. We have found models near 2.2 solar masses with anti-solar differential rotation which match simultaneously the absolute magnitude, B-V color index, and projected axial ratio measured for Alderamin. The model images differ from the observations in brightness-temperature distribution over the projected stellar surface, the strength of the Mg II line profile, and the strength of the ultraviolet continuum. This work is

  3. The self-consistent electron pairs method for multiconfiguration reference state functions

    NASA Astrophysics Data System (ADS)

    Werner, Hans-Joachim; Reinsch, Ernst-Albrecht

    1982-03-01

    An efficient direct CI method which includes all singly and doubly substituted configurations with respect to an arbitrary multiconfiguration (MCSCF) reference function is described. The configurations are generated by subsequently applying spin-coupled two-particle annihilation and creation operators to the complete MCSCF function. This considerably reduces the size of the n-electron basis and the computational effort as compared to previous multireference CI treatments, in which the configurations are defined with respect to the individual reference configurations. The formalism of the method is very similar to the closed-shell ''self-consistent electron pairs'' (SCEP) method of Meyer. The vector Hc is obtained in terms of simple matrix operations involving coefficient and integral matrices. A full transformation of the two-electron integrals is not required. Test calculations with large basis sets have been performed for the 3B1 and 1A1 states of CH2 (ΔE = 9.5 kcal/mol) and for the CH2(3B1) +H2→CH3+H reaction barrier (ΔE = 10.7 kcal/mol). As a preliminary test for the accuracy of the results obtained with contracted wave functions of the above type the potential energy and dipole moment functions of the OH X 2Π and A 2Σ+ states have been calculated. For the 2Π state re and ωe deviate by less than 10-3 Å and 1 cm-1, respectively, from the experimental data. For the 2Σ+ state the agreement is somewhat less good, which is probably due to basis set defects. Around the equilibrium distance the calculated dipole moment functions are in very close agreement with those previously obtained from PNO- CEPA functions.

  4. Self-Consistency Requirements of the Renormalization Group for Setting the Renormalization Scale

    SciTech Connect

    Brodsky, Stanley J.; Wu, Xing-Gang

    2012-08-07

    In conventional treatments, predictions from fixed-order perturbative QCD calculations cannot be fixed with certainty due to ambiguities in the choice of the renormalization scale as well as the renormalization scheme. In this paper we present a general discussion of the constraints of the renormalization group (RG) invariance on the choice of the renormalization scale. We adopt the RG based equations, which incorporate the scheme parameters, for a general exposition of RG invariance, since they simultaneously express the invariance of physical observables under both the variation of the renormalization scale and the renormalization scheme parameters. We then discuss the self-consistency requirements of the RG, such as reflexivity, symmetry, and transitivity, which must be satisfied by the scale-setting method. The Principle of Minimal Sensitivity (PMS) requires the slope of the approximant of an observable to vanish at the renormalization point. This criterion provides a scheme-independent estimation, but it violates the symmetry and transitivity properties of the RG and does not reproduce the Gell-Mann-Low scale for QED observables. The Principle of Maximum Conformality (PMC) satisfies all of the deductions of the RG invariance - reflectivity, symmetry, and transitivity. Using the PMC, all non-conformal {βRi}-terms (R stands for an arbitrary renormalization scheme) in the perturbative expansion series are summed into the running coupling, and one obtains a unique, scale-fixed, scheme-independent prediction at any finite order. The PMC scales and the resulting finite-order PMC predictions are both to high accuracy independent of the choice of initial renormalization scale, consistent with RG invariance.

  5. Super-Earth Atmospheres: Self-consistent Gas Accretion and Retention

    NASA Astrophysics Data System (ADS)

    Ginzburg, Sivan; Schlichting, Hilke E.; Sari, Re'em

    2016-07-01

    Some recently discovered short-period Earth- to Neptune-sized exoplanets (super-Earths) have low observed mean densities that can only be explained by voluminous gaseous atmospheres. Here, we study the conditions allowing the accretion and retention of such atmospheres. We self-consistently couple the nebular gas accretion onto rocky cores and the subsequent evolution of gas envelopes following the dispersal of the protoplanetary disk. Specifically, we address mass-loss due to both photo-evaporation and cooling of the planet. We find that planets shed their outer layers (dozens of percent in mass) following the disk's dispersal (even without photo-evaporation), and their atmospheres shrink in a few Myr to a thickness comparable to the radius of the underlying rocky core. At this stage, atmospheres containing less particles than the core (equivalently, lighter than a few percent of the planet's mass) can be blown away by heat coming from the cooling core, while heavier atmospheres cool and contract on a timescale of Gyr at most. By relating the mass-loss timescale to the accretion time, we analytically identify a Goldilocks region in the mass-temperature plane in which low-density super-Earths can be found: planets have to be massive and cold enough to accrete and retain their atmospheres, but not too massive or cold, such that they do not enter runaway accretion and become gas giants (Jupiters). We compare our results to the observed super-Earth population and find that low-density planets are indeed concentrated in the theoretically allowed region. Our analytical and intuitive model can be used to investigate possible super-Earth formation scenarios.

  6. Dipole response in 208Pb within a self-consistent multiphonon approach

    NASA Astrophysics Data System (ADS)

    Knapp, F.; Lo Iudice, N.; Veselý, P.; Andreozzi, F.; De Gregorio, G.; Porrino, A.

    2015-11-01

    Background: The electric dipole strength detected around the particle threshold and commonly associated with the pygmy dipole resonance offers unique information on neutron skin and symmetry energy, and is of astrophysical interest. The nature of such a resonance is still under debate. Purpose: We intend to describe the giant and pygmy resonances in 208Pb by enhancing their fragmentation with respect to the random-phase approximation. Method: We adopt the equation of motion phonon method to perform a fully self-consistent calculation in a space spanned by one-phonon and two-phonon basis states using an optimized chiral two-body potential. A phenomenological density-dependent term, derived from a contact three-body force, is added to get single-particle spectra more realistic than the ones obtained by using the chiral potential only. The calculation takes into full account the Pauli principle and is free of spurious center-of-mass admixtures. Results: We obtain a fair description of the giant resonance and obtain a dense low-lying spectrum in qualitative agreement with the experimental data. The transition densities as well as the phonon and particle-hole composition of the most strongly excited states support the pygmy nature of the low-lying resonance. Finally, we obtain realistic values for the dipole polarizability and the neutron skin radius. Conclusions: The results emphasize the role of the two-phonon states in enhancing the fragmentation of the strength in the giant resonance region and at low energy, consistently with experiments. For a more detailed agreement with the data, the calculation suggests the inclusion of the three-phonon states as well as a fine tuning of the single-particle spectrum to be obtained by a refinement of the nuclear potential.

  7. Tidal Evolution of Exomoons using a Self-Consistent Tidal and Dynamical Model

    NASA Astrophysics Data System (ADS)

    Zollinger, Rhett; Armstrong, J. C.; Bromley, B. C.

    2014-01-01

    The recent success of Kepler and other planet hunting missions has helped motivate new interest in planet habitability. Now that the detection of massive satellites that orbit extrasolar planets has become feasible, interest in the habitability of exomoons has also emerged. Stellar insulation is commonly used as the main constraint on potential habitability. Exomoon habitability models have also considered additional energy sources such as stellar eclipses by the planet, the planet’s thermal emission and its stellar reflected light, as well as tidal heating of the moon. Tidal processes between a moon and its parent planet will determine the orbit and spin evolution of the moon. Gravitational perturbations will also have an effect on the evolution of a moon in a closely packed system with many massive bodies. Such examples include a large moon orbiting a giant planet in the habitable zone of a low mass star or a giant planet with multiple large moons. For resonant systems the evolution equations must be integrated directly to test for instability and to allow for variation of the semimajor axes. Therefore, to further constrain exomoon habitability it is necessary to simulate the orbital evolution of a satellite with a model that considers both gravitational scattering and tidal evolution. We have developed a simulation that uses an efficient method for calculating self-consistently the tidal, spin, and dynamical evolution of a many-body system. The method is based on formulations by Heggie and Eggleton (1998) as well as work by Mardling and Lin (2002). A planet and moon are given extended structure while other bodies are treated as point masses. The tidal evolution as well as the evolution of spin rates and obliquities are calculated for the extended bodies using arbitrary initial conditions. Our results will be presented for theoretical low mass stellar systems as well as hypothetical moons around some recently discovered exoplanets.

  8. Self-consistent Model of Martian Dichotomy Formation and Tharsis Evolution?

    NASA Astrophysics Data System (ADS)

    Sramek, O.; Zhong, S.

    2010-12-01

    plausibility of a self-consistent endogenic model of dichotomy formation by partial melting and Tharsis evolution.

  9. Self-consistent modeling of radio-frequency plasma generation in stellarators

    SciTech Connect

    Moiseenko, V. E. Stadnik, Yu. S.; Lysoivan, A. I.; Korovin, V. B.

    2013-11-15

    A self-consistent model of radio-frequency (RF) plasma generation in stellarators in the ion cyclotron frequency range is described. The model includes equations for the particle and energy balance and boundary conditions for Maxwell’s equations. The equation of charged particle balance takes into account the influx of particles due to ionization and their loss via diffusion and convection. The equation of electron energy balance takes into account the RF heating power source, as well as energy losses due to the excitation and electron-impact ionization of gas atoms, energy exchange via Coulomb collisions, and plasma heat conduction. The deposited RF power is calculated by solving the boundary problem for Maxwell’s equations. When describing the dissipation of the energy of the RF field, collisional absorption and Landau damping are taken into account. At each time step, Maxwell’s equations are solved for the current profiles of the plasma density and plasma temperature. The calculations are performed for a cylindrical plasma. The plasma is assumed to be axisymmetric and homogeneous along the plasma column. The system of balance equations is solved using the Crank-Nicholson scheme. Maxwell’s equations are solved in a one-dimensional approximation by using the Fourier transformation along the azimuthal and longitudinal coordinates. Results of simulations of RF plasma generation in the Uragan-2M stellarator by using a frame antenna operating at frequencies lower than the ion cyclotron frequency are presented. The calculations show that the slow wave generated by the antenna is efficiently absorbed at the periphery of the plasma column, due to which only a small fraction of the input power reaches the confinement region. As a result, the temperature on the axis of the plasma column remains low, whereas at the periphery it is substantially higher. This leads to strong absorption of the RF field at the periphery via the Landau mechanism.

  10. Incorporating Sediment Compaction Into a Gravitationally Self-consistent Model for Global Sea-level Change

    NASA Astrophysics Data System (ADS)

    Ferrier, K.; Mitrovica, J. X.

    2015-12-01

    In sedimentary deltas and fans, sea-level changes are strongly modulated by the deposition and compaction of marine sediment. The deposition of sediment and incorporation of water into the sedimentary pore space reduces sea level by increasing the elevation of the seafloor, which reduces the thickness of sea-water above the bed. In a similar manner, the compaction of sediment and purging of water out of the sedimentary pore space increases sea level by reducing the elevation of the seafloor, which increases the thickness of sea water above the bed. Here we show how one can incorporate the effects of sediment deposition and compaction into the global, gravitationally self-consistent sea-level model of Dalca et al. (2013). Incorporating sediment compaction requires accounting for only one additional quantity that had not been accounted for in Dalca et al. (2013): the mean porosity in the sediment column. We provide a general analytic framework for global sea-level changes including sediment deposition and compaction, and we demonstrate how sea level responds to deposition and compaction under one simple parameterization for compaction. The compaction of sediment generates changes in sea level only by changing the elevation of the seafloor. That is, sediment compaction does not affect the mass load on the crust, and therefore does not generate perturbations in crustal elevation or the gravity field that would further perturb sea level. These results have implications for understanding sedimentary effects on sea-level changes and thus for disentangling the various drivers of sea-level change. ReferencesDalca A.V., Ferrier K.L., Mitrovica J.X., Perron J.T., Milne G.A., Creveling J.R., 2013. On postglacial sea level - III. Incorporating sediment redistribution. Geophysical Journal International, doi: 10.1093/gji/ggt089.

  11. Self-consistent particle-in-cell simulations of fundamental and harmonic radio plasma emission mechanisms

    NASA Astrophysics Data System (ADS)

    Tsiklauri, D.; Thurgood, J. O.

    2015-12-01

    first co-author Jonathan O. Thurgood (QMUL) The simulation of three-wave interaction based plasma emission, an underlying mechanism for type III solar radio bursts, is a challenging task requiring fully-kinetic, multi-dimensional models. This paper aims to resolve a contradiction in past attempts, whereby some authors report that no such processes occur and others draw conflicting conclusions, by using 2D, fully kinetic, particle-in-cell simulations of relaxing electron beams. Here we present the results of particle-in-cell simulations which for different physical parameters permit or prohibit the plasma emission. We show that the possibility of plasma emission is contingent upon the frequency of the initial electrostatic waves generated by the bump-in-tail instability, and that these waves may be prohibited from participating in the necessary three-wave interactions due to the frequency beat requirements. We caution against simulating astrophysical radio bursts using unrealistically dense beams (a common approach which reduces run time), as the resulting non-Langmuir characteristics of the initial wave modes significantly suppresses the emission. Comparison of our results indicates that, contrary to the suggestions of previous authors, a plasma emission mechanism based on two counter-propagating beams is unnecessary in astrophysical context. Finally, we also consider the action of the Weibel instability, which generates an electromagnetic beam mode. As this provides a stronger contribution to electromagnetic energy than the emission, we stress that evidence of plasma emission in simulations must disentangle the two contributions and not simply interpret changes in total electromagnetic energy as the evidence of plasma emission. In summary, we present the first self-consistent demonstration of fundamental and harmonic plasma emission from a single-beam system via fully kinetic numerical simulation. Pre-print can be found at http://astro.qmul.ac.uk/~tsiklauri/jtdt1

  12. Convection in large icy satellites with self-consistent grain-size evolution

    NASA Astrophysics Data System (ADS)

    Barr, A. C.; McKinnon, W. B.

    2005-12-01

    The viscosity of ice I is grain-size dependent for temperature and stress conditions appropriate for ice I shells of midsized and large icy satellites. Satellite thermal evolution, heat flux, critical shell thickness for convection, brittle/ductile transition depth, and potential surface deformation are grain size-dependent. We estimate grain sizes in a convecting shell using the empirical observation from polar ice sheets that d ~ A σ-1, where A is a thermal activation term, and σ is shear stress [De La Chappelle et al., JGR 103, 1998] due to dynamic recrystallization. We use a composite volume diffusion/GBS rheology for ice I in the convection model Citcom [Barr et al., JGR, 2004] to self-consistently model strain rates and grain sizes in convecting shells. Estimates of grain size are reasonable if the grain-growth time scale is less than the convective overturn time scale (~ 105 - 107 yr for large icy satellites), and the shell is free of impurities that limit grain growth. For large icy satellites, the composite rheology and uniform grain size predict sluggish convection unless the grain size is small (<1 mm). Convection can only occur if d < 2 cm [Barr and Pappalardo, JGR, in press, 2005], and then only for d < 2-4 mm if initial thermal perturbations are small [McKinnon, Icarus, in press]. Dynamic recrystallization predicts, for example, d ~ 1 mm in the convecting interior and d ~ 10 cm in the stagnant lid for an ice shell 50 km thick. Compared with models with a similar but uniform grain size in the convective region, heat fluxes are larger, and shallower brittle/ductile transition depths.

  13. A self-consistent chemically stratified atmosphere model for the roAp star 10 Aquilae

    NASA Astrophysics Data System (ADS)

    Nesvacil, N.; Shulyak, D.; Ryabchikova, T. A.; Kochukhov, O.; Akberov, A.; Weiss, W.

    2013-04-01

    Context. Chemically peculiar A-type (Ap) stars are a subgroup of the CP2 stars that exhibit anomalous overabundances of numerous elements, e.g. Fe, Cr, Sr, and rare earth elements. The pulsating subgroup of Ap stars, the roAp stars, present ideal laboratories to observe and model pulsational signatures, as well as the interplay of the pulsations with strong magnetic fields and vertical abundance gradients. Aims: Based on high-resolution spectroscopic observations and observed stellar energy distributions, we construct a self-consistent model atmosphere for the roAp star 10 Aquilae (HD 176232). It accounts for modulations of the temperature-pressure structure caused by vertical abundance gradients. We demonstrate that such an analysis can be used to determine precisely the fundamental atmospheric parameters required for pulsation modelling. Methods: Average abundances were derived for 56 species. For Mg, Si, Ca, Cr, Fe, Co, Sr, Pr, and Nd, vertical stratification profiles were empirically derived using the DDAFit minimisation routine together with the magnetic spectrum synthesis codeSynthmag. Model atmospheres were computed with the LLmodels code, which accounts for the individual abundances and stratification of chemical elements. Results: For the final model atmosphere, Teff = 7550 K and log (g) = 3.8 were adopted. While Mg, Si, Co, and Cr exhibit steep abundance gradients, Ca, Fe, and Sr showed much wider abundance gradients between logτ5000 = -1.5 and 0.5. Elements Mg and Co were found to be the least stratified, while Ca and Sr showed strong depth variations in abundance of up to ≈ 6 dex. Table 4 and Figs. 10-12 are available in electronic form at http://www.aanda.org

  14. Quasiparticle bandstructure of antiferromagnetic EuTe

    NASA Astrophysics Data System (ADS)

    Mathi Jaya, S.; Nolting, W.

    1997-11-01

    The temperature-dependent electronic quasiparticle spectrum of the antiferromagnetic semiconductor EuTe is derived by use of a combination of a many-body model procedure with a tight-binding - `linear muffin tin orbital' (TB - LMTO) band structure calculation. The central part is the d - f model for a single band electron (`test electron') being exchange coupled to the antiferromagnetically ordered localized moments of the Eu ions. The single-electron Bloch energies of the d - f model are taken from a TB - LMTO calculation for paramagnetic EuTe. The d - f model is evaluated by a recently proposed moment conserving Green function technique to get the temperature-dependent sublattice - quasiparticle bandstructure (S - QBS) and sublattice - quasiparticle density of states (S - QDOS) of the unoccupied 5d - 6s energy bands. Unconventional correlation effects and the appearance of characteristic quasiparticles (`magnetic polarons') are worked out in detail. The temperature dependence of the S - QDOS and S - QBS is mainly provoked by the spectral weights of the energy dispersions. Minority- and majority-spin spectra coincide for all temperatures but with different densities of states. Upon cooling from 0953-8984/9/47/012/img1 to T = 0 K the lower conduction band edge exhibits a small blue shift of -0.025 eV in accordance with the experiment. Quasiparticle damping manifesting itself in a temperature-dependent broadening of the spectral density peaks arises from spin exchange processes between (5d - 6s) conduction band electrons and localized 4f moments.

