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Sample records for quasiparticle self-consistent gw

  1. Quasi-Particle Self-Consistent GW for Molecules.

    PubMed

    Kaplan, F; Harding, M E; Seiler, C; Weigend, F; Evers, F; van Setten, M J

    2016-06-14

    We present the formalism and implementation of quasi-particle self-consistent GW (qsGW) and eigenvalue only quasi-particle self-consistent GW (evGW) adapted to standard quantum chemistry packages. Our implementation is benchmarked against high-level quantum chemistry computations (coupled-cluster theory) and experimental results using a representative set of molecules. Furthermore, we compare the qsGW approach for five molecules relevant for organic photovoltaics to self-consistent GW results (scGW) and analyze the effects of the self-consistency on the ground state density by comparing calculated dipole moments to their experimental values. We show that qsGW makes a significant improvement over conventional G0W0 and that partially self-consistent flavors (in particular evGW) can be excellent alternatives. PMID:27168352

  2. Electronic structure from relativistic quasiparticle self-consistent GW calculations

    NASA Astrophysics Data System (ADS)

    Blügel, Stefan

    Most theoretical studies of topological insulators (TIs) are based on tight-binding descriptions and density functional theory (DFT). But recently, many-body calculations within the GW approximation attract much attention in the study of these materials. We present an implementation of the quasiparticle self-consistent (QS) GW method where the spin-orbit coupling (SOC) is fully taken into account in each iteration rather than added a posteriori. Within the all-electron FLAPW formalism, we show DFT, one-shot GW , and QS GW calculations for several, well-known TIs. We present a comparison of the calculations to photoemission spectroscopy and show that the GW corrected bands agree much better with experiment. For example, we show that Bi2Se3 is a direct gap semiconductor, in contrast to what was believed for many years by interpreting experimental results on the basis of DFT and that small strains in Bi can lead to a semimetal-to-semiconductor or trivial-to-topological transitions. Quasiparticle calculations for low-dimensional systems are still very demanding. In order to study the topological surface states with an approach based on GW , we use Wannier functions to construct a Hamiltonian that reproduces the many-body band structure of the bulk, and that is used to construct a slab Hamiltonian. With this approach, we discuss the effect of quasiparticle corrections on the surface states of TIs and on the interaction between bulk and surface states Work was funded by the Virtual Institute for Topological Insulators of the Helmholtz Association and carried out in collaboration with Irene Aguilera, Gustav Bihlmayer, and Christoph Friedrich.

  3. A Plane-Wave Implementation of Quasiparticle Self-Consistent GW (QSGW)

    NASA Astrophysics Data System (ADS)

    Vigil Currey, Derek; Deslippe, Jack; Louie, Steven G.

    2011-03-01

    The use of GW techniques in calculating the quasiparticle properties of certain classes of materials, e.g. complex oxides, is sometimes hindered by the poor mean-field starting point that density functional theory (DFT) within standard Kohn-Sham implementations provides. There has been considerable effort in the community to improve upon the mean-field starting point for a broad range of materials. A recently proposed method, the quasiparticle self-consistent GW (QSGW) method, employs a process in which a mean-field exchange-correlation potential is approximated from and updated self-consistently using the self-energy operator from previous iteration GW calculations. We present an implementation of this method in a plane-wave basis, and discuss its accuracy, computational cost, and physical implications for a variety of semiconducting materials. This work was supported by NSF Grant No. DMR10-1006184 and U.S. DOE Contract No. DE-AC02-05CH11231. Computational resources were provided by NERSC. Derek Vigil Currey acknowledges funding from UC-Berkeley through the Chancellor's Fellowship.

  4. Quasiparticle self-consistent GW calculation of Sr2RuO4 and SrRuO3

    NASA Astrophysics Data System (ADS)

    Ryee, Siheon; Jang, Seung Woo; Kino, Hiori; Kotani, Takao; Han, Myung Joon

    2016-02-01

    By using quasiparticle self-consistent GW calculations, we reexamined the electronic structure of Sr2RuO4 and SrRuO3. Our calculations show that the correlation effects beyond the conventional local density approximation and generalized gradient approximation are reasonably well captured by the QSGW self-energy without any ad hoc parameter or any ambiguity related to the double-counting and the downfolding issues. While spectral weight transfer to the lower and upper Hubbard band is not observed, the noticeable bandwidth reduction and effective-mass enhancement are obtained. Important features in the electronic structures that have been debated over the last decades such as the photoemission spectra at around -3 eV in Sr2RuO4 and the half-metallicity for SrRuO3 are discussed in the light of our QSGW results and in comparison with the previous studies. The promising aspects of QSGW are highlighted as a first-principles calculation method to describe the moderately correlated 4 d transition-metal oxides along with the limitations of QSGW.

  5. 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.

  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 PAGESBeta

    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. Effects of self-consistency and plasmon-pole models on GW calculations for closed-shell molecules

    NASA Astrophysics Data System (ADS)

    Lischner, Johannes; Sharifzadeh, Sahar; Deslippe, Jack; Neaton, Jeffrey B.; Louie, Steven G.

    2014-09-01

    We present theoretical calculations of quasiparticle energies in closed-shell molecules using the GW method. We compare three different approaches: a full-frequency G0W0 (FF-G0W0) method with density functional theory (DFT-PBE) used as a starting mean field; a full-frequency GW0 (FF-GW0) method where the interacting Green's function is approximated by replacing the DFT energies with self-consistent quasiparticle energies or Hartree-Fock energies; and a G0W0 method with a Hybertsen-Louie generalized plasmon-pole model (HL GPP-G0W0). While the latter two methods lead to good agreement with experimental ionization potentials and electron affinities for methane, ozone, and beryllium oxide molecules, FF-G0W0 results can differ by more than one electron volt from experiment. We trace this failure of the FF-G0W0 method to the occurrence of incorrect self-energy poles describing shake-up processes in the vicinity of the quasiparticle energies.

  10. Thermodynamic properties of hot nuclei within the self-consistent quasiparticle random-phase approximation

    SciTech Connect

    Hung, N. Quang; Dang, N. Dinh

    2010-10-15

    The thermodynamic properties of hot nuclei are described within the canonical and microcanonical ensemble approaches. These approaches are derived based on the solutions of the BCS and self-consistent quasiparticle random-phase approximation at zero temperature embedded into the canonical and microcanonical ensembles. The results obtained agree well with the recent data extracted from experimental level densities by the Oslo group for {sup 94}Mo, {sup 98}Mo, {sup 162}Dy, and {sup 172}Yb nuclei.

  11. Linear response of light deformed nuclei investigated by self-consistent quasiparticle random-phase approximation

    SciTech Connect

    Losa, C.; Doessing, T.; Pastore, A.; Vigezzi, E.; Broglia, R. A.

    2010-06-15

    We present a calculation of the properties of vibrational states in deformed, axially-symmetric even-even nuclei, within the framework of a fully self-consistent quasiparticle random phase approximation (QRPA). The same Skyrme energy density and density-dependent pairing functionals are used to calculate the mean field and the residual interaction in the particle-hole and particle-particle channels. We have tested our software in the case of spherical nuclei against fully self-consistent calculations published in the literature, finding excellent agreement. We investigate the consequences of neglecting the spin-orbit and Coulomb residual interactions in QRPA. Furthermore we discuss the improvement obtained in the QRPA result associated with the removal of spurious modes. Isoscalar and isovector responses in the deformed {sup 24-26}Mg, {sup 34}Mg isotopes are presented and compared to experimental findings.

  12. Quasiparticle electronic structure of Bi2Se3 via the sc-COHSEX+GW approach

    NASA Astrophysics Data System (ADS)

    Barker, Bradford A.; Deslippe, Jack; Yazyev, Oleg; Louie, Steven G.

    We present ab initio calculations of the quasiparticle electronic band structure of three-dimensional topological insulator material Bi2Se3 using the full spinor GW approach. The mean-field is initially computed at the DFT level in the local density approximation (LDA) using fully-relativistic pseudopotentials. We then improve the mean-field electronic structure by solving Dyson's equation in the static COHSEX approximation, self-consistently updating the eigenvalues, eigenvectors, and dielectric screening. After a few iterations, we then perform a GW calculation to determine the quasiparticle energies. We compare our calculated results to experimental values of the band gaps and effective masses. This work was supported by NSF Grant No. DMR15-1508412 and U.S. DOE under Contract No. DE-AC02-05CH11231. Computational resources have been provided by DOE at LBNL's NERSC facility and the NSF through XSEDE resources at NICS.

  13. 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.

  14. A self-consistent GW approach to the van der Waals potential for a helium dimer.

    PubMed

    Shoji, Toru; Kuwahara, Riichi; Ono, Shota; Ohno, Kaoru

    2016-09-21

    van der Waals interaction between two helium (He) atoms is studied by calculating the total energy as a function of the He-He distance within the self-consistent GW approximation, which is expected to behave correctly in the long wavelength limit. In the Born-Oppenheimer (BO) approximation, the pair potential curve has its minimum value at 2.87 Å, which is somewhat larger than the local density approximation result, 2.40 Å, and is closer to previous quantum chemistry results. The expectation value for the interatomic distance, calculated by solving the Schrödinger equation for the two nuclei problem using the BO potential energy curve, is 30 Å, which is smaller but of the same order as previous experimental and theoretical results. PMID:27538378

  15. GW correlation effects on plutonium quasiparticle energies: changes in crystal-field splitting

    SciTech Connect

    Albers, Robert C; Chantis, Athanasios N; Svane, Axel; Christensen, Niels E

    2009-01-01

    We present results for the electronic structure of plutonium by using a recently developed quasiparticle self-consistent GW method (QSGW). We consider a paramagnetic solution without spin-orbit interaction as a function of volume for the face-centered cubic (fcc) unit cell. We span unit-cell volumes ranging from 10% greater than the equilibrium volume of the 8 phase to 90 % of the equivalent for the a phase of Pu. The self-consistent GW quasiparticle energies are compared to those obtained within the Local Density Approximation (LDA). The goal of the calculations is to understand systematic trends in the effects of electronic correlations on the quasiparticle energy bands of Pu as a function of the localization of the J orbitals. We show that correlation effects narrow the f bands in two significantly different ways. Besides the expected narrowing of individual f bands (flatter dispersion), we find that an even more significant effect on the f bands is a decrease in the crystal-field splitting of the different bands

  16. 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.

  17. Quasiparticle electronic structure of bismuth telluride in the GW approximation

    NASA Astrophysics Data System (ADS)

    Kioupakis, Emmanouil; Tiago, Murilo L.; Louie, Steven G.

    2010-12-01

    The quasiparticle band structure of bismuth telluride (Bi2Te3) , an important thermoelectric material that exhibits topologically insulating surface states, is calculated from first principles in the GW approximation. The quasiparticle energies are evaluated in fine detail in the first Brillouin zone using a Wannier-function interpolation method, allowing the accurate determination of the location of the band extrema (which is in the mirror plane) as well as the values of the quasiparticle band gap (0.17 eV) and effective-mass tensors. Spin-orbit interaction effects were included. The valence band exhibits two distinct maxima in the mirror plane that differ by just 1 meV, giving rise to one direct and one indirect band gap of very similar magnitude. The effective-mass tensors are in reasonable agreement with experiment. The Wannier interpolation coefficients can be used for the tight-binding parametrization of the band structure. Our work elucidates the electronic structure of Bi2Te3 and sheds light on its exceptional thermoelectric and topologically insulating properties.

  18. GW Γ + Bethe-Salpeter equation approach for photoabsorption spectra: Importance of self-consistent GW Γ calculations in small atomic systems

    NASA Astrophysics Data System (ADS)

    Kuwahara, Riichi; Noguchi, Yoshifumi; Ohno, Kaoru

    2016-09-01

    The self-consistent GW Γ method satisfies the Ward-Takahashi identity (i.e., the gauge invariance or the local charge continuity) for arbitrary energy (ω ) and momentum (q ) transfers. Its self-consistent first-principles treatment of the vertex Γ =Γv or ΓW is possible to first order in the bare (v ) or dynamically screened (W ) Coulomb interaction. It is developed within a linearized scheme and combined with the Bethe-Salpeter equation (BSE) to accurately calculate photoabsorption spectra (PAS) and photoemission (or inverse photoemission) spectra (PES) simultaneously. The method greatly improves the PAS of Na, Na3, B2, and C2H2 calculated using the standard one-shot G0W0+BSE method that results in significantly redshifted PAS by 0.8-3.1 eV, although the PES are well reproduced already in G0W0 .

  19. Many-body quasiparticle spectrum of Co-doped ZnO: A GW perspective

    NASA Astrophysics Data System (ADS)

    Sarsari, I. Abdolhosseini; Pemmaraju, C. D.; Salamati, Hadi; Sanvito, S.

    2013-06-01

    In transition-metal-doped ZnO the energy position of the dopant 3d states relative to the host conduction and valence bands determines the possibility of long-range ferromagnetism. Density functional theory (DFT) can estimate the energy position of the Co-3d states in ZnO:Co but this depends substantially upon the choice of exchange-correlation functional. In this paper we investigate many-body GW corrections built on top of DFT+U and hybrid-DFT ground states to provide a theoretical benchmark for the quasiparticle energies in wurtzite ZnO:Co. Both single shot G0W0 as well as partially self-consistent GW0, wherein the wave functions are held fixed at the DFT level but the eigenvalues in G are iterated, are considered. The predicted energy position of the minority spin Co-t2 states is 3.0-3.6 eV above the ZnO conduction band minimum, which is closer to hybrid-DFT-based estimates. Such an electronic structure does not support carrier-mediated long-range ferromagnetism at achievable n-doping conditions.

  20. Breaking the Theoretical Scaling Limit for Predicting Quasiparticle Energies: The Stochastic GW Approach

    NASA Astrophysics Data System (ADS)

    Neuhauser, Daniel; Gao, Yi; Arntsen, Christopher; Karshenas, Cyrus; Rabani, Eran; Baer, Roi

    2014-08-01

    We develop a formalism to calculate the quasiparticle energy within the GW many-body perturbation correction to the density functional theory. The occupied and virtual orbitals of the Kohn-Sham Hamiltonian are replaced by stochastic orbitals used to evaluate the Green function G, the polarization potential W, and, thereby, the GW self-energy. The stochastic GW (sGW) formalism relies on novel theoretical concepts such as stochastic time-dependent Hartree propagation, stochastic matrix compression, and spatial or temporal stochastic decoupling techniques. Beyond the theoretical interest, the formalism enables linear scaling GW calculations breaking the theoretical scaling limit for GW as well as circumventing the need for energy cutoff approximations. We illustrate the method for silicon nanocrystals of varying sizes with Ne>3000 electrons.

  1. Screening and nonlocal correlations in the extended Hubbard model from self-consistent combined GW and dynamical mean field theory

    NASA Astrophysics Data System (ADS)

    Ayral, Thomas; Biermann, Silke; Werner, Philipp

    2013-03-01

    We describe a recent implementation of the combined GW and dynamical mean field method (GW+DMFT) for the two-dimensional Hubbard model with onsite and nearest-neighbor repulsion. We clarify the relation of the GW+DMFT scheme to alternative approaches in the literature, and discuss the corresponding approximations to the free-energy functional of the model. Furthermore, we describe a numerically exact technique for the solution of the GW+DMFT equations, namely, the hybridization expansion continuous-time algorithm for impurity models with retarded interactions. We compute the low-temperature phase diagram of the half-filled extended Hubbard model, addressing the metal-insulator transition at small intersite interactions and the transition to a charge-ordered state for stronger intersite repulsions. GW+DMFT introduces a nontrivial momentum dependence into the many-body self-energy and polarization. We find that the charge fluctuations included in the present approach have a larger impact on the latter than on the former. Finally, within the GW+DMFT framework, as in extended DMFT, the intersite repulsion translates into a frequency dependence of the local effective interaction. We analyze this dependence and show how it affects the local spectral function.

  2. Comparing quasiparticle GW+DMFT and LDA+DMFT for the test bed material SrVO3

    NASA Astrophysics Data System (ADS)

    Taranto, C.; Kaltak, M.; Parragh, N.; Sangiovanni, G.; Kresse, G.; Toschi, A.; Held, K.

    2013-10-01

    We have implemented the quasiparticle GW+dynamical mean field theory (DMFT) approach in the Vienna ab initio simulation package. To this end, a quasiparticle Hermitization of the G0W0 self-energy a lá Kotani-Schilfgaarde is employed, and the interaction values are obtained from the locally unscreened random phase approximation (RPA) using a projection onto Wannier orbitals. We compare quasiparticle GW+DMFT and local density approximation (LDA)+DMFT against each other and against experiment for SrVO3. We observe a partial compensation of stronger electronic correlations due to the reduced GW bandwidth and weaker correlations due to a larger screening of the RPA interaction, so that the obtained spectra are quite similar and agree well with experiment. Noteworthy, the quasiparticle GW+DMFT better reproduces the position of the lower Hubbard side band.

  3. Ab initio Sternheimer-GW method for quasiparticle calculations using plane waves

    NASA Astrophysics Data System (ADS)

    Lambert, Henry; Giustino, Feliciano

    2013-08-01

    We report on the extension and implementation of the Sternheimer-GW method introduced by Giustino [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.81.115105 81, 115105 (2010)] to the case of first-principles pseudopotential calculations based on a plane-waves basis. The Sternheimer-GW method consists of calculating the GW self-energy operator without resorting to the standard expansion over unoccupied Kohn-Sham electronic states. The Green's function is calculated by solving linear systems for frequencies along the real axis. The screened Coulomb interaction is calculated for frequencies along the imaginary axis by using the Sternheimer equation. Analytic continuation to the real axis is performed using Padé approximants. The generalized plasmon-pole approximation is avoided by performing explicit calculations at multiple frequencies using Frommer's multishift solver. We demonstrate our methodology by reporting tests on common insulators and semiconductors, including Si, diamond, LiCl, and SiC. Our calculated quasiparticle energies are in agreement with the results of fully converged calculations based on the sum-over-states approach. As the Sternheimer-GW method yields the complete self-energy Σ(r,r',ω) and not only its expectation values on Kohn-Sham states, this work opens the way to nonperturbative GW calculations and to direct calculations of spectral functions for angle-resolved photoemission spectroscopy. As an example of the capabilities of the method we calculate the G0W0 spectral functions of silicon and diamond.

  4. Self-consistent Calculation of the Quasi-particle Energy Spectrum of Sodium using the Correlated Hartree Fock Method

    NASA Astrophysics Data System (ADS)

    Ishihara, Takamitsu; Yamagami, Hiroshi; Yasuhara, Hiroshi

    2001-12-01

    Self-consistent band calculation of sodium is performed in the correlated Hartree Fock scheme proposed by Yasuhara and Takada [Phys. Rev. B 43 (1991) 7200], which contains information on the effective mass of the electron liquid in the form of a nonlocal spin-parallel potential, and the remaining information of the self-energy operator in the form of a local potential. The bandwidth of occupied states is somewhat increased under the influence of the non-local spin-parallel potential, compared with the free electron value. No significant difference can be found in the distortion of the Fermi surface between the present theory and the LDA.

  5. 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.

  6. Quasiparticle and Optical Properties of Mono- and Bi-layer SnS2: A First-Principles GW and GW +BSE Study

    NASA Astrophysics Data System (ADS)

    Wu, Meng; Qiu, Diana; Louie, Steven G.

    2015-03-01

    Unlike most semiconducting transition metal dichalcogenides, SnS2, another layered metal dichalcogenide, is calculated within density functional theory to be an indirect bandgap semiconductor in both its bulk and monolayer forms. Experimental characterization of mono- and bi-layer SnS2 has been performed, but the details of its quasiparticle and excitonic properties remain unclear. Thus, we employ ab initio GW and GW +BSE calculations to study the quasiparticle band structure and optical absorption spectrum, respectively, of mono- and bi-layer SnS2 with spin-orbit coupling included throughout the calculations. We further investigate the character of excitonic states contributing to the optical spectrum. This work was supported by NSF Grant No. DMR10-1006184 and the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Computational resources have been provided by DOE at Lawrence Berkeley National Laboratory's NERSC facility.

  7. 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.

  8. Quasi-particle band structure of potassium-doped few-layer black phosphorus with GW approximation

    NASA Astrophysics Data System (ADS)

    Kim, Han-Gyu; Baik, Seung Su; Choi, Hyoung Joon

    We calculate the quasi-particle band structure of pristine and potassium-doped black phosphorus (BP) by using the GW approximation. We obtain band gaps of pristine bulk and few-layer BP and compare them with the result of the density functional calculations and experimental measurements. For potassium-doped cases, we calculate the electronic band structure of potassium-doped few-layer BPs with various doping densities. We obtain the critical doping density for the band-gap closing, and the energy-band dispersions when the band gap is inverted. We discuss Dirac semimetal properties of doped few-layer BPs obtained by the GW approximation. This work was supported by NRF of Korea (Grant No. 2011-0018306) and KISTI supercomputing center (Project No. KSC-2015-C3-039).

  9. On the combined use of GW approximation and cumulant expansion in the calculations of quasiparticle spectra: The paradigm of Si valence bands

    NASA Astrophysics Data System (ADS)

    Gumhalter, Branko; Kovač, Vjekoslav; Caruso, Fabio; Lambert, Henry; Giustino, Feliciano

    2016-07-01

    Since the earliest implementations of the various GW approximations and cumulant expansion in the calculations of quasiparticle propagators and spectra, several attempts have been made to combine the advantageous properties and results of these two theoretical approaches. While the GW-plus-cumulant approach has proven successful in interpreting photoemission spectroscopy data in solids, the formal connection between the two methods has not been investigated in detail. By introducing a general bijective integral representation of the cumulants, we can rigorously identify at which point these two approximations can be connected for the paradigmatic model of quasiparticle interaction with the dielectric response of the system that has been extensively exploited in recent interpretations of the satellite structures in photoelectron spectra. We establish a protocol for consistent practical implementation of the thus established GW +cumulant scheme and illustrate it by comprehensive state-of-the-art first-principles calculations of intrinsic angle-resolved photoemission spectra from Si valence bands.

  10. 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.

  11. 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.

  12. Maximally localized Wannier functions in LaMnO3 within PBE + U, hybrid functionals and partially self-consistent GW: an efficient route to construct ab initio tight-binding parameters for eg perovskites

    NASA Astrophysics Data System (ADS)

    Franchini, C.; Kováčik, R.; Marsman, M.; Sathyanarayana Murthy, S.; He, J.; Ederer, C.; Kresse, G.

    2012-06-01

    Using the newly developed VASP2WANNIER90 interface we have constructed maximally localized Wannier functions (MLWFs) for the eg states of the prototypical Jahn-Teller magnetic perovskite LaMnO3 at different levels of approximation for the exchange-correlation kernel. These include conventional density functional theory (DFT) with and without the additional on-site Hubbard U term, hybrid DFT and partially self-consistent GW. By suitably mapping the MLWFs onto an effective eg tight-binding (TB) Hamiltonian we have computed a complete set of TB parameters which should serve as guidance for more elaborate treatments of correlation effects in effective Hamiltonian-based approaches. The method-dependent changes of the calculated TB parameters and their interplay with the electron-electron (el-el) interaction term are discussed and interpreted. We discuss two alternative model parameterizations: one in which the effects of the el-el interaction are implicitly incorporated in the otherwise ‘noninteracting’ TB parameters and a second where we include an explicit mean-field el-el interaction term in the TB Hamiltonian. Both models yield a set of tabulated TB parameters which provide the band dispersion in excellent agreement with the underlying ab initio and MLWF bands.

  13. 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.

  14. Combination of Hedin's GW and dynamical mean-field theory tested on H2 molecule

    NASA Astrophysics Data System (ADS)

    Lee, Juho; Haule, Kristjan

    We compare various flavors of `` GW +DMFT'' approach with LDA+DMFT for the simplest strongly correlated system, the H2 molecule. The following GW +DMFT methodologies are compared: (i) the fully self-consistent GW+DMFT, (ii) the quasi-particle self-consistent QS-GW+DMFT with dynamic double-counting, (iii) QS-GW+DMFT with static double-counting schemes. We found that fully self-consistent GW +DMFT with exact double-counting yields very precise spectra around equilibrium H-H distance, as well as reasonable total energy (comparable to LDA+DMFT). However, this scheme breaks down in the correlated regime due to causality violation. The QS-GW+DMFT approaches, which are not derivable from a functional, yield similar spectra as full GW+DMFT near equilibrium distance, and in static double-counting schemes, can also be extended into correlated regime. However, the total energy of these approaches is much worse than the total energy of LDA+DMFT. In summary, this toy model of correlated physics suggests that QS-GW+DMFT with constant double-counting should give accurate predictions of spectra, but not total energy, while LDA+DMFT gives very precise total energy, but somewhat less precise spectra.

  15. 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).

  16. Quasiparticle band structure of vanadium dioxide.

    PubMed

    Sakuma, R; Miyake, T; Aryasetiawan, F

    2009-02-11

    Vanadium dioxide is insulating below 340 K in experiments, whereas the band structure calculated in the local density approximation (LDA) is gapless. We study the self-energy effects using the ab initio GW method. We found that the self-energy depends strongly on the energy, and proper treatment of the dynamical effect is essential for getting precise quasiparticle energies. Off-diagonal matrix elements in the Kohn-Sham basis are also important for disentangling bands. Inclusion of the two effects opens up a direct gap. Our results also suggest that one-shot GW on top of LDA is not enough, and the impact of self-consistency is significant.

  17. First Principles Real-Space GW+BSE Calculations for Confined Systems

    NASA Astrophysics Data System (ADS)

    Hung, Linda; Ogut, Serdar; Souto, Jaime; Lee, Alex; Lena, Charles; Chelikowsky, James R.; Jornada, Felipe H. Da; Louie, Steven G.

    2014-03-01

    We investigate the performance of various levels of GW theories for electronic excitations as well as the resulting solutions of the Bethe-Salpeter-Equation (BSE) for optical excitations in a wide range of confined systems including atoms, ions, diatomic molecules, and organic molecules relevant for photovoltaic applications. Starting with solutions of the Kohn-Sham equations for ground state properties computed via the real-space ab initio pseudopotential code PARSEC, we perform the GW calculations in the space of single-particle transitions at various levels of theory, and compare the results with photoemission data. The levels of theory include such approximations as G0W0 with RPA screening, G0Wf that includes vertex corrections through the use of a dielectric screening within the time-dependent-local-density approximation (TDLDA), the GW0 , and the self-consistent GW. The resulting quasiparticle energies and wave functions from the GW calculations are used to solve the BSE for optical excitations, which are then compared with experiments and results from calculations performed within the TDLDA. The effects of the vertex corrections, self-consistency in GW, and core-valence partitioning are discussed. Supported by DOE Grant No. DE-SC0001853.

  18. Improved quasiparticle wave functions and mean field for G0W0 calculations: Initialization with the COHSEX operator

    NASA Astrophysics Data System (ADS)

    Jain, Manish; Deslippe, Jack; Samsonidze, Georgy; Cohen, Marvin L.; Chelikowsky, James R.; Louie, Steven G.

    2014-09-01

    The GW approximation to the electron self-energy has become a standard method for ab initio calculation of excited-state properties of condensed-matter systems. In many calculations, the GW self-energy operator, Σ, is taken to be diagonal in the density functional theory (DFT) Kohn-Sham basis within the G0W0 scheme. However, there are known situations in which this diagonal G0W0 approximation starting from DFT is inadequate. We present two schemes to resolve such problems. The first, which we called sc -COHSEX+GW, involves construction of an improved mean field using the static limit of GW, known as COHSEX (Coulomb hole and screened exchange), which is significantly simpler to treat than GW. In this scheme, frequency-dependent self energy Σ (ω), is constructed and taken to be diagonal in the COHSEX orbitals after the system is solved self-consistently within this formalism. The second method is called off diagonal-COHSEX GW (od -COHSEX+GW). In this method, one does not self-consistently change the mean-field starting point but diagonalizes the COHSEX Hamiltonian within the Kohn-Sham basis to obtain quasiparticle wave functions and uses the resulting orbitals to construct the GW Σ in the diagonal form. We apply both methods to a molecular system, silane, and to two bulk systems, Si and Ge under pressure. For silane, both methods give good quasiparticle wave functions and energies. Both methods give good band gaps for bulk silicon and maintain good agreement with experiment. Further, the sc -COHSEX+GW method solves the qualitatively incorrect DFT mean-field starting point (having a band overlap) in bulk Ge under pressure.

  19. GW-1000. GW Pharmaceuticals.

    PubMed

    Smith, Paul F

    2004-07-01

    GW Pharmaceuticals is developing GW-1000 (Sativex), a narrow ratio delta9-tetrahydrocannabinol:cannabidiol product for the potential treatment of multiple sclerosis, spinal cord injury, neurogenic pain and peripheral neuropathy. In March 2003, the company filed for approval for the treatment of MS with the UK Medicines Control Agency, and in May 2004, filed for new drug submission with Health Canada. PMID:15298072

  20. Self-consistent flattened isochrones

    NASA Astrophysics Data System (ADS)

    Binney, James

    2014-05-01

    We present a family of self-consistent axisymmetric stellar systems that have analytic distribution functions (DFs) of the form f(J), so they depend on three integrals of motion and have triaxial velocity ellipsoids. The models, which are generalizations of Hénon's isochrone sphere, have four dimensionless parameters, two determining the part of the DF that is even in Lz and two determining the odd part of the DF (which determines the azimuthal velocity distribution). Outside their cores, the velocity ellipsoids of all models tend to point to the model's centre, and we argue that this behaviour is generic, so near the symmetry axis of a flattened model, the long axis of the velocity ellipsoid is naturally aligned with the symmetry axis and not perpendicular to it as in many published dynamical models of well-studied galaxies. By varying one of the DF parameters, the intensity of rotation can be increased from zero up to a maximum value set by the requirement that the DF be non-negative. Since angle-action coordinates are easily computed for these models, they are ideally suited for perturbative treatments and stability analysis. They can also be used to choose initial conditions for an N-body model that starts in perfect equilibrium, and to model observations of early-type galaxies. The modelling technique introduced here is readily extended to different radial density profiles, more complex kinematics and multicomponent systems. A number of important technical issues surrounding the determination of the models' observable properties are explained in two appendices.

  1. 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.