  15. Bounds and self-consistent estimates for elastic constants of granular polycrystals composed of orthorhombics or crystal with higher symmetries

    SciTech Connect

    Berryman, J. G.

    2011-02-01

    Methods for computing Hashin-Shtrikman bounds and related self-consistent estimates of elastic constants for polycrystals composed of crystals having orthorhombic symmetry have been known for about three decades. However, these methods are underutilized, perhaps because of some perceived difficulties with implementing the necessary computational procedures. Several simplifications of these techniques are introduced, thereby reducing the overall computational burden, as well as the complications inherent in mapping out the Hashin-Shtrikman bounding curves. The self-consistent estimates of the effective elastic constants are very robust, involving a quickly converging iteration procedure. Once these self-consistent values are known, they may then be used to speed up the computations of the Hashin-Shtrikman bounds themselves. It is shown furthermore that the resulting orthorhombic polycrystal code can be used as well to compute both bounds and self-consistent estimates for polycrystals of higher-symmetry tetragonal, hexagonal, and cubic (but not trigonal) materials. The self-consistent results found this way are shown to be the same as those obtained using the earlier methods, specifically those methods designed specially for each individual symmetry type. But the Hashin-Shtrikman bounds found using the orthorhombic code are either the same or (more typically) tighter than those found previously for these special cases (i.e., tetragonal, hexagonal, and cubic). The improvement in the Hashin-Shtrikman bounds is presumably due to the additional degrees of freedom introduced into the available search space.

  16. On the self-consistency of the principle of profile consistency results for sawtoothing tokamak discharges

    SciTech Connect

    Arunasalam, V.; Bretz, N.L.; Efthimion, P.C.; Goldston, R.J.; Grek, B.; Johnson, D.W.; Murakami, M.; McGuire, K.; Rasmussen, D.A.; Stauffer, F.J.

    1989-05-01

    The principle of profile consistency states that for fixed limiter safety factor q/sub a/, there exists unique natural equilibrium profile shapes for the current density j(r), and the electron temperature T/sub e/(r) for any tokamak plasma independent of the shapes of the heating power deposition profiles. The mathematical statement of the three basic consequences of this principle for sawtoothing discharges are: (r/sub 1//a) = F/sub 1/ (1/q/sub a/), /T/sub eo/ = F/sub 2/(1/q/sub a/), and a unique scaling law for the central electron temperature T/sub eo/, where r/sub 1/ is the sawtooth inversion radius and is the volume average T/sub e/. Since for a given T/sub e/(r), the ohmic current j(r) can be deduced from Ohm's law, given the function F/sub 1/, the function F/sub 2/ is uniquely fixed and vice versa. Also given F/sub 1/(1/q/sub a/), the central current density j/sub o/ = (V/sub L//2..pi..bRZ/sub eff/) T/sub eo//sup 3/2/ = (I/sub p//..pi..a/sup 2/) F/sub 3/(q/sub a/), where the function F/sub 3/ = (q/sub a//q/sub o/) is uniquely fixed by F/sub 1/. Here b approx. 6.53 /times/ 10/sup 3/ ln..lambda.., and I/sub p/, V/sub L/, Z/sub eff/, R, a, and q/sub o/ are the plasma current, loop voltage, effective ion charge, major and minor radius, and the central safety factor, respectively. Thus for a fixed j(r) or T/sub e/(r), the set of functions F/sub 1/, F/sub 2/, and F/sub 3/ is uniquely fixed. Further, the principle of profile consistency dictates that this set of functions F/sub 1/, F/sub 2/, and F/sub 3/ remain the same for all sawtoothing discharges in any tokamak regardless of its size, I/sub p/, V/sub L/, B/sub T/, etc. Here, we present a rather complete and detailed theoretical examination of this self-consistency of the measured values of T/sub e/(r), F/sub 1/, F/sub 2/, and F/sub 3/ for sawtoothing TFTR discharges. 55 refs., 15 figs., 1 tab.

  17. Self-Consistent Simulation of the Brownian Stage of Dust Growth

    NASA Technical Reports Server (NTRS)

    Kempf, S.; Pfalzner, S.; Henning, Th.

    1996-01-01

    It is a widely accepted view that in proto-planetary accretion disks the collision and following sticking of dust particles embedded in the gas eventually leads to the formation of planetesimals (coagulation). For the smallest dust grains, Brownian motion is assumed to be the dominant source of their relative velocities leading to collisions between these dust grains. As the dust grains grow they eventually couple to the turbulent motion of the gas which then drives the coagulation much more efficiently. Many numerical coagulation simulations have been carried out to calculate the fractal dimension of the aggregates, which determines the duration of the ineffective Brownian stage of growth. Predominantly on-lattice and off-lattice methods were used. However, both methods require simplification of the astrophysical conditions. The aggregates found by those methods had a fractal dimension of approximately 2 which is equivalent to a constant, mass-independent friction time. If this value were valid for the conditions in an accretion disk, this would mean that the coagulation process would finally 'freeze out' and the growth of a planetesimal would be impossible within the lifetime of an accretion disk. In order to investigate whether this fractal dimension is model independent, we simulate self-consistently the Brownian stage of the coagulation by an N-particle code. This method has the advantage that no further assumptions about homogeneity of the dust have to be made. In our model, the dust grains are considered as aggregates built up of spheres. The equation of motion of the dust grains is based on the probability density for the diffusive transport within the gas atmosphere. Because of the very low number density of the dust grains, only 2-body-collisions have to be considered. As the Brownian stage of growth is very inefficient, the system is to be simulated over long periods of time. In order to find close particle pairs of the system which are most likely to

  18. Mass loss from evolved massive stars: self-consistent modeling of the wind and photosphere

    NASA Astrophysics Data System (ADS)

    Groh, J. H.

    2007-03-01

    This work analyzes the mass loss phenomenon in evolved massive stars through self-consistent modeling of the wind and photosphere of such stars, using the radiative transfer code CMFGEN. In the first part, fundamental physical parameters of Wolf-Rayet stars of spectral types WN3-w (WR 46 e WR 152) and WN6-s (WR 136) were obtained. The results clearly indicate that hydrogen is present on the surface of those stars in a considerable fraction, defying current evolutionary models. For both WN subtypes, significant difference between the physical parameters obtained here and in previous works were noticed. The 20-year evolution of the luminous blue variable (LBV) AG Carinae was analyzed in detail in the second part of this work. The results indicate unexpected changes in the current paradigm of massive star evolution during the S Dor cycle. In this work, the high rotational velocity obtained during the hot phases, and the transition between the bistability regimes of line-driven winds were detected for the first time in LBVs. Those results need to be considered in future analysis of such massive stars. This Thesis also presents a pioneering study about the impact of the time variability effects on the analysis of the winds of LBVs. The results achieved here are valid for the whole LBV class, and show that the mass-loss rates derived from Hα and radio free-free emission are affected by time-dependent effects. The mass-loss rate evolution during the S Dor cycle, derived using time-dependent models, implies that LBV eruptions begin well before the maximum in the visual lightcurve during this phase. The analysis of the full S Dor cycle of AG Car rule out that the S Dor variability is caused exclusively by an expanding pseudo-photosphere. The AG Car hydrostatic radius was found to vary by a factor of six between cool and hot phases, while the bolometric luminosity is 50% higher during the hot phase. Both results provide observational contraints for the physical mechanism

  19. Self-consistent physical parameters for five intermediate-age SMC stellar clusters from CMD modelling

    NASA Astrophysics Data System (ADS)

    Dias, B.; Kerber, L. O.; Barbuy, B.; Santiago, B.; Ortolani, S.; Balbinot, E.

    2014-01-01

    Context. Stellar clusters in the Small Magellanic Cloud (SMC) are useful probes for studying the chemical and dynamical evolution of this neighbouring dwarf galaxy, enabling inspection of a large period covering over 10 Gyr. Aims: The main goals of this work are the derivation of age, metallicity, distance modulus, reddening, core radius, and central density profiles for six sample clusters, in order to place them in the context of the Small Cloud evolution. The studied clusters are AM 3, HW 1, HW 34, HW 40, Lindsay 2, and Lindsay 3; HW 1, HW 34, and Lindsay 2 are studied for the first time. Methods: Optical colour-magnitude diagrams (V,B - V CMDs) and radial density profiles were built from images obtained with the 4.1 m Southern Astrophysical Research (SOAR) telescope, reaching V ~ 23. The determination of structural parameters were carried out by applying King profile fitting. The other parameters were derived in a self-consistent way by means of isochrone fitting, which uses likelihood statistics to identify the synthetic CMDs that best reproduce the observed ones. Membership probabilities were determined comparing the cluster and control field CMDs. Completeness and photometric uncertainties were obtained by performing artificial star tests. Results: The results confirm that these clusters (except HW 34, identified as a field fluctuation) are intermediate-age clusters, with ages between 1.2 Gyr (Lindsay 3) and ~5.0 Gyr (HW 1). In particular HW 1, Lindsay 2 and Lindsay 3 are located in a region that we called West Halo, where studies of ages and metallicity gradients are still lacking. Moreover, Lindsay 2 was identified as a moderately metal-poor cluster with [Fe/H] = -1.4 ± 0.2 dex, lower than expected from the age-metallicity relation by Pagel & Tautvaisiene (1998). We also found distances varying from ~53 kpc to 66 kpc, compatible with the large depth of the SMC. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which

  20. Self-consistent phonons in MgSiO3 perovskite

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Sun, T.; Wentzcovitch, R. M.

    2012-12-01

    There are numerous materials under conditions of interest for which MD is required but still too demanding for first principles. In these cases 1) phonon-phonon interactions are non-negligible, 2) the material is on the verge of mechanical and/or vibrational instabilities, 3) or the material is stabilized by anharmonic fluctuations at high temperatures. MD is suitable for investigating these states as intrinsic anharmonic effects caused by phonon-phonon interactions are naturally included, but the requirement on size and length of the simulations call for more efficient and accurate approaches for phase space sampling. Indeed, MD needs thousands of atoms and 10^4 to 10^5 picosenconds of simulations for thorough sampling of phase space and accurate free energy calculations (e.g. in thermodynamical integration method). Nevertheless, we note that none of these states can be physical-properly addressed by quasi-harmonic approximation (QHA) approach. This is because QHA overlooks the intrinsic harmonicity and only suits mechanically and dynamically stable phases with a limited range in temperature (Up to approximately 2/3 of the melting temperature). Recently, a new breed of methods for calculating anharmonic vibrational spectra has been developed. These methods use MD to extract phonon frequencies renormalized by phonon-phonon interactions (self-consistent phonons - SCPh). More than one procedure to extract SCPh frequencies has been introduced and applied to solids with lattice structures relatively simple compared to those of silicate minerals. Here, we developed an efficient approach that can offer SCPh dispersions in materials with complex crystal lattice structures containing tens of atoms per primitive cell. First-principles MD simulations on supercells containing hundreds of atoms permits the extraction of dynamical matrices and force-constant matrices that can be Fourier interpolated to produce SCPh dispersions. Thoroughly sampling of these dispersions

  1. Transition Zone Structure and Dynamics in Mantle Convection Calculations with Self-Consistently Calculated Mineralogy

    NASA Astrophysics Data System (ADS)

    Tackley, P. J.; Nakagawa, T.; Deschamps, F.; Connolly, J.

    2011-12-01

    Phase diagrams of materials in Earth's transition zone (TZ) are complex and composition-dependent and phase transitions have a first-order influence on mantle dynamics, yet simulations of mantle convection typically include only one or two major phase transitions in the olivine system. In our recent work [1,2], phase assemblages of mantle rocks calculated by free energy minimization for MORB and harzburgite compositions expressed as the ratios of 5 or 6 oxides (CaO-FeO-MgO-Al2O3- SiO2-Na2O) are used to calculate the material properties density, thermal expansivity, specific heat capacity, and seismic velocity as a function of temperature and pressure, which are then incorporated into a numerical thermo-chemical mantle convection model in a 2-D spherical annulus or 3-D spherical shell. The advantage of using such an approach is that thermodynamic parameters affecting dynamics and seismic velocities are included implicitly and self-consistently, obviating the need for ad hoc parameterizations. Here we focus on the resulting thermo-chemical structures in the transition zone and their seismic signature. A robust result is some compositional stratification around 660 km depth caused by the inversion of the MORB-harzburgite density difference between ~660-740 km depth [3], with MORB enrichment in the lower TZ and depletion just below the TZ. The extent of this is quite sensitive to variations in MORB composition of the order 1-2% oxide fraction, particularly FeO and Al2O3, which influence the magnitude and depth of this effect and the density difference. The detailed structure also has a strong lateral variation. We plot radial profiles from different parts of our models, characterizing typical structures and the range of structures, and compare to local seismological profiles as well as profiles from regional inversions [4]. [1] Nakagawa, T., P.J. Tackley, F. Deschamps & J.A.D. Connolly (2009) Geochem. Geophys. Geosyst. 10, doi:10.1029/2008GC002280. [2] Nakagawa, T., P

  2. Towards three-dimensional continuum models of self-consistent along-strike megathrust segmentation

    NASA Astrophysics Data System (ADS)

    Pranger, Casper; van Dinther, Ylona; May, Dave; Le Pourhiet, Laetitia; Gerya, Taras

    2016-04-01

    into one algorithm. We are working towards presenting the first benchmarked 3D dynamic rupture models as an important step towards seismic cycle modelling of megathrust segmentation in a three-dimensional subduction setting with slow tectonic loading, self consistent fault development, and spontaneous seismicity.

  3. Linking lipid architecture to bilayer structure and mechanics using self-consistent field modelling

    SciTech Connect

    Pera, H.; Kleijn, J. M.; Leermakers, F. A. M.

    2014-02-14

    To understand how lipid architecture determines the lipid bilayer structure and its mechanics, we implement a molecularly detailed model that uses the self-consistent field theory. This numerical model accurately predicts parameters such as Helfrichs mean and Gaussian bending modulus k{sub c} and k{sup ¯} and the preferred monolayer curvature J{sub 0}{sup m}, and also delivers structural membrane properties like the core thickness, and head group position and orientation. We studied how these mechanical parameters vary with system variations, such as lipid tail length, membrane composition, and those parameters that control the lipid tail and head group solvent quality. For the membrane composition, negatively charged phosphatidylglycerol (PG) or zwitterionic, phosphatidylcholine (PC), and -ethanolamine (PE) lipids were used. In line with experimental findings, we find that the values of k{sub c} and the area compression modulus k{sub A} are always positive. They respond similarly to parameters that affect the core thickness, but differently to parameters that affect the head group properties. We found that the trends for k{sup ¯} and J{sub 0}{sup m} can be rationalised by the concept of Israelachivili's surfactant packing parameter, and that both k{sup ¯} and J{sub 0}{sup m} change sign with relevant parameter changes. Although typically k{sup ¯}<0, membranes can form stable cubic phases when the Gaussian bending modulus becomes positive, which occurs with membranes composed of PC lipids with long tails. Similarly, negative monolayer curvatures appear when a small head group such as PE is combined with long lipid tails, which hints towards the stability of inverse hexagonal phases at the cost of the bilayer topology. To prevent the destabilisation of bilayers, PG lipids can be mixed into these PC or PE lipid membranes. Progressive loading of bilayers with PG lipids lead to highly charged membranes, resulting in J{sub 0}{sup m}≫0, especially at low ionic

  4. Self-consistent two-phase AGN torus models⋆. SED library for observers

    NASA Astrophysics Data System (ADS)

    Siebenmorgen, Ralf; Heymann, Frank; Efstathiou, Andreas

    2015-11-01

    We assume that dust near active galactic nuclei (AGNs) is distributed in a torus-like geometry, which can be described as a clumpy medium or a homogeneous disk, or as a combination of the two (i.e. a two-phase medium). The dust particles considered are fluffy and have higher submillimeter emissivities than grains in the diffuse interstellar medium. The dust-photon interaction is treated in a fully self-consistent three-dimensional radiative transfer code. We provide an AGN library of spectral energy distributions (SEDs). Its purpose is to quickly obtain estimates of the basic parameters of the AGNs, such as the intrinsic luminosity of the central source, the viewing angle, the inner radius, the volume filling factor and optical depth of the clouds, and the optical depth of the disk midplane, and to predict the flux at yet unobserved wavelengths. The procedure is simple and consists of finding an element in the library that matches the observations. We discuss the general properties of the models and in particular the 10 μm silicate band. The AGN library accounts well for the observed scatter of the feature strengths and wavelengths of the peak emission. AGN extinction curves are discussed and we find that there is no direct one-to-one link between the observed extinction and the wavelength dependence of the dust cross sections. We show that objects in the library cover the observed range of mid-infrared colors of known AGNs. The validity of the approach is demonstrated by matching the SEDs of a number of representative objects: Four Seyferts and two quasars for which we present new Herschel photometry, two radio galaxies, and one hyperluminous infrared galaxy. Strikingly, for the five luminous objects we find that pure AGN models fit the SED without needing to postulate starburst activity. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.The SED

  5. A complete active space self-consistent field study of the photochemistry of nitrosamine

    NASA Astrophysics Data System (ADS)

    Peláez, Daniel; Arenas, Juan F.; Otero, Juan C.; Soto, Juan

    2006-10-01

    Photodissociation mechanisms of nitrosamine (NH2NO) have been studied at the complete active space self-consistent field level of theory in conjunction with atomic-natural-orbital-type basis sets. In addition, the energies of all the critical points and the potential energy curves connecting them have been recomputed with the multiconfigurational second-order perturbation method. Ground state minimum of nitrosamine has a C1 nonplanar structure with the hydrogen atoms of the amino moiety out of the plane defined by the N-N-O bonds. Electronic transitions to the three lowest states are allowed by selection rules: (i) S0→S3 (7.41eV) has an oscillator strength of f =0.0006 and it is assigned as an (npO)0→(πNO*)2 transition, (ii) S0→S2 (5.86eV ) has an oscillator strength of f =0.14 and it is assigned as an npN→πNO* transition, and (iii) S0→S1 (2.98eV ) has an oscillator strength of f =0.002 and it is assigned as an npO→πNO* transition. It is found that N-N bond cleavage is the most likely process in all the photochemical relevant states, namely, S1 (1A″1), S2 (2A'1), and T1 (1A″3). While S1 and T1 yield exclusively homolytic dissociation: NH2NO →NH2 (1B12)+NO(XΠ2), on S2 the latter process constitutes the major path, but two additional minor channels are also available: adiabatic homolytic dissociation: NH2NO →NH2 (1A12)+NO(XΠ2), and adiabatic oxygen extrusion: NH2NO →NH2N (1A13)+O(P3). The excited species NH2 (1A12) experiences a subsequent ultrafast decay to the ground state, the final products in all cases the fragments being in their lowest electronic state. We have not found a unimolecular mechanism connecting excited states with the ground state. In addition, homolytic dissociation in the ground state, tautomerizations to NHNOH and NHNHO, and intersystem crossings to T1 are considered. The most favorable process on this state is the isomerization to NHNOH.