  2. 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

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Self-consistent gravitational self-force

    NASA Astrophysics Data System (ADS)

    Pound, Adam

    2010-01-01

    I review the problem of motion for small bodies in general relativity, with an emphasis on developing a self-consistent treatment of the gravitational self-force. An analysis of the various derivations extant in the literature leads me to formulate an asymptotic expansion in which the metric is expanded while a representative worldline is held fixed. I discuss the utility of this expansion for both exact point particles and asymptotically small bodies, contrasting it with a regular expansion in which both the metric and the worldline are expanded. Based on these preliminary analyses, I present a general method of deriving self-consistent equations of motion for arbitrarily structured (sufficiently compact) small bodies. My method utilizes two expansions: an inner expansion that keeps the size of the body fixed, and an outer expansion that lets the body shrink while holding its worldline fixed. By imposing the Lorenz gauge, I express the global solution to the Einstein equation in the outer expansion in terms of an integral over a worldtube of small radius surrounding the body. Appropriate boundary data on the tube are determined from a local-in-space expansion in a buffer region where both the inner and outer expansions are valid. This buffer-region expansion also results in an expression for the self-force in terms of irreducible pieces of the metric perturbation on the worldline. Based on the global solution, these pieces of the perturbation can be written in terms of a tail integral over the body’s past history. This approach can be applied at any order to obtain a self-consistent approximation that is valid on long time scales, both near and far from the small body. I conclude by discussing possible extensions of my method and comparing it to alternative approaches.

  6. 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.

  7. Self-Consistent Scattering and Transport Calculations

    NASA Astrophysics Data System (ADS)

    Hansen, S. B.; Grabowski, P. E.

    2015-11-01

    An average-atom model with ion correlations provides a compact and complete description of atomic-scale physics in dense, finite-temperature plasmas. The self-consistent ionic and electronic distributions from the model enable calculation of x-ray scattering signals and conductivities for material across a wide range of temperatures and densities. We propose a definition for the bound electronic states that ensures smooth behavior of these measurable properties under pressure ionization and compare the predictions of this model with those of less consistent models for Be, C, Al, and Fe. SNL is a multi-program laboratory managed and operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp, for the U.S. DoE NNSA under contract DE-AC04-94AL85000. This work was supported by DoE OFES Early Career grant FWP-14-017426.

  8. 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.

  9. Plasma diffusion in self-consistent fluctuations

    SciTech Connect

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

    2011-10-15

    The problem of particle diffusion in position space, as a consequence of electromagnetic 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 (resulting from an agyrotropic initial setting) is stationary, wide band white noise, and associated to Gaussian probability distribution function for the magnetic fluctuations. The second type (resulting from a Kelvin-Helmholtz instability) is non-stationary, with a power-law spectrum, and a non-Gaussian probability distribution function. The results of the study allow revisiting the question of loading particles of solar wind origin in the Earth magnetosphere.

  10. Self consistency grouping: a stringent clustering method

    PubMed Central

    2012-01-01

    Background Numerous types of clustering like single linkage and K-means have been widely studied and applied to a variety of scientific problems. However, the existing methods are not readily applicable for the problems that demand high stringency. Methods Our method, self consistency grouping, i.e. SCG, yields clusters whose members are closer in rank to each other than to any member outside the cluster. We do not define a distance metric; we use the best known distance metric and presume that it measures the correct distance. SCG does not impose any restriction on the size or the number of the clusters that it finds. The boundaries of clusters are determined by the inconsistencies in the ranks. In addition to the direct implementation that finds the complete structure of the (sub)clusters we implemented two faster versions. The fastest version is guaranteed to find only the clusters that are not subclusters of any other clusters and the other version yields the same output as the direct implementation but does so more efficiently. Results Our tests have demonstrated that SCG yields very few false positives. This was accomplished by introducing errors in the distance measurement. Clustering of protein domain representatives by structural similarity showed that SCG could recover homologous groups with high precision. Conclusions SCG has potential for finding biological relationships under stringent conditions. PMID:23320864

  11. Color-spin locking in a self-consistent Dyson-Schwinger approach

    SciTech Connect

    Marhauser, Florian; Nickel, Dominik; Buballa, Michael; Wambach, Jochen

    2007-03-01

    We investigate the color-spin locked phase of spin-one color-superconducting quark matter using a truncated Dyson-Schwinger equation for the quark propagator in Landau gauge. Starting from the most general parity conserving ansatz allowed by the color-spin locked symmetry, the Dyson-Schwinger equation is solved self-consistently and dispersion relations are discussed. We find that chiral symmetry is spontaneously broken due to terms which have previously been neglected. As a consequence, the excitation spectrum contains only gapped modes even for massless quarks. Moreover, at moderate chemical potentials the quasiparticle pairing gaps are several times larger than expected from extrapolated weak-coupling results.

  12. Quasiparticle calculations for solids and molecules

    NASA Astrophysics Data System (ADS)

    Kioupakis, Emmanouil Stylianos

    Advances in modern materials research have a direct impact in technological innovation. Devices such as transistors, light emitting diodes, photovoltaic cells and thermoelectric modules are only possible due to the nature of the underlying materials. One challenge for theorists is the understanding and prediction of the properties of these materials. With the advent of density functional theory, highly accurate ab initio electronic structure calculations for the electronic ground state became a routine and valuable research tool[1, 2, 3, 4]. Fundamental properties such as the atomic structure, chemical bonding, total energy and vibrational frequencies can be determined, and issues like the surface reconstruction, interface geometry, atomic diffusion and the energetics of reactions can be addressed. However, not all relevant material properties are determined by the ground state. For those that involve excited states, such as the band structure and electronic band gap, the optical absorption spectrum and optical gap, the electron transport properties, the effective mass tensor and the alignment of the bands at the interface of two materials, we need an understanding of the excited quasiparticles of the system. While density functional theory gives accurate values for the ground state properties, the Kohn-Sham eigenvalues do not have a direct physical meaning and cannot be identified with quasiparticle energies. For these, we need to use methods that correctly provide excited state properties. One method that can provide accurate quasiparticle energies and wave functions is the GW method, where G is the one-particle Green's function and W the screened Coulomb interaction. Today, GW quasiparticle calculations can routinely be performed for a wide array of solids, molecules and nanosystems with a quasiparticle energy accuracy of ˜0.1 eV. Moreover, one can employ the Bethe-Salpeter equation formalism to take into account the electron-hole interaction and determine the

  13. Deformations and Quasiparticle Spectra of Nuclei in the Nobelium Region

    NASA Astrophysics Data System (ADS)

    Shi, Yue; Dobaczewski, J.; Greenlees, P. T.; Toivanen, J.; Toivanen, P.

    2014-09-01

    We have performed self-consistent Skyrme Hartree-Fock-Bogolyubov calculations for nuclei close to 254No. Self-consistent deformations, including β2,4,6,8 as functions of the rotational frequency, were determined for even-even nuclei 246,248,250Fm, 252,254No, and 256Rf. The quasiparticle spectra for N = 151 isotones and Z = 99 isotopes were calculated and compared with experimental data and the results of Woods-Saxon calculations. We found that our calculations give high-order deformations similar to those obtained for the Woods-Saxon potential, and that the experimental quasiparticle energies are reasonably well reproduced.

  14. Spin-Orbit Effects in the Quasiparticle Bandstructure of Noble Metals

    NASA Astrophysics Data System (ADS)

    Mustafa, Jamal; Louie, Steven

    2014-03-01

    Applications of the GW approximation to the electron self-energy have proven quite successful for calculating the quasiparticle properties of materials. We find that for the noble metals, in line with previous work in such calculations, the semicore states need to be taken into account. We show that, with these semicore states, a large cutoff must be used to describe the screening and, in turn, a large number of empty states must be included. Taking all of this into account, and carefully checking convergence, shows G0W0 can describe experimental results from angle-resolved photoemission spectroscopy quite well when the effects of spin-orbit coupling is also included. We compare our results to recent self-consistent GW calculations on gold. This work was supported by NSF grant No. DMR10-1006184 and U.S. DOE under Contract No. DE-AC02-05CH11231. Computational resources have been provided by DOE at LBNL's NERSC facility.

  15. Self-Consistent Field Calculations on Atoms Using Excel

    ERIC Educational Resources Information Center

    Hoffman, Gary G.

    2005-01-01

    An Excel file that performs self-consistent field (SCF) calculations for the two-electron atoms is described. It is readily constructed and is relatively simple to use, providing a visual demonstration of how the self-consistent field (SCF) procedure is applied and what issues are involved.

  16. 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.

  17. 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.

  18. An approach to a self-consistent nuclear energy system

    SciTech Connect

    Fujii-e, Yoichi ); Arie, Kazuo; Endo, Hiroshi )

    1992-01-01

    A nuclear energy system should provide a stable supply of energy without endangering the environment or humans. If there is fear about exhausting world energy resources, accumulating radionuclides, and nuclear reactor safety, tension is created in human society. Nuclear energy systems of the future should be able to eliminate fear from people's minds. In other words, the whole system, including the nuclear fuel cycle, should be self-consistent. This is the ultimate goal of nuclear energy. If it can be realized, public acceptance of nuclear energy will increase significantly. In a self-consistent nuclear energy system, misunderstandings between experts on nuclear energy and the public should be minimized. The way to achieve this goal is to explain using simple logic. This paper proposes specific targets for self-consistent nuclear energy systems and shows that the fast breeder reactor (FBR) lies on the route to attaining the final goal.

  19. 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.

  20. Superfluid 4He dynamics beyond quasiparticle excitations

    NASA Astrophysics Data System (ADS)

    Beauvois, K.; Campbell, C. E.; Dawidowski, J.; Fâk, B.; Godfrin, H.; Krotscheck, E.; Lauter, H.-J.; Lichtenegger, T.; Ollivier, J.; Sultan, A.

    2016-07-01

    The dynamics of superfluid 4He at and above the Landau quasiparticle regime is investigated by high-precision inelastic neutron scattering measurements of the dynamic structure factor. A highly structured response is observed above the familiar phonon-maxon-roton spectrum, characterized by sharp thresholds for phonon-phonon, maxon-roton, and roton-roton coupling processes. The experimental dynamic structure factor is compared to the calculation of the same physical quantity by a dynamic many-body theory including three-phonon processes self-consistently. The theory is found to provide a quantitative description of the dynamics of the correlated bosons for energies up to about three times that of the Landau quasiparticles.

  1. Self-consistent methods in nuclear structure physics

    SciTech Connect

    Dobaczewski, J. |

    1997-11-01

    The authors present a very brief description of the Hartree Fock method in nuclear structure physics, discuss the numerical methods used to solve the self-consistent equations, and analyze the precision and convergence properties of solutions. As an application, they present results pertaining to quadrupole moments and single-particle quadrupole polarizations in superdeformed nuclei with A {approximately} 60.

  2. 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.

  3. 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…

  4. 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…

  5. A self-consistent picture of Jupiter's nightside magnetosphere

    NASA Astrophysics Data System (ADS)

    Zimbardo, G.

    1989-07-01

    A model of Jupiter's nightside magnetosphere, based on the theory of self-consistent axisymmetric MHD equilibrium, is presented. The model assumes that the plasma forms a thin disk, while the magnetopause is considered as a surface that confines the magnetic flux of the dipole and of the current disk. Data from the Voyager missions were used as input for the solution of the equation determining the self-consistent equilibrium magnetic structure, and computations are performed by varying the hot-plasma composition and the current disk cutoff radius. It was found that, with sufficiently large disks, the magnetic configuration has an X line and an O line, with the X line located between 37 and 45 Jovian radii; the position of O line is less certain. The results of the model agree well with the magnetic field data in the tail.

  6. Self-consistent nonperturbative theory for classical systems.

    PubMed

    Mederos, L; Navascués, G; Velasco, E

    2002-01-01

    We construct a self-consistent nonperturbative theory for the structure and thermodynamics of a classical system of particles that goes beyond the usual approaches based on perturbation theory. Our theory, which gives accurate predictions for the phase diagram, is based on two ingredients: first, use is made of an exact expression for the free energy of a many-body system in terms of a reference system and a coupling integral connecting the latter to the final system; second, correlation functions may be very accurately approximated using a number of sum rules relating the radial distribution function with thermodynamic quantities. Consistency between the coupling integral expression and the sum rules may be achieved by means of a self-consistent process. PMID:11800760

  7. Self-consistent Castaing Distribution of Solar Wind Turbulent Fluctuations

    NASA Astrophysics Data System (ADS)

    Sorriso-Valvo, L.; Marino, R.; Lijoi, L.; Perri, S.; Carbone, V.

    2015-07-01

    The intermittent behavior of solar wind turbulent fluctuations has often been investigated through the modeling of their probability distribution functions (PDFs). Among others, the Castaing model has successfully been used in the past. In this paper, the energy dissipation field of solar wind turbulence has been studied for fast, slow, and polar wind samples recorded by Helios 2 and Ulysses spacecraft. The statistical description of the dissipation rate has then been used to remove intermittency through conditioning of the PDFs. Based on such observation, a self-consistent, parameter-free Castaing model is presented. The self-consistent model is tested against experimental PDFs, showing good agreement and supporting the picture of a multifractal energy cascade at the origin of solar wind intermittency.

  8. Self-consistent calculations of alpha-decay energies

    SciTech Connect

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

    2013-06-15

    On the basis of the self-consistent theory of finite Fermi systems, the energies of alphadecay chains were calculated for several new superheavy nuclei discovered recently in experiments of the Dubna-Livermore Collaboration headed by Yu.Ts. Oganessian. The approach in question is implemented on the basis of the generalized method of the density functional proposed by Fayans and his coauthors. The version used here relies on the functional DF3-a proposed recently for describing a wide array of nuclear data, including data on superheavy nuclei. A detailed comparison of the results obtained on this basis with the predictions of different approaches, including the self-consistent Skyrme-Hartree-Fock method, the micro-macro method in the version developed by Sobiczewski and his coauthors, and the phenomenological method of Liran and his coauthors, is performed. The resulting alpha-decay energies are used to calculate respective lifetimes with the aid of the phenomenological Parkhomenko-Sobiczewski formula.

  9. Self-consistent, unbiased root-mean-square emittance analysis

    NASA Astrophysics Data System (ADS)

    Stockli, Martin P.; Welton, R. F.; Keller, R.

    2004-05-01

    We present a self-consistent method for analyzing measured emittance data that yields unbiased estimates for the root-mean-square (rms) emittance. The self-consistent, unbiased elliptical exclusion analysis uses an ellipse to determine the bias from the data outside the ellipse, before calculating the rms emittance from the bias-subtracted data within the ellipse. Increasing the ellipse size until the rms emittance estimate saturates allows for determining the minimum elliptical area that includes all real signals, even those buried in the noise. Variations of the ellipse shape and orientations are used to test the robustness of the results. Background fluctuations cause fluctuations in the rms emittance estimate, which are an estimate of the uncertainty incurred through the analysis.

  10. A minimal model of self-consistent partial synchrony

    NASA Astrophysics Data System (ADS)

    Clusella, Pau; Politi, Antonio; Rosenblum, Michael

    2016-09-01

    We show that self-consistent partial synchrony in globally coupled oscillatory ensembles is a general phenomenon. We analyze in detail appearance and stability properties of this state in possibly the simplest setup of a biharmonic Kuramoto–Daido phase model as well as demonstrate the effect in limit-cycle relaxational Rayleigh oscillators. Such a regime extends the notion of splay state from a uniform distribution of phases to an oscillating one. Suitable collective observables such as the Kuramoto order parameter allow detecting the presence of an inhomogeneous distribution. The characteristic and most peculiar property of self-consistent partial synchrony is the difference between the frequency of single units and that of the macroscopic field.

  11. The Kelvin equation and self-consistent nucleation theory

    SciTech Connect

    Wilemski, G. |

    1995-07-15

    Issues of self-consistency are reviewed for several unary equilibrium size distributions based on the capillarity approximation. Some apparent difficulties of interpretation are resolved. In terms of the kinetic approach to nucleation theory, the influence of self-consistency on the nucleation rate is shown to arise entirely from differences in the dimer evaporation rates for nearly all versions of classical theory. The nucleation rate behavior of the Kelvin model is explored. In this model, the Kelvin equation is used to prescribe all cluster evaporation rates. Nucleation rates predicted by the Kelvin model are quantitatively similar to those of the self-consistent classical (SCC) theory, but not to other simple versions of the classical theory. This behavior arises entirely from the relatively close coincidence of the SCC and Kelvin dimer evaporation rates. This means that, for the distribution-based versions of classical theory, the SCC model is the closest analogue of the Kelvin model. Because the Kelvin equation is fundamentally inadequate for very small clusters, the close relationship between the Kelvin and SCC formulations indicates that both are equally lacking in fundamental justification. The Kelvin model may, however, have some pragmatic utility, and a simple analytical rate expression is also derived for it to simplify the calculation of nucleation rates for this model. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  12. Quasi-particle electronic band structure and alignment of the V-VI-VII semiconductors SbSI, SbSBr, and SbSeI for solar cells

    NASA Astrophysics Data System (ADS)

    Butler, Keith T.; McKechnie, Scott; Azarhoosh, Pooya; van Schilfgaarde, Mark; Scanlon, David O.; Walsh, Aron

    2016-03-01

    The ternary V-VI-VII chalcohalides consist of one cation and two anions. Trivalent antimony—with a distinctive 5s2 electronic configuration—can be combined with a chalcogen (e.g., S or Se) and halide (e.g., Br or I) to produce photoactive ferroelectric semiconductors with similarities to the Pb halide perovskites. We report—from relativistic quasi-particle self-consistent GW theory—that these materials have a multi-valley electronic structure with several electron and hole basins close to the band extrema. We predict ionisation potentials of 5.3-5.8 eV from first-principles for the three materials, and assess electrical contacts that will be suitable for achieving photovoltaic action from these unconventional compounds.

  13. A self-consistent study of triaxial black hole nuclei

    NASA Astrophysics Data System (ADS)

    Poon, Ming Yan

    Knowledge of the three-dimensional shapes of elliptical galaxies has not advanced much since the time of Edwin Hubble. Elliptical galaxies are still classified according to their luminosity distributions and the isophotal contour shapes of their two-dimensional images projected on the sky. Their intrinsic shapes could be oblate, prolate, or fully triaxial, since all such shapes produce perfectly elliptical contours on projection. One way to constrain the possible 3D shapes of elliptical galaxies is to attempt to construct self-consistent dynamical models with various shapes. In this study, models were constructed of the central regions (“nuclei”) of elliptical galaxies. Observed nuclei have a power-law dependence of stellar density on radius, and universally contain a single supermassive black hole at their center, with mass ˜106 109 M⊙ . At low energies in such nuclei, the motion was found to be essentially regular, i.e. non-chaotic; the gravitational potential can be considered as a perturbation to the integrable Keplerian potential. At higher energies, where the enclosed stellar mass is a few times the black hole mass, the black hole renders those orbits that come close to the black hole stochastic. This transition to global stochasticity is rapid and occurs at lower energies in more elongated nuclei. The self-consistency of triaxial models of black hole nuclei was demonstrated by using Schwarzschild's method to construct self-consistent orbital superpositions representing nuclei with different shapes. N-body integrations of Monte-Carlo realizations of the Schwarzschild solutions showed that some of these nuclei are stable; nearly prolate nuclei were found to be unstable, and they evolve rapidly to axisymmetric shapes. The possibility that nuclei may be triaxial in shape complicates the interpretation of stellar kinematical data from the centers of galaxies and may alter the inferred interaction rates between stars and supermassive black holes.

  14. Self-Consistent Models of Barred Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Kaufmann, David E.

    1994-02-01

    Self-consistent models of barred spiral galaxies based on the observed properties of NGC3992, NGC1073, and NGC1398 are constructed and analyzed. The method of model construction is a slight modification of the technique developed by Contopoulos and Grosbol for the case of unbarred spirals. The main factors which influence self-consistency are the amplitude, pitch angle, scale length and z-thickness of the spirals, the mass of the bar, the angular velocity of the bar/spiral pattern, the central surface density and scale length of the disk, and the central value and slope of the velocity dispersion. Stochastic orbits whose Jacobi constants lie between the values at the Lagrange points L_1 and L_4 are found to play a significant role in supporting self-consistent spiral structure, especially in the regions just beyond the ends of the bar. Stochastic orbits whose Jacobi constants lie below this interval tend to fill more or less uniformly either rings in the outer disk or ovals in the bar region, depending on the regions to which they are confined. Stochastic orbits whose Jacobi constants lie above that of L_4 also tend not to support any imposed structure. The model bars are predominantly comprised of elongated orbits trapped around the x_1 family and terminate close to corotation. The response of gas to the forces of the most successful models is calculated using a two-dimensional smoothed particle hydrodynamics code. The results confirm that a bar alone is not sufficient to drive a strong spiral response in the gas of the outer disk. An underlying spiral structure in the more massive stellar component appears to be required. If stellar spirals are present, strong gas spirals may persist for long times. (SECTION: Dissertation Summaries)

  15. Self-consistent models of barred spiral galaxies

    NASA Astrophysics Data System (ADS)

    Kaufmann, David Eugene

    1993-01-01

    Self-consistent models of barred spiral galaxies based on the observed properties of NGC 3992, NGC 1073, and NGC 1398 are constructed and analyzed. The method of model construction is a slight modification of the technique developed by Contopoulos and Grosbol for the case of unbarred spirals. The main factors which influence self-consistency are the amplitude, pitch angle, scale length and z-thickness of the spirals, the mass of the bar, the angular velocity of the bar/spiral pattern, the central surface density and scale length of the disk, and the central value and slope of the velocity dispersion. Stochastic orbits whose Jacobi constants lie between the values at the Lagrange points L1 and L4 are found to play a significant role in supporting self-consistent spiral structure, especially in the regions just beyond the ends of the bar. Stochastic orbits whose Jacobi constants lie below this interval tend to fill more or less uniformly either rings in the outer disk or ovals in the bar region, depending on the regions to which they are confined. Stochastic orbits whose Jacobi constants lie above that of L4 also tend not to support any imposed structure. The model bars are predominantly comprised of elongated orbits trapped around the chi1 family and terminate close to corotation. The response of gas to the forces of the most successful models is calculated using a two-dimensional smoothed particle hydrodynamics code. The results confirm that a bar alone is not sufficient to drive a strong spiral response in the gas of the outer disk. An underlying spiral structure in the more massive stellar component appears to be required. If stellar spirals are present, strong gas spirals may persist for long times.

  16. 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.

  17. Hydrodynamic self-consistent field theory for inhomogeneous polymer melts.

    PubMed

    Hall, David M; Lookman, Turab; Fredrickson, Glenn H; Banerjee, Sanjoy

    2006-09-15

    We introduce a mesoscale technique for simulating the structure and rheology of block-copolymer melts and blends in hydrodynamic flows. The technique couples dynamic self-consistent field theory with continuum hydrodynamics and flow penalization to simulate polymeric fluid flows in channels of arbitrary geometry. We demonstrate the method by studying phase separation of an ABC triblock copolymer melt in a submicron channel with neutral wall wetting conditions. We find that surface wetting effects and shear effects compete, producing wall-perpendicular lamellae in the absence of flow and wall-parallel lamellae in cases where the shear rate exceeds some critical Weissenberg number.

  18. Self consistent modeling of accretion columns in accretion powered pulsars

    NASA Astrophysics Data System (ADS)

    Falkner, Sebastian; Schwarm, Fritz-Walter; Wolff, Michael Thomas; Becker, Peter A.; Wilms, Joern

    2016-04-01

    We combine three physical models to self-consistently derive the observed flux and pulse profiles of neutron stars' accretion columns. From the thermal and bulk Comptonization model by Becker & Wolff (2006) we obtain seed photon continua produced in the dense inner regions of the accretion column. In a thin outer layer these seed continua are imprinted with cyclotron resonant scattering features calculated using Monte Carlo simulations. The observed phase and energy dependent flux corresponding to these emission profiles is then calculated, taking relativistic light bending into account. We present simulated pulse profiles and the predicted dependency of the observable X-ray spectrum as a function of pulse phase.

  19. 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.

  20. Isoscalar and isovector giant resonances in a self-consistent phonon coupling approach

    NASA Astrophysics Data System (ADS)

    Lyutorovich, N.; Tselyaev, V.; Speth, J.; Krewald, S.; Grümmer, F.; Reinhard, P.-G.

    2015-10-01

    We present fully self-consistent calculations of isoscalar giant monopole and quadrupole as well as isovector giant dipole resonances in heavy and light nuclei. The description is based on Skyrme energy-density functionals determining the static Hartree-Fock ground state and the excitation spectra within random-phase approximation (RPA) and RPA extended by including the quasiparticle-phonon coupling at the level of the time-blocking approximation (TBA). All matrix elements were derived consistently from the given energy-density functional and calculated without any approximation. As a new feature in these calculations, the single-particle continuum was included thus avoiding the artificial discretization usually implied in RPA and TBA. The step to include phonon coupling in TBA leads to small, but systematic, down shifts of the centroid energies of the giant resonances. These shifts are similar in size for all Skyrme parametrizations investigated here. After all, we demonstrate that one can find Skyrme parametrizations which deliver a good simultaneous reproduction of all three giant resonances within TBA.

  1. Self-consistent pitch angle diffusion of newborn ions

    SciTech Connect

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

    1991-04-01

    It is well known from the study of ion pickup process by the solar wind that hydromagnetic turbulence can cause the newborn ions to undergo rapid pitch angle diffusion or scattering, thus forming a partial or complete velocity shell distribution. In most of the recent discussions based on quasi-linear theory it is assumed that the spectral wave energy density associated with the hydromagnetic turbulence is constant in time, implying a saturated turbulence level. In contrast, in this work the effect of self-consistently generated waves on the ion dynamics is discussed on the basis of a simple theoretical model, and it is shown both analytically and numerically that the self-consistent diffusion process leads to a time-asymptotic partial shell distribution which extends approximately from the initial pitch angle cos{sup {minus}1}{mu}{sub 0} to {approximately}{pi}/2 in pitch angle space. Particularly, the role of resonant versus nonresonant diffusion processes is discussed in detail. In addition, the effect of continuous ion source term is also incorporated in the numerical analysis since in cometary environment the ions are continuously created.

  2. 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.

  3. Self-consistent chaos in the beam-plasma instability

    SciTech Connect

    Tennyson, J.L. ); Meiss, J.D. . Applied Mathematics Program); Morrison, P.J. )

    1993-02-08

    The effect of self-consistency on Hamiltonian systems with a large number of degrees-of-freedom is investigated for the beam-plasma instability using the single-wave model of O'Neil, Winfrey, and Malmberg.The single-wave model is reviewed and then rederived within the Hamiltonian context, which leads naturally to canonical action- angle variables. Simulations are performed with a large (10[sup 4]) number of beam particles interacting with the single wave. It is observed that the system relaxes into a time asymptotic periodic state where only a few collective degrees are active; namely, a clump of trapped particles oscillating in a modulated wave, within a uniform chaotic sea with oscillating phase space boundaries. Thus self-consistency is seen to effectively reduce the number of degrees- of-freedom. A simple low degree-of-freedom model is derived that treats the clump as a single macroparticle, interacting with the wave and chaotic sea. The uniform chaotic sea is modeled by a fluid waterbag, where the waterbag boundaries correspond approximately to invariant tori. This low degree-of-freedom model is seen to compare well with the simulation.

  4. Self-consistent chaos in the beam-plasma instability

    SciTech Connect

    Tennyson, J.L.; Meiss, J.D.; Morrison, P.J.

    1993-02-08

    The effect of self-consistency on Hamiltonian systems with a large number of degrees-of-freedom is investigated for the beam-plasma instability using the single-wave model of O`Neil, Winfrey, and Malmberg.The single-wave model is reviewed and then rederived within the Hamiltonian context, which leads naturally to canonical action- angle variables. Simulations are performed with a large (10{sup 4}) number of beam particles interacting with the single wave. It is observed that the system relaxes into a time asymptotic periodic state where only a few collective degrees are active; namely, a clump of trapped particles oscillating in a modulated wave, within a uniform chaotic sea with oscillating phase space boundaries. Thus self-consistency is seen to effectively reduce the number of degrees- of-freedom. A simple low degree-of-freedom model is derived that treats the clump as a single macroparticle, interacting with the wave and chaotic sea. The uniform chaotic sea is modeled by a fluid waterbag, where the waterbag boundaries correspond approximately to invariant tori. This low degree-of-freedom model is seen to compare well with the simulation.

  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 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Tunneling in a self-consistent dynamic image potential

    SciTech Connect

    Rudberg, B.G.R. ); Jonson, M. Department of Physics, University of Tennessee, Knoxville, Tennessee 37996-1501 )

    1991-04-15

    We have calculated the self-consistent effective potential for an electron tunneling through a square barrier while interacting with surface plasmons. This potential reduces to the classical image potential in the static limit. In the opposite limit, when the velocity'' of the tunneling electron is large, it reduces to the unperturbed square-barrier potential. For a wide variety of parameters the dynamic effects on the transmission coefficient {ital T}={vert bar}{ital t}{sup 2}{vert bar} can, for instance, be related to the Buettiker-Landauer traversal time for tunneling, given by {tau}{sup BL}={h bar}{vert bar}{ital d} ln{ital t}/{ital dV}{vert bar}.

  14. 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.

  15. Self-Consistent Field Theory of ABn Miktoarm Copolymer Melts

    NASA Astrophysics Data System (ADS)

    Grason, Gregory; Kamien, Randall

    2004-03-01

    Using self-consistent field theory (SCFT) techniques we investigate the phase behavior of AB_n, miktoarm copolymer melts. In particular, we examine how the molecularasymmetry stabilizes morpholgies with highly curved interfaces. While strong-segregation theory tends to overestimate this effect for asymmetric molecules, the SCFT results are in strong agreement with experiments on PI-PS miktoarm copolymer melts. In addition, we report the stability of a new cubic phase of one-component block copolymer melts, with Pm bar3 n symmetry. This phase, the A15 phase of spherical micelles, is stable in melts of ABn copolymers for n ≥ 2. We interpret the relative stability of the sphere phases in terms of well-studied, geometric moments of the candidate sphere lattices.

  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. Self-consistent simulation of cyclotron autoresonance maser amplifiers

    SciTech Connect

    Pendergast, K.D.; Danly, B.G.; Temkin, R.J.; Wurtele, J.S.

    1988-04-01

    A self-consistent, one-dimensional model of the cyclotron autoresonance maser (CARM) amplifier is developed, and numerical simulations based on this model are described. Detailed studies of the CARM gain and efficiency for a wide range of initial energy and velocity spreads are presented. The interaction efficiency is found to be substantially increased when the axial magnetic field is tapered. For example, efficiencies of greater than 41 percent are obtained for a 140-GHz CARM amplifier with a tapered axial magnetic field and a 700-kV 4.5-A electron beam with parallel velocity spreads of less than 1 percent. A discussion of the nonlinear bandwidth and interaction sensitivity to axial field inhomogeneities is presented.

  18. Self-consistent estimation of mislocated fixations during reading.

    PubMed

    Engbert, Ralf; Nuthmann, Antje

    2008-01-01

    During reading, we generate saccadic eye movements to move words into the center of the visual field for word processing. However, due to systematic and random errors in the oculomotor system, distributions of within-word landing positions are rather broad and show overlapping tails, which suggests that a fraction of fixations is mislocated and falls on words to the left or right of the selected target word. Here we propose a new procedure for the self-consistent estimation of the likelihood of mislocated fixations in normal reading. Our approach is based on iterative computation of the proportions of several types of oculomotor errors, the underlying probabilities for word-targeting, and corrected distributions of landing positions. We found that the average fraction of mislocated fixations ranges from about 10% to more than 30% depending on word length. These results show that fixation probabilities are strongly affected by oculomotor errors.

  19. Linear Multigrid Techniques in Self-consistent Electronic Structure Calculations

    SciTech Connect

    Fattebert, J-L

    2000-05-23

    Ab initio DFT electronic structure calculations involve an iterative process to solve the Kohn-Sham equations for an Hamiltonian depending on the electronic density. We discretize these equations on a grid by finite differences. Trial eigenfunctions are improved at each step of the algorithm using multigrid techniques to efficiently reduce the error at all length scale, until self-consistency is achieved. In this paper we focus on an iterative eigensolver based on the idea of inexact inverse iteration, using multigrid as a preconditioner. We also discuss how this technique can be used for electrons described by general non-orthogonal wave functions, and how that leads to a linear scaling with the system size for the computational cost of the most expensive parts of the algorithm.

  20. Turbulent MHD transport coefficients - An attempt at self-consistency

    NASA Technical Reports Server (NTRS)

    Chen, H.; Montgomery, D.

    1987-01-01

    In this paper, some multiple scale perturbation calculations of turbulent MHD transport coefficients begun in earlier papers are first completed. These generalize 'alpha effect' calculations by treating the velocity field and magnetic field on the same footing. Then the problem of rendering such calculations self-consistent is addressed, generalizing an eddy-viscosity hypothesis similar to that of Heisenberg for the Navier-Stokes case. The method also borrows from Kraichnan's direct interaction approximation. The output is a set of integral equations relating the spectra and the turbulent transport coefficients. Previous 'alpha effect' and 'beta effect' coefficients emerge as limiting cases. A treatment of the inertial range can also be given, consistent with a -5/3 energy spectrum power law. In the Navier-Stokes limit, a value of 1.72 is extracted for the Kolmogorov constant. Further applications to MHD are possible.

  1. 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. PMID:27415371

  2. Self-consistent model of edge doping in graphene

    NASA Astrophysics Data System (ADS)

    Pedersen, Thomas Garm

    2015-02-01

    Dopants positioned near edges in nanostructured graphene behave differently from bulk dopants. Most notable, the amount of charge transferred to delocalized states (i.e., doping efficiency) depends on position as well as edge chirality. We apply a self-consistent tight-binding model to analyze this problem focusing on substitutional nitrogen and boron doping. Using a Green's-function technique, very large structures can be studied, and artificial interactions between dopants in periodically repeated simulations cells are avoided. We find pronounced signatures of edges in the local impurity density of states. Importantly, the doping efficiency is found to oscillate with sublattice position, in particular, for dopants near zigzag edges. Finally, to assess the effect of electron-electron interactions, we compute the self-energy corrected Green's function.

  3. 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}.

  4. 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.

  5. First-principles description of charge transfer in donor-acceptor compounds from self-consistent many-body perturbation theory

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    We investigate charge transfer in prototypical molecular donor-acceptor compounds using hybrid density functional theory (DFT) and the GW approximation at the perturbative level (G0W0) and at full self-consistency (sc-GW). For the systems considered here, no charge transfer should be expected at large intermolecular separation according to photoemission experiments and accurate quantum-chemistry calculations. The capability of hybrid exchange-correlation functionals of reproducing this feature depends critically on the fraction of exact exchange α, as for small values of α spurious fractional charge transfer is observed between the donor and the acceptor. G0W0 based on hybrid DFT yields the correct alignment of the frontier orbitals for all values of α. However, G0W0 has no capacity to alter the ground-state properties of the system because of its perturbative nature. The electron density in donor-acceptor compounds thus remains incorrect for small α values. In sc-GW, where the Green's function is obtained from the iterative solution of the Dyson equation, the electron density is updated and reflects the correct description of the level alignment at the GW level, demonstrating the importance of self-consistent many-body approaches for the description of ground- and excited-state properties in donor-acceptor systems.

  6. 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

  7. Parallel framework for wormlike chains using self consistent field theory

    NASA Astrophysics Data System (ADS)

    Ackerman, David; Ganapathysubramanian, Baskar

    2015-03-01

    The Gaussian chain model commonly used in Self Consistent Field Theory (SCFT) has enabled study of a wide range of macromolecule systems; however, the flexible nature of the model makes it unsuitable for many biomolecules and systems such as liquid crystals where alignment effects are critical. The orientations accounted for in a wormlike chain model can correctly capture the physics of these systems. The primary problem with a wormlike chain model is the computational cost of implementation, which far exceeds that of the Gaussian chain model. We address this problem though a parallel SCFT framework for wormlike chains incorporating orientation interactions. The framework can scale to 10s of thousands of processors using an efficient finite element (FE) approach. Orientations are treated with an FE in FE method which overlays a surface orientation mesh on top of the spatial geometry mesh. The finite element approach allows use of arbitrarily shaped systems and is ideal for studying confinement effects. We explore how this framework works on a few examples for polymers confined to a sphere.

  8. Self-consistent field theory for obligatory coassembly

    NASA Astrophysics Data System (ADS)

    Voets, I. K.; Leermakers, F. A. M.

    2008-12-01

    We present a first-order model for obligatory coassembly of block copolymers via an associative driving force in a nonselective solvent, making use of the classical self-consistent field (SCF) theory. The key idea is to use a generic associative driving force to bring two polymer blocks together into the core of the micelle and to employ one block of the copolymer(s) to provide a classical stopping mechanism for micelle formation. The driving force is generated by assuming a negative value for the relevant short-range Flory-Huggins interaction parameter. Hence, the model may be adopted to study micellization via H bonding, acceptor-donor interactions, and electrostatic interactions. Here, we limit ourselves to systems that resemble experimental ones where the mechanism of coassembly is electrostatic attraction leading to charge compensation. The resulting micelles are termed complex coacervate core micelles (CCCMs). We show that the predictions are qualitatively consistent with a wide variety of experimentally observed phenomena, even though the model does not yet account for the charges explicitly. For example, it successfully mimics the effect of salt on CCCMs. In the absence of salt CCCMs are far more stable than in excess salt, where the driving force for self-assembly is screened. The main limitations of the SCF model are related to the occurrence of soluble complexes, i.e., soluble, charged particles that coexist with the CCCMs.

  9. Self-Consistent Monte Carlo Simulations of Positive Column Discharges

    NASA Astrophysics Data System (ADS)

    Lawler, J. E.; Kortshagen, U.

    1998-10-01

    In recent years it has become widely recognized that electron distribution functions in atomic gas positive column discharges are best described as non local over most of the range of R× N (column radius × gas density) where positive columns are stable. The use of an efficient Monte Carlo code with a radial potential expansion in powers of r^2 and with judiciously chosen constraints on the potential near the axis and wall now provides fully self-consistent kinetic solutions using only small computers. A set of solutions at smaller R× N and lower currents are presented which exhibit the classic negative dynamic resistance of the positive column at low currents. The negative dynamic resistance is due to a non-negligible Debye length and is sometimes described as a transition from free to ambipolar diffusion. This phenomenon is sensitive to radial variations of key parameters in the positive column and thus kinetic theory simulations are likely to provide a more realistic description than classic isothermal fluid models of the positive column. Comparisons of kinetic theory simulations to various fluid models of the positive column continue to provide new insight on this `corner stone' problem of Gaseous Electronics.

  10. 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.

  11. Two regimes of self-consistent heating of charged particles.

    PubMed

    Doveil, Fabrice; Macor, Alessandro

    2011-10-01

    An experimental illustration of the transition between two basic transport regimes for wave-particle interaction is reported. A striking feature is that chaos, although present in both regimes, does not need to be invoked to explain the observed behavior. This experimental realization for a theoretical paradigm opens the possibility to check the validity of basic models, as is normally required in physics. Indeed, among seemingly simple problems exhibiting complex behavior is the classical interaction of an electron with electrostatic waves. Launching a low-intensity electron beam in a Traveling Wave Tube (TWT) recently allowed observing the real-world consequences of the richness of the electron trajectory. Here we show that self-consistent effects are nevertheless acting on a modulated test electron beam through the collective excitation of beam modes. The transition between two different particle transport regimes (stochastic diffusion in a set of waves and slow chaos associated to a pulsating separatrix) is directly measured by increasing the amplitude of the excitation. PMID:22181220

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. Towards a Self-consistent Orbital Evolution for EMRIs

    NASA Astrophysics Data System (ADS)

    Spallicci, A.; Ritter, P.; Jubertie, S.; Cordier, S.; Aoudia, S.

    2013-01-01

    We intend to develop part of the theoretical tools needed for the detection of gravitational waves coming from the capture of a compact object, 1-100 M⊙, by a Supermassive Black Hole, up to a 109 M⊙, located at the centre of most galaxies. The analysis of the accretion activity unveils the star population around the galactic nuclei, and tests the physics of black holes and general relativity. The captured small mass is considered a probe of the gravitational field of the massive body, allowing a precise measurement of the particle motion up to the final absorption. The knowledge of the gravitational signal, strongly affected by the self-force — the orbital displacement due to the captured mass and the emitted radiation — is imperative for a successful detection. The results include a strategy for wave equations with a singular source term for all type of orbits. We are now tackling the evolution problem, first for radial fall in Regge-Wheeler gauge, and later for generic orbits in the harmonic or de Donder gauge for Schwarzschild-Droste black holes. In the Extreme Mass Ratio Inspiral, the determination of the orbital evolution demands that the motion of the small mass be continuously corrected by the self-force, i.e. the self-consistent evolution. At each of the integration steps, the self-force must be computed over an adequate number of modes; further, a differential-integral system of general relativistic equations is to be solved and the outputs regularised for suppressing divergences. Finally, for the provision of the computational power, parallelisation is under examination.

  19. 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.

  20. Self-consistent Dynamical And Thermodynamical Evolutions Of Protoplanetary Disks.

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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...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 for which most parameters are self-consistently calculated at each time step. We integrate the Hueso and Guillot, 2005 model of disk evolution and couple the radiative transfer description of Calvet et al, 1991 allowing us to handle a non-isothermal disk. We also take into account the collapse of the molecular cloud that feeds the disk. Using the same temperature model in the vertical direction, we estimate 2D thermal maps of the disk. The central star itself is modeled using recent stellar evolution code described in Piau et al, 2011. We first test our model in the case of an already formed Minimum Mass solar Nebula, trying to match the observational constraints on the radial surface density gradients and photosphere height profiles of the Taurus-Auriga or Ophiucus disks for instance. We then follow the full long-term evolution of a disk fed by the collapse of the molecular cloud. We estimate disk temperatures and accretion rates and try to constrain the favourable zone for the formation of the first solids. This will help targeting future JWST observations.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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... 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 for which most parameters are self-consistently calculated at each time step. We integrate the Hueso and Guillot, 2005 model of disk evolution and couple the radiative transfer description of Calvet et al, 1991 allowing us to handle a non-isothermal disk. We also take into account the collapse of the molecular cloud that feeds the disk. Using the same temperature model in the vertical direction, we estimate 2D thermal maps of the disk. The central star itself is modeled using recent stellar evolution code described in Piau et al, 2011. We first test our model in the case of an already formed Minimum Mass solar Nebula, trying to match the observational constraints on the radial surface density gradients and photosphere height profiles of the Taurus-Auriga or Ophiucus disks for instance. We then follow the full long-term evolution of a disk fed by the collapse of the molecular cloud. We estimate disk temperatures and accretion rates and try to constrain the favourable zone for the formation of the first solids. This will help targeting future JWST observations.

  2. Self-Consistent Formation of a low Viscosity Zone

    NASA Astrophysics Data System (ADS)

    Stein, C.; Hansen, U.

    2003-12-01

    The role of a low viscosity zone in stabilizing plate motion has been proposed by convection models in which a low viscosity zone (LVZ) below the surface has been prescribed. In this case a plastic yield stress serving as deformation mechanism for the stiff surface is combined with a viscosity drop below the thermal boundary layer. As a result regions of constant velocity and continuous motion was observed.In contrast to models that prescribe the formation of the LVZ, we combine a three-dimensional numerical mantle convection model with a temperature-, stress- and pressure-dependent rheology. The additional variation of viscosity with pressure yields the self-consistent formation of a low viscosity zone. However in pressure-dependent viscosity convection not automatically a low viscosity zone forms. The LVZ only appears under a certain parameter combination. Depending on the parameter combination different regimes of convection arise. A stagnant lid type of convection prevails at high yield stresses and a mobile lid type at low yield stresses. In between an episodic regime occurs in which regions of constant velocity are observed on short timescales. These regimes have already been discussed in studies considering a temperature and stress dependence. But for additional pressure dependence of the viscosity a further regime results. In this regime a plate-like (i.e. rigidly moving) surface is observed and plate motion is stable on long timescales. The variation of viscosity with pressure thus is of capital importance in the generation of the LVZ, but furthermore the interaction of all rheological parameters is relevant. In none of the regimes apart from that showing stable plates a viscosity drop beneath the surface was observed even though a pressure dependence was assumed. Thus the existence of continuously moving plates and the presence of a low viscosity zone are two coupled phenomena.

  3. 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.

  4. Quasiparticle theory of transport coefficients for hadronic matter at finite temperature and baryon density

    NASA Astrophysics Data System (ADS)

    Albright, M.; Kapusta, J. I.

    2016-01-01

    We develop a flexible quasiparticle theory of transport coefficients of hot hadronic matter at finite baryon density. We begin with a hadronic quasiparticle model which includes a scalar and a vector mean field. Quasiparticle energies and the mean fields depend on temperature and baryon chemical potential. Starting with the quasiparticle dispersion relation, we derive the Boltzmann equation and use the Chapman-Enskog expansion to derive formulas for the shear and bulk viscosities and thermal conductivity. We obtain both relaxation-time approximation formulas and more general integral equations. Throughout the work, we explicitly enforce the Landau-Lifshitz conditions of fit and ensure the theory is thermodynamically self-consistent. The derived formulas should be useful for predicting the transport coefficients of the hadronic phase of matter produced in heavy-ion collisions at the Relativistic Heavy Ion Collider and at other accelerators.

  5. Fast RPA and GW calculations: cubic system size scaling

    NASA Astrophysics Data System (ADS)

    Kresse, Georg

    The random phase approximation (RPA) to the correlation energy and the related GW approximation are among the most promising methods to obtain accurate correlation energy differences and QP energies from diagrammatic perturbation theory at reasonable computational cost. The calculations are, however, usually one to two orders of magnitude more demanding than conventional density functional theory calculations. Here, we show that a cubic system size scaling can be readily obtained reducing the computation time by one to two orders of magnitude for large systems. Furthermore, the scaling with respect to the number of k points used to sample the Brillouin zone can be reduced to linear order. In combination, this allows accurate and very well-converged single-point RPA and GW calculations, with a time complexity that is roughly on par or better than for self-consistent Hartree-Fock and hybrid-functional calculations. Furthermore, the talk discusses the relation between the RPA correlation energy and the GW approximation: the self-energy is the derivative of the RPA correlation energy with respect to the Green's function. The calculated self-energy can be used to compute QP-energies in the GW approximation, any first derivative of the total energy, as well as corrections to the correlation energy from the changes of the charge density when switching from DFT to a many-body body description (GW singles energy contribution).

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

    NASA Astrophysics Data System (ADS)

    Avogadro, Paolo; Nakatsukasa, Takashi

    2011-07-01

    We present the finite amplitude method (FAM), originally proposed in Ref. , 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 174Sn, modifying the hfbrad code, to demonstrate the accuracy, feasibility, and usefulness of the FAM.

  7. Quasiparticle and optical properties of polythiophene-derived polymers

    NASA Astrophysics Data System (ADS)

    Samsonidze, Georgy; Ribeiro, Filipe J.; Cohen, Marvin L.; Louie, Steven G.

    2014-07-01

    Electron donor conjugated polymers blended with electron acceptor fullerene derivatives is one of the promising technologies for organic photovoltaics. However, with the energy conversion efficiency of only 9% in a single bulk heterojunction device structure, these solar cells are not yet competitive with conventional inorganic semiconductor technology. Some of the limitations are large optical band gaps and small electron affinities of polymers preventing the absorption of infrared radiation and leading to energy losses during charge separation at the donor-acceptor interface, respectively. In this work, we compute from first principles the quasiparticle and optical spectra of several different thiophene-, ethyne-, and vinylene-based copolymers using the GW method and the GW plus Bethe-Salpeter equation approach. One of the polymers is identified which has a preferential alignment of the energy levels at the interface with fullerene molecule compared to the reference case of polythiophene.

  8. 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.

  9. Evaluating the GW Approximation with CCSD(T) for Charged Excitations Across the Oligoacenes.

    PubMed

    Rangel, Tonatiuh; Hamed, Samia M; Bruneval, Fabien; Neaton, Jeffrey B

    2016-06-14

    Charged excitations of the oligoacene family of molecules, relevant for astrophysics and technological applications, are widely studied and therefore provide an excellent system for benchmarking theoretical methods. In this work, we evaluate the performance of many-body perturbation theory within the GW approximation relative to new high-quality CCSD(T) reference data for charged excitations of the acenes. We compare GW calculations with a number of hybrid density functional theory starting points and with eigenvalue self-consistency. Special focus is given to elucidating the trend of GW-predicted excitations with molecule length increasing from benzene to hexacene. We find that GW calculations with starting points based on an optimally tuned range-separated hybrid (OTRSH) density functional and eigenvalue self-consistency can yield quantitative ionization potentials for the acenes. However, for larger acenes, the predicted electron affinities can deviate considerably from reference values. Our work paves the way for predictive and cost-effective GW calculations of charged excitations of molecules and identifies certain limitations of current GW methods used in practice for larger molecules. PMID:27123935

  10. Dielectric anisotropy in the GW space time method

    NASA Astrophysics Data System (ADS)

    Freysoldt, Christoph; Eggert, Philipp; Rinke, Patrick; Schindlmayr, Arno; Godby, R. W.; Scheffler, Matthias

    2007-01-01

    Excited-state calculations, notably for quasiparticle band structures, are nowadays routinely performed within the GW approximation for the electronic self-energy. Nevertheless, certain numerical approximations and simplifications are still employed in practice to make the computations feasible. An important aspect for periodic systems is the proper treatment of the singularity of the screened Coulomb interaction in reciprocal space, which results from the slow 1/r decay in real space. This must be done without introducing artificial interactions between the quasiparticles and their periodic images in repeated cells, which occur when integrals of the screened Coulomb interaction are discretised in reciprocal space. An adequate treatment of both aspects is crucial for a numerically stable computation of the self-energy. In this article we build on existing schemes for isotropic screening and present an extension for anisotropic systems. We also show how the contributions to the dielectric function arising from the non-local part of the pseudopotentials can be computed efficiently. These improvements are crucial for obtaining a fast convergence with respect to the number of points used for the Brillouin zone integration and prove to be essential to make GW calculations for strongly anisotropic systems, such as slabs or multilayers, efficient.

  11. 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.

  12. Bounds and self-consistent estimates of the elastic constants of polycrystals

    NASA Astrophysics Data System (ADS)

    Kube, Christopher M.; Arguelles, Andrea P.

    2016-10-01

    The Hashin-Shtrikman bounds on the elastic constants have been previously calculated for polycrystalline materials with crystallites having general elastic symmetry (triclinic crystallite symmetry). However, the calculation of tighter bounds and the self-consistent estimates of these elastic constants has remained unsolved. In this paper, a general theoretical expression for the self-consistent elastic constants is formulated. An iterative method is used to solve the expression for the self-consistent estimates. Each iteration of the solution gives the next tighter set of bounds including the well-known Voigt-Reuss and Hashin-Shtrikman bounds. Thus, all of the bounds on the elastic constants and the self-consistent estimates for any crystallite symmetry are obtained in a single, computationally efficient procedure. The bounds and self-consistent elastic constants are reported for several geophysical materials having crystallites of monoclinic and triclinic symmetries.

  13. Multi-quasiparticle high-K isomeric states in deformed nuclei

    NASA Astrophysics Data System (ADS)

    Xu, F. R.; Shi, Y.; Liu, H. L.; Liang, W. Y.; Walker, P. M.; Dracoulis, G. D.

    2016-09-01

    In the past years, we have made many theoretical investigations on multi-quasiparticle high-K isomeric states. A deformation-pairing-configuration self-consistent calculation has been developed by calculating a configuration-constrained multi-quasiparticle potential energy surface (PES). The specific single-particle orbits that define the high-K configuration are identified and tracked (adiabatically blocked) by calculating the average Nilsson numbers. The deformed Woods-Saxon potential was taken to give single-particle orbits. The configuration-constrained PES takes into account the shape polarization effect. Such calculations give good results on excitation energies, deformations and other structure information about multi-quasiparticle high-K isomeric states. Many different mass regions have been investigated.

  14. Self-consistent Green's function embedding for advanced electronic structure methods based on a dynamical mean-field concept

    NASA Astrophysics Data System (ADS)

    Chibani, Wael; Ren, Xinguo; Scheffler, Matthias; Rinke, Patrick

    2016-04-01

    We present an embedding scheme for periodic systems that facilitates the treatment of the physically important part (here a unit cell or a supercell) with advanced electronic structure methods, that are computationally too expensive for periodic systems. The rest of the periodic system is treated with computationally less demanding approaches, e.g., Kohn-Sham density-functional theory, in a self-consistent manner. Our scheme is based on the concept of dynamical mean-field theory formulated in terms of Green's functions. Our real-space dynamical mean-field embedding scheme features two nested Dyson equations, one for the embedded cluster and another for the periodic surrounding. The total energy is computed from the resulting Green's functions. The performance of our scheme is demonstrated by treating the embedded region with hybrid functionals and many-body perturbation theory in the GW approach for simple bulk systems. The total energy and the density of states converge rapidly with respect to the computational parameters and approach their bulk limit with increasing cluster (i.e., computational supercell) size.

  15. Quasiparticle electronic structure of bulk and slab Bi2Se3 and Bi2Te3

    NASA Astrophysics Data System (ADS)

    Barker, Bradford; Deslippe, Jack; Yazyev, Oleg; Louie, Steven G.

    2014-03-01

    We present ab initio calculations of the quasiparticle electronic band structure of three-dimensional topological insulator materials Bi2Se3 and Bi2Te3. The mean-field DFT calculation is performed with fully relativistic pseudopotentials, generating spinor wavefunctions in a plane-wave basis. Quasiparticle properties are computed with a one-shot ab initio GW calculation. We use both bulk and slab forms of the materials to better understand the quasiparticle band gaps and Fermi velocities of the topological surface states of these materials. This work was supported by NSF grant No. DMR10-1006184 and U.S. DOE under Contract No. DE-AC02-05CH11231. Computational resources have been provided by DOE at LBNL's NERSC facility and the NSF through XSEDE resources at NICS.

  16. Remembering and telling self-consistent and self-discrepant memories.

    PubMed

    Mutlutürk, Aysu; Tekcan, Ali I

    2016-01-01

    It has been argued that memories that are inconsistent with one's self would differ from those that are consistent with the self. The present study addresses retrieval, phenomenology, rehearsal and narrative characteristics of autobiographical memories that are consistent versus discrepant with one's self. One hundred participants were asked to recall one self-consistent and one self-discrepant memory as well as an episode of telling these memories to others. They also filled out the Autobiographical Memory Questionnaire and the Centrality of Event Scale for each memory. Results showed no difference between self-consistent and self-discrepant memories in retrieval time, specificity or phenomenology. However, self-discrepant memory narratives contained more meaning-making statements and less autonomy than self-consistent memories. Compared to self-consistent memories, self-discrepant memories were told to fewer people, and listener responses were more negative when they were told. Results are discussed in relation to the functions these memories serve.

  17. Quasiparticle band structures and optical properties of magnesium fluoride

    NASA Astrophysics Data System (ADS)

    Yi, Zhijun; Jia, Ran

    2012-02-01

    The quasiparticle and optical properties of magnesium fluoride (MgF2) 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.

  18. 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.

  19. GW study of the half metallic band gap of zinc blende CrAs

    NASA Astrophysics Data System (ADS)

    Damewood, Liam; Fong, Ching Yao

    2009-11-01

    We determined the semiconducting gap of zinc blende (ZB) CrAs within the GW approximation (GWA). This is the first GW calculation of a half-metal. Previous calculations using density functional theory within the generalized gradient approximation (GGA) determined a gap of 1.8 eV, but the GGA is known to give too small of a value for this quantity in semiconductors. Additionally, since ZB CrAs is a half metal, one of its spin channels behaves like a metal and changes the quasiparticle screening compared to the insulating case. Due to the local field effect, we only included the γ-point term in the metallic channel calculation of the polarizability while keeping the full set of terms in the insulating channel GW calculation. Preliminary results suggest these terms from the polarizability produce little change in the value of the semiconducting gap when compared to the ``full'' GWA calculation.

  20. Doubly self-consistent field theory of grafted polymers under simple shear in steady state

    SciTech Connect

    Suo, Tongchuan; Whitmore, Mark D.

    2014-03-21

    We present a generalization of the numerical self-consistent mean-field theory of polymers to the case of grafted polymers under simple shear. The general theoretical framework is presented, and then applied to three different chain models: rods, Gaussian chains, and finitely extensible nonlinear elastic (FENE) chains. The approach is self-consistent at two levels. First, for any flow field, the polymer density profile and effective potential are calculated self-consistently in a manner similar to the usual self-consistent field theory of polymers, except that the calculation is inherently two-dimensional even for a laterally homogeneous system. Second, through the use of a modified Brinkman equation, the flow field and the polymer profile are made self-consistent with respect to each other. For all chain models, we find that reasonable levels of shear cause the chains to tilt, but it has very little effect on the overall thickness of the polymer layer, causing a small decrease for rods, and an increase of no more than a few percent for the Gaussian and FENE chains. Using the FENE model, we also probe the individual bond lengths, bond correlations, and bond angles along the chains, the effects of the shear on them, and the solvent and bonded stress profiles. We find that the approximations needed within the theory for the Brinkman equation affect the bonded stress, but none of the other quantities.

  1. 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.

  2. 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.

  3. Self-consistent dynamical models for early-type galaxies in the CALIFA Survey

    NASA Astrophysics Data System (ADS)

    Posti, L.; van de Ven, G.; Binney, J.; Nipoti, C.; Ciotti, L.

    2016-06-01

    We present the first application of self-consistent, continuous models with distribution functions (DFs) depending on the action integrals, to a sample of nearby early-type galaxies in the CALIFA Survey. Each model is axisymmetric, flattened, anisotropic and rotating and the total gravitational potential is self-consistently generated by the density distribution. The spatially-resolved kinematics of the CALIFA Survey gives solid constraints to the models' parameters: we fit the galaxies' surface brightness and the galaxies' spatially resolved kinematics and we estimate dynamical masses in agreement with other dynamical modelling approaches. For each galaxy, the best model provides an analytic DF which fully characterizes the velocity distribution of the stars. The fact that the DF depends on the action integrals makes it easy to extend the present models to have multiple components, such as bulge, stellar disc and dark and stellar halo, in equilibrium with their self-consistent gravitational potential.

  4. 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.

  5. Statistical dynamics of classical systems: A self-consistent field approach

    SciTech Connect

    Grzetic, Douglas J. Wickham, Robert A.; Shi, An-Chang

    2014-06-28

    We develop a self-consistent field theory for particle dynamics by extremizing the functional integral representation of a microscopic Langevin equation with respect to the collective fields. Although our approach is general, here we formulate it in the context of polymer dynamics to highlight satisfying formal analogies with equilibrium self-consistent field theory. An exact treatment of the dynamics of a single chain in a mean force field emerges naturally via a functional Smoluchowski equation, while the time-dependent monomer density and mean force field are determined self-consistently. As a simple initial demonstration of the theory, leaving an application to polymer dynamics for future work, we examine the dynamics of trapped interacting Brownian particles. For binary particle mixtures, we observe the kinetics of phase separation.

  6. 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.

  7. Stationary self-consistent distributions for a charged particle beam in the longitudinal magnetic field

    NASA Astrophysics Data System (ADS)

    Drivotin, O. I.; Ovsyannikov, D. A.

    2016-09-01

    A review of analytical solutions of the Vlasov equation for a beam of charged particles is given. These results are analyzed on the basis of a unified approach developed by the authors. In the context of this method, a space of integrals of motion is introduced in which the integrals of motion of particles are considered as coordinates. In this case, specifying a self-consistent distribution is reduced to defining a distribution density in this space. This approach allows us to simplify the construction and analysis of different self-consistent distributions. In particular, it is possible, in some cases, to derive new solutions by considering linear combinations of well-known solutions. This approach also makes it possible in many cases to give a visual geometric representation of self-consistent distributions in the space of integrals of motion.

  8. 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.

  9. 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.

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

    SciTech Connect

    Biglari, H.; Diamond, P.H.

    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.

  11. 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.

  12. 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.

  13. 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)

  14. Self-consistent Gödel cosmology with spin-density in Riemann-Cartan spacetime

    NASA Astrophysics Data System (ADS)

    Smalley, Larry L.

    1986-01-01

    We show that the Gödel metric for a rotating cosmology is compatible with the self-consistent formulation of the Einstein-Cartan metric-torsion theory for a spinning fluid. Fruitful discussions with J.R. Ray and F.W. Hehl are greatfully acknowledged. I wish to also thank J. Bradas who brought a reference to my attention.