  6. Spatial Verification of Earthquake Simulators Using Self-Consistent Metrics for Off-Fault Seismicity

    NASA Astrophysics Data System (ADS)

    Wilson, J. M.; Yoder, M. R.; Rundle, J. B.

    2015-12-01

    We address the problem of verifying the self-consistency of earthquake simulators with the data from which their parameters are drawn. Earthquake simulators are a class of computational simulations which attempt to mirror the topological complexity of the earthquake fault system on which the earthquakes occur. In addition, the physics of friction and elastic interactions between fault elements can be included in these simulations as well. In general, the parameters are adjusted so that natural earthquake sequences are matched in their scaling properties in an optimal way. Generally, these parameters choices are based on paleoseismic data extending over many hundreds and thousands of years. However, one of the problems encountered is the verification of the simulations applied to current earthquake seismicity. It is this problem, for which no currently accepted solution has been proposed, that is the objective of the present paper. Physically-based earthquake simulators allow the generation of many thousands of years of simulated seismicity, allowing for robust capture of statistical properties of large, damaging earthquakes that have long recurrence time scales for observation. Following past simulator and forecast model verification efforts, we approach the challenges in spatial forecast verification fo simulators; namely, that simulator output events are confined to the modeled faults, while observed earthquakes often occur off of known faults. We present two methods for overcoming this discrepancy: a simplistic approach whereby observed earthquakes are shifted to the nearest fault element and a variation of the Epidemic-type aftershock (ETAS) model, which smears the simulator catalog seismicity over the entire test region. To test these methods, a Receiver Operating Characteristic (ROC) plot was produced by comparing the rate maps to observed m>6.0 earthquakes since 1980. We found that the nearest-neighbor mapping produced poor forecasts, while the modified ETAS

  7. Quasiparticle-continuum level repulsion in a quantum magnet

    SciTech Connect

    Plumb, K. W.; Hwang, Kyusung; Qiu, Y.; Harriger, Leland W.; Granroth, G.  E.; Kolesnikov, Alexander I.; Shu, G. J.; Chou, F. C.; Rüegg, Ch.; Kim, Yong Baek; Kim, Young-June

    2015-11-30

    When the energy eigenvalues of two coupled quantum states approach each other in a certain parameter space, their energy levels repel each other and level crossing is avoided. Such level repulsion, or avoided level crossing, is commonly used to describe the dispersion relation of quasiparticles in solids. But, little is known about the level repulsion when more than two quasiparticles are present; for example, in a strongly interacting quantum system where a quasiparticle can spontaneously decay into a many-particle continuum. Here we show that even in this case level repulsion exists between a long-lived quasiparticle state and a continuum. Here, we observe a renormalization of the quasiparticle dispersion relation due to the presence of the continuum of multi-quasiparticle states, in our fine-resolution neutron spectroscopy study of magnetic quasiparticles in the frustrated quantum magnet BiCu2PO6.

  8. Quasiparticle-continuum level repulsion in a quantum magnet

    DOE PAGES

    Plumb, K. W.; Hwang, Kyusung; Qiu, Y.; ...

    2015-11-30

    When the energy eigenvalues of two coupled quantum states approach each other in a certain parameter space, their energy levels repel each other and level crossing is avoided. Such level repulsion, or avoided level crossing, is commonly used to describe the dispersion relation of quasiparticles in solids. But, little is known about the level repulsion when more than two quasiparticles are present; for example, in a strongly interacting quantum system where a quasiparticle can spontaneously decay into a many-particle continuum. Here we show that even in this case level repulsion exists between a long-lived quasiparticle state and a continuum. Here,more » we observe a renormalization of the quasiparticle dispersion relation due to the presence of the continuum of multi-quasiparticle states, in our fine-resolution neutron spectroscopy study of magnetic quasiparticles in the frustrated quantum magnet BiCu2PO6.« less

  9. Local self-consistent Ornstein-Zernike integral equation theory and application to a generalized Lennard-Jones potential.

    PubMed

    Zhou, Shiqi

    2010-09-09

    Local self-consistent Ornstein-Zernike (OZ) integral equation theory (IET) provides a rapid and easy route for obtaining independently thermodynamic and structural information for a single state point. Because of neglect of information of neighboring state points in determining a self-consistent adjustable parameter performance of the local self-consistent OZ IET is somewhat vulnerable and worthy of intensive investigation. For this reason, we have performed Monte Carlo simulations to obtain thermodynamic and structural properties of fluid with a generalized Lennard-Jones potential, and the present simulation results are employed to verify the quality of a local version of a recently developed global self-consistent OZ IET and a local expression for computation of excess chemical potential directly from the structural functions of the state point of interest. Comprehensive comparison and analysis demonstrate the following (i) the present local self-consistent OZ IET performs quite well for calculation of pressure and excess internal energy; (ii) using the same structural functions from the present local self-consistent OZ IET, the previously derived local expression by the present author has by and large the same accuracy in calculating the excess chemical potential as an exact virial formula for the pressure; (iii) although the excellent performance exhibited for the above thermodynamic quantities persists to very low temperature and very short-ranged potential and remains even in the liquid-solid coexistence region, the excess Helmholtz free energy calculated from the pressure and excess chemical potential shows evident inaccuracy for a density-temperature combination deep in the liquid-solid coexistence region, and this makes it necessary to derive a local formulation for the excess free energy.

  10. GW approach to electron-electron interactions within the Anderson impurity model: Kondo correlated quantum transport through two coupled molecules

    NASA Astrophysics Data System (ADS)

    Aksu, H.; Goker, A.

    2017-03-01

    We invoke the nonequilibrium self-consistent GW method within the Anderson impurity model to investigate the dynamical effects occurring in a nanojunction comprised of two coupled molecules. Contrary to the previous single impurity model calculations based on the GW approximation, we observe that the density of states manages to capture both the Kondo resonance and the Breit-Wigner resonances associated with the HOMO and LUMO levels of the molecule. Moreover, the prominence of the Kondo resonance grows dramatically upon switching from the intermediate to the weak coupling regime involving large U / Γ values. The conductance is calculated as a function of the HOMO level and the applied bias across the molecular nanojunction. Calculated conductance curves deviate from the monotonic decay behaviour as a function of the bias when the half-filling condition is not met. The importance of the effect of the molecule-molecule coupling for the electron transport phenomena is also investigated.

  11. A generalized self-consistent method for estimating effective shear properties of unidirectional composites comprising cylindrical orthotropic constituents

    NASA Astrophysics Data System (ADS)

    Minhat, M.; Mahmud Zuhudi, N. Z.; Shamsudin, M. H.; Isa, M. D.; Harun, M. K.

    2016-10-01

    A micromechanics model based on generalized self-consistent method is proposed to estimate shear elastic properties of unidirectional fibre composites comprising cylindrical orthotropic layers. The features of the generalized self-consistent method are briefly presented and the homogenization schemes in determining the effective shear moduli of transversely isotropic medium are demonstrated. Numerical examples on the prediction of axial and transverse shear moduli of polymer composite reinforced with nanostructure hybrid fibres are illustrated. The close agreement between the prediction results and the results obtained from the available experimental data and finite element study validates the solutions produced by the proposed model.

  12. Constraining noncommutative spacetime from GW150914

    NASA Astrophysics Data System (ADS)

    Kobakhidze, Archil; Lagger, Cyril; Manning, Adrian

    2016-09-01

    The gravitational wave signal GW150914, recently detected by LIGO and Virgo collaborations, is used to place a bound on the scale of quantum fuzziness of noncommutative space-time. We show that the leading noncommutative correction to the phase of the gravitational waves produced by a binary system appears at the second order of the post-Newtonian expansion. This correction is proportional to Λ2≡|θ0 i|2/(lPtP)2, where θμ ν is the antisymmetric tensor of noncommutativity. To comply with GW150914 data, we find that √{Λ }≲3.5 , namely at the order of the Planck scale. This is the most stringent bound on the noncommutative scale, exceeding the previous constraints from particle physics processes by ˜15 orders of magnitude.

  13. A complete active space self-consistent field study of the photochemistry of nitrosamine

    SciTech Connect

    Pelaez, Daniel; Arenas, Juan F.; Otero, Juan C.; Soto, Juan

    2006-10-28

    Photodissociation mechanisms of nitrosamine (NH{sub 2}NO) have been studied at the complete active space self-consistent field level of theory in conjunction with atomic-natural-orbital-type basis sets. In addition, the energies of all the critical points and the potential energy curves connecting them have been recomputed with the multiconfigurational second-order perturbation method. Ground state minimum of nitrosamine has a C{sub 1} nonplanar structure with the hydrogen atoms of the amino moiety out of the plane defined by the N-N-O bonds. Electronic transitions to the three lowest states are allowed by selection rules: (i) S{sub 0}{yields}S{sub 3} (7.41 eV) has an oscillator strength of f=0.0006 and it is assigned as an (np{sub O}){sup 0}{yields}({pi}{sub NO}*){sup 2} transition, (ii) S{sub 0}{yields}S{sub 2} (5.86 eV) has an oscillator strength of f=0.14 and it is assigned as an np{sub N}{yields}{pi}{sub NO}* transition, and (iii) S{sub 0}{yields}S{sub 1} (2.98 eV) has an oscillator strength of f=0.002 and it is assigned as an np{sub O}{yields}{pi}{sub NO}* transition. It is found that N-N bond cleavage is the most likely process in all the photochemical relevant states, namely, S{sub 1} (1 {sup 1}A{sup ''}), S{sub 2} (2 {sup 1}A{sup '}), and T{sub 1} (1 {sup 3}A{sup ''}). While S{sub 1} and T{sub 1} yield exclusively homolytic dissociation: NH{sub 2}NO{yields}NH{sub 2} (1 {sup 2}B{sub 1})+NO(X {sup 2}{pi}), on S{sub 2} the latter process constitutes the major path, but two additional minor channels are also available: adiabatic homolytic dissociation: NH{sub 2}NO{yields}NH{sub 2} (1 {sup 2}A{sub 1})+NO(X {sup 2}{pi}), and adiabatic oxygen extrusion: NH{sub 2}NO{yields}NH{sub 2}N (1 {sup 3}A{sub 1})+O({sup 3}P). The excited species NH{sub 2} (1 {sup 2}A{sub 1}) experiences a subsequent ultrafast decay to the ground state, the final products in all cases the fragments being in their lowest electronic state. We have not found a unimolecular mechanism connecting

  14. Theoretical physics implications of the binary black-hole mergers GW150914 and GW151226

    NASA Astrophysics Data System (ADS)

    Yunes, Nicolás; Yagi, Kent; Pretorius, Frans

    2016-10-01

    The gravitational wave observations GW150914 and GW151226 by Advanced LIGO provide the first opportunity to learn about physics in the extreme gravity environment of coalescing binary black holes. The LIGO Scientific Collaboration and the Virgo Collaboration have verified that this observation is consistent with Einstein's theory of general relativity, constraining the presence of certain parametric anomalies in the signal. This paper expands their analysis to a larger class of anomalies, highlighting the inferences that can be drawn on nonstandard theoretical physics mechanisms that could otherwise have affected the observed signals. We find that these gravitational wave events constrain a plethora of mechanisms associated with the generation and propagation of gravitational waves, including the activation of scalar fields, gravitational leakage into large extra dimensions, the variability of Newton's constant, the speed of gravity, a modified dispersion relation, gravitational Lorentz violation and the strong equivalence principle. Though other observations limit many of these mechanisms already, GW150914 and GW151226 are unique in that they are direct probes of dynamical strong-field gravity and of gravitational wave propagation. We also show that GW150914 constrains inferred properties of exotic compact object alternatives to Kerr black holes. We argue, however, that the true potential for GW150914 to both rule out exotic objects and constrain physics beyond general relativity is severely limited by the lack of understanding of the coalescence regime in almost all relevant modified gravity theories. This event thus significantly raises the bar that these theories have to pass, both in terms of having a sound theoretical underpinning and reaching the minimal level of being able to solve the equations of motion for binary merger events. We conclude with a discussion of the additional inferences that can be drawn if the lower-confidence observation of an

  15. Magnetic and quasiparticle excitations in cuprates

    NASA Astrophysics Data System (ADS)

    Bennemann, K.-H.

    2005-09-01

    [Dedicated to Bernhard Mühlschlegel on the occasion ofhis 80th birthday]Assuming for simplicity that the electrons or the holes in cuprate superconductors interact predominantly with spin-fluctuations, we determine within the random phase approximation (RPA)the dynamical susceptibility, in particular the resonance peak resulting as feedback from superconductivity, as well as the elementary quasiparticle excitations in hole-doped systems.

  16. Investigation of Quantum Computing With Laughlin Quasiparticles

    DTIC Science & Technology

    2007-12-31

    Review B 72, 075342, 1-8 (2005) F.E.Camino, W.Zhou, and V.J.Goldman Aharonov - Bohm electron interferometer in the integer quantum Hall regime Physical...Review B 72, 155313, 1-6 (2005) F.E.Camino, W.Zhou, and V.J.Goldman Aharonov - Bohm Superperiod in a Laughlin Quasiparticle Interferometer Physical...is the number of particles being encircled. This quantization condition explicitly adds the Aharonov - Bohm and the statistical contributions to the

  17. Tests of General Relativity with GW150914.

    PubMed

    Abbott, B P; Abbott, R; Abbott, T D; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Adya, V B; Affeldt, C; Agathos, M; Agatsuma, K; Aggarwal, N; Aguiar, O D; Aiello, L; Ain, A; Ajith, P; Allen, B; Allocca, A; Altin, P A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C C; Areeda, J S; Arnaud, N; Arun, K G; Ascenzi, S; Ashton, G; Ast, M; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Babak, S; Bacon, P; Bader, M K M; Baker, P T; Baldaccini, F; Ballardin, G; Ballmer, S W; Barayoga, J C; Barclay, S E; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barta, D; Bartlett, J; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Baune, C; Bavigadda, V; Bazzan, M; Behnke, B; Bejger, M; Bell, A S; Bell, C J; Berger, B K; Bergman, J; Bergmann, G; Berry, C P L; Bersanetti, D; Bertolini, A; Betzwieser, J; Bhagwat, S; Bhandare, R; Bilenko, I A; Billingsley, G; Birch, J; Birney, R; Birnholtz, O; Biscans, S; Bisht, A; Bitossi, M; 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Gopakumar, A; Gordon, N A; Gorodetsky, M L; Gossan, S E; Gosselin, M; Gouaty, R; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greco, G; Green, A C; Groot, P; Grote, H; Grunewald, S; Guidi, G M; Guo, X; Gupta, A; Gupta, M K; Gushwa, K E; Gustafson, E K; Gustafson, R; Hacker, J J; Hall, B R; Hall, E D; Hammond, G; Haney, M; Hanke, M M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Hardwick, T; Harms, J; Harry, G M; Harry, I W; Hart, M J; Hartman, M T; Haster, C-J; Haughian, K; Healy, J; Heidmann, A; Heintze, M C; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Hennig, J; Heptonstall, A W; Heurs, M; Hild, S; Hoak, D; Hodge, K A; Hofman, D; Hollitt, S E; Holt, K; Holz, D E; Hopkins, P; Hosken, D J; Hough, J; Houston, E A; Howell, E J; Hu, Y M; Huang, S; Huerta, E A; Huet, D; Hughey, B; Husa, S; Huttner, S H; Huynh-Dinh, T; Idrisy, A; Indik, N; Ingram, D R; Inta, R; Isa, H N; Isac, J-M; Isi, M; Islas, G; Isogai, T; Iyer, B R; Izumi, K; Jacqmin, T; Jang, H; Jani, K; Jaranowski, P; Jawahar, S; Jiménez-Forteza, F; Johnson, W W; Johnson-McDaniel, N K; Jones, D I; Jones, R; Jonker, R J G; Ju, L; Haris, M K; Kalaghatgi, C V; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karki, S; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; Kéfélian, F; Kehl, M S; Keitel, D; Kelley, D B; Kells, W; Kennedy, R; Key, J S; Khalaidovski, A; Khalili, F Y; Khan, I; Khan, S; Khan, Z; Khazanov, E A; Kijbunchoo, N; Kim, C; Kim, J; Kim, K; Kim, Nam-Gyu; Kim, Namjun; Kim, Y-M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Kleybolte, L; Klimenko, S; Koehlenbeck, S M; Kokeyama, K; Koley, S; Kondrashov, V; Kontos, A; Korobko, M; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Krishnan, B; Królak, A; Krueger, C; Kuehn, G; Kumar, P; Kuo, L; Kutynia, A; Lackey, B D; Landry, M; Lange, J; Lantz, B; Lasky, P D; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, K; Lenon, A; Leonardi, M; Leong, J R; Leroy, N; Letendre, N; 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Palashov, O; Palomba, C; Pal-Singh, A; Pan, H; Pan, Y; Pankow, C; Pannarale, F; Pant, B C; Paoletti, F; Paoli, A; Papa, M A; Paris, H R; Parker, W; Pascucci, D; Pasqualetti, A; Passaquieti, R; Passuello, D; Patricelli, B; Patrick, Z; Pearlstone, B L; Pedraza, M; Pedurand, R; Pekowsky, L; Pele, A; Penn, S; Perreca, A; Pfeiffer, H P; Phelps, M; Piccinni, O; Pichot, M; Piergiovanni, F; Pierro, V; Pillant, G; Pinard, L; Pinto, I M; Pitkin, M; Poggiani, R; Popolizio, P; Post, A; Powell, J; Prasad, J; Predoi, V; Premachandra, S S; Prestegard, T; Price, L R; Prijatelj, M; Principe, M; Privitera, S; Prix, R; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Pürrer, M; Qi, H; Qin, J; Quetschke, V; Quintero, E A; Quitzow-James, R; Raab, F J; Rabeling, D S; Radkins, H; Raffai, P; Raja, S; Rakhmanov, M; Rapagnani, P; Raymond, V; Razzano, M; Re, V; Read, J; Reed, C M; Regimbau, T; Rei, L; Reid, S; Reitze, D H; Rew, H; Reyes, S D; Ricci, F; Riles, K; Robertson, N A; Robie, R; Robinet, F; Rocchi, A; Rolland, L; Rollins, J G; Roma, V J; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Sachdev, S; Sadecki, T; Sadeghian, L; Salconi, L; Saleem, M; Salemi, F; Samajdar, A; Sammut, L; Sanchez, E J; Sandberg, V; Sandeen, B; Sanders, J R; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Sauter, O; Savage, R L; Sawadsky, A; Schale, P; Schilling, R; Schmidt, J; Schmidt, P; Schnabel, R; Schofield, R M S; Schönbeck, A; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sengupta, A S; Sentenac, D; Sequino, V; Sergeev, A; Serna, G; Setyawati, Y; Sevigny, A; Shaddock, D A; Shah, S; Shahriar, M S; Shaltev, M; Shao, Z; Shapiro, B; Shawhan, P; Sheperd, A; Shoemaker, D H; Shoemaker, D M; Siellez, K; Siemens, X; Sigg, D; Silva, A D; Simakov, D; Singer, A; Singer, L P; Singh, A; Singh, R; Singhal, A; Sintes, A M; Slagmolen, B J J; Smith, J R; Smith, N D; Smith, R J E; Son, E J; Sorazu, B; Sorrentino, F; Souradeep, T; Srivastava, A K; Staley, A; 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    2016-06-03