  15. 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…

  16. Self-consistent chaos in a mean-field Hamiltonian model of fluids and plasmas

    NASA Astrophysics Data System (ADS)

    del-Castillo-Negrete, D.; Firpo, Marie-Christine

    2002-11-01

    We present a mean-field Hamiltonian model that describes the collective dynamics of marginally stable fluids and plasmas. In plasmas, the model describes the self-consistent evolution of electron holes and clumps in phase space. In fluids, the model describes the dynamics of vortices with negative and positive circulation in shear flows. The mean-field nature of the system makes it a tractable model to study the dynamics of large degrees-of-freedom, coupled Hamiltonian systems. Here we focus in the role of self-consistent chaos in the formation and destruction of phase space coherent structures. Numerical simulations in the finite N and in the Narrow kinetic limit (where N is the number of particles) show the existence of coherent, rotating dipole states. We approximate the dipole as two macroparticles, and show that the N = 2 limit has a family of rotating integrable solutions described by a one degree-of-freedom nontwist Hamiltonian. The coherence of the dipole is explained in terms of a parametric resonance between the rotation frequency of the macroparticles and the oscillation frequency of the self-consistent mean field. For a class of initial conditions, the mean field exhibits a self-consistent, elliptic-hyperbolic bifurcation that leads to the destruction of the dipole and violent mixing of the phase space.

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

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

    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.

  18. 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.

  19. 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.

  20. Self-consistent solution of the Dyson equation for atoms and molecules within a conserving approximation.

    PubMed

    Dahlen, Nils Erik; van Leeuwen, Robert

    2005-04-22

    We have calculated the self-consistent Green's function for a number of atoms and diatomic molecules. This Green's function is obtained from a conserving self-energy approximation, which implies that the observables calculated from the Green's functions agree with the macroscopic conservation laws for particle number, momentum, and energy. As a further consequence, the kinetic and potential energies agree with the virial theorem, and the many possible methods for calculating the total energy all give the same result. In these calculations we use the finite temperature formalism and calculate the Green's function on the imaginary time axis. This allows for a simple extension to nonequilibrium systems. We have compared the energies from self-consistent Green's functions to those of nonselfconsistent schemes and also calculated ionization potentials from the Green's functions by using the extended Koopmans' theorem.

  1. Self-consistent Ornstein-Zernike approximation for molecules with soft cores.

    PubMed

    Høye, J S; Reiner, A

    2006-09-14

    The self-consistent Ornstein-Zernike approximation (SCOZA) is an accurate liquid state theory. So far it has been tied to interactions composed of hard core repulsion and long-range attraction, whereas real molecules have soft core repulsion at short distances. In the present work, this is taken into account through the introduction of an effective hard core with a diameter that depends upon temperature only. It is found that the contribution to the configurational internal energy due to the repulsive reference fluid is of prime importance and must be included in the thermodynamic self-consistency requirement on which SCOZA is based. An approximate but accurate evaluation of this contribution relies on the virial theorem to gauge the amplitude of the pair distribution function close to the molecular surface. Finally, the SCOZA equation is transformed by which the problem is reformulated in terms of the usual SCOZA with fixed hard core reference system and temperature-dependent interaction.

  2. 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.

  3. A self-consistent thermodynamic model of metallic systems. Application for the description of gold

    SciTech Connect

    Balcerzak, T. Szałowski, K.

    2014-07-28

    A self-consistent thermodynamic model of metallic system is presented. The expression for the Gibbs energy is derived, which incorporates elastic (static) energy, vibrational energy within the Debye model, and electronic part in Hartee-Fock approximation. The elastic energy is introduced by a volume-dependent anharmonic potential. From the Gibbs energy all thermodynamic quantities, as well as the equation of state, are self-consistently obtained. The model is applied for the description of bulk gold in temperature range 0 ≤ T ≲ 1300 K and external pressure up to 30 GPa. The calculated thermodynamic properties are illustrated in figures and show satisfactory agreement with experimental data. The advantages and opportunities for further development of the method are discussed.

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

    SciTech Connect

    Meneghini, Orso; Snyder, P. B.; Smith, S. P.; Candy, J.; Staebler, G. M.; Belli, E. A.; Lao, L. L.; Park, J. M.; Green, David L; Elwasif, Wael R; Grierson, Brian A.; Holland, C.

    2016-01-01

    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. 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 Z eff.

  5. Self-consistent solution of the Dyson equation for atoms and molecules within a conserving approximation.

    PubMed

    Dahlen, Nils Erik; van Leeuwen, Robert

    2005-04-22

    We have calculated the self-consistent Green's function for a number of atoms and diatomic molecules. This Green's function is obtained from a conserving self-energy approximation, which implies that the observables calculated from the Green's functions agree with the macroscopic conservation laws for particle number, momentum, and energy. As a further consequence, the kinetic and potential energies agree with the virial theorem, and the many possible methods for calculating the total energy all give the same result. In these calculations we use the finite temperature formalism and calculate the Green's function on the imaginary time axis. This allows for a simple extension to nonequilibrium systems. We have compared the energies from self-consistent Green's functions to those of nonselfconsistent schemes and also calculated ionization potentials from the Green's functions by using the extended Koopmans' theorem. PMID:15945667

  6. Self-consistent Ornstein-Zernike approximation for molecules with soft cores.

    PubMed

    Høye, J S; Reiner, A

    2006-09-14

    The self-consistent Ornstein-Zernike approximation (SCOZA) is an accurate liquid state theory. So far it has been tied to interactions composed of hard core repulsion and long-range attraction, whereas real molecules have soft core repulsion at short distances. In the present work, this is taken into account through the introduction of an effective hard core with a diameter that depends upon temperature only. It is found that the contribution to the configurational internal energy due to the repulsive reference fluid is of prime importance and must be included in the thermodynamic self-consistency requirement on which SCOZA is based. An approximate but accurate evaluation of this contribution relies on the virial theorem to gauge the amplitude of the pair distribution function close to the molecular surface. Finally, the SCOZA equation is transformed by which the problem is reformulated in terms of the usual SCOZA with fixed hard core reference system and temperature-dependent interaction. PMID:16999537

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

    DOE PAGESBeta

    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.; et al

    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

  8. 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.

  9. Self-consistent field theory based molecular dynamics with linear system-size scaling

    SciTech Connect

    Richters, Dorothee; Kühne, Thomas D.

    2014-04-07

    We present an improved field-theoretic approach to the grand-canonical potential suitable for linear scaling molecular dynamics simulations using forces from self-consistent electronic structure calculations. It is based on an exact decomposition of the grand canonical potential for independent fermions and does neither rely on the ability to localize the orbitals nor that the Hamilton operator is well-conditioned. Hence, this scheme enables highly accurate all-electron linear scaling calculations even for metallic systems. The inherent energy drift of Born-Oppenheimer molecular dynamics simulations, arising from an incomplete convergence of the self-consistent field cycle, is circumvented by means of a properly modified Langevin equation. The predictive power of the present approach is illustrated using the example of liquid methane under extreme conditions.

  10. Self-consistent field theory based molecular dynamics with linear system-size scaling.

    PubMed

    Richters, Dorothee; Kühne, Thomas D

    2014-04-01

    We present an improved field-theoretic approach to the grand-canonical potential suitable for linear scaling molecular dynamics simulations using forces from self-consistent electronic structure calculations. It is based on an exact decomposition of the grand canonical potential for independent fermions and does neither rely on the ability to localize the orbitals nor that the Hamilton operator is well-conditioned. Hence, this scheme enables highly accurate all-electron linear scaling calculations even for metallic systems. The inherent energy drift of Born-Oppenheimer molecular dynamics simulations, arising from an incomplete convergence of the self-consistent field cycle, is circumvented by means of a properly modified Langevin equation. The predictive power of the present approach is illustrated using the example of liquid methane under extreme conditions.

  11. 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 .

  12. Dynamics and Self-consistent Chaos in a Mean Field Hamiltonian Model

    NASA Astrophysics Data System (ADS)

    del-Castillo-Negrete, Diego

    We study a mean field Hamiltonian model that describes the collective dynamics of marginally stable fluids and plasmas in the finite N and N-> infty kinetic limit (where N is the number of particles). The linear stability of equilibria in the kinetic model is studied as well as the initial value problem including Landau damping . Numerical simulations show the existence of coherent, rotating dipole states. We approximate the dipole as two macroparticles and show that the N=2 limit has a family of rotating integrable solutions that provide an accurate description of the dynamics. We discuss the role of self-consistent Hamiltonian chaos in the formation of coherent structures, and discuss a mechanism of "violent" mixing caused by a self-consistent elliptic-hyperbolic bifurcation in phase space.

  13. Electron Pumping under Non-Markovian Dissipation: The Role of the Self-Consistent Field

    NASA Astrophysics Data System (ADS)

    Grossmann, Frank; Sakurai, Atsunori; Tanimura, Yoshitaka

    2016-03-01

    Focusing on electron transport through a periodically driven resonant tunneling diode, we study the generation of a non-vanishing dc-current by applying symmetry breaking external ac fields with phase difference φ in a statically unbiased system. The effect of an environment is investigated using the system-bath Hamiltonian represented by the electron system coupled to harmonic oscillator modes with a Drude-Lorentz spectral density. To carry out simulations, we use the hierarchal equations of motion approach in the Wigner representation including a self-consistently constructed electric field that is determined from the electron distribution using the Poisson equation. We show that the maximal pumping current at a phase difference near φ = π/2 is strongly influenced by the system-bath coupling strength. The effect of dissipation is diminished if the self-consistent part of the potential is ignored.

  14. 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.

  15. 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.

  16. Accuracy of the Generalized Self-Consistent Method in Modelling the Elastic Behaviour of Periodic Composites

    NASA Technical Reports Server (NTRS)

    Walker, Kevin P.; Freed, Alan D.; Jordan, Eric H.

    1993-01-01

    Local stress and strain fields in the unit cell of an infinite, two-dimensional, periodic fibrous lattice have been determined by an integral equation approach. The effect of the fibres is assimilated to an infinite two-dimensional array of fictitious body forces in the matrix constituent phase of the unit cell. By subtracting a volume averaged strain polarization term from the integral equation we effectively embed a finite number of unit cells in a homogenized medium in which the overall stress and strain correspond to the volume averaged stress and strain of the constrained unit cell. This paper demonstrates that the zeroth term in the governing integral equation expansion, which embeds one unit cell in the homogenized medium, corresponds to the generalized self-consistent approximation. By comparing the zeroth term approximation with higher order approximations to the integral equation summation, both the accuracy of the generalized self-consistent composite model and the rate of convergence of the integral summation can be assessed. Two example composites are studied. For a tungsten/copper elastic fibrous composite the generalized self-consistent model is shown to provide accurate, effective, elastic moduli and local field representations. The local elastic transverse stress field within the representative volume element of the generalized self-consistent method is shown to be in error by much larger amounts for a composite with periodically distributed voids, but homogenization leads to a cancelling of errors, and the effective transverse Young's modulus of the voided composite is shown to be in error by only 23% at a void volume fraction of 75%.

  17. Magnetic field generation from Self-Consistent collective neutrino-plasma interactions

    SciTech Connect

    Brizard, A.J.; Murayama H.; Wurtele, J.S.

    1999-11-24

    A new Lagrangian formalism for self-consistent collective neutrino-plasma interactions is presented in which each neutrino species is described as a classical ideal fluid. The neutrino-plasma fluid equations are derived from a covariant relativistic variational principle in which finite-temperature effects are retained. This new formalism is then used to investigate the generation of magnetic fields and the production of magnetic helicity as a result of collective neutrino-plasma interactions.

  18. 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.

  19. Convergence Properties of the Harris Density Functional and the Self-Consistent Atom Fragment Approximation

    SciTech Connect

    Averill, Frank; Painter, Gayle S

    2006-01-01

    Describing materials properties and behavior over increasing scales of dimension and complexity requires an optimal balance of completeness and accuracy in solving the local density equations. In this study, the convergence properties of a set of schemes that aim to achieve increasing accuracy are systematically examined according to the hierarchical approximations upon which they are based. Specifically, the Harris density functional (HDF) and related schemes that express the total energy in terms of atomic densities and limited self-consistency are compared within a single consistent framework. Convergence of the HDF energy relative to input density is first tested by carrying out calculations within the non-self-consistent atom fragment and self-consistent atom fragment (SCAF) approximations and then by supplementing the SCAF density by increasing numbers of partial waves about each atomic site using the self-consistent partial wave (SCPW) method. The construct of the SCPW method, that solves the local density equations with controlled precision according to the number of partial waves in the site density expansions, enables this study. The rapid convergence of structural properties with an increasing number of partial waves on each site, sometimes even with only L=0 partial waves, provides additional justification for HDF-based tight-binding and molecular dynamics methods where the interatomic potentials are obtained from the superposition of atomic-like densities. The convergence of ground state structural properties is demonstrated by application to the set of molecules: carbon monoxide, water, orthosilicic acid (H{sub 4}SiO{sub 4}) , formamide (HCONH{sub 2}) , iron pentacarbonyl [Fe(CO){sub 5}] , and dimanganese decacarbonyl [Mn{sub 2}(CO){sub 10}] .

  20. Monte Carlo test of the self-consistent field theory of a polymer brush

    NASA Astrophysics Data System (ADS)

    Lai, Pik-Yin; Zhulina, E. B.

    1992-03-01

    The analytic predictions from the Self-Consistent Field(SCF) theory for grafted polymer layers are compared in detail with the recent Monte Carlo simulations using the bond-fluctuation model. Quantities describing the equilibrium structure of the brush are derived from the SCF theory and compared with the Monte Carlo data with no free parameter. In most cases the results are in agreement wiht the SCF predictions. Causes for discrepancies are also discussed.

  1. 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.

  2. Hamiltonian description of a self-consistent interaction between charged particles and electromagnetic waves.

    PubMed

    Bachelard, R; Chandre, C; Vittot, M

    2008-09-01

    The Hamiltonian description of the self-consistent interaction between an electromagnetic plane wave and a copropagating beam of charged particles is considered. We show how the motion can be reduced to a one-dimensional Hamiltonian model (in a canonical setting) from the Vlasov-Maxwell Poisson brackets. The reduction to this paradigmatic Hamiltonian model is performed using a Lie algebraic formalism which allows us to preserve the Hamiltonian character at each step of the derivation.

  3. Higher analytic derivatives. II. The fourth derivative of self-consistent-field energy

    NASA Astrophysics Data System (ADS)

    Maslen, Paul E.; Jayatilaka, Dylan; Colwell, Susan M.; Amos, Roger D.; Handy, Nicholas C.

    1991-11-01

    This is the second in a series on the ab initio calculation of the second, third, and fourth derivatives of the energy of a molecule with respect to nuclear coordinates. A knowledge of these derivatives yields, in particular, anharmonic spectroscopic constants. Here we discuss our implementation of the formula for the fourth derivative of the self-consistent-field energy and present full quartic force fields in internal coordinates for H2O and CO2.

  4. Self-consistent analysis of gain saturation in channeled-substrate-planar double-heterojunction lasers

    NASA Technical Reports Server (NTRS)

    Butler, Jerome K.; Evans, Gary A.

    1987-01-01

    A self-consistent model for semiconductor lasers (using the channeled-substrate-planar (CSP) double-heterojunction (DH) laser as an example) which does not assume constant optical power along the laser axis is developed. This approach allows for the analysis of high-power lasers with low facet reflectivities which produce nonuniform photon densities along the propagation direction. Analytical equations for the modal gain coefficient, the threshold current density, and the radiated power for a specific CSP laser structure are obtained.

  5. COMPARISON OF SELF-CONSISTENT SKYRME AND GOGNY CALCULATIONS FOR LIGHT Hg ISOTOPES

    SciTech Connect

    Warda, Michal J; Prochniak, L.; Staszczak, Andrzej

    2010-01-01

    The ground-state properties of neutron-deficient Hg isotopes have been investigated by the constrained self-consistent Hartree-Fock-Bogoliubov approach with the Skyrme and Gogny effective forces. In the case of the Skyrme interaction we have also applied the Hartree-Fock+BCS model with the state-dependent {delta}-pairing interaction. Potential energy surfaces and pairing properties have been compared for the both types of forces.

  6. A self-consistent model of stripe geometry lasers based on the beam propagation method

    SciTech Connect

    Meissner, P.; Patzak, E.; Yevick, D.

    1984-08-01

    Using the propagating beam technique to solve Maxwell's equations together with a shooting method solution to the carrier diffusion equation, the authors develop an iterative, self-consistent procedure for determing the properties of stripe geometry lasers. This procedure allows the authors to calculate the power-current characteristics, differential quantum efficiencies, gain distributions and near and far fields over a wide range of currents at and above threshold. Far above threshold, as expected, that symmetric and antisymmetric transverse modes can lase simultaneously.

  7. 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.

  8. Self-consistent Equilibrium Model of Low-aspect-ratio Toroidal Plasma with Energetic Beam Ions

    SciTech Connect

    E.V. Belova; N.N. Gorelenkov; C.Z. Cheng

    2003-04-09

    A theoretical model is developed which allows the self-consistent inclusion of the effects of energetic beam ions in equilibrium calculations of low-aspect-ratio toroidal devices. A two-component plasma is considered, where the energetic ions are treated using a kinetic Vlasov description, while a one-fluid magnetohydrodynamic description is used to represent the thermal plasma. The model allows for an anisotropic distribution function and a large Larmor radius of the beam ions. Numerical results are obtained for neutral-beam-heated plasmas in the National Spherical Torus Experiment (NSTX). Self-consistent equilibria with an anisotropic fast-ion distribution have been calculated for NSTX. It is shown for typical experimental parameters that the contribution of the energetic neutral-beam ions to the total current can be comparable to that of the background plasma, and that the kinetic modifications of the equilibrium can be significant. The range of validity of the finite-Larmor-radius expansion and of the reduced kinetic descriptions for the beam ions in NSTX is discussed. The calculated kinetic equilibria can be used for self-consistent numerical studies of beam-ion-driven instabilities in NSTX.

  9. Fast, Kinetically self-consistent simulation of RF modulated plasma boundary sheaths

    NASA Astrophysics Data System (ADS)

    Shihab, Mohammed; Brinkmann, Ralf Peter

    2012-10-01

    A mathematical model is presented which enables the efficent, kinetically self-consistent simulation of RF modulated plasma boundary sheaths in all technically relevant discharge regimes. The model consists of a set of kinetic equations for the ions, Boltzmann's relation for the electrons and Poisson's equation for the electrical field. Boundary conditions specify the ion flux at a point deep in the bulk and a periodically modulated sheath voltage or sheath charge. The equations are solved in a statistical sense. However, it is not the well-known particle-in-cell (PIC) scheme that is employed, but an alternative iterative algorithm termed ensemble-in-spacetime (EST). Three modules are called in a sequence: a Monte Carlo module, a harmonic analysis module, and a field module. The iteration is started with the potential values of a self-consistent fluid model and terminates when the updates become sufficiently small, i.e. when self-consistency is achieved. A drastic reduction of the computational effort compared with PIC calculations is achieved. As a first application of the new model, the influence of ion inertia on the dynamics of a collisionless sheath is studied and a comparison of the simulated ion energy distribution with published analytical solutions is performed.

  10. Variational self-consistent estimates for cubic viscoplastic polycrystals: the effects of grain anisotropy and shape

    NASA Astrophysics Data System (ADS)

    Nebozhyn, Michael V.; Gilormini, Pierre; Ponte Castañeda, Pedro

    2001-02-01

    A fundamental problem in mechanics of materials is the computation of the macroscopic response of polycrystalline aggregates from the properties of their constituent single-crystal grains and the microstructure. In this work, the nonlinear homogenization method of deBotton and Ponte Castañeda (1995) [deBotton, G., Ponte Castañeda, P., 1995. Variational estimates for the creep behavior of polycrystals. Proc. R. Soc. Lond. A 448, 121-142] is used to compute "variational" self-consistent estimates for the effective behavior of various types of cubic viscoplastic polycrystals. In contrast with earlier estimates of the self-consistent type, such as those arising from the "incremental" and "tangent" schemes, the new estimates are found to satisfy all known bounds, even in the strongly nonlinear, rate-insensitive limit, and to exhibit a more realistic scaling law at large grain anisotropy. Also, unlike the Taylor and Reuss estimates, they are able to account for grain shape in a rigorous statistical sense. For these reasons, they can be shown to be significantly more accurate than earlier estimates. Thus, for example, the new self-consistent estimates can be less than half the corresponding Taylor estimates for ionic polycrystals with highly anisotropic "flat" grains.

  11. Self-consistent calculation of particle-hole diagrams on the Matsubara frequency: Flex approximation

    SciTech Connect

    Rodriguez-Nunez, J.J.; Schafroth, S.

    1997-10-01

    The authors implement the numerical method of summing Green function diagrams on the Matsubara frequency axis for the fluctuation exchange (FLEX) approximation. Their method has previously been applied to the attractive Hubbard model for low density. Here they apply their numerical algorithm to the Hubbard model close to half filling ({rho} = 0.40), and for T/t = 0.03, in order to study the dynamics of one- and two-particle Green functions. For the values of the chosen parameters the authors see the formation of three branches which they associate with the two-peak structure in the imaginary part of the self-energy. From the imaginary part of the self-energy they conclude that their system is a Fermi liquid (for the temperature investigated here), since Im{Sigma}(k, {omega}) {approx} w{sup 2} around the chemical potential. The authors have compared their fully self-consistent FLEX solutions with a lower order approximation where the internal Green functions are approximated by free Green functions. These two approaches, i.e., the fully self-consistent and the non-self-consistent ones give different results for the parameters considered here. However, they have similar global results for small densities.

  12. 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.

  13. Properties of quark matter in a new quasiparticle model with QCD running coupling

    NASA Astrophysics Data System (ADS)

    Lu, ZhenYan; Peng, GuangXiong; Xu, JianFeng; Zhang, ShiPeng

    2016-06-01

    The running of the QCD coupling in the effective mass causes thermodynamic inconsistency problem in the conventional quasiparticle model. We provide a novel treatment which removes the inconsistency by an effective bag constant. The chemical potential dependence of the renormalization subtraction point is constrained by the Cauchy condition in the chemical potential space. The stability and microscopic properties of strange quark matter are then studied within the completely self-consistent quasiparticle model, and the obtained equation of state of quark matter is applied to the investigation of strange stars. It is found that our improved model can describe well compact stars with mass about two times the solar mass, which indicates that such massive compact stars could be strange stars.

  14. 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

  15. Self-consistent environment-dependent tight-binding: Methodology and applications

    NASA Astrophysics Data System (ADS)

    Areshkin, Denis Alexeyevich

    In the last several years dramatic advances have been demonstrated in the area of quantum electronic transport. A large part of transport methodology is borrowed from quantum chemistry methods. Many studies in this field use well-established general-purpose ab-initio computer codes, which are sometimes not well suited for transport problems. The present research is motivated by a need for a tool that meets specific requirements essential for quantum transport simulation techniques. These requirements include: (a) self-consistency, (b) a minimal and (c) orthogonal basis set. Self-consistency is necessary for simulations involving charge transfer and applied fields. A minimal basis set is desirable because non-equilibrium charge density evaluation requires massive O(N3) operations. The orthogonality constraint is imposed because popular energy minimization techniques can not be used to accelerate self-consistency convergence in non-equilibrium cases. The choice for a convergence acceleration algorithm is limited to the class of methods that evaluate the derivatives of the output charge density with respect to input density. The size of the matrices involved in these techniques is proportional to the number of non-zero overlap matrix elements and becomes prohibitively large for non-orthogonal basis sets. We developed a hybrid scheme for hydrocarbons based on Density Functional Theory, which is the self-consistent extension of the Environment Dependent Tight Binding (EDTB) method for carbon. The EDTB model refers to an orthogonal minimal basis set tight-binding (TB) method with two-center hopping matrix integrals that depend not only on the mutual arrangement of the two atoms on which the basis functions are centered, but also on the arrangement of neighboring atoms as well. The EDTB model effectively includes the dependence of hopping integrals on the surrounding electron density. This feature makes the EDTB approach highly transferable compared to standard TB, and in

  16. GW calculations of band offsets at AlN/GaN interfaces.

    NASA Astrophysics Data System (ADS)

    Cociorva, Daniel; Wilkins, John W.

    1998-03-01

    We study the quasiparticle bands at the interface of AlN and GaN using the GW approximation for the electron self-energy. Two structures are studied: the zinc-blende (cubic) interface in the (111) direction and the wurtzite (hexagonal) interface in the (001) direction. Our short superlattices are consistent with 4×4 LDA work(F. Bernardini et al.), Materials Research Society symposia proceedings 449, 923 (1997). and ``1×2'' GW work.(A. Rubio et al.), Phys. Rev. B 49, 1952 (1994). For comparison with recent experiments we are implementing a scalable parallel algorithm based on the reciprocal space formulation(M. S. Hybertsen and S. G. Louie, Phys. Rev. Lett. 55), 1418 (1985). to determine the self energy for thicker superlattices.

  17. Quasiparticle breakdown in a quantum spin liquid.

    PubMed

    Stone, Matthew B; Zaliznyak, Igor A; Hong, Tao; Broholm, Collin L; Reich, Daniel H

    2006-03-01

    Much of modern condensed matter physics is understood in terms of elementary excitations, or quasiparticles--fundamental quanta of energy and momentum. Various strongly interacting atomic systems are successfully treated as a collection of quasiparticles with weak or no interactions. However, there are interesting limitations to this description: in some systems the very existence of quasiparticles cannot be taken for granted. Like unstable elementary particles, quasiparticles cannot survive beyond a threshold where certain decay channels become allowed by conservation laws; their spectrum terminates at this threshold. Such quasiparticle breakdown was first predicted for an exotic state of matter--super-fluid 4He at temperatures close to absolute zero, a quantum Bose liquid where zero-point atomic motion precludes crystallization. Here we show, using neutron scattering, that quasiparticle breakdown can also occur in a quantum magnet and, by implication, in other systems with Bose quasiparticles. We have measured spin excitations in a two-dimensional quantum magnet, piperazinium hexachlorodicuprate (PHCC), in which spin-1/2 copper ions form a non-magnetic quantum spin liquid, and find remarkable similarities with excitations in superfluid 4He. We observe a threshold momentum beyond which the quasiparticle peak merges with the two-quasiparticle continuum. It then acquires a finite energy width and becomes indistinguishable from a leading-edge singularity, so that excited states are no longer quasiparticles but occupy a wide band of energy. Our findings have important ramifications for understanding excitations with gapped spectra in many condensed matter systems, ranging from band insulators to high-transition-temperature superconductors.

  18. Quasiparticle breakdown in a quantum spin liquid.

    PubMed

    Stone, Matthew B; Zaliznyak, Igor A; Hong, Tao; Broholm, Collin L; Reich, Daniel H

    2006-03-01

    Much of modern condensed matter physics is understood in terms of elementary excitations, or quasiparticles--fundamental quanta of energy and momentum. Various strongly interacting atomic systems are successfully treated as a collection of quasiparticles with weak or no interactions. However, there are interesting limitations to this description: in some systems the very existence of quasiparticles cannot be taken for granted. Like unstable elementary particles, quasiparticles cannot survive beyond a threshold where certain decay channels become allowed by conservation laws; their spectrum terminates at this threshold. Such quasiparticle breakdown was first predicted for an exotic state of matter--super-fluid 4He at temperatures close to absolute zero, a quantum Bose liquid where zero-point atomic motion precludes crystallization. Here we show, using neutron scattering, that quasiparticle breakdown can also occur in a quantum magnet and, by implication, in other systems with Bose quasiparticles. We have measured spin excitations in a two-dimensional quantum magnet, piperazinium hexachlorodicuprate (PHCC), in which spin-1/2 copper ions form a non-magnetic quantum spin liquid, and find remarkable similarities with excitations in superfluid 4He. We observe a threshold momentum beyond which the quasiparticle peak merges with the two-quasiparticle continuum. It then acquires a finite energy width and becomes indistinguishable from a leading-edge singularity, so that excited states are no longer quasiparticles but occupy a wide band of energy. Our findings have important ramifications for understanding excitations with gapped spectra in many condensed matter systems, ranging from band insulators to high-transition-temperature superconductors. PMID:16525467

  19. 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.

  20. Hidden Fermi liquid: Self-consistent theory for the normal state of high-Tc superconductors

    NASA Astrophysics Data System (ADS)

    Casey, Philip A.

    The anomalous "strange metal" properties of the normal, non-superconducting state of the high-Tc cuprate superconductors have been extensively studied for over two decades. The resistivity is robustly T-linear at high temperatures, while at low T it appears to maintain linearity near optimal doping and is T2 at higher doping. The inverse Hall angle is strictly T2 and hence has a distinct scattering lifetime from the resistivity. The transport scattering lifetime is highly anisotropic as directly measured by angle-dependent magnetoresistance (ADMR) and indirectly in more traditional transport experiments. The IR conductivity exhibits a non-integer power-law in frequency, which we take as a defining characteristic of the "strange metal". A phenomenological theory of the transport and spectroscopic properties at a self-consistent and predictive level has been much sought after, yet elusive. Hidden Fermi liquid theory (HFL) explicitly accounts for the effects of Gutzwiller projection in the t-J Hamiltonian, widely believed to contain the essential physics of the high-Tc superconductors. We show this theory to be the first self-consistent description for the normal state of the cuprates based on transparent, fundamental assumptions. Our well-defined formalism also serves as a guide for further experimental confirmation. Chapter 1 reviews the "strange metal" properties and the relevant aspects of competing models. Chapter 2 presents the theoretical foundations of the formalism. Chapters 3 and 4 derive expressions for the entire normal state relating many of the properties, for example: angle-resolved photoemission, IR conductivity, resistivity, Hall angle, and by generalizing the formalism to include the Fermi surface topology---ADMR. Self-consistency is demonstrated with experimental comparisons, including the most recent laser-ARPES and ADMR. Chapter 5 discusses entropy transport, as in the thermal conductivity, thermal Hall conductivity, and consequent metrics of non

  1. Interstellar turbulence model : A self-consistent coupling of plasma and neutral fluids

    SciTech Connect

    Shaikh, Dastgeer; Zank, Gary P.; Pogorelov, Nikolai

    2006-09-26

    We present results of a preliminary investigation of interstellar turbulence based on a self-consistent two-dimensional fluid simulation model. Our model describes a partially ionized magnetofluid interstellar medium (ISM) that couples a neutral hydrogen fluid to a plasma through charge exchange interactions and assumes that the ISM turbulent correlation scales are much bigger than the shock characteristic length-scales, but smaller than the charge exchange mean free path length-scales. The shocks have no influence on the ISM turbulent fluctuations. We find that nonlinear interactions in coupled plasma-neutral ISM turbulence are influenced substantially by charge exchange processes.

  2. A MinMax self-consistent-field approach for auxiliary density functional theory.

    PubMed

    Köster, Andreas M; Del Campo, Jorge M; Janetzko, Florian; Zuniga-Gutierrez, Bernardo

    2009-03-21

    A MinMax self-consistent-field (SCF) approach is derived in the framework of auxiliary density functional theory. It is shown that the SCF convergence can be guided by the fitting coefficients that arise from the variational fitting of the Coulomb potential. An in-core direct inversion of the iterative subspace (DIIS) algorithm is presented. Due to its reduced memory demand this new in-core DIIS method can be applied without overhead to very large systems with tens of thousands of basis and auxiliary functions. Due to the new DIIS error definition systems with fractional occupation numbers can be treated, too.

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

    PubMed

    Bjorgaard, J A; Kuzmenko, V; Velizhanin, K A; Tretiak, S

    2015-01-28

    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. PMID:25637965

  4. 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.

  5. Assessment of self-consistent field convergence in spin-dependent relativistic calculations

    NASA Astrophysics Data System (ADS)

    Nakano, Masahiko; Seino, Junji; Nakai, Hiromi

    2016-07-01

    This Letter assesses the self-consistent field (SCF) convergence behavior in the generalized Hartree-Fock (GHF) method. Four acceleration algorithms were implemented for efficient SCF convergence in the GHF method: the damping algorithm, the conventional direct inversion in the iterative subspace (DIIS), the energy-DIIS (EDIIS), and a combination of DIIS and EDIIS. Four different systems with varying complexity were used to investigate the SCF convergence using these algorithms, ranging from atomic systems to metal complexes. The numerical assessments demonstrated the effectiveness of a combination of DIIS and EDIIS for GHF calculations in comparison with the other discussed algorithms.

  6. A self-consistent approach to the reflection component in 4U 1705-44

    NASA Astrophysics Data System (ADS)

    D'Aì, A.; di Salvo, T.; Iaria, R.; Papitto, A.; Ballantyne, D.

    2010-07-01

    High-resolution spectroscopy has recently revealed in many neutron-star Low-Mass X-ray binaries that the shape of the broad iron line observed in the 6.4-6.97 keV range is consistently well fitted by a relativistically smeared line profile. We show here spectral fitting results using a newly developed self-consistent reflection model on XMM-Newton data of the LMXB 4U 1705-44 during a period when the source was in a bright soft state. This reflection model adopts a blackbody prescription for the shape of the impinging radiation field, that we physically associate with the boundary layer emission.

  7. The concept of coupling impedance in the self-consistent plasma wake field excitation

    NASA Astrophysics Data System (ADS)

    Fedele, R.; Akhter, T.; De Nicola, S.; Migliorati, M.; Marocchino, A.; Massimo, F.; Palumbo, L.

    2016-09-01

    Within the framework of the Vlasov-Maxwell system of equations, we describe the self-consistent interaction of a relativistic charged-particle beam with the surroundings while propagating through a plasma-based acceleration device. This is done in terms of the concept of coupling (longitudinal) impedance in full analogy with the conventional accelerators. It is shown that also here the coupling impedance is a very useful tool for the Nyquist-type stability analysis. Examples of specific physical situations are finally illustrated.

  8. 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.

  9. Self-consistent calculation of dephasing in quantum cascade structures within a density matrix method

    NASA Astrophysics Data System (ADS)

    Freeman, Will

    2016-05-01

    Dephasing in terahertz quantum cascade structures is studied within a density matrix formalism. We self-consistently calculate the pure dephasing time from the intrasubband interactions within the upper and lower lasing states. Interface roughness and ionized impurity scattering interactions are included in the calculation. Dephasing times are shown to be consistent with measured spontaneous emission spectra, and the lattice temperature dependence of the device output power is consistent with experiment. The importance of including multiple optical transitions when a lower miniband continuum is present and the resulting multi-longitudinal modes within the waveguide resonant cavity are also shown.

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

    SciTech Connect

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

    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.

  11. Self-consistent static analysis of using nested-well plasma traps for achieving antihydrogen recombination

    SciTech Connect

    Dolliver, D. D.; Ordonez, C. A.

    1999-12-10

    The use of a Malmberg-Penning type trap with nested electric potential wells to confine overlapping antiproton and positron plasmas for the purpose of producing low temperature antihydrogen is studied. Two approaches for confining antiproton and positron plasmas with a region of overlap are considered. In one approach the two components have a large temperature difference. In the other, one of the components is in a nonequilibrium 'antishielding' plasma state. A finite differences algorithm is used to solve Poisson's equation based on a simultaneous overrelaxation numerical approach. Self-consistent numerical results for required trap potentials and possible particle density profiles are presented.

  12. Self-consistent density functional calculation of field emission currents from metals

    PubMed

    Gohda; Nakamura; Watanabe; Watanabe

    2000-08-21

    We have developed a fully self-consistent method which is suitable to examine field emission currents, on the basis of the density functional theory. In our method, the nearby counterelectrode is not necessary. By using this method, we have investigated field emission currents from a biased metallic surface represented by the jellium model. We have found that the energy barrier between the jellium and vacuum becomes lower than the Fermi energy under strong electric fields (e.g., 10 V/nm for r(s) = 4 bohr). In this situation, the slope of the Fowler-Nordheim plot becomes flatter than that under a weaker field.

  13. 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.

  14. Homogenization of Periodic Masonry Using Self-Consistent Scheme and Finite Element Method

    NASA Astrophysics Data System (ADS)

    Kumar, Nitin; Lambadi, Harish; Pandey, Manoj; Rajagopal, Amirtham

    2016-01-01

    Masonry is a heterogeneous anisotropic continuum, made up of the brick and mortar arranged in a periodic manner. Obtaining the effective elastic stiffness of the masonry structures has been a challenging task. In this study, the homogenization theory for periodic media is implemented in a very generic manner to derive the anisotropic global behavior of the masonry, through rigorous application of the homogenization theory in one step and through a full three-dimensional behavior. We have considered the periodic Eshelby self-consistent method and the finite element method. Two representative unit cells that represent the microstructure of the masonry wall exactly are considered for calibration and numerical application of the theory.

  15. Self-consistent, three-dimensional equilibrium effects on tokamak magnetic field ripple

    SciTech Connect

    Johnson, J.L.; Reiman, A.H.

    1987-10-01

    Self-consistent equilibrium effects on tokamak magnetic field ripple have been calculated using a three-dimensional equilibrium code. The effects are found to be large enough that they should be included in tokamak ignition experiment designs. Even the modification of the well depth associated with the flow of force-free plasma current along rippled field lines is substantial. An analysis of the results separates the contribution of the Shafranov shift to the ripple modification from the contributions of other finite-pressure effects. 5 refs., 10 figs., 1 tab.

  16. Self-consistent description of coexistence phenomena in medium mass nuclei

    SciTech Connect

    Petrovici, A.; Schmid, K. W.; Faessler, Amand; Andrei, O.

    2010-11-24

    Shape coexistence and mixing, isospin mixing, the competition between neutron-proton and like-nucleon pairing correlations have been identified as the main characteristic features of nuclei near the N = Z line in the A{approx_equal}70 mass region. The self-consistent treatment of exotic phenomena dominated by their interplay represents a challenge for the nuclear many-body models. The realistic description of tiny effects in this mass region aiming to test the fundamental interactions and symmetries as well as the required theoretical predictions concerning the nuclear properties relevant for astrophysical scenarios are still open problems of the low-energy nuclear physics today.

  17. Halo Formation in 3-D Bunches with Self-Consistent Stationary Distributions

    NASA Astrophysics Data System (ADS)

    Fedotov, A. V.; Gluckstern, R. L.; Kurennoy, S. S.; Ryne, R. D.

    1998-04-01

    We have constructed, analytically and numerically, a new class of self-consistent 6-D phase space stationary distributions. The beam is then mismatched longitudinally and/or transversely, and we explore the formation of longitudinal and transverse halos in 3-D axisymmetric beam bunches. The longitudinal phase space clearly shows the typical "peanut" diagram observed in 2-D calculations. We find that the longitudinal halo forms first for comparable longitudinal and transverse mismatches because the longitudinal tune depression is more severe than the transverse one for elongated bunches. Of particular importance is the coupling between longitudinal and transverse motion and its effect on halo formation.

  18. 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.

  19. Self-consistent tight-binding approach to modeling magnetic structure of materials

    NASA Astrophysics Data System (ADS)

    Zhuang, Min; Woods Halley, J.

    2000-03-01

    We describe an extension to magnetic system of a self-consistent tight-binding method previously used to study surfaces, polarons and grain boundaries in non-magnetic materials.[1] In the method, the model is fit to a first-principles calculation on the bulk system and to properties of isolated ions. We illustrate with results on both for a toy model in which there are two sites and two electrons, and for rutile structure β-MnO2 with screw spin structure. [1] P. K. Schelling, N. Yu and J. W. Halley, Phys. Rev. B58, 1279(1997).

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

    PubMed

    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.

  1. Accurate vibrational frequencies using the self-consistent-charge density-functional tight-binding method

    NASA Astrophysics Data System (ADS)

    Małolepsza, Edyta; Witek, Henryk A.; Morokuma, Keiji

    2005-09-01

    An optimization technique for enhancing the quality of repulsive two-body potentials of the self-consistent-charge density-functional tight-binding (SCC-DFTB) method is presented and tested. The new, optimized potentials allow for significant improvement of calculated harmonic vibrational frequencies. Mean absolute deviation from experiment computed for a group of 14 hydrocarbons is reduced from 59.0 to 33.2 cm -1 and maximal absolute deviation, from 436.2 to 140.4 cm -1. A drawback of the new family of potentials is a lower quality of reproduced geometrical and energetic parameters.

  2. 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.

  3. Structure of physical crystalline membranes within the self-consistent screening approximation

    NASA Astrophysics Data System (ADS)

    Gazit, Doron

    2009-10-01

    The anomalous exponents governing the long-wavelength behavior of the flat phase of physical crystalline membranes are calculated within a self-consistent screening approximation (SCSA) applied to second order expansion in 1/dC ( dC is the codimension), extending the seminal work of Le Doussal and Radzihovsky [Phys. Rev. Lett. 69, 1209 (1992)]. In particular, the bending rigidity is found to harden algebraically in the long-wavelength limit with an exponent η=0.789… , which is used to extract the elasticity softening exponent ηu=0.422… , and the roughness exponent ζ=0.605… . The scaling relation ηu=2-2η is proven to hold to all orders in SCSA. Further, applying the SCSA to an expansion in 1/dC , is found to be essential, as no solution to the self-consistent equations is found in a two-bubble level, which is the naive second-order expansion. Surprisingly, even though the expansion parameter for physical membrane is 1/dC=1 , the SCSA applied to second-order expansion deviates only slightly from the first order, increasing ζ by mere 0.016. This supports the high quality of the SCSA for physical crystalline membranes, as well as improves the comparison to experiments and numerical simulations of these systems. The prediction of SCSA applied to first order expansion for the Poisson ratio is shown to be exact to all orders.

  4. Kinetic theory of protein filament growth: Self-consistent methods and perturbative techniques

    NASA Astrophysics Data System (ADS)

    Michaels, Thomas C. T.; Knowles, Tuomas P. J.

    2015-12-01

    Filamentous protein structures are of high relevance for the normal functioning of the cell, where they provide the structural component for the cytoskeleton, but are also implicated in the pathogenesis of many disease states. The self-assembly of these supra-molecular structures from monomeric proteins has been studied extensively in the past 50 years and much interest has focused on elucidating the microscopic events that drive linear growth phenomena in a biological setting. Master equations have proven to be particularly fruitful in this context, allowing specific assembly mechanisms to be linked directly to experimental observations of filamentous growth. Recently, these approaches have increasingly been applied to aberrant protein polymerization, elucidating potential implications for controlling or combating the formation of pathological filamentous structures. This article reviews recent theoretical advances in the field of filamentous growth phenomena through the use of the master-equation formalism. We use perturbation and self-consistent methods for obtaining analytical solutions to the rate equations describing fibrillar growth and show how the resulting closed-form expressions can be used to shed light on the general physical laws underlying this complex phenomenon. We also present a connection between the underlying ideas of the self-consistent analysis of filamentous growth and the perturbative renormalization group.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Morozovska, Anna N.; Ievlev, Anton V.; Obukhovskii, Vyacheslav V.; Fomichov, Yevhen; Varenyk, Oleksandr V.; Shur, Vladimir Ya.; Kalinin, Sergei V.; Eliseev, Eugene A.

    2016-04-01

    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 LiNb O3 and can give insight into the anisotropic dynamics of nanoscale polarization reversal in strongly inhomogeneous electric fields.

  7. Self-consistent separable random-phase approximation for Skyrme forces: Giant resonances in axial nuclei

    SciTech Connect

    Nesterenko, V. O.; Dolci, D. S.; Kleinig, W.; Kvasil, J.; Vesely, P.; Reinhard, P.-G.

    2006-12-15

    We formulate the self-consistent separable random phase approximation (SRPA) method and specify it for Skyrme forces with pairing for the case of axially symmetric deformed nuclei. The factorization of the residual interaction allows diagonalization of high-ranking RPA matrices to be avoided, which dramatically reduces the computational expense. This advantage is crucial for the systems with a huge configuration space, first of all for deformed nuclei. SRPA self-consistently takes into account the contributions of both time-even and time-odd Skyrme terms as well as of the Coulomb force and pairing. The method is implemented to describe isovector E1 and isoscalar E2 giant resonances in a representative set of deformed nuclei: {sup 154}Sm, {sup 238}U, and {sup 254}No. Four different Skyrme parameterizations (SkT6, SkM*, SLy6, and SkI3) are employed to explore the dependence of the strength distributions on some basic characteristics of the Skyrme functional and nuclear matter. In particular, we discuss the role of isoscalar and isovector effective masses and their relation to time-odd contributions. The high sensitivity of the right flank of E1 resonance to different Skyrme forces and the related artificial structure effects are analyzed.

  8. 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.

  9. 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.

  10. Simulation of collisionless ultrarelativistic electron-proton plasma dynamics in a self-consistent electromagnetic field

    NASA Astrophysics Data System (ADS)

    Ginzburg, S. L.; Dyachenko, V. F.; Orlov, Yu. N.; Fimin, N. N.; Chechetkin, V. M.

    2016-09-01

    The evolution of a collisionless electron-proton plasma in the self-consistent approximation is investigated. The plasma is assumed to move initially as a whole in a vacuum with the Lorentz factor. The behavior of the dynamical system is analyzed by applying a three-dimensional model based on the Vlasov-Maxwell equations with allowance for retarded potentials. It is shown that the analysis of the solution to the problem is not valid in the "center-of-mass frame" of the plasmoid (since it cannot be correctly defined for a relativistic plasma interacting via an electromagnetic field) and the transition to a laboratory frame of reference is required. In the course of problem solving, a chaotic electromagnetic field is generated by the plasma particles. As a result, the particle distribution functions in the phase space change substantially and differ from their Maxwell-Juttner form. Computations show that the kinetic energies of the electron and proton components and the energy of the self-consistent electromagnetic field become identical. A tendency to the isotropization of the particle momentum distribution in the direction of the initial plasmoid motion is observed.

  11. 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.

  12. "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.

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

    PubMed

    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. 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}% ).

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

    PubMed

    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.

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

    DOE PAGESBeta

    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 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

  18. 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.

  19. 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.

  20. 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.

  1. Self-consistent calculation of hyperfine fields and adiabatic potential of impurities in iron

    NASA Astrophysics Data System (ADS)

    Kanamori, Junjiro; Akai, Hisazumi; Akai, Masako

    1984-01-01

    Hyperfine fields of impurities of the atomic number Z=1 56 at the substitutional site and those of light impurities of Z=1 9 at the interstitial sites in ferromagnetic iron are calculated by the KKR method adapted to the system containing a single impurity atom. The potential of the impurity atom is determined self-consistently by use of the local spin density functional formalism. The results for nonmagnetic sp valence impurities agree with those of the previous nonself-consistent calculation by Katayama-Yoshida, Terakura and Kanamori except for a few cases, confirming their theory of the systematic variation of hyperfine fields. The calculation for magnetic impurities of transition elements is presented for the first time in this paper. The calculations mentioned so far assume that impurities are situated at the center of each site. For the purpose of discussing the stability of the impurity positions, the change of the adiabatic potential due to displacements from the center is calculated by carrying out similar self-consistent calculations for off-center impurity positions. It is concluded that positive muon and some light impurities including boron will be displaced from the center when trapped in a vacancy.

  2. 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

  3. Formulation of a self-consistent model for quantum well pin solar cells

    NASA Astrophysics Data System (ADS)

    Ramey, S.; Khoie, R.

    1997-04-01

    A self-consistent numerical simulation model for a pin single-cell solar cell is formulated. The solar cell device consists of a p-AlGaAs region, an intrinsic i-AlGaAs/GaAs region with several quantum wells, and a n-AlGaAs region. Our simulator solves a field-dependent Schrödinger equation self-consistently with Poisson and Drift-Diffusion equations. The emphasis is given to the study of the capture of electrons by the quantum wells, the escape of electrons from the quantum wells, and the absorption and recombination within the quantum wells. We believe this would be the first such comprehensive model ever reported. The field-dependent Schrödinger equation is solved using the transfer matrix method. The eigenfunctions and eigenenergies obtained are used to calculate the escape rate of electrons from the quantum wells, and the non-radiative recombination rates of electrons at the boundaries of the quantum wells. These rates together with the capture rates of electrons by the quantum wells are then used in a self-consistent numerical Poisson-Drift-Diffusion solver. The resulting field profiles are then used in the field-dependent Schrödinger solver, and the iteration process is repeated until convergence is reached. In a p-AlGaAs i-AlGaAs/GaAs n-AlGaAs cell with aluminum mole fraction of 0.3, with one 100 Å-wide 284 meV-deep quantum well, the eigenenergies with zero field are 36meV, 136meV, and 267meV, for the first, second and third subbands, respectively. With an electric field of 50 kV/cm, the eigenenergies are shifted to 58meV, 160meV, and 282meV, respectively. With these eigenenergies, the thermionic escape time of electrons from the GaAs Γ-valley, varies from 220 pS to 90 pS for electric fields ranging from 10 to 50 kV/cm. These preliminary results are in good agreement with those reported by other researchers.

  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. Fast, kinetically self-consistent simulation of RF modulated plasma boundary sheaths

    NASA Astrophysics Data System (ADS)

    Shihab, Mohammed; Ziegler, Dennis; Brinkmann, Ralf Peter

    2012-05-01

    A mathematical model is presented which enables the efficient, kinetically self-consistent simulation of RF modulated plasma boundary sheaths in all technically relevant discharge regimes. It is defined on a one-dimensional geometry where a Cartesian x-axis points from the electrode or wall at xE ≡ 0 towards the plasma bulk. An arbitrary endpoint xB is chosen ‘deep in the bulk’. The model consists of a set of kinetic equations for the ions, Boltzmann's relation for the electrons and Poisson's equation for the electrical field. Boundary conditions specify the ion flux at xB and a periodically—not necessarily harmonically—modulated sheath voltage V(t) or sheath charge Q(t). The equations are solved in a statistical sense. However, it is not the well-known particle-in-cell (PIC) scheme that is employed, but an alternative iterative algorithm termed ensemble-in-spacetime (EST). The basis of the scheme is a discretization of the spacetime, the product of the domain [xE, xB] and the RF period [0, T]. Three modules are called in a sequence. A Monte Carlo module calculates the trajectories of a large set of ions from their start at xB until they reach the electrode at xE, utilizing the potential values on the nodes of the spatio-temporal grid. A harmonic analysis module reconstructs the Fourier modes nim(x) of the ion density ni(x, t) from the calculated trajectories. A field module finally solves the Boltzmann-Poisson equation with the calculated ion densities to generate an updated set of potential values for the spatio-temporal grid. The iteration is started with the potential values of a self-consistent fluid model and terminates when the updates become sufficiently small, i.e. when self-consistency is achieved. A subsequent post-processing determines important quantities, in particular the phase-resolved and phase-averaged values of the ion energy and angular distributions and the total energy flux at the electrode. A drastic reduction of the computational

  6. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  8. 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.

  9. 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.

  10. 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.

  11. Self-consistent continuum solvation for optical absorption of complex molecular systems in solution

    SciTech Connect

    Timrov, Iurii; Biancardi, Alessandro; Andreussi, Oliviero; Marzari, Nicola; Baroni, Stefano

    2015-01-21

    We introduce a new method to compute the optical absorption spectra of complex molecular systems in solution, based on the Liouville approach to time-dependent density-functional perturbation theory and the revised self-consistent continuum solvation model. The former allows one to obtain the absorption spectrum over a whole wide frequency range, using a recently proposed Lanczos-based technique, or selected excitation energies, using the Casida equation, without having to ever compute any unoccupied molecular orbitals. The latter is conceptually similar to the polarizable continuum model and offers the further advantages of allowing an easy computation of atomic forces via the Hellmann-Feynman theorem and a ready implementation in periodic-boundary conditions. The new method has been implemented using pseudopotentials and plane-wave basis sets, benchmarked against polarizable continuum model calculations on 4-aminophthalimide, alizarin, and cyanin and made available through the QUANTUM ESPRESSO distribution of open-source codes.

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

    PubMed

    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. PMID:19206962

  13. Ab initio self-consistent x-ray absorption fine structure analysis for metalloproteins.

    PubMed

    Dimakis, Nicholas; Bunker, Grant

    2006-12-01

    X-ray absorption fine structure is a powerful tool for probing the structures of metals in proteins in both crystalline and noncrystalline environments. Until recently, a fundamental problem in biological XAFS has been that ad hoc assumptions must be made concerning the vibrational properties of the amino acid residues that are coordinated to the metal to fit the data. Here, an automatic procedure for accurate structural determination of active sites of metalloproteins is presented. It is based on direct multiple-scattering simulation of experimental X-ray absorption fine structure spectra combining electron multiple scattering calculations with density functional theory calculations of vibrational modes of amino acid residues and the genetic algorithm differential evolution to determine a global minimum in the space of fitting parameters. Structure determination of the metalloprotein active site is obtained through a self-consistent iterative procedure with only minimal initial information.

  14. 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.

  15. Transport enhancement and suppression in turbulent magnetic reconnection: A self-consistent turbulence model

    SciTech Connect

    Yokoi, N.; Higashimori, K.; Hoshino, M.

    2013-12-15

    Through the enhancement of transport, turbulence is expected to contribute to the fast reconnection. However, the effects of turbulence are not so straightforward. In addition to the enhancement of transport, turbulence under some environment shows effects that suppress the transport. In the presence of turbulent cross helicity, such dynamic balance between the transport enhancement and suppression occurs. As this result of dynamic balance, the region of effective enhanced magnetic diffusivity is confined to a narrow region, leading to the fast reconnection. In order to confirm this idea, a self-consistent turbulence model for the magnetic reconnection is proposed. With the aid of numerical simulations where turbulence effects are incorporated in a consistent manner through the turbulence model, the dynamic balance in the turbulence magnetic reconnection is confirmed.

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

    PubMed

    Zhang, Hou-Dao; Yan, YiJing

    2015-12-01

    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.

  17. 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.

  18. 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.

  19. 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.

  20. Occupation numbers of spherical orbits in self-consistent beyond-mean-field methods

    NASA Astrophysics Data System (ADS)

    Rodríguez, Tomás R.; Poves, Alfredo; Nowacki, Frédéric

    2016-05-01

    We present a method to compute the number of particles occupying spherical single-particle (SSP) levels within the energy density functional (EDF) framework. These SSP levels are defined for each nucleus by performing self-consistent mean-field calculations. The nuclear many-body states, in which the occupation numbers are evaluated, are obtained with a symmetry conserving configuration mixing (SCCM) method based on the Gogny EDF. The method allows a closer comparison between EDF and shell model with configuration mixing in large valence spaces (SM-CI) results, and can serve as a guidance to define physically sound valence spaces for SM-CI calculations. As a first application of the method, we analyze the onset of deformation in neutron-rich N =40 isotones and the role of the SSP levels around this harmonic oscillator magic number, with particular emphasis in the structure of 64Cr.

  1. Self-Consistent Model of an Ozone Layer on Ancient Mars

    NASA Astrophysics Data System (ADS)

    Deighan, Justin; Johnson, R. E.

    2010-10-01

    When modeling thick, early Martian atmospheres, it is often assumed that the mixing ratios of CO2, O2, CO, and O3 were similar to those observed today. Even when photochemical models are used to determine the composition of past atmospheres, a temperature profile similar in form to that currently observed is often imposed as a simplification. However, neither of these may be accurate assumptions. A 1D line-by-line radiative-convective model coupled self-consistently with a simple photochemical model is presented here to explore the relaxation of these assumptions. A primary consequence is the possibility of a substantial O3 layer on ancient Mars. Areas of impact considered include the loss of H2O to space, an enhanced greenhouse effect, inhibition of CO2 condensation in the stratosphere, and reduced surface UV.

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

    PubMed

    Zhang, Hou-Dao; Yan, YiJing

    2015-12-01

    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. PMID:26646874

  4. A thermodynamic self-consistent theory of asymmetric hard-core Yukawa mixtures.

    PubMed

    Pellicane, Giuseppe; Caccamo, Carlo

    2016-10-19

    We perform structural and thermodynamic calculations in the framework of the modified hypernetted chain (MHNC) integral equation closure to the Ornstein-Zernike equation for binary mixtures of size-different particles interacting with hard-core Yukawa pair potentials. We use the Percus-Yevick (PY) bridge functions of a binary mixture of hard-sphere (HSM) particles. The hard-sphere diameters of the PY bridge functions of the HSM system are adjusted so to achieve thermodynamic consistency between the virial and compressibility equations of state. We show the benefit of thermodynamic consistency by comparing the MHNC results with the available computer simulation data reported in the literature, and we demonstrate that the self-consistent thermodynamic theory provides a better reproduction of the simulation data over other microscopic theories. PMID:27545096

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

    DOE PAGESBeta

    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 tomore » demonstrate the accuracy of the solver and then show results unique to the 2D case.« less

  6. Rare transition event with self-consistent theory of large-amplitude collective motion

    SciTech Connect

    Tsumura, Kyosuke Maeda, Yoshitaka; Watanabe, Hiroyuki

    2015-06-15

    A numerical simulation method, based on Dang et al.’s self-consistent theory of large-amplitude collective motion, for rare transition events is presented. The method provides a one-dimensional pathway without knowledge of the final configuration, which includes a dynamical effect caused by not only a potential but also kinetic term. Although it is difficult to apply the molecular dynamics simulation to a narrow-gate potential, the method presented is applicable to the case. A toy model with a high-energy barrier and/or the narrow gate shows that while the Dang et al. treatment is unstable for a changing of model parameters, our method stable for it.

  7. Non-perturbative and self-consistent models of neutron stars in R-squared gravity

    SciTech Connect

    Yazadjiev, Stoytcho S.; Doneva, Daniela D.; Kokkotas, Kostas D.; Staykov, Kalin V. E-mail: daniela.doneva@uni-tuebingen.de E-mail: kalin.v.staikov@gmail.com

    2014-06-01

    In the present paper we investigate non-perturbatively and self-consistently the structure of neutron stars in R-squared gravity by simultaneously solving the interior and exterior problem. The mass-radius relations are obtained for several equations of state and for wide range of the R-squared gravity parameter a. Even though the deviation from general relativity for nonzero values of a can be large, they are still comparable with the variations due to different modern realistic equations of state. That is why the current observations of the neutron star masses and radii alone can not put constraints on the value of the parameter a. We also compare our results with those obtained within the perturbative method and we discuss the differences between them.

  8. 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.

  9. A thermodynamic self-consistent theory of asymmetric hard-core Yukawa mixtures

    NASA Astrophysics Data System (ADS)

    Pellicane, Giuseppe; Caccamo, Carlo

    2016-10-01

    We perform structural and thermodynamic calculations in the framework of the modified hypernetted chain (MHNC) integral equation closure to the Ornstein-Zernike equation for binary mixtures of size-different particles interacting with hard-core Yukawa pair potentials. We use the Percus-Yevick (PY) bridge functions of a binary mixture of hard-sphere (HSM) particles. The hard-sphere diameters of the PY bridge functions of the HSM system are adjusted so to achieve thermodynamic consistency between the virial and compressibility equations of state. We show the benefit of thermodynamic consistency by comparing the MHNC results with the available computer simulation data reported in the literature, and we demonstrate that the self-consistent thermodynamic theory provides a better reproduction of the simulation data over other microscopic theories.

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

    PubMed

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

    2015-07-01

    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.

  11. A self-consistent turbulence generated scenario for L-H transition. [Banana polarization currents

    SciTech Connect

    Zhang, Y.Z.; Mahajan, S.M.

    1992-10-01

    The turbulence-induced ion banana polarization current associated with steep ion temperature gradients is explored as a possible mechanism for generating poloidal momentum at the tokamak edge. In the light of a recently developed two-dimensional turbulence theory, one can obtain a simple closed expression relating this current (determined by turbulence levels) to the derivatives of the poloidal rotation speed. A self-consistent system, then, emerges, if we balance the turbulence-induced poloidal momentum with that dissipated by viscosity. Under suitable conditions this system may show a bifurcation controlled by a parameter dependent on temperature gradients. Both the bifurcation point, and the shear layer width are predicted for a prescribed flow in terms of a scale characterizing the nonlinearity of viscosity. The crucial relevance of the flow parity with the turbulence scenario is analyzed.

  12. 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.