    The LIGO detection of GW150914 provides an unprecedented opportunity to study the two-body motion of a compact-object binary in the large-velocity, highly nonlinear regime, and to witness the final merger of the binary and the excitation of uniquely relativistic modes of the gravitational field. We carry out several investigations to determine whether GW150914 is consistent with a binary black-hole merger in general relativity. We find that the final remnant's mass and spin, as determined from the low-frequency (inspiral) and high-frequency (postinspiral) phases of the signal, are mutually consistent with the binary black-hole solution in general relativity. Furthermore, the data following the peak of GW150914 are consistent with the least-damped quasinormal mode inferred from the mass and spin of the remnant black hole. By using waveform models that allow for parametrized general-relativity violations during the inspiral and merger phases, we perform quantitative tests on the gravitational-wave phase in the dynamical regime and we determine the first empirical bounds on several high-order post-Newtonian coefficients. We constrain the graviton Compton wavelength, assuming that gravitons are dispersed in vacuum in the same way as particles with mass, obtaining a 90%-confidence lower bound of 10^{13}  km. In conclusion, within our statistical uncertainties, we find no evidence for violations of general relativity in the genuinely strong-field regime of gravity.

  18. Tests of General Relativity with GW150914

    NASA Astrophysics Data System (ADS)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Behnke, B.; Bejger, M.; Bell, A. S.; Bell, C. J.; Berger, B. K.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, C.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, H. Y.; Chen, Y.; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gatto, A.; Gaur, G.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Holz, D. E.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Islas, G.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Johnson-McDaniel, N. K.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, M. K.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, C.; Kim, J.; Kim, K.; Kim, Nam-Gyu; Kim, Namjun; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Kokeyama, K.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B. M.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Logue, J.; Lombardi, A. L.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Lück, H.; Lundgren, A. P.; Luo, J.; Lynch, R.; Ma, Y.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magee, R. M.; Mageswaran, M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P. G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Neri, M.; Neunzert, A.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pan, Y.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perreca, A.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S. S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Setyawati, Y.; Sevigny, A.; Shaddock, D. A.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, N. D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; Vallisneri, M.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; White, D. J.; Whiting, B. F.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Wright, J. L.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, H.; Yvert, M.; ZadroŻny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, F.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; Boyle, M.; Campanelli, M.; Hemberger, D. A.; Kidder, L. E.; Ossokine, S.; Scheel, M. A.; Szilagyi, B.; Teukolsky, S.; Zlochower, Y.; LIGO Scientific; Virgo Collaborations

    2016-06-01

    The LIGO detection of GW150914 provides an unprecedented opportunity to study the two-body motion of a compact-object binary in the large-velocity, highly nonlinear regime, and to witness the final merger of the binary and the excitation of uniquely relativistic modes of the gravitational field. We carry out several investigations to determine whether GW150914 is consistent with a binary black-hole merger in general relativity. We find that the final remnant's mass and spin, as determined from the low-frequency (inspiral) and high-frequency (postinspiral) phases of the signal, are mutually consistent with the binary black-hole solution in general relativity. Furthermore, the data following the peak of GW150914 are consistent with the least-damped quasinormal mode inferred from the mass and spin of the remnant black hole. By using waveform models that allow for parametrized general-relativity violations during the inspiral and merger phases, we perform quantitative tests on the gravitational-wave phase in the dynamical regime and we determine the first empirical bounds on several high-order post-Newtonian coefficients. We constrain the graviton Compton wavelength, assuming that gravitons are dispersed in vacuum in the same way as particles with mass, obtaining a 90%-confidence lower bound of 1013 km . In conclusion, within our statistical uncertainties, we find no evidence for violations of general relativity in the genuinely strong-field regime of gravity.

  19. Self-consistent computation of the electric field near ICRH antennas. Application to the Tore Supra antenna

    SciTech Connect

    Pecoul, S.; Heuraux, S.; Koch, R.; Leclert, G.; Becoulet, A.; Colas, L.

    1999-09-20

    Self-consistent calculations of the 3D electric field patterns between the screen and the plasma have been made with the ICANT code for realistic antennas. Here we explain how the ICRH antennas of the Tore Supra tokamak are modelled.

  20. Self-consistent double-hybrid density-functional theory using the optimized-effective-potential method

    NASA Astrophysics Data System (ADS)

    Śmiga, Szymon; Franck, Odile; Mussard, Bastien; Buksztel, Adam; Grabowski, Ireneusz; Luppi, Eleonora; Toulouse, Julien

    2016-10-01

    We introduce an orbital-optimized double-hybrid (DH) scheme using the optimized-effective-potential (OEP) method. The orbitals are optimized using a local potential corresponding to the complete exchange-correlation energy expression including the second-order Møller-Plesset correlation contribution. We have implemented a one-parameter version of this OEP-based self-consistent DH scheme using the BLYP density-functional approximation and compared it to the corresponding non-self-consistent DH scheme for calculations on a few closed-shell atoms and molecules. While the OEP-based self-consistency does not provide any improvement for the calculations of ground-state total energies and ionization potentials, it does improve the accuracy of electron affinities and restores the meaning of the LUMO orbital energy as being connected to a neutral excitation energy. Moreover, the OEP-based self-consistent DH scheme provides reasonably accurate exchange-correlation potentials and correlated densities.

  1. QRAP: A numerical code for projected (Q)uasiparticle (RA)ndom (P)hase approximation

    NASA Astrophysics Data System (ADS)

    Samana, A. R.; Krmpotić, F.; Bertulani, C. A.

    2010-06-01

    A computer code for quasiparticle random phase approximation - QRPA and projected quasiparticle random phase approximation - PQRPA models of nuclear structure is explained in details. The residual interaction is approximated by a simple δ-force. An important application of the code consists in evaluating nuclear matrix elements involved in neutrino-nucleus reactions. As an example, cross sections for 56Fe and 12C are calculated and the code output is explained. The application to other nuclei and the description of other nuclear and weak decay processes are also discussed. Program summaryTitle of program: QRAP ( Quasiparticle RAndom Phase approximation) Computers: The code has been created on a PC, but also runs on UNIX or LINUX machines Operating systems: WINDOWS or UNIX Program language used: Fortran-77 Memory required to execute with typical data: 16 Mbytes of RAM memory and 2 MB of hard disk space No. of lines in distributed program, including test data, etc.: ˜ 8000 No. of bytes in distributed program, including test data, etc.: ˜ 256 kB Distribution format: tar.gz Nature of physical problem: The program calculates neutrino- and antineutrino-nucleus cross sections as a function of the incident neutrino energy, and muon capture rates, using the QRPA or PQRPA as nuclear structure models. Method of solution: The QRPA, or PQRPA, equations are solved in a self-consistent way for even-even nuclei. The nuclear matrix elements for the neutrino-nucleus interaction are treated as the beta inverse reaction of odd-odd nuclei as function of the transfer momentum. Typical running time: ≈ 5 min on a 3 GHz processor for Data set 1.

  2. Quasiparticle Lifetime Broadening in Resonant X-ray Scattering of NH4NO3

    PubMed Central

    Vinson, John; Jach, Terrence; Müller, Matthias; Unterumsberger, Rainer; Beckhoff, Burkhard

    2016-01-01

    It has been previously shown that two effects cause dramatic changes in the x-ray absorption and emission spectra from the N K edge of the insulating crystal ammonium nitrate. First, vibrational disorder causes major changes in the absorption spectrum, originating not only from the thermal population of phonons, but, significantly, from zero-point motion as well. Second, the anomalously large broadening (~ 4 eV) of the emission originating from nitrate σ states is due to unusually short lifetimes of quasiparticles in an otherwise extremely narrow band. In this work we investigate the coupling of these effects to core and valence excitons that are created as the initial x-ray excitation energy is progressively reduced toward the N edge. Using a GW/Bethe-Salpeter approach, we show the extent to which this anomalous broadening is captured by the GW approximation. The data and calculations demonstrate the importance that the complex self-energies (finite lifetimes) of valence bands have on the interpretation of emission spectra. We produce a scheme to explain why extreme lifetimes should appear in σ states of other similar compounds. PMID:27747308

  3. Calculation of the spectrum of quasiparticle electron excitations in organic molecular semiconductors

    SciTech Connect

    Tikhonov, E. V.; Uspenskii, Yu. A.; Khokhlov, D. R.

    2015-06-15

    A quasiparticle electronic spectrum belongs to the characteristics of nanoobjects that are most important for applications. The following methods of calculating the electronic spectrum are analyzed: the Kohn-Sham equations of the density functional theory (DFT), the hybrid functional method, the GW approximation, and the Lehmann approximation used in the spectral representation of one-electron Green’s function. The results of these approaches are compared with the data of photoemission measurements of benzene, PTCDA, and phthalocyanine (CuPc, H{sub 2}Pc, FePc, PtPc) molecules, which are typical representatives of organic molecular semiconductors (OMS). This comparison demonstrates that the Kohn-Sham equations of DFT incorrectly reproduce the electronic spectrum of OMS. The hybrid functional method correctly describes the spectrum of the valence and conduction bands; however, the HOMO-LUMO gap width is significantly underestimated. The correct gap width is obtained in both the GW approximation and the Lehmann approach, and the total energy in this approach can be calculated in the local density approximation of DFT.

  4. Calculation of the spectrum of quasiparticle electron excitations in organic molecular semiconductors

    NASA Astrophysics Data System (ADS)

    Tikhonov, E. V.; Uspenskii, Yu. A.; Khokhlov, D. R.

    2015-06-01

    A quasiparticle electronic spectrum belongs to the characteristics of nanoobjects that are most important for applications. The following methods of calculating the electronic spectrum are analyzed: the Kohn-Sham equations of the density functional theory (DFT), the hybrid functional method, the GW approximation, and the Lehmann approximation used in the spectral representation of one-electron Green's function. The results of these approaches are compared with the data of photoemission measurements of benzene, PTCDA, and phthalocyanine (CuPc, H2Pc, FePc, PtPc) molecules, which are typical representatives of organic molecular semiconductors (OMS). This comparison demonstrates that the Kohn-Sham equations of DFT incorrectly reproduce the electronic spectrum of OMS. The hybrid functional method correctly describes the spectrum of the valence and conduction bands; however, the HOMO-LUMO gap width is significantly underestimated. The correct gap width is obtained in both the GW approximation and the Lehmann approach, and the total energy in this approach can be calculated in the local density approximation of DFT.

  5. Number Fluctuations of Sparse Quasiparticles in a Superconductor

    NASA Astrophysics Data System (ADS)

    de Visser, P. J.; Baselmans, J. J. A.; Diener, P.; Yates, S. J. C.; Endo, A.; Klapwijk, T. M.

    2011-04-01

    We have directly measured quasiparticle number fluctuations in a thin film superconducting Al resonator in thermal equilibrium. The spectrum of these fluctuations provides a measure of both the density and the lifetime of the quasiparticles. We observe that the quasiparticle density decreases exponentially with decreasing temperature, as theoretically predicted, but saturates below 160 mK to 25-55/μm3. We show that this saturation is consistent with the measured saturation in the quasiparticle lifetime, which also explains similar observations in qubit decoherence times.

  6. Aharonov-Bohm superperiod in a Laughlin quasiparticle interferometer.

    PubMed

    Camino, F E; Zhou, Wei; Goldman, V J

    2005-12-09

    We report an Aharonov-Bohm superperiod of five magnetic flux quanta (5h/e) observed in a Laughlin quasiparticle interferometer, where an edge channel of the 1/3 fractional quantum Hall fluid encircles an island of the 2/5 fluid. This result does not violate the gauge invariance argument of the Byers-Yang theorem because the magnetic flux, in addition to affecting the Aharonov-Bohm phase of the encircling 1/3 quasiparticles, creates the 2/5 quasiparticles in the island. The superperiod is accordingly understood as imposed by the anyonic statistical interaction of Laughlin quasiparticles.

  7. Fully relativistic complete active space self-consistent field for large molecules: Quasi-second-order minimax optimization

    SciTech Connect

    Bates, Jefferson E.; Shiozaki, Toru

    2015-01-28

    We develop an efficient algorithm for four-component complete active space self-consistent field (CASSCF) methods on the basis of the Dirac equation that takes into account spin–orbit and other relativistic effects self-consistently. Orbitals are optimized using a trust-region quasi-Newton method with Hessian updates so that energies are minimized with respect to rotations among electronic orbitals and maximized with respect to rotations between electronic and positronic orbitals. Utilizing density fitting and parallel computation, we demonstrate that Dirac–Coulomb CASSCF calculations can be routinely performed on systems with 100 atoms and a few heavy-elements. The convergence behavior and wall times for octachloridodirhenate(III) and a tungsten methylidene complex are presented. In addition, the excitation energies of octachloridodirhenate(III) are reported using a state-averaged variant.

  8. A self-consistent model for the study of electronic properties of hot dense plasmas in the superconfiguration approximation

    NASA Astrophysics Data System (ADS)

    Pain, J. C.; Dejonghe, G.; Blenski, T.

    2006-05-01

    We propose a thermodynamically consistent model involving detailed screened ions, described by superconfigurations, in plasmas. In the present work, the electrons, bound and free, are treated quantum-mechanically so that resonances are carefully taken into account in the self-consistent calculation of the electronic structure of each superconfiguration. The procedure is in some sense similar to the one used in Inferno code developed by D.A. Liberman; however, here we perform this calculation in the ion-sphere model for each superconfiguration. The superconfiguration approximation allows rapid calculation of necessary averages over all possible configurations representing excited states of bound electrons. The model enables a fully quantum-mechanical self-consistent calculation of the electronic structure of ions and provides the relevant thermodynamic quantities (e.g., internal energy, Helmholtz free energy and pressure), together with an improved treatment of pressure ionization. It should therefore give a better insight into the impact of plasma effects on photoabsorption spectra.

  9. Self-consistent analysis of sub-barrier fusion enhancement effect in Ca + Ca and Ni + Ni

    NASA Astrophysics Data System (ADS)

    Ma, Nan-Ru; Jia, Hui-Ming; Lin, Cheng-Jian; Yang, Lei; Xu, Xin-Xing; Sun, Li-Jie; Yang, Feng; Wu, Zhen-Dong; Zhang, Huan-Qiao; Liu, Zu-Hua; Wang, Dong-Xi

    2016-11-01

    The fusion dynamic mechanism of heavy ions at energies near the Coulomb barrier is complicated and still not very clear up to now. Accordingly, a self-consistent method based on the CCFULL calculations has been developed and applied for an ongoing study of the effect of the positive Q-value neutron transfer (PQNT) channels in this work. The typical experimental fusion data of Ca + Ca and Ni + Ni is analyzed within the unified calculation scheme. The PQNT effect in near-barrier fusion is further confirmed based on the self-consistent analysis and extracted quantitatively. Supported by the National Key Basic Research Development Program of China (2013CB834404) and the National Natural Science Foundation of China (11475263, 11375268, U1432246 and U1432127)

  10. Self-consistent high Reynolds number asymptotics based on the log-law for ZPG turbulent boundary layers

    NASA Astrophysics Data System (ADS)

    Monkewitz, Peter A.; Nagib, Hassan M.; Chauhan, Kapil A.

    2007-11-01

    The large Reynolds number behavior of flat plate turbulent boundary layers under zero pressure gradient (ZPG) is revisited. Starting from the classical two-layer approach of Millikan and Clauser with a logarithmic velocity profile in the overlap region between ``inner" and ``outer" layer, a fully self-consistent leading-order description of the mean velocity profile, all integral parameters and the downstream evolution of the boundary layer thickness is developed. The latter requires the knowledge of the virtual origin of the boundary layer which is determined from the K'arm'an equation. It is demonstrated that this self-consistent description based on the classical log-law fits all the known high Reynolds number data, and in particular their Reynolds number dependence, exceedingly well; i.e. within experimental errors.

  11. A relativistic self-consistent model for studying enhancement of space charge limited emission due to counter-streaming ions

    NASA Astrophysics Data System (ADS)

    Lin, M. C.; Verboncoeur, J.

    2016-10-01

    A maximum electron current transmitted through a planar diode gap is limited by space charge of electrons dwelling across the gap region, the so called space charge limited (SCL) emission. By introducing a counter-streaming ion flow to neutralize the electron charge density, the SCL emission can be dramatically raised, so electron current transmission gets enhanced. In this work, we have developed a relativistic self-consistent model for studying the enhancement of maximum transmission by a counter-streaming ion current. The maximum enhancement is found when the ion effect is saturated, as shown analytically. The solutions in non-relativistic, intermediate, and ultra-relativistic regimes are obtained and verified with 1-D particle-in-cell simulations. This self-consistent model is general and can also serve as a comparison for verification of simulation codes, as well as extension to higher dimensions.