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

    PubMed

    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. PMID:27357125

  15. Optical absorption of dilute nitride alloys using self-consistent Green’s function method

    PubMed Central

    2014-01-01

    We have calculated the optical absorption for InGaNAs and GaNSb using the band anticrossing (BAC) model and a self-consistent Green’s function (SCGF) method. In the BAC model, we include the interaction of isolated and pair N levels with the host matrix conduction and valence bands. In the SCGF approach, we include a full distribution of N states, with non-parabolic conduction and light-hole bands, and parabolic heavy-hole and spin-split-off bands. The comparison with experiments shows that the first model accounts for many features of the absorption spectrum in InGaNAs; including the full distribution of N states improves this agreement. Our calculated absorption spectra for GaNSb alloys predict the band edges correctly but show more features than are seen experimentally. This suggests the presence of more disorder in GaNSb alloys in comparison with InGaNAs. PMID:24475947

  16. A self-consistent reduced model for dusty magnetorotationally unstable discs

    NASA Astrophysics Data System (ADS)

    Jacquet, Emmanuel; Balbus, Steven

    2012-06-01

    The interaction between settling of dust grains and magnetorotational instability (MRI) turbulence in protoplanetary discs is analysed. We use a reduced system of coupled ordinary differential equations to represent the interaction between the diffusion of grains and the inhibition of the MRI. The coupled equations are styled on a Landau equation for the turbulence and a Fokker-Planck equation for the diffusion. The turbulence-grain interaction is probably most relevant near the outer edge of the disc's quiescent, or 'dead' zone. Settling is most pronounced near the mid-plane, where a high dust concentration can self-consistently suppress the MRI. Under certain conditions, however, grains can reach high altitudes, a result of some observational interest. Finally, we show that the equilibrium solutions are linearly stable.

  17. Dynamic Self-Consistent Field Theory of Inhomogeneous Complex Fluids Under Shear

    NASA Astrophysics Data System (ADS)

    Mihajlovic, Maja; Lo, Tak Shing; Shnidman, Yitzhak

    2003-03-01

    Understanding and predicting the interplay between morphology and rheology of sheared, inhomogeneous, complex fluids is of great importance. Yet modeling of such phenomena is in its infancy. We have developed a novel dynamic self-consistent field (DSCF) theory that makes possible detailed computational study of such phenomena. Our DSCF theory couples the time evolution of chain conformation statistics with probabilistic transport equations for volume fractions and momenta, based on local conservation laws formulated on a segmental scale. To generate chain conformation statistics, we are using a modification of the lattice random walk formalism of Scheutjens and Fleer. Their static SCF theory is limited to equilibrium systems, since probability distributions are obtained by free energy minimization, assuming isotropic Gaussian chain conformations. In contrast, our DSCF approach accounts for explicit time evolution of the segmental and (anisotropic) stepping probabilities used for generating chain conformations. We will present highlights of DSCF studies of a variety of inhomogenous fluids containing homopolymers, block copolymers and nanoparticles.

  18. Improved master equation approach to quantum transport: From Born to self-consistent Born approximation

    SciTech Connect

    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.

  19. 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.

  20. Self-consistent formation of parallel electric fields in the auroral zone

    NASA Technical Reports Server (NTRS)

    Schriver, David; Ashour-Abdalla, Maha

    1993-01-01

    This paper presents results from a fully self-consistent kinetic particle simulation of the time-dependent formation of large scale parallel electric fields in the auroral zone. The results show that magnetic mirroring of the hot plasma that streams earthward from the magnetotail leads to a charge separation potential drop of many kilovolts, over an altitude range of a few thousand kilometers. Once the potential drop is formed, it remains relatively static and is maintained in time by the constant input of hot plasma from the tail; the parallel electric field accelerates ions away from Earth and ionospheric electrons towards the Earth. At altitudes above where the ions are mirror reflected and accelerated by the parallel electric field, low frequency waves are generated, possibly due to an ion/ion two-stream interaction.

  1. Self-Consistent Model for Planar Ferrite Growth in Fe-C-X Alloys

    NASA Astrophysics Data System (ADS)

    Zurob, H. S.; Panahi, D.; Hutchinson, C. R.; Brechet, Y.; Purdy, G. R.

    2013-08-01

    A self-consistent model for non-partitioning planar ferrite growth from alloyed austenite is presented. The model captures the evolution with time of interfacial contact conditions for substitutional and interstitial solutes. Substitutional element solute drag is evaluated in terms of the dissipation of free energy within the interface, and an estimate is provided for the rate of buildup of the alloying element "spike" in austenite. The transport of the alloying elements within the interface region is modeled using a discrete-jump model, while the bulk diffusion of C is treated using a standard continuum treatment. The model is validated against ferrite precipitation and decarburization kinetics in the Fe-Ni-C, Fe-Mn-C, and Fe-Mo-C systems.

  2. 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.

  3. Phase Behavior of SIS'O Tetrablock Terpolymers: A Self-consistent Field Theory Study

    NASA Astrophysics Data System (ADS)

    Arora, Akash; Morse, David C.; Bates, Frank S.; Dorfman, Kevin D.

    Block copolymers with three or more blocks show richer phase behavior than diblock copolymers. In this work, we use self-consistent field theory (SCFT) to study the phase behavior of ABA' C type tetrablock terpolymers. In particular, we are motivated by experimental studies on poly(styrene- b-isoprene- b-styrene- b-ethylene oxide) (SIS'O) that report interesting phases such as core-shell spheres and cylinders, the Frank-Kasper σ phase, and the dodecagonal quasicrystalline morphology. We compare SCFT predictions to experimental results for SIS'O copolymers using values of the Flory-Huggins interaction parameters that are estimated from analysis of literature data on related systems.

  4. Self-consistent collective coordinate method in nuclear rotation and wobbling motion at high spin

    SciTech Connect

    Kaneko, K. )

    1994-06-01

    We propose a method, using the self-consistent collective coordinate method based on the time-dependent Hartree-Bogoliubov theory, to describe nuclear rotation and wobbling motion in triaxially deformed nuclei beyond the random-phase approximation to higher orders. In this perturbation method, the zero modes can be eliminated by imposing constraints to determine the intrinsic frame: a spin-orientation frame or a principal axis frame. The basic equations on the collective submanifold are derived as canonical conditions and equations of collective submanifold. These equations are solved by an iterative method expanded with collective variables. In lowest order, the basic equations in both the principal-axis frame and the spin-orientation frame lead to the same result as that derived by Marshalek.

  5. 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.

  6. Experiments to validate self-consistent beam-gas-electron code

    NASA Astrophysics Data System (ADS)

    Molvik, A. W.; Sharp, W. M.; Kireeff Covo, M.; Cohen, R. H.; Friedman, A.; Lund, S. M.; Vay, J.-L.; Coleman, J. E.; Bieniosek, F. M.; Furman, M. A.; Roy, P. K.; Seidl, P. A.

    2007-11-01

    The WARP-POSINST model tracks beam ions and secondary particles (ions, electrons, gas molecules) in a self-consistent manner with techniques developed for heavy-ion fusion and e-cloud studies in high-intensity accelerators. We have developed simple experiments to exercise the code. Heavy-ion beams striking a surface cause gas desorption and electron emission, both of which can limit beam performance. Subsequent beam ions can ionize the gas, producing additional electrons. Two parallel plates, on either side of the beam and orthogonal to the end wall, are biased as a dipole: one grounded and the other biased to ± 10 kV. The electron current to a positive plate jumps to the electron emission value; then ramps slowly due to ionization of desorbed gas. This is a rigorous test of the particle dynamics of the model and constrains the secondary particle production coefficients.

  7. 3D self-consistent percolative model for networks of randomly aligned carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Colasanti, S.; Deep Bhatt, V.; Abdellah, A.; Lugli, P.

    2015-10-01

    A numerical percolative model for simulations of random networks of carbon nanotubes is presented. This algorithm takes into account the real 3D nature of these networks, allowing for a better understanding of their electrical properties. The nanotubes are modeled as non-rigid bendable cylinders with geometrical properties derived according to some statistical distributions inferred from the experiments. For the transport mechanisms we refer to the theory of one-dimensional ballistic channels which is based on the computation of the density of states. The behavior of the entire network is then simulated by coupling a SPICE program with an iterative algorithm that calculates self-consistently the electrostatic potential and the current flow in each node of the network. We performed several simulations on the resistivity of networks with different thicknesses and over different simulation domains. Our results confirm the percolative nature of the electrical transport, which are more pronounced in films close to their percolation threshold.

  8. Self-consistent continuum solvation for optical absorption of complex molecular systems in solution.

    PubMed

    Timrov, Iurii; Andreussi, Oliviero; Biancardi, Alessandro; Marzari, Nicola; Baroni, Stefano

    2015-01-21

    We introduce a new method to compute the optical absorption spectra of complex molecular systems in solution, based on the Liouville approach to time-dependent density-functional perturbation theory and the revised self-consistent continuum solvation model. The former allows one to obtain the absorption spectrum over a whole wide frequency range, using a recently proposed Lanczos-based technique, or selected excitation energies, using the Casida equation, without having to ever compute any unoccupied molecular orbitals. The latter is conceptually similar to the polarizable continuum model and offers the further advantages of allowing an easy computation of atomic forces via the Hellmann-Feynman theorem and a ready implementation in periodic-boundary conditions. The new method has been implemented using pseudopotentials and plane-wave basis sets, benchmarked against polarizable continuum model calculations on 4-aminophthalimide, alizarin, and cyanin and made available through the Quantum ESPRESSO distribution of open-source codes. PMID:25612693

  9. 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.

  10. Longitudinal halo in beam bunches with self-consistent 6-D distributions

    NASA Astrophysics Data System (ADS)

    Gluckstern, R. L.; Fedotov, A. V.; Kurennoy, S. S.; Ryne, R. D.

    1998-11-01

    We have explored the formation of longitudinal and transverse halos in 3-D axisymmetric beam bunches by starting with a self-consistent 6-D phase space distribution. Stationary distributions allow us to study the halo development mechanism without being obscured by beam redistribution and its effect on halo formation. The beam is then mismatched longitudinally and/or transversely, and we explore the rate, intensity and spatial extent of the halos which form, as a function of the beam charge and the mismatches. We find that the longitudinal halo forms first because the longitudinal tune depression is more severe than the transverse one for elongated bunches and conclude that it plays a major role in halo formation.

  11. Binary mixed homopolymer brushes grafted on nanorod particles: A self-consistent field theory study

    NASA Astrophysics Data System (ADS)

    Ma, Xin; Yang, Yingzi; Zhu, Lei; Zhao, Bin; Tang, Ping; Qiu, Feng

    2013-12-01

    We employ the self-consistent field theory to study phase structures of brush-rod systems composed of two chemically distinct linear homopolymers. The polymer chains are uniformly grafted on the surface of a nanorod particle of finite length and comparable radius to the polymer radius of gyration. A "masking" technique treating the cylindrical boundary is introduced to solve the modified diffusion equations with an efficient and high-order accurate pseudospectral method involving fast Fourier transform on an orthorhombic cell. A rich variety of structures for the phase separated brushes is predicted. Phase diagrams involving a series of system parameters, such as the aspect ratio of the nanorod, the grafting density, and the chain length are constructed. The results indicate that the phase structure of the mixed brush-rod system can be tailored by varying the grafted chain length and/or the aspect ratio of the rod to benefit the fabrication of polymeric nanocomposites.

  12. Multiconfiguration self-consistent field procedure employing linear combination of atomic-electron distributions

    NASA Astrophysics Data System (ADS)

    Ten-no, Seiichiro; Iwata, Suehiro

    1996-09-01

    We present a multiconfiguration self-consistent field (MCSCF) procedure employing recently developed approximations for electron repulsion integrals. Molecular charge distributions in the two-electron interaction part are expanded into atomic-electron distributions without linear dependencies, and the four-center quantities of electron repulsion integrals are reduced to two- and three-center quantities. The method is plugged into the approximate second-order MCSCF procedure and applied to calculations of the HNO molecule. This procedure enables us to reduce the CPU time of the integral transformation step which is usually the most time consuming. It is also shown that the present approximation is very accurate not only for the ground state but also for the low-lying excited states, even after a substantial reduction of the number of required integrals.

  13. 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.

  14. 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. PMID:21117493

  15. 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.

  16. 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.

  17. 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.

  18. Self-consistent Maxwell-Bloch theory of quantum-dot-population switching in photonic crystals

    SciTech Connect

    Takeda, Hiroyuki; John, Sajeev

    2011-05-15

    We theoretically demonstrate the population switching of quantum dots (QD's), modeled as two-level atoms in idealized one-dimensional (1D) and two-dimensional (2D) photonic crystals (PC's) by self-consistent solution of the Maxwell-Bloch equations. In our semiclassical theory, energy states of the electron are quantized, and electron dynamics is described by the atomic Bloch equation, while electromagnetic waves satisfy the classical Maxwell equations. Near a waveguide cutoff in a photonic band gap, the local electromagnetic density of states (LDOS) and spontaneous emission rates exhibit abrupt changes with frequency, enabling large QD population inversion driven by both continuous and pulsed optical fields. We recapture and generalize this ultrafast population switching using the Maxwell-Bloch equations. Radiative emission from the QD is obtained directly from the surrounding PC geometry using finite-difference time-domain simulation of the electromagnetic field. The atomic Bloch equations provide a source term for the electromagnetic field. The total electromagnetic field, consisting of the external input and radiated field, drives the polarization components of the atomic Bloch vector. We also include a microscopic model for phonon dephasing of the atomic polarization and nonradiative decay caused by damped phonons. Our self-consistent theory captures stimulated emission and coherent feedback effects of the atomic Mollow sidebands, neglected in earlier treatments. This leads to remarkable high-contrast QD-population switching with relatively modest (factor of 10) jump discontinuities in the electromagnetic LDOS. Switching is demonstrated in three separate models of QD's placed (i) in the vicinity of a band edge of a 1D PC, (ii) near a cutoff frequency in a bimodal waveguide channel of a 2D PC, and (iii) in the vicinity of a localized defect mode side coupled to a single-mode waveguide channel in a 2D PC.

  19. Self-consistent polarization neglect of diatomic differential overlap: Application to water clusters

    SciTech Connect

    Chang, Daniel T.; Schenter, Gregory K.; Garrett, Bruce C.

    2008-04-24

    Semiempirical SCF methods such as MNDO, AM1, and PM3 have the ability to treat the formation and breaking of chemical bonds but have been found to poorly describe hydrogen bonding and weak electrostatic complexes. In contrast, most empirical potentials are not able to describe bond-breaking and formation, but have the ability to add missing elements of hydrogen bonding using classical electrostatic interactions. We present a new method which combines aspects of both NDDO-based SCF techniques and classical descriptions of polarization to describe the diffuse nature of the electronic wavefunction in a self-consistent manner. We develop the “self-consistent polarization neglect of differential diatomic overlap” (SCP-NDDO) theory with the additional description of molecular dispersion developed as a second-order perturbation theory expression. The current study seeks to model water-water interactions as a test case. To this end, we have parameterized the SCP-NDDO model to the accurate MP2/CBS estimates of small water cluster binding energies of Xantheas et al.[S. S. Xantheas, C. J. Burnham, and R. J. Harrison, J. Chem. Phys. 116, 1493 (2002); S. S. Xantheas and E. Aprà, J. Chem. Phys. 120, 823 (2004)]. Overall agreement with the ab initio binding energies (n = 2 – 6, 8) is achieved with an RMS error of 0.20 kcal/mol. We achieve noticeable improvements in the structure, vibrational frequencies, and energetic predictions of water clusters (n ≤ 21) relative to standard NDDO-based methods.

  20. Self-consistent simulation of high-frequency driven plasma sheaths

    NASA Astrophysics Data System (ADS)

    Shihab, Mohammed; Eremin, Denis; Mussenbrock, Thomas; Brinkmann, Ralf

    2011-10-01

    Low pressure capacitively coupled plasmas are widely used in plasma processing and microelectronics industry. Understanding the dynamics of the boundary sheath is a fundamental problem. It controls the energy and angular distribution of ions bombarding the electrode, which in turn affects the surface reaction rate and the profile of microscopic features. In this contribution, we investigate the dynamics of plasma boundary sheaths by means of a kinetic self-consistent model, which is able to resolve the ion dynamics. Asymmetric sheath dynamics is observed for the intermediate RF regime, i.e., in the regime where the ion plasma frequency is equal to the driving frequency. The ion inertia causes an additional phase difference between the expansion and the contraction phase of the plasma sheath and an asymmetry for the ion energy distribution bimodal shape. A comparison with experimental results and particle in cell simulations is performed. Low pressure capacitively coupled plasmas are widely used in plasma processing and microelectronics industry. Understanding the dynamics of the boundary sheath is a fundamental problem. It controls the energy and angular distribution of ions bombarding the electrode, which in turn affects the surface reaction rate and the profile of microscopic features. In this contribution, we investigate the dynamics of plasma boundary sheaths by means of a kinetic self-consistent model, which is able to resolve the ion dynamics. Asymmetric sheath dynamics is observed for the intermediate RF regime, i.e., in the regime where the ion plasma frequency is equal to the driving frequency. The ion inertia causes an additional phase difference between the expansion and the contraction phase of the plasma sheath and an asymmetry for the ion energy distribution bimodal shape. A comparison with experimental results and particle in cell simulations is performed. The financial support from the Federal Ministry of Education and Research within the frame of

  1. Self-consistent models of quasi-relaxed rotating stellar systems

    NASA Astrophysics Data System (ADS)

    Varri, A. L.; Bertin, G.

    2012-04-01

    Aims: Two new families of self-consistent axisymmetric truncated equilibrium models for the description of quasi-relaxed rotating stellar systems are presented. The first extends the well-known spherical King models to the case of solid-body rotation. The second is characterized by differential rotation, designed to be rigid in the central regions and to vanish in the outer parts, where the imposed energy truncation becomes effective. Methods: The models are constructed by solving the relevant nonlinear Poisson equation for the self-consistent mean-field potential. For rigidly rotating configurations, the solutions are obtained by an asymptotic expansion based on the rotation strength parameter, following a procedure developed earlier by us for the case of tidally generated triaxial models. The differentially rotating models are constructed by means of a spectral iterative approach, with a numerical scheme based on a Legendre series expansion of the density and the potential. Results: The two classes of models exhibit complementary properties. The rigidly rotating configurations are flattened toward the equatorial plane, with deviations from spherical symmetry that increase with the distance from the center. For models of the second family, the deviations from spherical symmetry are strongest in the central region, whereas the outer parts tend to be quasi-spherical. The relevant parameter spaces are thoroughly explored and the corresponding intrinsic and projected structural properties are described. Special attention is given to the effect of different options for the truncation of the distribution function in phase space. Conclusions: Models in the moderate rotation regime are best suited to applications to globular clusters. For general interest in stellar dynamics, at high values of the rotation strength the differentially rotating models tend to exhibit a toroidal core embedded in an otherwise quasi-spherical configuration. Physically simple analytical models

  2. 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/.

  3. Model Wavefunctions For Non-Abelian Quasiparticles

    NASA Astrophysics Data System (ADS)

    Bernevig, B. Andrei; Haldane, F. D. M.

    2008-03-01

    We present model wavefunctions for quasiparticle (as opposed to quasihole)excitations of the Zk parafermion sequence (Laughlin/Moore-Read/Read-Rezayi) of Fractional Quantum Hall states. These states satisfy two generalized clustering conditions: they vanish when either a cluster of k+2 electrons is put together, or when two clusters of k+1 electrons are formed at different positions. For Abelian Fractional Quantum Hall states (k=1), our construction reproduces the Jain quasielectron wavefunction, and elucidates the difference between the Jain and Laughlin quasiparticle constructions. For two (or more) quasiparticles, our states differ from those constructed using Jain's method. By adding our quasiparticles to the Laughlin state, we obtain a hierarchy scheme which gives rise to a non-abelian ν=2 5 FQH state.

  4. Ab Initio Study of Quasiparticle and Excitonic Properties of MoS2

    NASA Astrophysics Data System (ADS)

    Qiu, Diana; Jornada, Felipe; Louie, Steven

    2013-03-01

    MoS2 is a layered, transition-metal dichalcogenide that can be cleaved into single-layer sheets, in a manner similar to graphene. Monolayer MoS2 has a direct band gap, strong spin-orbit coupling and strongly enhanced photoluminescence, compared with the bulk. MoS2's interesting electronic and optical properties mean that it could have many applications in single-layer electronic devices, but on the theoretical level, when many-electron interaction effects are included, there is still some uncertainty about the quasiparticle and excitonic properties of MoS2. We use first-principles calculations to study the quasiparticle band structure and optical absorption spectrum of MoS2 at the GW +BSE level. We include spin-orbit coupling as a perturbation either before or after the GW calculation of the band structure, and we demonstrate that our calculations are fully converged with respect to the dielectric cutoff and summation over empty bands. This work was supported by NSF grant No. DMR10-1006184 and U.S. DOE under Contract No. DE-AC02-05CH11231. Computational resources have been provided by NERSC.

  5. Quasi-particle corrections to the LSDA+U electronic structure of solid bcc hydrogen

    NASA Astrophysics Data System (ADS)

    Kioupakis, Emmanouil

    2005-03-01

    Quasi-particle calculations within the GW approximation usually start with the LDA electronic structure as mean field solution, which works well for moderately correlated materials. For strongly correlated systems, such as the transition metal oxides, LSDA can give qualitatively wrong ground states, making any further improvement difficult. By starting with the LSDA+U mean field results in the GW approximation calculation of the electron self-energy, we expect to have a better understanding of the quasi-particle properties in these systems. We employ this approach in the study of solid hydrogen, a model system for which previous results exist in the literature. This will test the applicability of the technique to more realistic systems. This work was supported by National Science Foundation Grant No. DMR04-39768 and by the Director, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, U.S. Department of Energy under Contract No. DE-AC03-76SF00098. Computational resources have been provided by NSF at the National Partnership for Advanced Computational Infrastructure (NPACI) and DOE at the National Energy Research Scientific Computing Center (NERSC)

  6. Ab initio quasiparticle band structure of ABA and ABC-stacked graphene trilayers

    NASA Astrophysics Data System (ADS)

    Menezes, Marcos G.; Capaz, Rodrigo B.; Louie, Steven G.

    2014-01-01

    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 self-energy 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 self-energy corrections. Finally, other effects, such as trigonal warping, electron-hole asymmetry, and energy gaps, are discussed in terms of the associated parameters.

  7. 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.

  8. 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.

  9. Self Consistent Monte Carlo Method to Study CSR Effects in Bunch Compressors

    SciTech Connect

    Warnock, R.L.; Bassi, G.; Ellison, J.A.; Heinemann, K.A.; /New Mexico U.

    2008-01-08

    In this paper we report on the results of a self-consistent calculation of CSR effects on a particle bunch moving through the benchmark Zeuthen bunch compressors. The theoretical framework is based on a 4D Vlasov-Maxwell approach including shielding from the vacuum chamber. We calculate the fields in the lab frame, where time is the independent variable, and evolve the phase space density/points in the beam frame, where arc length, s, along a reference orbit, is the independent variable. Some details are given in [2], where we also discuss three approaches, the unperturbed source model (UPS), the self consistent Monte Carlo (SCMC) method and the method of local characteristics. Results for the UPS have been presented for 5 GeV before [3], here we compare them with our new results from the SCMC and study the 500MeV case. Our work using the method of characteristics is in progress. The SCMC algorithm begins by randomly generating an initial ensemble of beam frame phase space points according to a given initial phase space density. The algorithm then reduces to laying out one arc length step. Assume that at arc length s we know the location of the phase space points and the history of the source prior to s. We then (1) create a smooth representation of the lab frame charge and current densities, {rho}{sub L} and J{sub L}, (2) calculate the fields at s from the history of {rho}{sub L} and J{sub L}, and (3) move the beam frame phase space points according to the beam frame equations of motion. This is then iterated. The UPS calculation is similar except the fields are calculated from a function of s computed a priori from the beam frame equations of motion without the self-fields. The phase space points are then evolved according to the equations of motion with these ''unperturbed'' fields. In the UPS we use a Gaussian initial density which evolves under the linear beam frame equations as a Gaussian. This gives us an analytic formula for the source, which significantly

  10. Self-consistent RPA calculations with Skyrme-type interactions: The skyrme_rpa program

    NASA Astrophysics Data System (ADS)

    Colò, Gianluca; Cao, Ligang; Van Giai, Nguyen; Capelli, Luigi

    2013-01-01

    Random Phase Approximation (RPA) calculations are nowadays an indispensable tool in nuclear physics studies. We present here a complete version implemented with Skyrme-type interactions, with the spherical symmetry assumption, that can be used in cases where the effects of pairing correlations and of deformation can be ignored. The full self-consistency between the Hartree-Fock mean field and the RPA excitations is enforced, and it is numerically controlled by comparison with energy-weighted sum rules. The main limitations are that charge-exchange excitations and transitions involving spin operators are not included in this version. Program summaryProgram title: skyrme_rpa (v 1.00) Catalogue identifier: AENF_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AENF_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 5531 No. of bytes in distributed program, including test data, etc.: 39435 Distribution format: tar.gz Programming language: FORTRAN-90/95; easily downgradable to FORTRAN-77. Computer: PC with Intel Celeron, Intel Pentium, AMD Athlon and Intel Core Duo processors. Operating system: Linux, Windows. RAM: From 4 MBytes to 150 MBytes, depending on the size of the nucleus and of the model space for RPA. Word size: The code is written with a prevalent use of double precision or REAL(8) variables; this assures 15 significant digits. Classification: 17.24. Nature of problem: Systematic observations of excitation properties in finite nuclear systems can lead to improved knowledge of the nuclear matter equation of state as well as a better understanding of the effective interaction in the medium. This is the case of the nuclear giant resonances and low-lying collective excitations, which can be described as small amplitude collective motions in the framework of

  11. Thin current sheet embedded within a thicker plasma sheet: Self-consistent kinetic theory

    NASA Astrophysics Data System (ADS)

    Sitnov, M. I.; Zelenyi, L. M.; Malova, H. V.; Sharma, A. S.

    2000-06-01

    A self-consistent theory of thin current sheets, where the magnetic field line tension is balanced by the ion inertia rather than by the pressure gradient, is presented. Assuming that ions are the main current carriers and their dynamics is quasi-adiabatic, the Maxwell-Vlasov equations are reduced to the nonlocal analogue of the Grad-Shafranov equation using a new set of integrals of motion, namely, the particle energy and the sheet invariant of the quasi-adiabatic motion. It is shown that for a drifting Maxwellian distribution of ions outside the sheet the equilibrium equation can be reduced in the limits of strong and weak anisotropy to universal equations that determine families of equilibria with similar profiles of the magnetic field. In the region Bn/B0>1) the self-consistent current sheet equilibrium may also exist with no indications of the catastrophe reported earlier by Burkhart et al. [1992a]. On the contrary, it is found that in this limit the magnetic field profiles again become similar to each other with the characteristic thickness ~ρ0. The profiles of plasma and current densities as well as the components of the pressure tensor are calculated for arbitrary ion anisotropy outside the sheet. It is shown that the thin current sheet for the equilibrium considered here is usually embedded into a much thicker plasma sheet. Moreover, in the case of weak anisotropy the perturbation of the plasma density inside the sheet is shown to be proportional to the parameter vD/vT, and as a result the electrostatic effects should be small, consistent with observations. This model of the thin current sheet

  12. 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

  13. 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

  14. The nearby eclipsing stellar system δ Velorum. III. Self-consistent fundamental parameters and distance

    NASA Astrophysics Data System (ADS)

    Mérand, A.; Kervella, P.; Pribulla, T.; Petr-Gotzens, M. G.; Benisty, M.; Natta, A.; Duvert, G.; Schertl, D.; Vannier, M.

    2011-08-01

    Context. The triple stellar system δ Vel (composed of two A-type and one F-type main-sequence stars) is particularly interesting because it contains one of the nearest and brightest eclipsing binaries. It therefore presents a unique opportunity to determine independently the physical properties of the three components of the system, as well as its distance. Aims: We aim at determining the fundamental parameters (masses, radii, luminosities, rotational velocities) of the three components of δ Vel, as well as the parallax of the system, independently from the existing Hipparcos measurement. Methods: We determined dynamical masses from high-precision astrometry of the orbits of Aab-B and Aa-Ab using adaptive optics (VLT/NACO) and optical interferometry (VLTI/AMBER). The main component is an eclipsing binary composed of two early A-type stars in rapid rotation. We modeled the photometric and radial velocity measurements of the eclipsing pair Aa-Ab using a self-consistent method based on physical parameters (mass, radius, luminosity, rotational velocity). Results: From our self-consistent modeling of the primary and secondary components of the δ Vel A eclipsing pair, we derive their fundamental parameters with a typical accuracy of 1%. We find that they have similar masses, 2.43 ± 0.02 M⊙ and 2.27 ± 0.02 M⊙. The physical parameters of the tertiary component (δ Vel B) are also estimated, although to a lower accuracy. We obtain a parallax π = 39.8 ± 0.4 mas for the system, in satisfactory agreement (-1.2 σ) with the Hipparcos value (πHip = 40.5 ± 0.4 mas). Conclusions: The physical parameters we derive represent a consistent set of constraints for the evolutionary modeling of this system. The agreement of the parallax we measure with the Hipparcos value to a 1% accuracy is also an interesting confirmation of the true accuracy of these two independent measurements. Based on observations made with ESO telescopes at Paranal Observatory, under ESO programs 076

  15. 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.

  16. A self-consistent approach to the analysis of thermionic devices

    NASA Astrophysics Data System (ADS)

    Khoshaman, Amir H.; Nojeh, Alireza

    2016-01-01

    Research in thermionics has been reinvigorated recently by the advent of nanotechnology and nanomaterials. Thermionic energy convertors are commonly modelled using the Poisson-Vlasov system of equations under various limitations and approximations. With the ever-growing demands of emergent thermionic devices, more comprehensive approaches are needed in order to be able to treat a broader range of device configurations and operational parameters. Here, we propose a self-consistent approach that, by iterating between the Poisson and Vlasov equations, does not rely on the existence of an analytical solution to the latter. Specifically, we present a particle-tracing implementation of this method for solving the system numerically in an efficient manner. In the case where an analytical solution does exist, we present an asymptotic expansion of the ill-behaving functions that arise; this approach improves the effectiveness of the method in the deep space-charge mode. We also demonstrate the applicability of this approach in the presence of back-emission.

  17. 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.

  18. 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.

  19. Reaction coordinates, one-dimensional Smoluchowski equations, and a test for dynamical self-consistency.

    PubMed

    Peters, Baron; Bolhuis, Peter G; Mullen, Ryan G; Shea, Joan-Emma

    2013-02-01

    We propose a method for identifying accurate reaction coordinates among a set of trial coordinates. The method applies to special cases where motion along the reaction coordinate follows a one-dimensional Smoluchowski equation. In these cases the reaction coordinate can predict its own short-time dynamical evolution, i.e., the dynamics projected from multiple dimensions onto the reaction coordinate depend only on the reaction coordinate itself. To test whether this property holds, we project an ensemble of short trajectory swarms onto trial coordinates and compare projections of individual swarms to projections of the ensemble of swarms. The comparison, quantified by the Kullback-Leibler divergence, is numerically performed for each isosurface of each trial coordinate. The ensemble of short dynamical trajectories is generated only once by sampling along an initial order parameter. The initial order parameter should separate the reactants and products with a free energy barrier, and distributions on isosurfaces of the initial parameter should be unimodal. The method is illustrated for three model free energy landscapes with anisotropic diffusion. Where exact coordinates can be obtained from Kramers-Langer-Berezhkovskii-Szabo theory, results from the new method agree with the exact results. We also examine characteristics of systems where the proposed method fails. We show how dynamical self-consistency is related (through the Chapman-Kolmogorov equation) to the earlier isocommittor criterion, which is based on longer paths.

  20. Self-consistent theory and simulation of quasiuniform states in thin rectangular magnetic nanoparticles

    SciTech Connect

    Tartakovskaya, E. V.; Tucker, J. W.; Ivanov, B. A.

    2001-06-15

    A self-consistent theory of the ground-state nonuniform magnetization distribution in small magnetic nanoelements is proposed, valid for thicknesses much less than the exchange length, and with natural fulfillment of boundary conditions allowing application to a variety of element shapes. The theory is applied to rectangular 2p{sub 1}l{times}2p{sub 2}l{times}2l permalloy elements. In contrast to that of square elements, there exists a range of particle sizes having an {open_quotes}intermediate{close_quotes} ground state (mixed flower and leaf symmetries) with average magnetization inclined at {var_phi} to the longer edge. With increasing p{sub 1}/p{sub 2} (p{sub 2} fixed), {var_phi} gradually decreases to zero (flower state). This intermediate{r_arrow}flower transition is of the second type, unlike the leaf{r_arrow}flower transition (first type) observed in square elements with reduction in p{sub 1}(=p{sub 2}). Simulation results support the analytic theory. {copyright} 2001 American Institute of Physics.

  1. 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.

  2. Modeling of LH current drive in self-consistent elongated tokamak MHD equilibria

    SciTech Connect

    Blackfield, D.T.; Devoto, R.S.; Fenstermacher, M.E.; Bonoli, P.T.; Porkolab, M.; Yugo, J.

    1989-05-09

    Calculations of non-inductive current drive typically have been used with model MHD equilibria which are independently generated from an assumed toroidal current profile or from a fit to an experiment. Such a method can lead to serious errors since the driven current can dramatically alter the equilibrium and changes in the equilibrium B-fields can dramatically alter the current drive. The latter effect is quite pronounced in LH current drive where the ray trajectories are sensitive to the local values of the magnetic shear and the density gradient. In order to overcome these problems, we have modified a LH simulation code to accommodate elongated plasmas with numerically generated equilibria. The new LH module has been added to the ACCOME code which solves for current drive by neutral beams, electric fields, and bootstrap effects in a self-consistent 2-D equilibrium. We briefly describe the model in the next section and then present results of a study of LH current drive in ITER. 2 refs., 6 figs., 2 tabs.

  3. Self-consistent field theory for the interactions between keratin intermediate filaments

    PubMed Central

    2013-01-01

    Background Keratins are important structural proteins found in skin, hair and nails. Keratin Intermediate Filaments are major components of corneocytes, nonviable horny cells of the Stratum Corneum, the outermost layer of skin. It is considered that interactions between unstructured domains of Keratin Intermediate Filaments are the key factor in maintaining the elasticity of the skin. Results We have developed a model for the interactions between keratin intermediate filaments based on self-consistent field theory. The intermediate filaments are represented by charged surfaces, and the disordered terminal domains of the keratins are represented by charged heteropolymers grafted to these surfaces. We estimate the system is close to a charge compensation point where the heteropolymer grafting density is matched to the surface charge density. Using a protein model with amino acid resolution for the terminal domains, we find that the terminal chains can mediate a weak attraction between the keratin surfaces. The origin of the attraction is a combination of bridging and electrostatics. The attraction disappears when the system moves away from the charge compensation point, or when excess small ions and/or NMF-representing free amino acids are added. Conclusions These results are in concordance with experimental observations, and support the idea that the interaction between keratin filaments, and ultimately in part the elastic properties of the keratin-containing tissue, is controlled by a combination of the physico-chemical properties of the disordered terminal domains and the composition of the medium in the inter-filament region. PMID:24007681

  4. 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.

  5. Large multiconfiguration self-consistent-field wave functions for the ozone molecule

    SciTech Connect

    Laidig, William D.; Schaefer, III, Henry F.

    1981-03-15

    The electronic structure of the ozone molecule is of particular interest in light of Goddard’s characterization of the ground state as a biradical. We determine rigorously optimized multiconfiguration self-consistent-field (MCSCF) wave functions of varying size for ozone via newly developed techniques utilizing the unitary group approach. The largest of these a b i n i t i o MCSCF wave functions includes 13413 configurations, i.e., all singly- and doubly excited configurations relative to the two reference configurations required for the biradical description of ozone. The convergence of the MCSCF procedures is discussed, as well as the structure of the MCSCF wave functions, and the effectiveness of different orbital transformations. There is a significant energy difference (0.034 hartrees) between the MCSCF wave functions involving one and two reference configurations. This gives emphasis to the fact that orbital optimization alone cannot compensate for the exclusion from the wave function of important classes of configurations. Lastly, a simple test for the determination of the fraction biradical character of systems such as ozone suggests 23% biradical character for 03 at its equilibrium geometry.

  6. Nucleosynthesis in self-consistent, multi-dimensional simulations of CCSNe

    NASA Astrophysics Data System (ADS)

    Harris, J. Austin; Hix, W. Raphael; Chertkow, Merek; Bruenn, Stephen; Lentz, Eric; Kasen, Daniel

    2016-03-01

    Observations of nuclear abundances in core-collapse supernova ejecta, highlighted by γ-ray observations of the 44Ti spatial distribution in the nearby supernova remnants Cas A and SN 1987A, allow nucleosynthesis calculations to place powerful constraints on conditions deep in the interiors of supernovae and their progenitor stars. This ability to probe where direct observations cannot makes such calculations an invaluable tool for understanding the CCSN mechanism. Unfortunately, despite knowing for two decades that supernovae are intrinsically multi-dimensional events, discussions of CCSN nucleosynthesis have been predominantly based on spherically symmetric models, which employ a contrived energy source to launch an explosion and often ignore important neutrino effects. As part of the effort to bridge the gap between first-principles simulations of the explosion mechanism and observations of both supernovae and SNRs, we investigate CCSN nucleosynthesis with self-consistent, 2D simulations using a multi-dimensional radiation-hydrodynamics code. We present nucleosynthesis results for several axisymmetric CCSN models models which qualitative differences from their parameterized counterparts in their ejecta composition and spatial distribution.

  7. 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.

  8. 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.

  9. Secondary electron emission and self-consistent charge transport in semi-insulating samples

    NASA Astrophysics Data System (ADS)

    Fitting, H.-J.; Touzin, M.

    2011-08-01

    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 δ(t) released from the target material and based on ballistic electrons and the spatial distributions of currents j(x,t), charges ρ(x,t), field F(x,t), and potential V(x,t) are obtained where V0 = 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., σ = η + δ < 1.

  10. Phase diagrams of diblock copolymers in electric fields: a self-consistent field theory study.

    PubMed

    Wu, Ji; Wang, Xianghong; Ji, Yongyun; He, Linli; Li, Shiben

    2016-04-21

    We investigated the phase diagrams of diblock copolymers in external electrostatic fields by using real-space self-consistent field theory. The lamella, cylinder, sphere, and ellipsoid structures were observed and analyzed by their segment distributions, which were arranged to two types of phase diagrams to examine the phase behavior in weak and strong electric fields. One type was constructed on the basis of Flory-Huggins interaction parameter and volume fraction. We identified an ellipsoid structure with a body-centered cuboid arrangement as a stable phase and discussed the shift of phase boundaries in the electric fields. The other type of phase diagrams was established on the basis of the dielectric constants of two blocks in the electric fields. We then determined the regions of ellipsoid phase in the phase diagrams to examine the influence of dielectric constants on the phase transition between ellipsoidal and hexagonally packed cylinder phases. A general agreement was obtained by comparing our results with those described in previous experimental and theoretical studies. PMID:27020849

  11. Self-consistent second-order Green's function perturbation theory for periodic systems

    NASA Astrophysics Data System (ADS)

    Rusakov, Alexander A.; Zgid, Dominika

    2016-02-01

    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.

  12. Improving the density functional theory description of water with self-consistent polarization

    SciTech Connect

    Murdachaew, Garold; Mundy, Christopher J.; Schenter, Gregory K.

    2010-04-30

    We present a comprehensive set of results for water, a case study of a hydrogen-bonded system, using the self-consistent polarization density functional theory (SCP-DFT). With minimal parametrization, SCP-DFT is found to give good results for the interaction energy of the dimer; the geometries, cohesion energies, and harmonic frequencies of larger clusters; and the structure and enthalpy of the liquid, as compared to accurate theoretical and experimental benchmarks. We also compared our SCP-DFT potential to the base DFT BLYP potential and also to a simpler dispersion-supplemented potential, BLYP-D. Using the symmetry-adapted perturbation theory (with a DFT description of monomers), the BLYP, BLYP-D, and SCP-DFT water dimer potentials were analyzed into their physically interpretable components. Comparison with the benchmark SAPT(DFT) components showed reasonable agreement for all the four components of electrostatics, exchange, induction, and dispersion energies. This procedure enhances understanding and can suggest further improvements. Thus, the SCP-DFT approach holds promise as a fast, efficient, and accurate method for performing ab initio dynamics that include additional polarization and dispersion interactions for large, complex systems involving solvation and bond breaking.

  13. 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.

  14. An Embedded Cluster Self-Consistent Partial Wave Method using Divide and Conquer

    SciTech Connect

    Averill, Frank; Painter, Gayle S

    2008-04-01

    An efficient approach to extending the spatial scale of electronic structure calculations is described in this work. The method is formulated as a combination of the interacting fragments concept of Harris [J. Harris, Phys. Rev. B 31, 1770 (1985)] and the D&C method of Yang [W. Yang, Phys. Rev. Lett. 66, 1438 (1991)], which recognizes the intrinsic locality of electron bonding and is devised to optimize the total electron charge density within an approximate representation of partitioned components. Beginning with a brief review of D&C concepts, we report results from this new method using the D&C as an embedding method for coupling an atomic cluster to its extended environment. The convergence properties as implemented within the self-consistent partial wave linear variational method (SCPW) are illustrated through various applications. In particular, results from a study of the adsorption of La atoms at the prism plane of -Si3N4 demonstrate the practicality of the SCPW using D&C as an embedding technique. PACS numbers: 71.15.Mb, 31.15.Ew, 31.50.Bc

  15. Self-consistent Modeling of the logN-logS in the Poisson Limit

    NASA Astrophysics Data System (ADS)

    Sourlas, E.; Kashyap, V.; Zezas, A.; van Dyk, D.

    2004-08-01

    logN-logS curves are a fundamental tool in the study of source populations, luminosity functions, and cosmological parameters. However, their determination is hampered by statistical effects such as the Eddington bias, incompleteness due to detection efficiency, faint source flux fluctuations, etc. Here we present a new and powerful method using the full Poisson machinery that allows us to model the logN-logS distribution of X-ray sources in a self-consistent manner. Because we properly account for all the above statistical effects, our modeling is valid over the full range of the data. We use a Bayesian approach, modeling the fluxes with known functional forms such as simple or broken power-laws. The expected photon counts are conditioned on the fluxes, the background contamination, effective area, detector vignetting, and detection probability. The built-in flexibility of the algorithm also allows a simultaneous analysis of multiple datasets. We demonstrate the power of our algorithm by applying it to a set of Chandra observations. This project is part of the California-Harvard/CXC AstroStatistics Collaboration. The authors gratefully acknowledge funding for this project partially provided by NSF grant DMS-01-04129 and by NASA Contract NAS8-39073, and NASA grants NCC2-1350 and NAG5-13056.

  16. Variational state specific solvent models for excited states from time dependent self-consistent field methods

    NASA Astrophysics Data System (ADS)

    Bjorgaard, Josiah; Velizhanin, Kirill; Tretiak, Sergei

    2015-03-01

    The effect of a dielectric environment on a molecule can be profound, causing changes in nuclear configuration and electronic structure. Quantum chemical simulation of a solute-solvent system can be prohibitively expensive due to the large number of degrees of freedom attributed to the solvent. To remedy this, the solvent can be treated as a dielectric cavity. Mutual polarization of the solute and solvent must be considered for accurate treatment of an optically excited state (ES) with a state-specific solvent model (SSM). In vacuum, time dependent self-consistent field (TD-SCF) methods (e,g, TD-HF, TD-DFT) give variational excitation energies. With the well known Z-vector equation, a variational ES energy is used to explore the ES potential energy surface (PES) with analytical gradients. Modification of the standard TD-SCF eigensystem to accommodate a SSM creates a nonlinear TD-SCF equation with non-variational excitation energies. This prevents analytical gradients from being formulated so that the ES PES cannot be explored. Here, we show how a variational formulation of existing SSMs can be derived from a Lagrangian formalism and give numerical results for the variability of calculated quantities. Model dynamics using SSMs are showcased.

  17. Self-consistently thermodynamic treatment for strange quark matter in the effective mass bag model

    NASA Astrophysics Data System (ADS)

    Bao, Tmurbagan; Liu, Guang-Zhou; Zhao, En-Guang; Zhu, Ming-Feng

    2008-12-01

    In the framework of the effective mass bag model (EMBM) we have performed the thermodynamical treatment for strange quark matter (SQM) self-consistently, which overcomes the inconsistencies in the thermodynamical properties of the system. Because of the existence of the pressure extra term, the SQM equation of state (EOS) becomes stiffer comparing with the one for the original EMBM. It is interesting to find that in our treatment the SQM EOS is almost independent of the strong coupling constant g . In this case the SQM EOS seems to get back to the EOS for the original MIT bag model. However, this treatment still has influence on the EOS for hybrid star matter and the corresponding mass-radius relations. With the increase of the strong coupling constant g , the EOS for hybrid star matter gets obviously stiff. From our treatment we notice that the pressure extra term can make a hybrid star more compact than the one described in the original EMBM and this model is more suitable to describe the hybrid stars with small radii.

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

    SciTech Connect

    Mezel, C.; Hallo, L.; Breil, J.; Souquet, A.; Guillemot, F.; Hebert, D.

    2009-12-15

    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.

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

    DOE PAGESBeta

    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 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

  20. 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.

  1. 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.

  2. Self-consistent mean-field model for palmitoyloleoylphosphatidylcholine-palmitoyl sphingomyelin–cholesterol lipid bilayers

    PubMed Central

    Tumaneng, Paul W.; Pandit, Sagar A.; Zhao, Guijun; Scott, H. L.

    2012-01-01

    The connection between membrane inhomogeneity and the structural basis of lipid rafts has sparked interest in the lateral organization of model lipid bilayers of two and three components. In an effort to investigate anisotropic lipid distribution in mixed bilayers, a self-consistent mean-field theoretical model is applied to palmitoyloleoylphosphatidylcholine (POPC)–palmitoyl sphingomyelin (PSM)–cholesterol mixtures. The compositional dependence of lateral organization in these mixtures is mapped onto a ternary plot. The model utilizes molecular dynamics simulations to estimate interaction parameters and to construct chain conformation libraries. We find that at some concentration ratios the bilayers separate spatially into regions of higher and lower chain order coinciding with areas enriched with PSM and POPC, respectively. To examine the effect of the asymmetric chain structure of POPC on bilayer lateral inhomogeneity, we consider POPC-lipid interactions with and without angular dependence. Results are compared with experimental data and with results from a similar model for mixtures of dioleoylphosphatidylcholine, steroyl sphingomyelin, and cholesterol. PMID:21517541

  3. Two dimensional self-consistent fluid simulation of rf inductive sources

    SciTech Connect

    DiPeso, G.; Vahedi, V.; Hewett, D.W.; Rognlien, T.D.

    1993-11-17

    The two-dimensional (R - Z) electromagnetic code FMRZ has been written to model inductive sources self-consistently in time. The code models an argon plasma with momentum-transfer, excitation and ionization as electron-neutral reactions and scattering and charge-exchange for the ion-neutral reactions. The electrons and ions are treated as Maxwellian fluid species and a reduced set of Maxwell`s equations is used to advance the electromagnetic fields. The set of equations used in FMRZ is not subject to typical numerical constraints present in many time dynamic codes allowing one to choose appropriate the and space scales to resolve only the frequencies and scale lengths of interest. The model retains nonlinear driving terms which give rise to a pondermotive force that distorts the density profile. Density and power profiles will be used to illustrate the physical effects of various terms in the equations. Trends in average density and temperature compare well with an analytic model.

  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. 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.

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

    SciTech Connect

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

    2015-01-15

    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.

  7. Automodelity of the biological evolution and the hypothesis of self-consistent Galaxy life origin

    NASA Astrophysics Data System (ADS)

    Panov, A.

    The evolution of the Earth's biosphere passed trough a sequence of biospheric revolutions. It is shown, that the arrangement of the biospheric revolutions on the time axis has the property of automodelity in very good approximation. Supposing that the automodel scale of the time of the evolution includes the prebiological chemical evolution as well, we obtain that the estimated duration of the prebiological chemical evolution is about 5.5\\cdot10^9 years. It is much longer then the actual time of the prebiological evolution on the Earth. One possible resolution of the contradiction is that the prebiological evolution took place on the Earth-like planets near the stars much older then the Sun and not on the Earth. The life could be brought to the Earth by the panspermia process. But if the panspermia of life is possible, then the panspermia of the prebiological chemical evolution products must be possible as well. The prebiological panspermia would synchronize the prebiological evolution on different planets in the Galaxy in the stage of the prebiological history of the Galaxy--before the moment when the life had appeared for the first time. Thus the life in the Galaxy in many different places originates almost simultaneously with the same common chemical base and with the same chirality. This event resembles a no-equilibrium phase transition. Thus the origin of life may be self-consistent collective Galaxy process, not a process localized on single planets.

  8. 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.

  9. 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.

  10. Self-consistent finite difference method for simulation and optimization of qunatum well electron transfer structures

    NASA Astrophysics Data System (ADS)

    Weinert, C. M.; Agrawal, N.

    1994-12-01

    A self-consistent finite difference method for the simulation of quantum well electron transfer structures is developed and applied to optimize InGaAsP/InP/InAlAs structures for fast optical switching devices. Simultaneous solution of Poisson's equation, continuity equation, and Schroedinger's equation on a discretized mesh yields a fast and accurate simulation method which may be applied to arbitrary layer structures and needs no artificial assumptions like abrupt space charge layers. Because of the exact treatment of charge distribution and leakage current the simulation gives new insight into the performance of barrier, reservoir, and quantum well electron transfer structrues, which could not be found by previous approximate theories. With this method we calculate the important physical parameters of these devices, namely, the shift of the optical absorption edge, band filling, leakage current, and capacitance. In addition, each layer is investigated separately with respect to its influence on device performance and fabrication tolerances; the results are used for optimization. Moreover, the exact numerical simulation is used to derive simplified relations for the dependence of band filling, capacitance, and high speed behavior on the heterostructure design.

  11. Self-consistent simulations of heavy-ion beams interacting with electron-clouds

    NASA Astrophysics Data System (ADS)

    Vay, J.-L.; Furman, M. A.; Seidl, P. A.; Cohen, R. H.; Friedman, A.; Grote, D. P.; Kireeff Covo, M.; Molvik, A. W.; Stoltz, P. H.; Veitzer, S.; Verboncoeur, J. P.

    2007-07-01

    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.

  12. 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.

  13. 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.

  14. 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.

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

    PubMed Central

    de Pablo, Juan J.

    2015-01-01

    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. PMID:26156466

  16. Self-consistent field theory for lipid-based liquid crystals: hydrogen bonding effect.

    PubMed

    Lee, Won Bo; Mezzenga, Raffaele; Fredrickson, Glenn H

    2008-02-21

    A model to describe the self-assembly properties of aqueous blends of nonionic lipids is developed in the framework of self-consistent field theory (SCFT). Thermally reversible hydrogen bonding between lipid heads and water turns out to be a key factor in describing the lyotropic and thermotropic phase behavior of such systems. Our model includes reversible hydrogen bonding imposed in the context of the grand canonical ensemble and exact conditions of binding equilibrium. The lipid molecules are modeled as a rigid head and a flexible Gaussian tail, and the water molecules are treated explicitly. Here, we focus on systems where the lipid molecule has a relatively small hydrophilic head compared to the hydrophobic tail, such as monoolein in water. Experimentally, this system has both normal phase sequences (inverted hexagonal to inverted double gyroid cubic phase) and reverse phase sequences (lamellar to inverted double gyroid cubic phase) as the water volume fraction increases. From SCFT simulations of the model, two phase diagrams corresponding to temperature independent or dependent interaction parameters chi are constructed, which qualitatively capture the phase behavior of the monoolein-water mixture. The lattice parameters of the simulated mesophases are compared with the experimental values and are found to be in semiquantitative agreement. The role of various structural and solution parameters on the phase diagrams is also discussed.

  17. Serial Generalized Ensemble Simulations of Biomolecules with Self-Consistent Determination of Weights.

    PubMed

    Chelli, Riccardo; Signorini, Giorgio F

    2012-03-13

    Serial generalized ensemble simulations, such as simulated tempering, enhance phase space sampling through non-Boltzmann weighting protocols. The most critical aspect of these methods with respect to the popular replica exchange schemes is the difficulty in determining the weight factors which enter the criterion for accepting replica transitions between different ensembles. Recently, a method, called BAR-SGE, was proposed for estimating optimal weight factors by resorting to a self-consistent procedure applied during the simulation (J. Chem. Theory Comput.2010, 6, 1935-1950). Calculations on model systems have shown that BAR-SGE outperforms other approaches proposed for determining optimal weights in serial generalized ensemble simulations. However, extensive tests on real systems and on convergence features with respect to the replica exchange method are lacking. Here, we report on a thorough analysis of BAR-SGE by performing molecular dynamics simulations of a solvated alanine dipeptide, a system often used as a benchmark to test new computational methodologies, and comparing results to the replica exchange method. To this aim, we have supplemented the ORAC program, a FORTRAN suite for molecular dynamics simulations (J. Comput. Chem.2010, 31, 1106-1116), with several variants of the BAR-SGE technique. An illustration of the specific BAR-SGE algorithms implemented in the ORAC program is also provided. PMID:26593345

  18. Sensitivity of vortex-shedding in unsteady wake based on a self-consistent model

    NASA Astrophysics Data System (ADS)

    Meliga, Philippe; Boujo, Edouard; Gallaire, François

    2015-11-01

    An adjoint method is used to obtain sensitivity maps for the limit-cycle frequency and amplitude of the Bénard-von Kàrmàn vortex street in the unsteady wake past a circular cylinder. The sensitivity analysis is based on a semi-linear self-consistent model recently introduced by Mantic, Arratia & Gallaire (2014), so as to properly take into account the effect of control not only on the mean flow but also on finite-amplitude fluctuations which couple back into the mean flow equation through steady Reynolds stresses. The sensitivity is computed with respect to steady forcing, synchronous time-harmonic forcing, as well as localized feedback. For each case, the obtained results are compared to those stemming from the classical mean flow approach in which the feeding back of the fluctuations on to the mean flow is simply overlooked. As an illustration, the method is applied to passive control by means of a small control cylinder, and the results are discussed in light of the seminal experiments of Strykowski & Sreenivasan (1990).

  19. Self-consistent mean-field model for palmitoyloleoylphosphatidylcholine-palmitoyl sphingomyelin-cholesterol lipid bilayers

    NASA Astrophysics Data System (ADS)

    Tumaneng, Paul W.; Pandit, Sagar A.; Zhao, Guijun; Scott, H. L.

    2011-03-01

    The connection between membrane inhomogeneity and the structural basis of lipid rafts has sparked interest in the lateral organization of model lipid bilayers of two and three components. In an effort to investigate anisotropic lipid distribution in mixed bilayers, a self-consistent mean-field theoretical model is applied to palmitoyloleoylphosphatidylcholine (POPC)-palmitoyl sphingomyelin (PSM)-cholesterol mixtures. The compositional dependence of lateral organization in these mixtures is mapped onto a ternary plot. The model utilizes molecular dynamics simulations to estimate interaction parameters and to construct chain conformation libraries. We find that at some concentration ratios the bilayers separate spatially into regions of higher and lower chain order coinciding with areas enriched with PSM and POPC, respectively. To examine the effect of the asymmetric chain structure of POPC on bilayer lateral inhomogeneity, we consider POPC-lipid interactions with and without angular dependence. Results are compared with experimental data and with results from a similar model for mixtures of dioleoylphosphatidylcholine, steroyl sphingomyelin, and cholesterol.

  20. A Self-Consistent Beam Loaded Travelling Wave Accelerator Model for use in TRACE-3D

    NASA Astrophysics Data System (ADS)

    Lampel, M. C.

    1997-05-01

    An optics model of a constant gradient traveling wave (CGTW) accelerator structure has been implemented for TRACE-3D. TRACE-3D is an envelope code including space charge that is used to model bunched beams in magnetic transport systems and radio frequency (rf) accelerators when the effects of beam current might be significant. The new matrix model has been developed to allow incorporation of particle beam loading (current) effects on the accelerator gradient and the accelerator structure's beam focusing properties in a self-consistent manner. The beam loaded electric field for a CGTW accelerator structure is constant for only a particular design current (e.g., 0 current), otherwise it can be written as a function of accelerator attenuation and axial position along the structure. The variation of the electric field through the structure has been taken into account in the new model. CGTW structures differ substantially in focusing properties and beam loading properties from standing wave structures. Examples will be presented using the new TW model, propagating electron beams with different currents through the Stanford Linear Accelerator Center's 3 m structure. The results will be compared to the zero current TW structure model in TRANSPORT and the Tank model (a standing wave structure model) in TRACE-3D. A computer demonstration of the code with the new element will also be presented.

  1. Testing molecular-cloud fragmentation theories: self-consistent analysis of OH Zeeman observations

    NASA Astrophysics Data System (ADS)

    Mouschovias, Telemachos Ch.; Tassis, Konstantinos

    2009-11-01

    The ambipolar-diffusion theory of star formation predicts the formation of fragments in molecular clouds with mass-to-flux ratios greater than that of the parent-cloud envelope. By contrast, scenarios of turbulence-induced fragmentation do not yield such a robust prediction. Based on this property, Crutcher et al. recently proposed an observational test that could potentially discriminate between fragmentation theories. However, the analysis applied to the data severely restricts the discriminative power of the test: the authors conclude that they can only constrain what they refer to as the `idealized' ambipolar-diffusion theory that assumes initially straight-parallel magnetic field lines in the parent cloud. We present an original, self-consistent analysis of the same data taking into account the non-uniformity of the magnetic field in the cloud envelopes, which is suggested by the data themselves, and we discuss important geometrical effects that must be accounted for in using this test. We show quantitatively that the quality of current data does not allow for a strong conclusion about any fragmentation theory. Given the discriminative potential of the test, we urge for more and better-quality data.

  2. 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.

  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. 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.

  5. Hot Tensile Behavior and Self-consistent Constitutive Modeling of TA15 Titanium Alloy Sheets

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Wang, Baoyu; Liu, Gang; Zhao, Huijun; Zhou, Jing

    2015-12-01

    Hot tensile behavior of TA15 sheets with bimodal microstructure was studied through tensile tests from 750 to 850 °C with an interval of 25 °C and at strain rates of 0.001, 0.01, and 0.1 s-1. Results of the tensile tests reveal that the flow stress reaches peak values at specific strains, and then softening or steady-state flow occurs. Metallographic examination of deformed specimens shows that the primary α-phase becomes equiaxed, while the secondary α-phase and the lamellar β-phase are curved until crushed, indicating that the deformation occurred mainly in the secondary α-phase and the lamellar β-phase. A self-consistent model was developed to predict the plastic flow behavior of the TA15 sheets. Model parameters were determined according to the composition contents of individual phases and the stress-strain curves. The stress-strain curves at 775 °C and at the strain rates of 0.001, 0.01, and 0.1 s-1 were predicted by the proposed model, showing good agreement with the experimental results.

  6. A Self-Consistent Approach for Calculating the Effective Hydraulic Conductivity of a Bimodal, Heterogeneous Medium

    SciTech Connect

    Pozdniakov, Sergey; Tsang, Chin-Fu

    2004-01-02

    In this paper, we consider an approach for estimating the effective hydraulic conductivity of a 3D medium with a binary distribution of local hydraulic conductivities. The medium heterogeneity is represented by a combination of matrix medium conductivity with spatially distributed sets of inclusions. Estimation of effective conductivity is based on a self-consistent approach introduced by Shvidler (1985). The tensor of effective hydraulic conductivity is calculated numerically by using a simple system of equations for the main diagonal elements. Verification of the method is done by comparison with theoretical results for special cases and numerical results of Desbarats (1987) and our own numerical modeling. The method was applied to estimating the effective hydraulic conductivity of a 2D and 3D fractured porous medium. The medium heterogeneity is represented by a combination of matrix conductivity and a spatially distributed set of highly conductive fractures. The tensor of effective hydraulic conductivity is calculated for parallel- and random-oriented sets of fractures. The obtained effective conductivity values coincide with Romm's (1966) and Snow's (1969) theories for infinite fracture length. These values are also physically acceptable for the sparsely-fractured-medium case with low fracture spatial density and finite fracture length. Verification of the effective hydraulic conductivity obtained for a fractured porous medium is done by comparison with our own numerical modeling for a 3D case and with Malkovsky and Pek's (1995) results for a 2D case.

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

    PubMed

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

    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. PMID:24832324

  8. Self-consistent evolution models for slow CMEs up to 1 AU

    NASA Astrophysics Data System (ADS)

    Poedts, S.; Pomoell, J.; Zuccarello, F. P.

    2016-02-01

    Our 2.5D (axi-symmetric) self-consistent numerical magneto-hydrodynamics (MHD) models for the onset of CMEs under solar minimum conditions and for their interaction with coronal streamers and subsequent evolution up to 1 AU, are presented and discussed. The CMEs are initiated by magnetic flux emergence/cancellation and/or by shearing the magnetic foot points of a magnetic arcade which is positioned above or below the equatorial plane and embedded in a larger helmet streamer. The overlying magnetic streamer field then deflects the CMEs towards the equator, and the deflection path is dependent on the driving velocity. The core of the CME, created during the onset process, contains a magnetic flux rope and the synthetic white light images often show the typical three-part CME structure. The resulting CMEs propagate only slightly faster than the background solar wind, but this small excess speed is high enough to create a fast MHD shock wave from a distance of 0.25 AU onwards. At 1 AU, the plasma shows the typical characteristics of a magnetic cloud, and the simulated data are in good agreement with the (ACE) observations.