  12. Charge and spin diffusion on the metallic side of the metal-insulator transition: A self-consistent approach

    NASA Astrophysics Data System (ADS)

    Wellens, Thomas; Jalabert, Rodolfo A.

    2016-10-01

    We develop a self-consistent theory describing the spin and spatial electron diffusion in the impurity band of doped semiconductors under the effect of a weak spin-orbit coupling. The resulting low-temperature spin-relaxation time and diffusion coefficient are calculated within different schemes of the self-consistent framework. The simplest of these schemes qualitatively reproduces previous phenomenological developments, while more elaborate calculations provide corrections that approach the values obtained in numerical simulations. The results are universal for zinc-blende semiconductors with electron conductance in the impurity band, and thus they are able to account for the measured spin-relaxation times of materials with very different physical parameters. From a general point of view, our theory opens a new perspective for describing the hopping dynamics in random quantum networks.

  13. Self-consistent analysis of mobility-lifetime products and subgap absorption on different PECVD a-Si:H films

    SciTech Connect

    Jiao, L.; Semoushikina, S.; Lee, Y.; Wronski, C.R.

    1997-07-01

    The photoconductivity and subband gap absorption measurements over a wide range of generation rate(G) have been carried out on diluted and undiluted a-Si:H. It is found that in these high quality films there are significant differences in the functional dependence of mobility-lifetime ({micro}{tau}) products on G. In addition to the different values of subgap absorption ({alpha}) there are also distinct differences in the dependence of {alpha} on photon energy (E) as well as G. It is difficult to self consistently analyze the results on the undiluted film with the previously used three gaussian distribution, particularly at high generation rates. Self consistent analysis is obtained when the (+/0) transitions of negative charged defects and the (0/{minus}) transitions of positive charged defects are introduced respectively closer to the valence and conduction bands. This new gap state distribution is a better representation for the defect pool model and potential fluctuation model.

  14. Fully relativistic complete active space self-consistent field for large molecules: Quasi-second-order minimax optimization

    NASA Astrophysics Data System (ADS)

    Bates, Jefferson E.; Shiozaki, Toru

    2015-01-01

    We develop an efficient algorithm for four-component complete active space self-consistent field (CASSCF) methods on the basis of the Dirac equation that takes into account spin-orbit and other relativistic effects self-consistently. Orbitals are optimized using a trust-region quasi-Newton method with Hessian updates so that energies are minimized with respect to rotations among electronic orbitals and maximized with respect to rotations between electronic and positronic orbitals. Utilizing density fitting and parallel computation, we demonstrate that Dirac-Coulomb CASSCF calculations can be routinely performed on systems with 100 atoms and a few heavy-elements. The convergence behavior and wall times for octachloridodirhenate(III) and a tungsten methylidene complex are presented. In addition, the excitation energies of octachloridodirhenate(III) are reported using a state-averaged variant.

  15. Fully relativistic complete active space self-consistent field for large molecules: quasi-second-order minimax optimization.

    PubMed

    Bates, Jefferson E; Shiozaki, Toru

    2015-01-28

    We develop an efficient algorithm for four-component complete active space self-consistent field (CASSCF) methods on the basis of the Dirac equation that takes into account spin-orbit and other relativistic effects self-consistently. Orbitals are optimized using a trust-region quasi-Newton method with Hessian updates so that energies are minimized with respect to rotations among electronic orbitals and maximized with respect to rotations between electronic and positronic orbitals. Utilizing density fitting and parallel computation, we demonstrate that Dirac-Coulomb CASSCF calculations can be routinely performed on systems with 100 atoms and a few heavy-elements. The convergence behavior and wall times for octachloridodirhenate(III) and a tungsten methylidene complex are presented. In addition, the excitation energies of octachloridodirhenate(III) are reported using a state-averaged variant.

  16. Local conditions for the Pauli potential in order to yield self-consistent electron densities exhibiting proper atomic shell structure

    SciTech Connect

    Finzel, Kati

    2016-01-21

    The local conditions for the Pauli potential that are necessary in order to yield self-consistent electron densities from orbital-free calculations are investigated for approximations that are expressed with the help of a local position variable. It is shown that those local conditions also apply when the Pauli potential is given in terms of the electron density. An explicit formula for the Ne atom is given, preserving the local conditions during the iterative procedure. The resulting orbital-free electron density exhibits proper shell structure behavior and is in close agreement with the Kohn-Sham electron density. This study demonstrates that it is possible to obtain self-consistent orbital-free electron densities with proper atomic shell structure from simple one-point approximations for the Pauli potential at local density level.

  17. Self-consistent dynamics of impurities in magnetically confined plasmas: turbulence intermittency and non-diffusive transport

    SciTech Connect

    Futatani, S.; Del-Castillo-Negrete, Diego B; Garbet, X; Benkadda, S.; Dubuit, N.

    2012-01-01

    Self-consistent turbulent transport of high concentration impurities in magnetically confined fusion plasmas is studied using a three-dimensional nonlinear fluid global turbulence model which includes ion temperature gradient (ITG) and trapped electron mode (TEM) instabilities. It is shown that the impurity concentration can have a dramatic feedback in the turbulence and, as a result, it can significantly change the transport properties of the plasma. High concentration impurities can trigger strong intermittency, that manifests in non-Gaussian heavy tails of the pdfs of E B and the ion-temperature flux fluctuations. At the heart of this self-consistent coupling is the existence of inward propagating ion temperature fronts with a sharp gradient at the leading edge that give rise to instabilities and avalanche-like bursty transport. Numerical evidence of time non-locality in the turbulent transport of high concentration impurities is also presented.

  18. Self-consistent study of Abelian and non-Abelian order in a two-dimensional topological superconductor

    NASA Astrophysics Data System (ADS)

    Goertzen, S. L.; Tanaka, K.; Nagai, Yuki

    2017-02-01

    We perform self-consistent studies of two-dimensional (2D) s -wave topological superconductivity (TSC) with Rashba spin-orbit coupling and Zeeman field by solving the Bogoliubov-de Gennes equations. In particular, we examine the effects of a nonmagnetic impurity in detail and show that the nature of the spin-polarized midgap bound state varies significantly depending on the material parameters. Most notably, a nonmagnetic impurity in a 2D s -wave topological superconductor can act like a magnetic impurity in a conventional s -wave superconductor, leading to phase transitions of the ground state as the impurity potential is varied. Furthermore, by solving for the spin-dependent Hartree potential self-consistently along with the superconducting order parameter, we demonstrate that topological charge density waves can coexist with TSC at half filling just as in a conventional s -wave superconductor.

  19. Quasiparticle interference in unconventional 2D systems

    NASA Astrophysics Data System (ADS)

    Chen, Lan; Cheng, Peng; Wu, Kehui

    2017-03-01

    At present, research of 2D systems mainly focuses on two kinds of materials: graphene-like materials and transition-metal dichalcogenides (TMDs). Both of them host unconventional 2D electronic properties: pseudospin and the associated chirality of electrons in graphene-like materials, and spin-valley-coupled electronic structures in the TMDs. These exotic electronic properties have attracted tremendous interest for possible applications in nanodevices in the future. Investigation on the quasiparticle interference (QPI) in 2D systems is an effective way to uncover these properties. In this review, we will begin with a brief introduction to 2D systems, including their atomic structures and electronic bands. Then, we will discuss the formation of Friedel oscillation due to QPI in constant energy contours of electron bands, and show the basic concept of Fourier-transform scanning tunneling microscopy/spectroscopy (FT-STM/STS), which can resolve Friedel oscillation patterns in real space and consequently obtain the QPI patterns in reciprocal space. In the next two parts, we will summarize some pivotal results in the investigation of QPI in graphene and silicene, in which systems the low-energy quasiparticles are described by the massless Dirac equation. The FT-STM experiments show there are two different interference channels (intervalley and intravalley scattering) and backscattering suppression, which associate with the Dirac cones and the chirality of quasiparticles. The monolayer and bilayer graphene on different substrates (SiC and metal surfaces), and the monolayer and multilayer silicene on a Ag(1 1 1) surface will be addressed. The fifth part will introduce the FT-STM research on QPI in TMDs (monolayer and bilayer of WSe2), which allow us to infer the spin texture of both conduction and valence bands, and present spin-valley coupling by tracking allowed and forbidden scattering channels.

  20. Self-consistent description of the core and boundary plasma in the high-field ignition experiment

    NASA Astrophysics Data System (ADS)

    Stankiewicz, R.; Zagórski, R.

    2000-03-01

    A model has been developed which is capable to describe in a self-consistent way plasma dynamics in the center and edge region of fusion reactor. The core plasma is treated in the frame of 1D radial transport model whereas a 1D analytical model along magnetic field lines for plasma and impurity transport outside the last closed magnetic surface (LCMS) is applied. The model has been used to investigate operation regimes of the high-field IGNITOR experiment.

  1. A self-consistent renormalized jellium approach for calculating structural and thermodynamic properties of charge stabilized colloidal suspensions.

    PubMed

    Colla, Thiago E; Levin, Yan; Trizac, Emmanuel

    2009-08-21

    An approach is proposed which allows to self-consistently calculate the structural and the thermodynamic properties of highly charged aqueous colloidal suspensions. The method is based on the renormalized jellium model with the background charge distribution related to the colloid-colloid correlation function. The theory is used to calculate the correlation functions and the effective colloidal charges for suspensions containing additional monovalent electrolyte. The predictions of the theory are in excellent agreement with Monte Carlo simulations.

  2. Generalized fractional supertrace identity for Hamiltonian structure of NLS-MKdV hierarchy with self-consistent sources

    NASA Astrophysics Data System (ADS)

    Dong, Huan He; Guo, Bao Yong; Yin, Bao Shu

    2016-06-01

    In the paper, based on the modified Riemann-Liouville fractional derivative and Tu scheme, the fractional super NLS-MKdV hierarchy is derived, especially the self-consistent sources term is considered. Meanwhile, the generalized fractional supertrace identity is proposed, which is a beneficial supplement to the existing literature on integrable system. As an application, the super Hamiltonian structure of fractional super NLS-MKdV hierarchy is obtained.

  3. Multiconfiguration self-consistent-field calculation of the dipole moment function of CO/X 1 sigma +/

    NASA Technical Reports Server (NTRS)

    Billingsley, F. P., II; Krauss, M.

    1974-01-01

    Using the optimized valence configurations (OVC) multiconfiguration self-consistent-field (MCSCF) method, the dipole moment function for the ground state of CO in the vicinity of the equilibrium internuclear distance has been calculated. The OVC MCSCF calculation results are compared with existing Hartree-Fock and configuration interaction treatments of this molecule at single points and also the dipole moment function deduced from experimental infrared intensities. A general prescription for constructing OVC wavefunctions for diatomic molecules is also presented.

  4. Self-consistent implementation of meta-GGA functionals for the ONETEP linear-scaling electronic structure package

    NASA Astrophysics Data System (ADS)

    Womack, James C.; Mardirossian, Narbe; Head-Gordon, Martin; Skylaris, Chris-Kriton

    2016-11-01

    Accurate and computationally efficient exchange-correlation functionals are critical to the successful application of linear-scaling density functional theory (DFT). Local and semi-local functionals of the density are naturally compatible with linear-scaling approaches, having a general form which assumes the locality of electronic interactions and which can be efficiently evaluated by numerical quadrature. Presently, the most sophisticated and flexible semi-local functionals are members of the meta-generalized-gradient approximation (meta-GGA) family, and depend upon the kinetic energy density, τ, in addition to the charge density and its gradient. In order to extend the theoretical and computational advantages of τ-dependent meta-GGA functionals to large-scale DFT calculations on thousands of atoms, we have implemented support for τ-dependent meta-GGA functionals in the ONETEP program. In this paper we lay out the theoretical innovations necessary to implement τ-dependent meta-GGA functionals within ONETEP's linear-scaling formalism. We present expressions for the gradient of the τ-dependent exchange-correlation energy, necessary for direct energy minimization. We also derive the forms of the τ-dependent exchange-correlation potential and kinetic energy density in terms of the strictly localized, self-consistently optimized orbitals used by ONETEP. To validate the numerical accuracy of our self-consistent meta-GGA implementation, we performed calculations using the B97M-V and PKZB meta-GGAs on a variety of small molecules. Using only a minimal basis set of self-consistently optimized local orbitals, we obtain energies in excellent agreement with large basis set calculations performed using other codes. Finally, to establish the linear-scaling computational cost and applicability of our approach to large-scale calculations, we present the outcome of self-consistent meta-GGA calculations on amyloid fibrils of increasing size, up to tens of thousands of atoms.

  5. Two-way self-consistent simulation of the inner magnetosphere driven by realistic electric and magnetic fields

    NASA Astrophysics Data System (ADS)

    Ilie, Raluca; Liemohn, Michael; Toth, Gabor

    2014-05-01

    The geomagnetic storm of August 6, 2011 is examined using the two-way self consistent coupling between the kinetic Hot Electron and Ion Drift Integrator (HEIDI) model, the Block Adaptive Tree Solar Wind Roes-Type Scheme (BATS-R-US) MHD model and the Ridley Ionospheric Model (RIM) through the Space Weather Modeling Framework (SWMF). HEIDI solves the time dependent, gyration and bounce-averaged kinetic equation for the phase space density of different ring current species and computes full pitch angle distributions for all local times and radial distances. This model was generalized to accommodate arbitrary magnetic fields and through the coupling with the SWMF it obtains magnetic field description along with plasma distribution at the model boundaries from the BATS-R-US model within the SWMF. Electric field self-consistency is assured by the passing of convection potentials from the Ridley Ionosphere Model (RIM) within SWMF. Our study tests the various levels of coupling between the three models, highlighting the role the magnetic field, plasma sheet conditions and the cross polar cap potential play in the formation and evolution of the ring current. We use the results of the coupled HEIDI, BATSRUS and RIM models during disturbed conditions to study the importance of a kinetic self-consistent approach to the description of geospace.

  6. Constraining alternative theories of gravity using GW150914 and GW151226

    NASA Astrophysics Data System (ADS)

    De Laurentis, Mariafelicia; Porth, Oliver; Bovard, Luke; Ahmedov, Bobomurat; Abdujabbarov, Ahmadjon

    2016-12-01

    The recently reported gravitational wave events GW150914 and GW151226 caused by the mergers of binary black holes [Abbott et al., Phys. Rev. Lett. 116, 221101 (2016); Phys. Rev. Lett. 116, 241103 (2016); Phys. Rev. X 6, 041015] provide a formidable way to set constraints on alternative metric theories of gravity in the strong field regime. In this paper, we develop an approach where an arbitrary theory of gravity can be parametrized by an effective coupling Geff and an effective gravitational potential Φ (r ). The standard Newtonian limit of general relativity is recovered as soon as Geff→GN and Φ (r )→ΦN. The upper bound on the graviton mass and the gravitational interaction length, reported by the LIGO-VIRGO Collaboration, can be directly recast in terms of the parameters of the theory that allows an analysis where the gravitational wave frequency modulation sets constraints on the range of possible alternative models of gravity. Numerical results based on published parameters for the binary black hole mergers are also reported. The comparison of the observed phases of GW150914 and GW151226 with the modulated phase in alternative theories of gravity does not give reasonable constraints due to the large uncertainties in the estimated parameters for the coalescing black holes. In addition to these general considerations, we obtain limits for the frequency dependence of the α parameter in scalar tensor theories of gravity.

  7. Thermal Dephasing in the Laughlin Quasiparticle Interferometer

    NASA Astrophysics Data System (ADS)

    Camino, F. E.; Zhou, Wei; Goldman, V. J.

    2006-03-01

    We report experiments on thermal dephasing of the Aharonov-Bohm oscillations in the novel Laughlin quasiparticle (LQP) interferometer, [1] where quasiparticles of the 1/3 FQH fluid execute a closed path around an island of the 2/5 fluid. In the 10.2 <=T <=141 mK temperature range, qualitatively, the experimental results follow a thermal dephasing dependence expected for an electron interferometer, and show clear distinction from the activated behavior observed in resonant tunneling and Coulomb blockade devices, both in the chiral Luttinger liquid (χLL) and the Fermi liquid regimes. The data fit very well the χLL dependence predicted for a g=1/3 two point-contact LQP interferometer. [2] The fit yields a value of the chiral edge excitation velocity, u=1.4x10^4 m/s obtained for the first time for a continuous FQH edge excitation spectrum. The small deviation from the zero-bias theory seen below 20 mK indicates yet unrecognized source of experimental decoherence, not included in theory. [1] F. E. Camino et al., Phys. Rev. B 72, 075342 (2005). [2] C. de C. Chamon et al., Phys. Rev. B 55, 2331 (1997).

  8. Charge of a quasiparticle in a superconductor.

    PubMed

    Ronen, Yuval; Cohen, Yonatan; Kang, Jung-Hyun; Haim, Arbel; Rieder, Maria-Theresa; Heiblum, Moty; Mahalu, Diana; Shtrikman, Hadas

    2016-02-16

    Nonlinear charge transport in superconductor-insulator-superconductor (SIS) Josephson junctions has a unique signature in the shuttled charge quantum between the two superconductors. In the zero-bias limit Cooper pairs, each with twice the electron charge, carry the Josephson current. An applied bias VSD leads to multiple Andreev reflections (MAR), which in the limit of weak tunneling probability should lead to integer multiples of the electron charge ne traversing the junction, with n integer larger than 2Δ/eVSD and Δ the superconducting order parameter. Exceptionally, just above the gap eVSD ≥ 2Δ, with Andreev reflections suppressed, one would expect the current to be carried by partitioned quasiparticles, each with energy-dependent charge, being a superposition of an electron and a hole. Using shot-noise measurements in an SIS junction induced in an InAs nanowire (with noise proportional to the partitioned charge), we first observed quantization of the partitioned charge q = e*/e = n, with n = 1-4, thus reaffirming the validity of our charge interpretation. Concentrating next on the bias region eVSD ~ 2Δ, we found a reproducible and clear dip in the extracted charge to q ~ 0.6, which, after excluding other possibilities, we attribute to the partitioned quasiparticle charge. Such dip is supported by numerical simulations of our SIS structure.

  9. Quasiparticle equation of state for anisotropic hydrodynamics

    NASA Astrophysics Data System (ADS)

    Alqahtani, Mubarak; Nopoush, Mohammad; Strickland, Michael

    2015-11-01

    We present a new method for imposing a realistic equation of state in anisotropic hydrodynamics. The method relies on the introduction of a single finite-temperature quasiparticle mass which is fit to lattice data. By taking moments of the Boltzmann equation, we obtain a set of coupled partial differential equations which can be used to describe the 3+1-dimensional (3+1d) spacetime evolution of an anisotropic relativistic system. We then specialize to the case of a 0+1d system undergoing boost-invariant Bjorken expansion and subject to the relaxation-time approximation collisional kernel. Using this setup, we compare results obtained using the new quasiparticle equation of state method with those obtained using the standard method for imposing the equation of state in anisotropic hydrodynamics. We demonstrate that the temperature evolution obtained using the two methods is nearly identical and that there are only small differences in the pressure anisotropy. However, we find that there are significant differences in the evolution of the bulk pressure correction.

  10. Irreducible tensor description. II. A quasiparticle gas

    NASA Astrophysics Data System (ADS)

    Banach, Zbigniew; Piekarski, Slawomir

    1989-08-01

    Let E be a three-dimensional Euclidean vector space and assume that ℏΩ(k) is a quasiparticle energy in the mode k∈E; thus k is a wave vector. Within the framework of the Boltzmann-Peierls equation and a broad class of isotropic dispersion relations [Ω(k)⇒Ω(k), k: =||k||], the exact system of irreducible equations of transfer for the symmetric traceless moments of the distribution function f is derived and the range of validity of Grad's moment procedure is extended to the case of quasiparticle gases. Thus not without reason, an expansion with respect to k of the one-particle density f around the local Bose-Einstein occupation probability f0 in terms of the appropriately chosen Tchebychef functions Aβ(z;Θ) and Ikenberry's harmonics Yα(g) is carefully recognized. Also, the importance of the Tchebychef basis {Aβ; β=0,1,...}, both in any serious analysis of equilibrium fluctuations and in exploiting the Chapman-Enskog procedure, is clearly established.

  11. Quasiparticle Aggregation in the Fractional Quantum Hall Effect

    DOE R&D Accomplishments Database

    Laughlin, R. B.

    1984-10-10

    Quasiparticles in the Fractional Quantum Hall Effect behave qualitatively like electrons confined to the lowest landau level, and can do everything electrons can do, including condense into second generation Fractional Quantum Hall ground states. I review in this paper the reasoning leading to variational wavefunctions for ground state and quasiparticles in the 1/3 effect. I then show how two-quasiparticle eigenstates are uniquely determined from symmetry, and how this leads in a natural way to variational wavefunctions for composite states which have the correct densities (2/5, 2/7, ...). I show in the process that the boson, anyon and fermion representations for the quasiparticles used by Haldane, Halperin, and me are all equivalent. I demonstrate a simple way to derive Halperin`s multiple-valued quasiparticle wavefunction from the correct single-valued electron wavefunction. (auth)

  12. A search for electron antineutrinos associated with gravitational-wave events GW150914 and GW151226 using KamLAND

    SciTech Connect

    Gando, A.; Gando, Y.; Hachiya, T.; Hayashi, A.; Hayashida, S.; Ikeda, H.; Inoue, K.; Ishidoshiro, K.; Karino, Y.; Koga, M.; Matsuda, S.; Mitsui, T.; Nakamura, K.; Obara, S.; Oura, T.; Ozaki, H.; Shimizu, I.; Shirahata, Y.; Shirai, J.; Suzuki, A.; Takai, T.; Tamae, K.; Teraoka, Y.; Ueshima, K.; Watanabe, H.; Kozlov, A.; Takemoto, Y.; Yoshida, S.; Fushimi, K.; Piepke, A.; Banks, T. I.; Berger, B. E.; Fujikawa, B. K.; O’Donnell, T.; Learned, J. G.; Maricic, J.; Sakai, M.; Winslow, L. A.; Krupczak, E.; Ouellet, J.; Efremenko, Y.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Detwiler, J. A.; Enomoto, S.; Decowski, M. P.

    2016-09-30

    Here, we present a search, using KamLAND, a kiloton-scale anti-neutrino detector, for low-energy anti-neutrino events that were coincident with the gravitational-wave (GW) events GW150914 and GW151226, and the candidate event LVT151012. We find no inverse beta-decay neutrino events within ±500 s of either GW signal. This non-detection is used to constrain the electron anti-neutrino fluence and the total integrated luminosity of the astrophysical sources.

  13. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 1; Waves in Multi Ion Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gumayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2006-01-01

    The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves [Khazanov et al., 2003] is presented. In order to adequately take into account the wave propagation and refraction in a multi-ion plasmasphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate spatial, temporal, and spectral evolutions of the ring current and electromagnetic ion cyclotron waves. To demonstrate the effects of EMIC wave propagation and refraction on the EMIC wave energy distributions and evolution we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, due to the density gradient at the plasmapause, the net wave refraction is suppressed, and He(+)-mode grows preferably at plasmapause. This result is in a total agreement with the previous ray tracing studies, and very clear observed in presented B-field spectrograms. Second, comparison the global wave distributions with the results from other ring current model [Kozyra et al., 1997] reveals that our model provides more intense and higher plasmapause organized distributions during the May, 1998 storm period. Finally, the found He(+)-mode energy distributions are not Gaussian distributions, and most important that wave energy can occupy not only the region of generation, i. e. the region of small wave normal angles, but the entire wave normal angle region and even only the region near 90 degrees. The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping, and subsequent downward heat transport and excitation of stable auroral red arcs.

  14. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves: Waves in Multi-Ion Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2006-01-01

    The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves (Khazanov et al., 2003) is presented In order to adequately take into account wave propagation and refraction in a multi-ion magnetosphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate the spatial, temporal, and spectral evolution of the ring current and of electromagnetic ion cyclotron waves To demonstrate the effects of EMIC wave propagation and refraction on the wave energy distribution and evolution, we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, owing to the density gradient at the plasmapause, the net wave refraction is suppressed, and He+-mode grows preferably at the plasmapause. This result is in total agreement with previous ray tracing studies and is very clearly found in presented B field spectrograms. Second, comparison of global wave distributions with the results from another ring current model (Kozyra et al., 1997) reveals that this new model provides more intense and more highly plasmapause-organized wave distributions during the May 1998 storm period Finally, it is found that He(+)-mode energy distributions are not Gaussian distributions and most important that wave energy can occupy not only the region of generation, i.e., the region of small wave normal angles, but all wave normal angles, including those to near 90 . The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping and subsequent downward heat transport and excitation of stable auroral red arcs.

  15. Self-Consistent Thermal Accretion Disk Corona Models for Compact Objects. II; Application to Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Dove, James B.; Wilms, Joern; Maisack, Michael; Begelman, Mitchell C.

    1997-01-01

    We apply our self-consistent accretion disk corona (ADC) model, with two different geometries, to the broadband X-ray spectrum of the black hole candidate Cygnus X-1. As shown in a companion paper, models in which the Comptonizing medium is a slab surrounding the cold accretion disk cannot have a temperature higher than about 140 keV for optical depths greater than 0.2, resulting in spectra that are much softer than the observed 10-30 keV spectrum of Cyg X-1. In addition, the slab-geometry models predict a substantial "soft excess" at low energies, a feature not observed for Cyg X-1, and Fe K-alpha fluorescence lines that are stronger than observed. Previous Comptonization models in the literature have invoked a slab geometry with optical depth tau(sub T) approx. greater than 0.3 and coronal temperature T(sub c) approx. 150 keV, but they are not self-consistent. Therefore, ADC models with a slab geometry are not appropriate for explaining the X-ray spectrum of Cyg X-1. Models with a spherical corona and an exterior disk, however, predict much higher self-consistent coronal temperatures than the slab-geometry models. The higher coronal temperatures are due to the lower amount of reprocessing of coronal radiation in the accretion disk, giving rise to a lower Compton cooling rate. Therefore, for the sphere-plus-disk geometry, the predicted spectrum can be hard enough to describe the observed X-ray continuum of Cyg X-1 while predicting Fe fluorescence lines having an equivalent width of approx. 40 eV. Our best-fit parameter values for the sphere-plus-disk geometry are tau(sub T) approx. equal to 1.5 and T(sub c) approx. equal to 90 keV.

  16. Self-Consistant Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

    SciTech Connect

    Vay, J-L.; Furman, M.A.; Secondo, R.; Venturini, M.; Fox, J.D.; Rivetta, C.H,

    2010-09-01

    The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the growth rate and frequency patterns in space-time of the electron cloud driven transverse instability for a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density. Comparisons to selected experimental data are also given. Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS and other accelerators. So far, simulations of electron cloud buildup and their effects on beam dynamics have been performed separately. This is a consequence of the large computational cost of the combined calculation due to large space and time scale disparities between the two processes. We have presented the latest improvements of the simulation package WARP-POSINST for the simulation of self-consistent ecloud effects, including mesh refinement, and generation of electrons from gas ionization and impact at the pipe walls. We also presented simulations of two consecutive bunches interacting with electrons clouds in the SPS, which included generation of secondary electrons. The distribution of electrons in front of the first beam was initialized from a dump taken from a preceding buildup calculation using the POSINST code. In this paper, we present an extension of this work where one full batch of 72 bunches is simulated in the SPS, including the entire buildup calculation and the self-consistent interaction between the bunches and the electrons. Comparisons to experimental data are also given.

  17. Probing neutrino physics with a self-consistent treatment of the weak decoupling, nucleosynthesis, and photon decoupling epochs

    SciTech Connect

    Grohs, E.; Fuller, George M.; Kishimoto, Chad T.; Paris, Mark W. E-mail: gfuller@ucsd.edu E-mail: mparis@lanl.gov

    2015-05-01

    We show that a self-consistent and coupled treatment of the weak decoupling, big bang nucleosynthesis, and photon decoupling epochs can be used to provide new insights and constraints on neutrino sector physics from high-precision measurements of light element abundances and Cosmic Microwave Background observables. Implications of beyond-standard-model physics in cosmology, especially within the neutrino sector, are assessed by comparing predictions against five observables: the baryon energy density, helium abundance, deuterium abundance, effective number of neutrinos, and sum of the light neutrino mass eigenstates. We give examples for constraints on dark radiation, neutrino rest mass, lepton numbers, and scenarios for light and heavy sterile neutrinos.

  18. Self-consistent description of the core and boundary plasma in the high-field ignition experiment

    NASA Astrophysics Data System (ADS)

    Stankiewicz, R.; Zagórski, R.

    2001-03-01

    A model has been developed which is capable to describe in a self-consistent way plasma dynamics in the center and edge regions of fusion reactor. The core plasma is treated in the frame of 1-D radial transport model whereas a 1-D analytical model along magnetic field lines for plasma and impurity transport outside the last closed magnetic surface (LCMS) is applied. The model is suitable to fast scans of the parameter space of the tokamak type reactor and has been used to investigate operation regimes of the high-field IGNITOR experiment.

  19. A new approach to modeling the effective thermal conductivity of ceramics porous media using a generalized self-consistent method

    NASA Astrophysics Data System (ADS)

    Edrisi, Siroos; Bidhendi, Norollah Kasiri; Haghighi, Maryam

    2017-01-01

    Effective thermal conductivity of the porous media was modeled based on a self-consistent method. This model estimates the heat transfer between insulator surface and air cavities accurately. In this method, the pore size and shape, the temperature gradient and other thermodynamic properties of the fluid was taken into consideration. The results are validated by experimental data for fire bricks used in cracking furnaces at the olefin plant of Maroon petrochemical complexes well as data published for polyurethane foam (synthetic polymers) IPTM and IPM. The model predictions present a good agreement against experimental data with thermal conductivity deviating <1 %.

  20. Perturbative correction for the basis set incompleteness error of complete-active-space self-consistent field.

    PubMed

    Kong, Liguo; Valeev, Edward F

    2010-11-07

    To reduce the basis set incompleteness of the complete-active-space self-consistent field (CASSCF) wave function and energy we develop a second-order perturbation correction due to single excitations to complete set of unoccupied states. Other than the one- and two-electron integrals, only one- and two-particle reduced density matrices are required to compute the correction, denoted as [2](S). Benchmark calculations on prototypical ground-state bond-breaking problems show that only the aug-cc-pVXZ basis is needed with the [2](S) correction to match the accuracy of CASSCF energies of the aug-cc-pV(X+1)Z quality.

  1. An atomic orbital-based formulation of the complete active space self-consistent field method on graphical processing units

    SciTech Connect

    Hohenstein, Edward G.; Luehr, Nathan; Ufimtsev, Ivan S.; Martínez, Todd J.

    2015-06-14

    Despite its importance, state-of-the-art algorithms for performing complete active space self-consistent field (CASSCF) computations have lagged far behind those for single reference methods. We develop an algorithm for the CASSCF orbital optimization that uses sparsity in the atomic orbital (AO) basis set to increase the applicability of CASSCF. Our implementation of this algorithm uses graphical processing units (GPUs) and has allowed us to perform CASSCF computations on molecular systems containing more than one thousand atoms. Additionally, we have implemented analytic gradients of the CASSCF energy; the gradients also benefit from GPU acceleration as well as sparsity in the AO basis.

  2. SCF and CI calculations of the dipole moment function of ozone. [Self-Consistent Field and Configuration-Interaction

    NASA Technical Reports Server (NTRS)

    Curtiss, L. A.; Langhoff, S. R.; Carney, G. D.

    1979-01-01

    The constant and linear terms in a Taylor series expansion of the dipole moment function of the ground state of ozone are calculated with Cartesian Gaussian basis sets ranging in quality from minimal to double zeta plus polarization. Results are presented at both the self-consistent field and configuration-interaction levels. Although the algebraic signs of the linear dipole moment derivatives are all established to be positive, the absolute magnitudes of these quantities, as well as the infrared intensities calculated from them, vary considerably with the level of theory.

  3. Self-consistent modelling of X-ray photoelectron spectra from air-exposed polycrystalline TiN thin films

    NASA Astrophysics Data System (ADS)

    Greczynski, G.; Hultman, L.

    2016-11-01

    We present first self-consistent modelling of x-ray photoelectron spectroscopy (XPS) Ti 2p, N 1s, O 1s, and C 1s core level spectra with a cross-peak quantitative agreement for a series of TiN thin films grown by dc magnetron sputtering and oxidized to different extent by varying the venting temperature Tv of the vacuum chamber before removing the deposited samples. So-obtained film series constitute a model case for XPS application studies, where certain degree of atmosphere exposure during sample transfer to the XPS instrument is unavoidable. The challenge is to extract information about surface chemistry without invoking destructive pre-cleaning with noble gas ions. All TiN surfaces are thus analyzed in the as-received state by XPS using monochromatic Al Kα radiation (hν = 1486.6 eV). Details of line shapes and relative peak areas obtained from deconvolution of the reference Ti 2p and N 1 s spectra representative of a native TiN surface serve as an input to model complex core level signals from air-exposed surfaces, where contributions from oxides and oxynitrides make the task very challenging considering the influence of the whole deposition process at hand. The essential part of the presented approach is that the deconvolution process is not only guided by the comparison to the reference binding energy values that often show large spread, but in order to increase reliability of the extracted chemical information the requirement for both qualitative and quantitative self-consistency between component peaks belonging to the same chemical species is imposed across all core-level spectra (including often neglected O 1s and C 1s signals). The relative ratios between contributions from different chemical species vary as a function of Tv presenting a self-consistency check for our model. We propose that the cross-peak self-consistency should be a prerequisite for reliable XPS peak modelling as it enhances credibility of obtained chemical information, while relying

  4. Theoretical prediction of the band offsets at the ZnO/anatase TiO{sub 2} and GaN/ZnO heterojunctions using the self-consistent ab initio DFT/GGA-1/2 method

    SciTech Connect

    Fang, D. Q. Zhang, S. L.

    2016-01-07

    The band offsets of the ZnO/anatase TiO{sub 2} and GaN/ZnO heterojunctions are calculated using the density functional theory/generalized gradient approximation (DFT/GGA)-1/2 method, which takes into account the self-energy corrections and can give an approximate description to the quasiparticle characteristics of the electronic structure of semiconductors. We present the results of the ionization potential (IP)-based and interfacial offset-based band alignments. In the interfacial offset-based band alignment, to get the natural band offset, we use the surface calculations to estimate the change of reference level due to the interfacial strain. Based on the interface models and GGA-1/2 calculations, we find that the valence band maximum and conduction band minimum of ZnO, respectively, lie 0.64 eV and 0.57 eV above those of anatase TiO{sub 2}, while lie 0.84 eV and 1.09 eV below those of GaN, which agree well with the experimental data. However, a large discrepancy exists between the IP-based band offset and the calculated natural band offset, the mechanism of which is discussed. Our results clarify band alignment of the ZnO/anatase TiO{sub 2} heterojunction and show good agreement with the GW calculations for the GaN/ZnO heterojunction.

  5. Quasiparticle interference, quasiparticle interactions, and the origin of the charge density wave in 2H–NbSe2

    DOE PAGES

    Arguello, C. J.; Rosenthal, E. P.; Andrade, E. F.; ...

    2015-01-21

    We show that a small number of intentionally introduced defects can be used as a spectroscopic tool to amplify quasiparticle interference in 2H-NbSe₂, that we measure by scanning tunneling spectroscopic imaging. We show from the momentum and energy dependence of the quasiparticle interference that Fermi surface nesting is inconsequential to charge density wave formation in 2H-NbSe₂. Thus, we demonstrate that by combining quasiparticle interference data with additional knowledge of the quasiparticle band structure from angle resolved photoemission measurements, one can extract the wavevector and energy dependence of the important electronic scattering processes thereby obtaining direct information both about the fermiologymore » and the interactions. In 2H-NbSe₂, we use this combination to show that the important near-Fermi-surface electronic physics is dominated by the coupling of the quasiparticles to soft mode phonons at a wave vector different from the CDW ordering wave vector.« less

  6. Excited-state potential-energy surfaces of metal-adsorbed organic molecules from linear expansion Δ-self-consistent field density-functional theory (ΔSCF-DFT)

    NASA Astrophysics Data System (ADS)

    Maurer, Reinhard J.; Reuter, Karsten

    2013-07-01

    Accurate and efficient simulation of excited state properties is an important and much aspired cornerstone in the study of adsorbate dynamics on metal surfaces. To this end, the recently proposed linear expansion Δ-self-consistent field method by Gavnholt et al. [Phys. Rev. B 78, 075441 (2008)], 10.1103/PhysRevB.78.075441 presents an efficient alternative to time consuming quasi-particle calculations. In this method, the standard Kohn-Sham equations of density-functional theory are solved with the constraint of a non-equilibrium occupation in a region of Hilbert-space resembling gas-phase orbitals of the adsorbate. In this work, we discuss the applicability of this method for the excited-state dynamics of metal-surface mounted organic adsorbates, specifically in the context of molecular switching. We present necessary advancements to allow for a consistent quality description of excited-state potential-energy surfaces (PESs), and illustrate the concept with the application to Azobenzene adsorbed on Ag(111) and Au(111) surfaces. We find that the explicit inclusion of substrate electronic states modifies the topologies of intra-molecular excited-state PESs of the molecule due to image charge and hybridization effects. While the molecule in gas phase shows a clear energetic separation of resonances that induce isomerization and backreaction, the surface-adsorbed molecule does not. The concomitant possibly simultaneous induction of both processes would lead to a significantly reduced switching efficiency of such a mechanism.

  7. Finite quasiparticle lifetime in disordered superconductors.

    SciTech Connect

    Zemlicka, M.; Neilinger, P.; Trgala, M; Rehak, M; Manca, D.; Grajcar, M.; Szabo, P.; Samuely, P.; Gazi, S.; Hubner, U.; Vinokur, V. M.; Il'ichev, E.

    2015-12-08

    We investigate the complex conductivity of a highly disordered MoC superconducting film with k(F)l approximate to 1, where k(F) is the Fermi wave number and l is the mean free path, derived from experimental transmission characteristics of coplanar waveguide resonators in a wide temperature range below the superconducting transition temperature T-c. We find that the original Mattis-Bardeen model with a finite quasiparticle lifetime, tau, offers a perfect description of the experimentally observed complex conductivity. We show that iota is appreciably reduced by scattering effects. Characteristics of the scattering centers are independently found by scanning tunneling spectroscopy and agree with those determined from the complex conductivity.

  8. Dynamical screening in correlated metals: Spectral properties of SrVO3 in the GW approximation and beyond

    NASA Astrophysics Data System (ADS)

    Gatti, Matteo; Guzzo, Matteo

    2013-04-01

    SrVO3 is a prototypical strongly correlated metal. Here we interpret the signatures of electronic correlation measured in photoemission spectroscopy by combining the many-body GW approximation of the self-energy with an exponential representation of the Green's function. We explain those correlation effects as the consequence of the dynamical screening of the Coulomb interaction and the coupling between elementary excitations in the solid. Moreover we address the issue of satellites for empty states and discuss the possibility of plasmon-satellite series above the Fermi energy EF. In good agreement with experiment, we obtain from first principles the renormalization of the V 3d quasiparticle bands and the satellites close to EF that so far have been interpreted on the basis of the Hubbard model. Finally, we identify incoherent features due to dynamical correlation also at the bottom of the O 2p bands, beyond the traditional three-band Hubbard-model description.

  9. A self-consistent mechanism for electron cyclotron maser emission and its application to type III solar radio bursts

    NASA Astrophysics Data System (ADS)

    Chen, L.; Wu, D. J.; Zhao, G. Q.; Tang, J. F.

    2017-01-01

    Type III solar radio bursts (SRBs) produced by fast electron beams (FEBs) traveling along solar magnetic fields are the best known and the most important kind of SRBs because of their clearest association with FEBs as well as most frequent observations during solar activities. However, the physics of their emitting mechanism has been a controversial issue. Based on the electron cyclotron maser (ECM) instability driven directly by a magnetized FEB, whose physics is fairly well known from the Earth's auroral kilometric radiation, this paper proposes a self-consistent mechanism for type III SRBs, in which the Alfvén wave (AW) produced by the current instability of the beam-return current system associated with the FEB, called the self-generated AW, plays an important and crucial role. Taking into account the return-current effect of the FEB, the growth rate and the saturation intensity of the self-generated AW are estimated. Then the effects of the self-generated AW on the ECM emission via the ECM instability driven by the magnetized FEB are further investigated. The results show that the self-generated AW can significantly influence and change the physical properties of the ECM emission. In particular, this novel ECM emission mechanism can effectively overcome the main difficulties of the conventional ECM emission mechanism in application to type III SRBs and may potentially provide a self-consistent physics scenario for type III SRBs.

  10. Self-consistent modelling of line-driven hot-star winds with Monte Carlo radiation hydrodynamics

    NASA Astrophysics Data System (ADS)

    Noebauer, U. M.; Sim, S. A.

    2015-11-01

    Radiative pressure exerted by line interactions is a prominent driver of outflows in astrophysical systems, being at work in the outflows emerging from hot stars or from the accretion discs of cataclysmic variables, massive young stars and active galactic nuclei. In this work, a new radiation hydrodynamical approach to model line-driven hot-star winds is presented. By coupling a Monte Carlo radiative transfer scheme with a finite volume fluid dynamical method, line-driven mass outflows may be modelled self-consistently, benefiting from the advantages of Monte Carlo techniques in treating multiline effects, such as multiple scatterings, and in dealing with arbitrary multidimensional configurations. In this work, we introduce our approach in detail by highlighting the key numerical techniques and verifying their operation in a number of simplified applications, specifically in a series of self-consistent, one-dimensional, Sobolev-type, hot-star wind calculations. The utility and accuracy of our approach are demonstrated by comparing the obtained results with the predictions of various formulations of the so-called CAK theory and by confronting the calculations with modern sophisticated techniques of predicting the wind structure. Using these calculations, we also point out some useful diagnostic capabilities our approach provides. Finally, we discuss some of the current limitations of our method, some possible extensions and potential future applications.

  11. Self-Consistent Model of Magnetospheric Ring Current and Electromagnetic Ion Cyclotron Waves: The 2-7 May 1998 Storm

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Jordanova, V. K.

    2003-01-01

    A complete description of a self-consistent model of magnetospheric ring current interacting with electromagnetic ion cyclotron waves is presented. The model is based on the system of two kinetic equations; one equation describes the ring current ion dynamics, and another equation describes the wave evolution. The effects on ring current ions interacting with electromagnetic ion cyclotron waves and back on waves are considered self-consistently by solving both equations on a global magnetospheric scale under nonsteady state conditions. The developed model is employed to simulate the entire 2-7 May 1998 storm period. First, the trapped number fluxes of the ring current protons are calculated and presented along with comparison with the data measured by the three- dimensional hot plasma instrument Polar/HYDRA. Incorporating in the model the wave-particle interaction leads to much better agreement between the experimental data and the model results. Second, examining of the wave (MLT, L shell) distributions produced by the model during the storm progress reveals an essential intensification of the wave emission about 2 days after the main phase of the storm. This result is well consistent with the earlier ground-based observations. Finally, the theoretical shapes and the occurrence rates of the wave power spectral densities are studied. It is found that about 2 days after the storm s main phase on 4 May, mainly non-Gaussian shapes of power spectral densities are produced.

  12. Self-consistent Non-LTE Model of Infrared Molecular Emissions and Oxygen Dayglows in the Mesosphere and Lower Thermosphere

    NASA Technical Reports Server (NTRS)

    Feofilov, Artem G.; Yankovsky, Valentine A.; Pesnell, William D.; Kutepov, Alexander A.; Goldberg, Richard A.; Mauilova, Rada O.

    2007-01-01

    We present the new version of the ALI-ARMS (for Accelerated Lambda Iterations for Atmospheric Radiation and Molecular Spectra) model. The model allows simultaneous self-consistent calculating the non-LTE populations of the electronic-vibrational levels of the O3 and O2 photolysis products and vibrational level populations of CO2, N2,O2, O3, H2O, CO and other molecules with detailed accounting for the variety of the electronic-vibrational, vibrational-vibrational and vibrational-translational energy exchange processes. The model was used as the reference one for modeling the O2 dayglows and infrared molecular emissions for self-consistent diagnostics of the multi-channel space observations of MLT in the SABER experiment It also allows reevaluating the thermalization efficiency of the absorbed solar ultraviolet energy and infrared radiative cooling/heating of MLT by detailed accounting of the electronic-vibrational relaxation of excited photolysis products via the complex chain of collisional energy conversion processes down to the vibrational energy of optically active trace gas molecules.

  13. On the importance of thermodynamic self-consistency for calculating clusterlike pair correlations in hard-core double Yukawa fluids

    NASA Astrophysics Data System (ADS)

    Kim, Jung Min; Castañeda-Priego, Ramón; Liu, Yun; Wagner, Norman J.

    2011-02-01

    Understanding the mechanisms of clustering in colloids, nanoparticles, and proteins is of significant interest in material science and both chemical and pharmaceutical industries. Recently, using an integral equation theory formalism, Bomont et al. [J. Chem. Phys. 132, 184508 (2010)] studied theoretically the temperature dependence, at a fixed density, of the cluster formation in systems where particles interact with a hard-core double Yukawa potential composed of a short-range attraction and a long-range repulsion. In this paper, we provide evidence that the low-q peak in the static structure factor, frequently associated with the formation of clusters, is a common behavior in systems with competing interactions. In particular, we demonstrate that, based on a thermodynamic self-consistency criterion, accurate structural functions are obtained for different choices of closure relations. Moreover, we explore the dependence of the low-q peak on the particle number density, temperature, and potential parameters. Our findings indicate that enforcing thermodynamic self-consistency is the key factor to calculate both thermodynamic properties and static structure factors, including the low-q behavior, for colloidal dispersions with both attractive and repulsive interactions. Additionally, a simple analysis of the mean number of neighboring particles provides a qualitative description of some of the cluster features.

  14. Self-consistent field theory of collisions: Orbital equations with asymptotic sources and self-averaged potentials

    NASA Astrophysics Data System (ADS)

    Hahn, Y. K.

    2014-12-01

    The self-consistent field theory of collisions is formulated, incorporating the unique dynamics generated by the self-averaged potentials. The bound state Hartree-Fock approach is extended for the first time to scattering states, by properly resolving the principal difficulties of non-integrable continuum orbitals and imposing complex asymptotic conditions. The recently developed asymptotic source theory provides the natural theoretical basis, as the asymptotic conditions are completely transferred to the source terms and the new scattering function is made fullyintegrable. The scattering solutions can then be directly expressed in terms of bound state HF configurations, establishing the relationship between the bound and scattering state solutions. Alternatively, the integrable spin orbitals are generated by constructing the individual orbital equations that contain asymptotic sources and self-averaged potentials. However, the orbital energies are not determined by the equations, and a special channel energy fixing procedure is developed to secure the solutions. It is also shown that the variational construction of the orbital equations has intrinsic ambiguities that are generally associated with the self-consistent approach. On the other hand, when a small subset of open channels is included in the source term, the solutions are only partiallyintegrable, but the individual open channels can then be treated more simply by properly selecting the orbital energies. The configuration mixing and channel coupling are then necessary to complete the solution. The new theory improves the earlier continuum HF model.

  15. Bounds and self-consistent estimates for elastic constants of random polycrystals with hexagonal, trigonal, and tetragonal symmetries

    SciTech Connect

    Berryman, J G

    2004-09-16

    Peselnick, Meister, and Watt have developed rigorous methods for bounding elastic constants of random polycrystals based on the Hashin-Shtrikman variational principles. In particular, a fairly complex set of equations that amounts to an algorithm has been presented previously for finding the bounds on effective elastic moduli for polycrystals having hexagonal, trigonal, and tetragonal symmetries. The more analytical approach developed here, although based on the same ideas, results in a new set of compact formulas for all the cases considered. Once these formulas have been established, it is then straightforward to perform what could be considered an analytic continuation of the formulas (into the region of parameter space between the bounds) that can subsequently be used to provide self-consistent estimates for the elastic constants in all cases. These self-consistent estimates are easily shown (essentially by construction) to lie within the bounds for all the choices of crystal symmetry considered. Estimates obtained this way are quite comparable to those found by the Gubernatis and Krumhansl CPA (coherent potential approximation), but do not require any computations of scattering coefficients.

  16. Towards including finite orbit effects in self-consistent calculations of ion cyclotron heating in non-Maxwellian plasmas

    NASA Astrophysics Data System (ADS)

    Green, D. L.; Berry, L. A.; Jaeger, E. F.; Choi, M.

    2008-11-01

    In burning plasma experiments, the combination of neutral beam injection, high power electromagnetic heating and fusion products give rise to significant non-thermal ion populations. The resulting non-Maxwellian plasma affects ICRF wave propagation and heating. Self-consistent simulation of these effects has been achieved by an iterative coupling of a full-wave electromagnetic solver with a bounce-averaged Fokker-Planck (F-P) code under the zero banana width approximation. Investigating the effects of finite width particle orbits is possible by iterating with a Monte-Carlo calculation of the ion distribution function in place of the F-P code. Here we present progress towards coupling the all-orders global wave solver AORSA with the ORBIT-RF Monte-Carlo code. ORBIT-RF solves the Hamiltonian guiding center equations under coulomb collisions and ICRF quasi-linear (QL) heating taking the QL diffusion coefficients calculated from the AORSA wave fields as inputs. However, completing the self-consistent, time dependent calculation requires adapting the resulting Monte-Carlo particle list to a distribution function suitable for input to AORSA. Issues associated with calculating the differentiable bounce-averaged distribution function from discrete particle data will be discussed. E. F. Jaeger, et al., Phys. of Plasmas, 13, 056101-1, 2006

  17. A self-consistent plasticity theory for modeling the thermo-mechanical properties of irradiated FCC metallic polycrystals

    NASA Astrophysics Data System (ADS)

    Xiao, Xiazi; Song, Dingkun; Xue, Jianming; Chu, Haijian; Duan, Huiling

    2015-05-01

    A self-consistent theoretical framework is developed to model the thermo-mechanical behaviors of irradiated face-centered cubic (FCC) polycrystalline metals at low to intermediate homologous temperatures. In this model, both irradiation and temperature effects are considered at the grain level with the assist of a tensorial plasticity crystal model, and the elastic-visocoplastic self-consistent method is applied for the scale transition from individual grains to macroscopic polycrystals. The proposed theory is applied to analyze the mechanical behaviors of irradiated FCC copper. It is found that: (1) the numerical results match well with experimental data, which includes the comparison of results for single crystals under the load in different directions, and for polycrystals with the influences of irradiation and temperature. Therefore, the feasibility and accuracy of the present model are well demonstrated. (2) The main irradiation effects including irradiation hardening, post-yield softening, strain-hardening coefficient (SHC) dropping and the non-zero stress offset are all captured by the proposed model. (3) The increase of temperature results in the decrease of yield strength and SHC. The former is attributed to the weakened dislocation-defect interaction, while the latter is due to the temperature-strengthened dynamic recovery of dislocations through the thermally activated mechanism. The present model may provide a theoretical guide to predict the thermo-mechanical behaviors of irradiated FCC metals for the selection of structural materials in nuclear equipment.

  18. Toward fully self-consistent simulation of the interaction of E-Clouds and beams with WARP-POSINST

    SciTech Connect

    LLNL; Furman, M.A.; Furman, M.A.; Celata, C.M.; Sonnad, K.; Venturini, M.; Cohen, R.H.; Friedman, A.; Grote, D.P.; Vay, J.-L.

    2012-04-09

    To predict the evolution of electron clouds and their effect on the beam, the high energy physics community has relied so far on the complementary use of 'buildup' and 'single/multi-bunch instability' reduced descriptions. The former describes the evolution of electron clouds at a given location in the ring, or 'station', under the influence of prescribed beams and external fields [1], while the latter (sometimes also referred as the 'quasi-static' approximation [2]) follows the interaction between the beams and the electron clouds around the accelerator with prescribed initial distributions of electrons, assumed to be concentrated at a number of discrete 'stations' around the ring. Examples of single bunch instability codes include HEADTAIL [3], QuickPIC [4, 5], and PEHTS [6]. By contrast, a fully self-consistent approach, in which both the electron cloud and beam distributions evolve simultaneously under their mutual influence without any restriction on their relative motion, is required for modeling the interaction of high-intensity beams with electron clouds for heavy-ion beam-driven fusion and warm-dense matter science. This community has relied on the use of Particle-In-Cell (PIC) methods through the development and use of the WARP-POSINST code suite [1, 7, 8]. The development of novel numerical techniques (including adaptive mesh refinement, and a new 'drift-Lorentz' particle mover for tracking charged particles in magnetic fields using large time steps) has enabled the first application of WARP-POSINST to the fully self-consistent modeling of beams and electron clouds in high energy accelerators [9], albeit for only a few betatron oscillations. It was recently observed [10] that there exists a preferred frame of reference which minimizes the number of computer operations needed to simulate the interaction of relativistic objects. This opens the possibility of reducing the cost of fully self-consistent simulations for the interaction of ultrarelativistic

  19. Quasiparticles in the pseudogap Phase of Underdoped Cuprate

    SciTech Connect

    Yang, K.; Yang, H; Johnson, P; Rice, T; Zhang, F

    2009-01-01

    Recent angle-resolved photoemission (Yang H.-B. et al., Nature, 456 (2008) 77) and scanning tunneling microscopy (Kohsaka Y. et al., Nature, 454 (2008) 1072) measurements on underdoped cuprates have yielded new spectroscopic information on quasiparticles in the pseudogap phase. New features of the normal state such as particle-hole asymmetry, maxima in the energy dispersion, and accompanying drops in the spectral weight of quasiparticles agree with the ansatz of Yang et al. for the single-particle propagator in the pseudogap phase. The coherent quasiparticle dispersion and reduced asymmetry in the tunneling density of states in the superconducting state can also be described by this propagator.

  20. Coulomb correlation effects in the quasiparticle band structure of ferromagnetic rare-earth insulators

    NASA Astrophysics Data System (ADS)

    Nolting, W.; Borgiel, W.; Borstel, G.

    1988-05-01

    We present a method for calculating the temperature dependence of the electronic quasiparticle density of states (QDOS) of a ferromagnetic rare-earth insulator like EuO. Special attention is devoted to how the ``localized'' ferromagnetism manifests itself in x-ray photoemission and bremsstrahlung isochromat spectra. Our study includes the first six conduction bands of EuO (the first five are Eu 5d like, the sixth is mainly of Eu 6s character) as well as the rather flat 4f levels. The starting point is an extended d-f exchange model, the main parts of which are an exchange interaction between 4f moments and conduction electrons, a Coulomb repulsion between highly correlated 4f electrons, and a hybridization of 4f with conduction-band states. We use an exact T=0 relationship between spin-up quasiparticle energies and one-electron Bloch energies ɛm(k) for an optimal determination of the latter by performing a self-consistent, spin-polarized band-structure calculation based on density-functional theory. For finite temperatures the model is approximately solved by a many-body procedure. The QDOS exhibits a striking temperature dependence mainly due to the d-f exchange. Two 4f-like peaks appear in the spin-polarized QDOS, the low-energy one being occupied, the high-energy one being empty. The temperature dependence of the localized ferromagnetism appears in the QDOS as a temperature-dependent shift of spectral weight between the low- and the high-energy peak.

  1. Quasi-Particle Spectrum around a Single Vortex in Superconductors ---dx2-y2- Wave Case ---

    NASA Astrophysics Data System (ADS)

    Kato, M.; Maki, K.

    2002-05-01

    Making use of the Bogoliubov-de Gennes equation for d-wave superconductors, we study the quasi-particle spectrum and the vortex core structure of a single vortex in quasi-2D d-wave superconductors for small pFξ0, where pF is the Fermi momentum and ξ0=vF/Δ0 is the coherence length (hbar=1). Unlike in previous analyses, the electron density conservation is strictly imposed on our self-consistent solution. The eigenstates are classified as bound states and extended states. The bound states play an important role in the Kramer-Pesch effect in d-wave superconductors. Further, they should be accessible through T1 and the Knight shift in NMR.

  2. Pattern formation of a reaction-diffusion system with self-consistent flow in the amoeboid organism Physarum plasmodium

    NASA Astrophysics Data System (ADS)

    Yamada, Hiroyasu; Nakagaki, Toshiyuki; Ito, Masami

    1999-01-01

    The amoeboid organism, the plasmodium of Physarum polycephalum, moves by forming a spatiotemporal pattern of contraction oscillators. This biological system can be regarded as a reaction-diffusion system with spatial interaction via active flow of protoplasmic sol in the cell. We present a reaction-diffusion system with self-consistent flow on the basis of the physiological evidence that the flow is determined by contraction patterns in the plasmodium. Such a coupling of reaction, diffusion, and advection is characteristic of biological systems, and is expected to be related to control mechanisms of amoeboid behavior. Using weakly nonlinear analysis, we show that the envelope dynamics obeys the complex Ginzburg-Landau (CGL) equation when a bifurcation occurs at finite wave number. The flow term affects the nonlinear term of the CGL equation through the critical wave number squared. A physiological role of pattern formation with the flow is discussed.

  3. Extended Lagrangian Born-Oppenheimer molecular dynamics in the limit of vanishing self-consistent field optimization

    SciTech Connect

    Souvatzis, Petros; Niklasson, Anders M. N.

    2013-12-07

    We present an efficient general approach to first principles molecular dynamics simulations based on extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The reduction of the optimization requirement reduces the computational cost to a minimum, but without causing any significant loss of accuracy or long-term energy drift. The optimization-free first principles molecular dynamics requires only one single diagonalization per time step, but is still able to provide trajectories at the same level of accuracy as “exact,” fully converged, Born-Oppenheimer molecular dynamics simulations. The optimization-free limit of extended Lagrangian Born-Oppenheimer molecular dynamics therefore represents an ideal starting point for robust and efficient first principles quantum mechanical molecular dynamics simulations.

  4. CMAD: A Self-consistent Parallel Code to Simulate the Electron Cloud Build-up and Instabilities

    SciTech Connect

    Pivi, M.T.F.; /SLAC

    2007-11-07

    We present the features of CMAD, a newly developed self-consistent code which simulates both the electron cloud build-up and related beam instabilities. By means of parallel (Message Passing Interface - MPI) computation, the code tracks the beam in an existing (MAD-type) lattice and continuously resolves the interaction between the beam and the cloud at each element location, with different cloud distributions at each magnet location. The goal of CMAD is to simulate single- and coupled-bunch instability, allowing tune shift, dynamic aperture and frequency map analysis and the determination of the secondary electron yield instability threshold. The code is in its phase of development and benchmarking with existing codes. Preliminary results on benchmarking are presented in this paper.

  5. A Redshift Survey of IRAS Galaxies. II. Methods for Determining Self-consistent Velocity and Density Fields: Erratum

    NASA Astrophysics Data System (ADS)

    Yahil, Amos; Strauss, Michael A.; Davis, Marc; Huchra, John P.

    1991-11-01

    In the paper, "A Redshift Survey of IRAS Galaxies. II. Methods for Determining Self-consistent Velocity and Density Fields" by Amos Yahil, Michael A. Strauss, Marc Davis, and John P. Huchra (ApJ, 372,380 [1991]), Figures 14 and 15 were presented out of order, with their legends reversed. Thus, the figure at the bottom of page 391 is Figure 15, and should have the legend: "Fig. 15.-As in Fig. 13, for the method 3 results." The figure at the top of page 392 is Figure 14, and should have the legend: "Fig. 14.-Plot in Galactic coordinates of the quantity V_diff_ for galaxies within 3000 km s^-1^ of the LG. The symbol size is proportional to V_diff_ - 400 km s^-1^, which measures the deviation of the redshift- distance relation along the line of sight to that galaxy from pure Hubble flow."

  6. On the full exploitation of symmetry in periodic (as well as molecular) self-consistent-field ab initio calculations

    SciTech Connect

    Orlando, Roberto Erba, Alessandro; Dovesi, Roberto; De La Pierre, Marco; Zicovich-Wilson, Claudio M.

    2014-09-14

    Use of symmetry can dramatically reduce the computational cost (running time and memory allocation) of self-consistent-field ab initio calculations for molecular and crystalline systems. Crucial for running time is symmetry exploitation in the evaluation of one- and two-electron integrals, diagonalization of the Fock matrix at selected points in reciprocal space, reconstruction of the density matrix. As regards memory allocation, full square matrices (overlap, Fock, and density) in the Atomic Orbital (AO) basis are avoided and a direct transformation from the packed AO to the symmetry adapted crystalline orbital basis is performed, so that the largest matrix to be handled has the size of the largest sub-block in the latter basis. Quantitative examples, referring to the implementation in the CRYSTAL code, are given for high symmetry families of compounds such as carbon fullerenes and nanotubes.

  7. Elliptic Preconditioner for Accelerating the Self-Consistent Field Iteration in Kohn--Sham Density Functional Theory

    SciTech Connect

    Lin, Lin; Yang, Chao

    2013-10-28

    We discuss techniques for accelerating the self consistent field (SCF) iteration for solving the Kohn-Sham equations. These techniques are all based on constructing approximations to the inverse of the Jacobian associated with a fixed point map satisfied by the total potential. They can be viewed as preconditioners for a fixed point iteration. We point out different requirements for constructing preconditioners for insulating and metallic systems respectively, and discuss how to construct preconditioners to keep the convergence rate of the fixed point iteration independent of the size of the atomistic system. We propose a new preconditioner that can treat insulating and metallic system in a unified way. The new preconditioner, which we call an elliptic preconditioner, is constructed by solving an elliptic partial differential equation. The elliptic preconditioner is shown to be more effective in accelerating the convergence of a fixed point iteration than the existing approaches for large inhomogeneous systems at low temperature.

  8. Incidence of an electron layer on an electrically insulated body with an unsteady self-consistent positive charge

    SciTech Connect

    Fedorov, V. A.

    2010-07-15

    Dynamics of an electron layer incident on the surface of an electrically insulated conducting body with an unsteady self-consistent positive charge is investigated. At the initial instant, the electron velocity is directed toward the body and the electron layer is not adjacent to the body surface. One-dimensional plane, cylindrical, and spherical electron motions in vacuum and against the background of motionless ions and neutral particles are considered. Exact analytical solutions to the set of nonlinear plasma hydrodynamics equations with absorbing boundary conditions for electrons are obtained. The spatial and time dependences of the electric field, electron density, and electron velocity are found. The time evolution of the surface charge density is determined.

  9. Self-consistent modelling of the polar thermosphere and ionosphere to magnetospheric convection and precipitation (invited review)

    NASA Technical Reports Server (NTRS)

    Rees, D.; Fuller-Rowell, T.; Quegan, S.; Moffett, R.

    1986-01-01

    It has recently been demonstrated that the dramatic effects of plasma precipitation and convection on the composition and dynamics of the polar thermosphere and ionosphere include a number of strong interactive, or feedback, processes. To aid the evaluation of these feedback processes, a joint three dimensional time dependent global model of the Earth's thermosphere and ionosphere was developed in a collaboration between University College London and Sheffield University. This model includes self consistent coupling between the thermosphere and the ionosphere in the polar regions. Some of the major features in the polar ionosphere, which the initial simulations indicate are due to the strong coupling of ions and neutrals in the presence of strong electric fields and energetic electron precipitation are reviewed. The model is also able to simulate seasonal and Universal time variations in the polar thermosphere and ionospheric regions which are due to the variations of solar photoionization in specific geomagnetic regions such as the cusp and polar cap.

  10. Hierarchical expansion of the kinetic energy operator in curvilinear coordinates for the vibrational self-consistent field method.

    PubMed

    Strobusch, D; Scheurer, Ch

    2011-09-28

    A new hierarchical expansion of the kinetic energy operator in curvilinear coordinates is presented and modified vibrational self-consistent field (VSCF) equations are derived including all kinematic effects within the mean field approximation. The new concept for the kinetic energy operator is based on many-body expansions for all G matrix elements and its determinant. As a test application VSCF computations were performed on the H(2)O(2) molecule using an analytic potential (PCPSDE) and different hierarchical approximations for the kinetic energy operator. The results indicate that coordinate-dependent reduced masses account for the largest part of the kinetic energy. Neither kinematic couplings nor derivatives of the G matrix nor its determinant had significant effects on the VSCF energies. Only the zero-point value of the pseudopotential yields an offset to absolute energies which, however, is irrelevant for spectroscopic problems.

  11. Communication: Smoothing out excited-state dynamics: Analytical gradients for dynamically weighted complete active space self-consistent field

    SciTech Connect

    Glover, W. J.

    2014-11-07

    State averaged complete active space self-consistent field (SA-CASSCF) is a workhorse for determining the excited-state electronic structure of molecules, particularly for states with multireference character; however, the method suffers from known issues that have prevented its wider adoption. One issue is the presence of discontinuities in potential energy surfaces when a state that is not included in the state averaging crosses with one that is. In this communication I introduce a new dynamical weight with spline (DWS) scheme that mimics SA-CASSCF while removing energy discontinuities due to unweighted state crossings. In addition, analytical gradients for DWS-CASSCF (and other dynamically weighted schemes) are derived for the first time, enabling energy-conserving excited-state ab initio molecular dynamics in instances where SA-CASSCF fails.

  12. Self-consistent mean field theory studies of the thermodynamics and quantum spin dynamics of magnetic Skyrmions.

    PubMed

    Wieser, R

    2017-05-04

    A self-consistent mean field theory is introduced and used to investigate the thermodynamics and spin dynamics of an S  =  1 quantum spin system with a magnetic Skyrmion. The temperature dependence of the Skyrmion profile as well as the phase diagram are calculated. In addition, the spin dynamics of a magnetic Skyrmion is described by solving the time dependent Schrödinger equation with additional damping term. The Skyrmion annihilation process driven by an electric field is used to compare the trajectories of the quantum mechanical simulation with a semi-classical description for the spin expectation values using a differential equation similar to the classical Landau-Lifshitz-Gilbert equation.

  13. Solvent effects in time-dependent self-consistent field methods. II. Variational formulations and analytical gradients

    SciTech Connect

    Bjorgaard, J. A.; Velizhanin, K. A.; Tretiak, S.

    2015-08-06

    This study describes variational energy expressions and analytical excited state energy gradients for time-dependent self-consistent field methods with polarizable solvent effects. Linear response, vertical excitation, and state-specific solventmodels are examined. Enforcing a variational ground stateenergy expression in the state-specific model is found to reduce it to the vertical excitation model. Variational excited state energy expressions are then provided for the linear response and vertical excitation models and analytical gradients are formulated. Using semiempiricalmodel chemistry, the variational expressions are verified by numerical and analytical differentiation with respect to a static external electric field. Lastly, analytical gradients are further tested by performing microcanonical excited state molecular dynamics with p-nitroaniline.

  14. Solvent effects in time-dependent self-consistent field methods. II. Variational formulations and analytical gradients

    DOE PAGES

    Bjorgaard, J. A.; Velizhanin, K. A.; Tretiak, S.

    2015-08-06

    This study describes variational energy expressions and analytical excited state energy gradients for time-dependent self-consistent field methods with polarizable solvent effects. Linear response, vertical excitation, and state-specific solventmodels are examined. Enforcing a variational ground stateenergy expression in the state-specific model is found to reduce it to the vertical excitation model. Variational excited state energy expressions are then provided for the linear response and vertical excitation models and analytical gradients are formulated. Using semiempiricalmodel chemistry, the variational expressions are verified by numerical and analytical differentiation with respect to a static external electric field. Lastly, analytical gradients are further tested by performingmore » microcanonical excited state molecular dynamics with p-nitroaniline.« less

  15. Probing neutrino physics with a self-consistent treatment of the weak decoupling, nucleosynthesis, and photon decoupling epochs

    DOE PAGES

    Grohs, E.; Fuller, George M.; Kishimoto, Chad T.; ...

    2015-05-11

    In this study, we show that a self-consistent and coupled treatment of the weak decoupling, big bang nucleosynthesis, and photon decoupling epochs can be used to provide new insights and constraints on neutrino sector physics from high-precision measurements of light element abundances and Cosmic Microwave Background observables. Implications of beyond-standard-model physics in cosmology, especially within the neutrino sector, are assessed by comparing predictions against five observables: the baryon energy density, helium abundance, deuterium abundance, effective number of neutrinos, and sum of the light neutrino mass eigenstates. We give examples for constraints on dark radiation, neutrino rest mass, lepton numbers, andmore » scenarios for light and heavy sterile neutrinos.« less

  16. Fully self-consistent study of charge-exchange resonances and the impact on the symmetry energy parameters

    NASA Astrophysics Data System (ADS)

    Roca-Maza, X.; Cao, Li-Gang; Colò, G.; Sagawa, H.

    2016-10-01

    We have examined within a fully self-consistent theoretical framework the energy difference between the anti-analog giant dipole resonance (AGDR) and the isobaric analog state (IAS), EAGDR-EIAS , as an indicator of the neutron skin and of the density behavior of the symmetry energy. We have improved two specific points in our HF+RPA calculations: (1) the exchange term of the two-body Coulomb interaction is treated exactly without Slater approximation; and (2) the two-parameters spin-orbit interaction is treated in a consistent way within the energy density functional theory. The estimated values for the neutron skin in 208Pb and the slope parameter of symmetry energy are compared with previous analysis available in the literature.

  17. Initial Self-Consistent 3D Electron-Cloud Simulations of the LHC Beam with the Code WARP+POSINST

    SciTech Connect

    Vay, J; Furman, M A; Cohen, R H; Friedman, A; Grote, D P

    2005-10-11

    We present initial results for the self-consistent beam-cloud dynamics simulations for a sample LHC beam, using a newly developed set of modeling capability based on a merge [1] of the three-dimensional parallel Particle-In-Cell (PIC) accelerator code WARP [2] and the electron-cloud code POSINST [3]. Although the storage ring model we use as a test bed to contain the beam is much simpler and shorter than the LHC, its lattice elements are realistically modeled, as is the beam and the electron cloud dynamics. The simulated mechanisms for generation and absorption of the electrons at the walls are based on previously validated models available in POSINST [3, 4].

  18. Self-consistent mean flow description of the nonlinear saturation of the vortex shedding in the cylinder wake.

    PubMed

    Mantič-Lugo, Vladislav; Arratia, Cristóbal; Gallaire, François

    2014-08-22

    The Bénard-von Kármán vortex shedding instability in the wake of a cylinder is perhaps the best known example of a supercritical Hopf bifurcation in fluid dynamics. However, a simplified physical description that accurately accounts for the saturation amplitude of the instability is still missing. Here, we present a simple self-consistent model that provides a clear description of the saturation mechanism and quantitatively predicts the saturated amplitude and flow fields. The model is formally constructed by a set of coupled equations governing the mean flow together with its most unstable eigenmode with finite size. The saturation amplitude is determined by requiring the mean flow to be neutrally stable. Without requiring any input from numerical or experimental data, the resolution of the model provides a good prediction of the amplitude and frequency of the vortex shedding as well as the spatial structure of the mean flow and the Reynolds stress.

  19. Linear scaling solution of the time-dependent self-consistent-field equations with quasi-independent Rayleigh quotient iteration

    SciTech Connect

    Challacombe, Matt

    2009-01-01

    An algorithm for solution of the Time-Dependent Self-Consistent-Field (TD-SCF) equations is developed, based on dual solution channels for non-linear optimization of the Tsiper functional [J.Phys.B, 34 L401 (2001)]. This formulation poses the TD-SCF problem as two Rayleigh quotients, coupled weakly through biorthogonality. Convergence rates for the Random Phase Approximation (RPA) are found to be equivalent to the Tamm-Dancoff approximation (TDA). Moreover, the variational nature of the quotient is robust to approximation errors, allowing linear scaling solution to the bulk limit of the RPA matrix-eigenvalue and exchange operator problem for molecular wires with extended conjugation, including polyphenylene vinylene and the (4,3) nanotube.

  20. Self-consistent modeling of thermal and elastic properties of unconventional superconductor PuCoGa5

    NASA Astrophysics Data System (ADS)

    Filanovich, A. N.; Povzner, A. A.

    2016-06-01

    A self-consistent thermodynamic model of PuCoGa5 is developed, which for the first time takes into account the anharmonicity of both acoustic phonons, described within a Debye model, and optical phonons, considered in an Einstein approximation. Within the framework of this model, we have calculated the temperature dependencies of lattice contributions to heat capacity, bulk modulus, volumetric coefficient of thermal expansion, Debye and Einstein temperatures and their Grüneisen parameters. The electronic heat capacity of PuCoGa5 is obtained, which demonstrates an unusual temperature dependence with two maxima. In addition, it is shown that an abnormal low temperature behavior of the bulk modulus of PuCoGa5 is not caused by the effects of lattice anharmonicity and is most likely due to the valence fluctuations, which is in agreement with previous studies.