  9. A New Self-Consistent Field Model of Polymer/Nanoparticle Mixture

    NASA Astrophysics Data System (ADS)

    Chen, Kang; Li, Hui-Shu; Zhang, Bo-Kai; Li, Jian; Tian, Wen-De

    2016-02-01

    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.

  10. 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) .

  11. Semi-holography for heavy ion collisions: self-consistency and first numerical tests

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Ayan; Preis, Florian; Rebhan, Anton; Stricker, Stefan A.

    2016-05-01

    We present an extended version of a recently proposed semi-holographic model for heavy-ion collisions, which includes self-consistent couplings between the Yang-Mills fields of the Color Glass Condensate framework and an infrared AdS/CFT sector, such as to guarantee the existence of a conserved energy-momentum tensor for the combined system that is local in space and time, which we also construct explicitly. Moreover, we include a coupling of the topological charge density in the glasma to the same of the holographic infrared CFT. The semi-holographic approach makes it possible to combine CGC initial conditions and weak-coupling glasma field equations with a simultaneous evolution of a strongly coupled infrared sector describing the soft gluons radiated by hard partons. As a first numerical test of the semi-holographic model we study the dynamics of fluctuating homogeneous color-spin-locked Yang-Mills fields when coupled to a homogeneous and isotropic energy-momentum tensor of the holographic IR-CFT, and we find rapid convergence of the iterative numerical procedure suggested earlier.

  12. 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.

  13. Self-Consistent Optimization of Excited States within Density-Functional Tight-Binding.

    PubMed

    Kowalczyk, Tim; Le, Khoa; Irle, Stephan

    2016-01-12

    We present an implementation of energies and gradients for the ΔDFTB method, an analogue of Δ-self-consistent-field density functional theory (ΔSCF) within density-functional tight-binding, for the lowest singlet excited state of closed-shell molecules. Benchmarks of ΔDFTB excitation energies, optimized geometries, Stokes shifts, and vibrational frequencies reveal that ΔDFTB provides a qualitatively correct description of changes in molecular geometries and vibrational frequencies due to excited-state relaxation. The accuracy of ΔDFTB Stokes shifts is comparable to that of ΔSCF-DFT, and ΔDFTB performs similarly to ΔSCF with the PBE functional for vertical excitation energies of larger chromophores where the need for efficient excited-state methods is most urgent. We provide some justification for the use of an excited-state reference density in the DFTB expansion of the electronic energy and demonstrate that ΔDFTB preserves many of the properties of its parent ΔSCF approach. This implementation fills an important gap in the extended framework of DFTB, where access to excited states has been limited to the time-dependent linear-response approach, and affords access to rapid exploration of a valuable class of excited-state potential energy surfaces.

  14. Different Tectonic Styles in a Self-Consistent Mantle Convection Model

    NASA Astrophysics Data System (ADS)

    Stein, C.; Hansen, U.

    2002-12-01

    By using a complex rheology in a three-dimensional numerical convection model, we are able to explain, in a self-consistent manner, some features of the surface behaviour of various terrestrial planets. With a temperature-, stress- and pressure-dependent viscosity, the plate-like behaviour of the Earth appears for small yield stresses, the episodic behaviour of Venus for intermediate values, and the stagnant lid convection of Mars and Mercury is found at high yield stresses. This last regime is, for an asymptotical value of the yield stress, identical to purely thermoviscous convection. In the episodic regime, the subduction is faster than the conductive cooling from above, leading to an intermittent behaviour. But in the Earth-like regime we have smoothly evolving extended plates. Due to the slow subduction, we have slowly moving plates. Furthermore, we find cylindrical upwellings, sheetlike downwellings and trench migration. The transitions to the different regimes as well as some diagnostical values (surface velocity, boundary-plate ratio, toroidal-poloidal ratio) are strongly influenced by the rheological parameters used. For example, we find that for a high amount of internal heating and a strongly depth-dependent thermal expansivity the stagnant lid regime exists over a wide range of yield stresses. In general we find, that the surface velocity, for example, decreases with stronger depth dependance but increases with a higher amount of internal heating or a higher Rayleigh number.

  15. A BPS study on GW sources

    NASA Astrophysics Data System (ADS)

    Liu, Jinzhong

    2015-08-01

    Gravitational Wave (GW) Astronomy is an emerging branch of observational astronomy which aims to collect observational data through observing the GW sources such as * double compact objects (DCOs: NS+WD, NS+NS, BH+NS, BH+BH binaries) * double white dwarf binaries (DWDs: CO+CO, He+He, and CO+He binaries) * super-massive black hole binaries (SMBHs) * and extreme mass ratio sources (EMRSs). These sources not only can be observed by eLISA during the in-spiral phase, but also, at some level, can be detected by ground based detectors during the merged phase. Note that they are also potential electromagnetic (EM) emitters. To study GW sources, a binary population synthesis (BPS) approach is investigated. Some results in the context of GW radiation using BPS method are shown in this talk.

  16. Optimizing GW for Petascale HPC and Beyond

    NASA Astrophysics Data System (ADS)

    Deslippe, Jack; Canning, Andrew; Saad, Yousef; Chelikowsky, James; Louie, Steven

    2014-03-01

    The traditional GW-Bethe-Salpeter (BSE) approach has, in practice, been prohibitively expensive on systems with more than 50 atoms. We show that through a combination of methodological and algorithmic improvements, the standard GW-BSE approach can be applied to systems with hundreds of atoms. We will discuss the massively parallel GW-BSE implementation in the BerkeleyGW package (on-top of common DFT packages) including the importance of hybrid MPI-OpenMP parallelism, parallel IO and library performance. We will discuss optimization strategies for and performance on many-core architectures. Support for this work is provided through Scientific Discovery through Advanced Computing (SciDAC) program funded by U.S. Department of Energy, Office of Science, Advanced Scientific Computing Research and Basic Energy Sciences. Grant Number DE-FG02-12ER4

  17. 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.

  18. Modeling of self-consistent artificial radiowave ionospheric turbulence pumping and damping

    NASA Astrophysics Data System (ADS)

    Kochetov, Andrey

    2011-10-01

    The numerical simulations of the action of self-consistent powerful radiowave absorption arising in the regions of artificial plasma turbulence excitation at formation, saturation and relaxation stages of the turbulence structures (Kochetov, A.V., Mironov, V.A., et. al., Physica D, Nonlinear phenomena, 2001, 152-153, 723) to refection index dynamics are carried out. The nonlinear Schrödinger equation in inhomogeneous plasma layer with incident electromagnetic wave pumping and backscattered radiation damping (Kochetov, et al, Adv. Space Res., 2002, 29, 1369 and 2006, 38, 2490) is extended with the imaginary part of plasma dielectric constant, which results the energy transformation from electromagnetic wave to plasma one at resonance interaction (D.V. Shapiro, V.I. Shevchenko, in Handbook of Plasma Physics 2, eds. A.A Galeev, R.N. Sudan. Elsevier, Amsterdam, 1984). The modeling reproduces the basic energy transformation peculiarities: hard excitation, non-linearity, hysteresis (A.V. Kochetov, E. Mjølhus, Proc. of IV Intern. Workshop ``SMP,'' Ed. A.G. Litvak, Vol.2, N. Novgorod, 2000, 491) and demonstrates that the calculated reflection and absorption index dynamics at the beginning of the saturation stage agrees qualitatively to the experimental results for ionosphere plasma modification study. (Thide B., E.N. Sergeev, S.M. Grach, et. al., Phys. Rev. Lett., 2005, 95, 255002). The numerical simulations of the action of self-consistent powerful radiowave absorption arising in the regions of artificial plasma turbulence excitation at formation, saturation and relaxation stages of the turbulence structures (Kochetov, A.V., Mironov, V.A., et. al., Physica D, Nonlinear phenomena, 2001, 152-153, 723) to refection index dynamics are carried out. The nonlinear Schrödinger equation in inhomogeneous plasma layer with incident electromagnetic wave pumping and backscattered radiation damping (Kochetov, et al, Adv. Space Res., 2002, 29, 1369 and 2006, 38, 2490) is extended

  19. Self-consistent microwave field and plasma discharge simulations for a moderate pressure hydrogen discharge reactor

    NASA Astrophysics Data System (ADS)

    Hassouni, K.; Grotjohn, T. A.; Gicquel, A.

    1999-07-01

    A self-consistent two-dimensional model of the electromagnetic field and the plasma in a hydrogen discharge system has been developed and tested in comparison to experimental measurements. The reactor studied is a 25 cm diameter resonant cavity structure operating at 2.45 GHz with a silica belljar of 10 cm diameter and 17 cm height contained within the microwave cavity. The inside of the belljar where the discharge occurs contains a substrate holder of 5 cm diameter that is used to hold substrates for diamond deposition. The electromagnetic field model solves for the microwave fields using a finite difference time-domain solution of Maxwell's equations. The plasma model is a three energy mode (gas, molecular vibration, and electron) and nine species (H2, H, H(n=2), H(n=3), H+, H2+, H3+, H-, electron) model which accounts for non-Boltzmann electron distribution function and has 35 reactions. Simulated characteristics of the reactor in two dimensions include gas temperature, electron temperature, electron density, atomic hydrogen molar fraction, microwave power absorption, and microwave fields. Comparisons of the model are made with close agreement to several experimental measurements including coherent anti-Stokes Raman Spectroscopy measurement of H2 temperature versus position above the substrate, Doppler broadening optical emission spectroscopy (OES) measurements of H temperature versus pressure, actinometry measurements of the relative H atom concentration, Hα OES intensity measurements versus position, and microwave electric field measurements. The parameter range studied includes pressures of 2500-11 000 Pa, microwave powers of 300-2000 W, and three vertical positions of the substrate holder.

  20. 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.

  1. Quantum mechanical simulation of electronic transport in nanostructured devices by efficient self-consistent pseudopotential calculation

    NASA Astrophysics Data System (ADS)

    Jiang, Xiang-Wei; Li, Shu-Shen; Xia, Jian-Bai; Wang, Lin-Wang

    2011-03-01

    We present a new empirical pseudopotential (EPM) calculation approach to simulate the million atom nanostructured semiconductor devices under potential bias using periodic boundary conditions. To treat the nonequilibrium condition, instead of directly calculating the scattering states from the source and drain, we calculate the stationary states by the linear combination of bulk band method and then decompose the stationary wave function into source and drain injecting scattering states according to an approximated top of the barrier splitting (TBS) scheme based on physical insight of ballistic and tunneling transports. The decomposed electronic scattering states are then occupied according to the source/drain Fermi-Levels to yield the occupied electron density which is then used to solve the potential, forming a self-consistent loop. The TBS is tested in a one-dimensional effective mass model by comparing with the direct scattering state calculation results. It is also tested in a three-dimensional 22 nm double gate ultra-thin-body field-effect transistor study, by comparing the TBS-EPM result with the nonequilibrium Green's function tight-binding result. We expected the TBS scheme will work whenever the potential in the barrier region is smoother than the wave function oscillations and it does not have local minimum, thus there is no multiple scattering as in a resonant tunneling diode, and when a three-dimensional problem can be represented as a quasi-one-dimensional problem, e.g., in a variable separation approximation. Using our approach, a million atom nonequilibrium nanostructure device can be simulated with EPM on a single processor computer.

  2. 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.

  3. 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.

  4. Self-consistent modeling of electrochemical strain microscopy of solid electrolytes

    DOE PAGESBeta

    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 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

  5. Modeling Extreme Solar Energetic Particle Acceleration with Self-Consistent Wave Generation

    NASA Astrophysics Data System (ADS)

    Arthur, A. D.; le Roux, J. A.

    2015-12-01

    Observations of extreme solar energetic particle (SEP) events associated with coronal mass ejection driven shocks have detected particle energies up to a few GeV at 1 AU within the first ~10 minutes to 1 hour of shock acceleration. Whether or not acceleration by a single shock is sufficient in these events or if some combination of multiple shocks or solar flares is required is currently not well understood. Furthermore, the observed onset times of the extreme SEP events place the shock in the corona when the particles escape upstream. We have updated our focused transport theory model that has successfully been applied to the termination shock and traveling interplanetary shocks in the past to investigate extreme SEP acceleration in the solar corona. This model solves the time-dependent Focused Transport Equation including particle preheating due to the cross shock electric field and the divergence, adiabatic compression, and acceleration of the solar wind flow. Diffusive shock acceleration of SEPs is included via the first-order Fermi mechanism for parallel shocks. To investigate the effects of the solar corona on the acceleration of SEPs, we have included an empirical model for the plasma number density, temperature, and velocity. The shock acceleration process becomes highly time-dependent due to the rapid variation of these coronal properties with heliocentric distance. Additionally, particle interaction with MHD wave turbulence is modeled in terms of gyroresonant interactions with parallel propagating Alfven waves. However, previous modeling efforts suggest that the background amplitude of the solar wind turbulence is not sufficient to accelerate SEPs to extreme energies over the short time scales observed. To account for this, we have included the transport and self-consistent amplification of MHD waves by the SEPs through wave-particle gyroresonance. We will present the results of this extended model for a single fast quasi-parallel CME driven shock in the

  6. 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.

  7. Self-consistent theory of the long-range order in solid solutions

    NASA Astrophysics Data System (ADS)

    Olemskoi, Alexander

    2005-02-01

    On the basis of the assumption that atoms play a role of effective Fermions at lattice distribution, the study of the long-range ordering is shown to be reduced to self-consistent consideration of single and collective excitations being relevant to the space distribution of atoms and Fourier transform of such distribution, respectively. A diagram method advanced allows to elaborate complete thermodynamic picture of the long-range ordering of the arbitrary compositional solid solution. The long-range order parameter is found for different chemical potentials of the components to obtain a scope of ordering solid solutions according to relation between degree of the chemical affinity of the components and mixing energy. The boundary composition of the ordering phase ABn is determined as a function of the chemical potentials of the components and concentrations of impurities and defects. Temperature-compositional dependencies of the order parameter and the sublattice difference of the chemical potentials are determined explicitly. Polarization effects and passing out of the compositional domain 0.318

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Investigation of electron-atom/molecule scattering resonances: Two complex multiconfigurational self-consistent field approaches

    SciTech Connect

    Samanta, Kousik; Yeager, Danny L.

    2015-01-22

    Resonances are temporarily bound states which lie in the continuum part of the Hamiltonian. If the electronic coordinates of the Hamiltonian are scaled (“dilated”) by a complex parameter, η = αe{sup iθ} (α, θ real), then its complex eigenvalues represent the scattering states (resonant and non-resonant) while the eigenvalues corresponding to the bound states and the ionization and the excitation thresholds remain real and unmodified. These make the study of these transient species amenable to the bound state methods. We developed a quadratically convergent multiconfigurational self-consistent field method (MCSCF), a well-established bound-state technique, combined with a dilated Hamiltonian to investigate resonances. This is made possible by the adoption of a second quantization algebra suitable for a set of “complex conjugate biorthonormal” spin orbitals and a modified step-length constraining algorithm to control the walk on the complex energy hypersurface while searching for the stationary point using a multidimensional Newton-Raphson scheme. We present our computational results for the {sup 2}PBe{sup −} shape resonances using two different computationally efficient methods that utilize complex scaled MCSCF (i.e., CMCSCF). These two methods are to straightforwardly use CMCSCF energy differences and to obtain energy differences using an approximation to the complex multiconfigurational electron propagator. It is found that, differing from previous computational studies by others, there are actually two {sup 2}PBe{sup −} shape resonances very close in energy. In addition, N{sub 2} resonances are examined using one of these methods.

  14. Tides, Rotation Or Anisotropy? Self-consistent Nonspherical Models For Globular Clusters

    NASA Astrophysics Data System (ADS)

    Varri, Anna L.; Bertin, G.

    2011-01-01

    Spherical models of quasi-relaxed stellar systems provide a successful zeroth-order description of globular clusters. Yet, the great progress made in recent years in the acquisition of detailed information of the structure of these stellar systems calls for a renewed effort on the side of modeling. In particular, more general analytical models would allow to address the long-standing issue of the physical origin of the deviations from spherical symmetry of the globular clusters, that now can be properly measured. In fact, it remains to be established which is the cause of the observed flattening, among external tides, internal rotation, and pressure anisotropy. In this paper we focus on the first two physical ingredients. We start by briefly describing a recently studied family of triaxial models that incorporate in a self-consistent way the tidal effects of the host galaxy, as a collisionless analogue of the Roche problem (Varri & Bertin ApJ 2009). We then present two new families of axisymmetric models in which the deviations from spherical symmetry are induced by the presence of internal rotation. The first one is an extension of the well-known family of King models to the case of axisymmetric equilibria flattened by solid-body rotation. The second family is characterized by differential rotation, designed to be rigid in the center and to vanish in the outer parts, where the imposed truncation in phase space becomes effective. For possible application to globular clusters, models of interest should be those, in both families, characterized by low values of the rotation strength parameter and quasi-spherical shape. For general interest in stellar dynamics, we show that, for high values of that parameter, the differentially rotating models may exhibit unexpected morphologies, even with a toroidal core.

  15. Simulation of Self-consistent Radio Wave Artificial Ionospheric Turbulence Pumping and Damping

    NASA Astrophysics Data System (ADS)

    Kochetov, Andrey

    The numerical simulations of the action of self-consistent incident powerful electromagnetic wave absorption arising in the regions of artificial plasma turbulence excitation at formation, saturation and relaxation stages of turbulent structures (Kochetov, A.V., Mironov, V.A., Te-rina, G.I., Bubukina V. N, Physica D, Nonlinear phenomena, 2001, 152-153, 723) to reflection index dynamics are carried out. The nonlinear Schrüdinger equation in inhomogeneous plasma layer with incident electromagnetic wave pumping and backscattered radiation damping (Ko-chetov, et al, Adv. Space Res., 2002, 29, 1369 and 2006, 38, 2490) is extended with the imagi-nary part of plasma dielectric constant (volume damping), which is should be taken into account in strong electromagnetic field plasma regions and results the energy transformation from elec-tromagnetic waves to plasma ones at resonance interaction (D.V. Shapiro, V.I. Shevchenko, in Handbook of Plasma Physics 2, eds. A.A Galeev, R.N. Sudan. Elsevier, Amsterdam, 1984). The volume damping reproduces the basic energy transformation peculiarities: hard excitation, nonlinearity, hysteresis (A.V. Kochetov, E. Mjoelhus, Proc. of IV Intern. Workshop "SMP", Ed. A.G. Litvak, Vol.2, N. Novgorod, 2000, 491). Computer modeling demonstrates that the amplitude and period of reflection index oscillations at the formation stage slowly depend on damping parameters of turbulent plasma regions. The transformation from complicated: quasi-periodic and chaotic dynamics, to quasi-stationary regimes is shown at the saturation stage. Transient processes time becomes longer if the incident wave amplitude and nonlinear plasma response increase, but damping decreases. It is obtained that the calculated reflection and absorption index dynamics at the beginning of the saturation stage agrees qualitatively to the experimental results for ionosphere plasma modification study (Thide B., E.N. Sergeev, S.M. Grach, et. al., Phys. Rev. Lett., 2005, 95, 255002). The

  16. 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.

  17. 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.

  18. Self-consistent dynamical and radiative models of low-luminosity active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Dolence, Joshua Cody

    Supermassive black holes are found in nearly all major galaxies and most are in a slowly accreting or quiescent state. The physical characteristics of these low-luminosity active galactic nuclei (LLAGN) allow a unique opportunity to build and test nearly ab initio models of black hole accretion. To that end, I describe numerical techniques we have developed to build self-consistent dynamical and radiative models of LLAGN and their application to modeling the galactic center source Sgr A*. Sgr A* is an extremely low luminosity LLAGN and is a particularly attractive target for modeling black hole accretion flows for a variety of reasons. First, its proximity has enabled excellent measurements of its mass and distance through long term monitoring of stellar orbits. Next, Sgr A* has been the target of extensive multiwavelength observing campaigns for decades, providing a wealth of information on its mean and fluctuating broadband spectrum. In the last few years, millimeter wavelength very long baseline interferometry has begun to resolve structure on the scale of the event horizon, providing constraints on the structure of the inner accretion flow. From a theoretical perspective, Sgr A* is an attractive target because its low luminosity implies that the dynamical and radiative problems are decoupled, greatly simplifying the construction of self-consistent models. I first describe grmonty, a fully relativistic Monte Carlo code for radiation transport that treats angle-dependent thermal synchrotron emission and absorption and Compton scattering essentially without approximation. One limitation of grmonty is that it assumes the background emitting plasma (which is provided by, e.g., a simulation) is time-independent which we refer to as the "fast-light" approximation. I then describe the generalization of grmonty to include light travel time effects in arbitrary time-dependent background flows and introduce a new technique for producing images based on time-dependent ray

  19. 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.

  20. Quasiparticle excitations of adsorbates on doped graphene

    NASA Astrophysics Data System (ADS)

    Lischner, Johannes; Wickenburg, Sebastian; Wong, Dillon; Karrasch, Christoph; Wang, Yang; Lu, Jiong; Omrani, Arash A.; Brar, Victor; Tsai, Hsin-Zon; Wu, Qiong; Corsetti, Fabiano; Mostofi, Arash; Kawakami, Roland K.; Moore, Joel; Zettl, Alex; Louie, Steven G.; Crommie, Mike

    Adsorbed atoms and molecules can modify the electronic structure of graphene, but in turn it is also possible to control the properties of adsorbates via the graphene substrate. In my talk, I will discuss the electronic structure of F4-TCNQ molecules on doped graphene and present a first-principles based theory of quasiparticle excitations that captures the interplay of doping-dependent image charge interactions between substrate and adsorbate and electron-electron interaction effects on the molecule. The resulting doping-dependent quasiparticle energies will be compared to experimental scanning tunnelling spectra. Finally, I will also discuss the effects of charged adsorbates on the electronic structure of doped graphene.

  1. A GW-based many-body perturbation theory approach for investigating materials with strong spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Barker, Bradford; Deslippe, Jack; Yazyev, Oleg; Louie, Steven

    2011-03-01

    Spin-orbit coupling is an essential ingredient in understanding the electronic properties of materials of recent interest. We have developed a means of incorporating spin-orbit coupling to the quasiparticle excitations in solids within the GW approach. We apply our method to the properties of materials with heavy ion cores. This work was supported by National Science Foundation Grant No. DMR10-1006184, the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Computational resources have been provided by NERSC.

  2. Astrod-Gw Overview and Progress

    NASA Astrophysics Data System (ADS)

    Ni, Wei-Tou

    2013-01-01

    In this paper, we present an overview of Astrodynamical Space Test of Relativity using Optical Devices (ASTROD-GW) optimized for Gravitational Wave (GW) detection mission concept and its studies. ASTROD-GW is an optimization of ASTROD which focuses on low frequency GW detection. The detection sensitivity is shifted by a factor of 260 (52) towards longer wavelengths compared with that of NGO/eLISA (LISA). The mission consists of three spacecraft, each of which orbits near one of the Sun-Earth Lagrange points (L3, L4 and L5), such that the array forms an almost equilateral triangle. The three spacecraft range interferometrically with one another with an arm length of about 260 million kilometers. The orbits have been optimized resulting in arm length changes of less than ± 0.00015 AU or, fractionally, less than ±10-4 in 20 years, and relative Doppler velocities of the three spacecraft of less than ±3 m/s. In this paper, we present an overview of the mission covering: the scientific aims, the sensitivity spectrum, the basic orbit configuration, the simulation and optimization of the spacecraft orbits, the deployment of ASTROD-GW formation, Time Delay Interferometry (TDI) and the payload. The science goals are the detection of GWs from (i) Supermassive Black Holes; (ii) Extreme-Mass-Ratio Black Hole Inspirals; (iii) Intermediate-Mass Black Holes; (iv) Galactic Compact Binaries and (v) Relic GW Background. For the purposes of primordial GW detection, a six spacecraft formation would be needed to enable the correlated detection of stochastic GWs. A brief discussion of the six spacecraft orbit optimization is also presented.

  3. 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.

  4. Topological quantum computing with only one mobile quasiparticle.

    PubMed

    Simon, S H; Bonesteel, N E; Freedman, M H; Petrovic, N; Hormozi, L

    2006-02-24

    In a topological quantum computer, universal quantum computation is performed by dragging quasiparticle excitations of certain two dimensional systems around each other to form braids of their world lines in 2 + 1 dimensional space-time. In this Letter we show that any such quantum computation that can be done by braiding n identical quasiparticles can also be done by moving a single quasiparticle around n - 1 other identical quasiparticles whose positions remain fixed.

  5. GRACE L1b inversion through a self-consistent modified radial basis function approach

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Kusche, Juergen; Rietbroek, Roelof; Eicker, Annette

    2016-04-01

    Implementing a regional geopotential representation such as mascons or, more general, RBFs (radial basis functions) has been widely accepted as an efficient and flexible approach to recover the gravity field from GRACE (Gravity Recovery and Climate Experiment), especially at higher latitude region like Greenland. This is since RBFs allow for regionally specific regularizations over areas which have sufficient and dense GRACE observations. Although existing RBF solutions show a better resolution than classical spherical harmonic solutions, the applied regularizations cause spatial leakage which should be carefully dealt with. It has been shown that leakage is a main error source which leads to an evident underestimation of yearly trend of ice-melting over Greenland. Unlike some popular post-processing techniques to mitigate leakage signals, this study, for the first time, attempts to reduce the leakage directly in the GRACE L1b inversion by constructing an innovative modified (MRBF) basis in place of the standard RBFs to retrieve a more realistic temporal gravity signal along the coastline. Our point of departure is that the surface mass loading associated with standard RBF is smooth but disregards physical consistency between continental mass and passive ocean response. In this contribution, based on earlier work by Clarke et al.(2007), a physically self-consistent MRBF representation is constructed from standard RBFs, with the help of the sea level equation: for a given standard RBF basis, the corresponding MRBF basis is first obtained by keeping the surface load over the continent unchanged, but imposing global mass conservation and equilibrium response of the oceans. Then, the updated set of MRBFs as well as standard RBFs are individually employed as the basis function to determine the temporal gravity field from GRACE L1b data. In this way, in the MRBF GRACE solution, the passive (e.g. ice melting and land hydrology response) sea level is automatically

  6. 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

  7. 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

  8. 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.

  9. Thermodynamically self-consistent theories of fluids interacting through short-range forces.

    PubMed

    Caccamo, C; Pellicane, G; Costa, D; Pini, D; Stell, G

    1999-11-01

    The self-consistent Ornstein-Zernike approximation (SCOZA), the generalized mean spherical approximation (GMSA), the modified hypernetted chain (MHNC) approximation, and the hierarchical reference theory (HRT) are applied to the determination of thermodynamic and structural properties, and the phase diagram of the hard-core Yukawa fluid (HCYF). We investigate different Yukawa-tail screening lengths lambda, ranging from lambda=1.8 (a value appropriate to approximate the shape of the Lennard-Jones potential) to lambda=9 (suitable for a simple one-body modelization of complex fluids like colloidal suspensions and globular protein solutions). The comparison of the results obtained with computer simulation data shows that at relatively low lambda's all the theories are fairly accurate in the prediction of thermodynamic and structural properties; as far as the phase diagram is concerned, the SCOZA and HRT are able to predict the binodal line and the critical parameters in a quantitative manner. At lambda=4 some discrepancies begin to emerge in the performances of the different theoretical approaches: the MHNC remains, on the whole, reasonably accurate in predicting the energy and the contact value of the radial distribution function; the SCOZA predicts well the equation of state up to the highest lambda values investigated. The GMSA and the MHNC underestimate and overestimate, respectively, the liquid coexisting density, while the SCOZA and HRT yield liquid branches that fall between the two former theoretical predictions, although both appear to overestimate the critical temperature somewhat. At higher lambda's the GMSA and MHNC binodals further worsen, while the SCOZA appears to remain usefully predictive. In general, the predictions of all the theories tend to slightly worsen at low temperatures and high density. The determination of the freezing line, performed by means of a one-phase "freezing criterion" (due to other authors) is not particularly satisfactory within

  10. 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

  11. Self-Consistent Steady-State Model of the Low - Boundary Layer

    NASA Astrophysics Data System (ADS)

    Drakou, Eleonora

    The interface between the shocked solar wind and the magnetosphere is marked by a current sheet which is called the magnetopause. The low-latitude boundary layer (LLBL) is a narrow region located in the magnetosphere, immediately inside the magnetopause current layer, at low geomagnetic latitudes. It contains magnetosheath-like plasma, which flows in a general antisunward direction, as well as entrained magnetospheric plasma. Results are presented from a steady-state numerical model of this layer on closed field lines and its coupling to the dayside auroral ionosphere. In the model, the boundary layer approximation is used, the result being that inertia forces are taken into account only in the main flow direction ( -x) where they are balanced by pressure forces, j times B forces, and viscous forces. Motion in the transverse directions (y and z) is treated kinematically, the force balances in these two directions being purely static. Computationally, the model is two dimensional, describing the motion of plasma and frozen-in magnetic field in the equatorial (xy) plane but allowing for lowest order polynomial variation of some quantities with the coordinate (z) perpendicular to that plane. For the solution of the resulting system of equations a Crank-Nicolson finite difference scheme was implemented. The numerical code was benchmarked against self-similar solutions. The plasma expands and compresses isentropically; the magnetic field is calculated self-consistently which leads to approximately parabolic field-line shape in planes parallel to the magnetopause (the xz plane), with maximum field curvature near the magnetopause edge of the LLBL. Coupling to the ionosphere via Region 1 field-aligned currents is included. The effects of the ionosphere are represented by two parallel resistive plates at fixed height above and below the equatorial plane. However, the model can be extended to include variable height of the layer as well as field-aligned potential drops in

  12. 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

  13. 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

  14. Dynamic self-consistent field theory of inhomogeneous complex fluids under shear

    NASA Astrophysics Data System (ADS)

    Mihajlovic, Maja Lazar

    Understanding and predicting the interplay between morphology and rheology of sheared, inhomogeneous, complex fluids is of great importance. Yet the modeling of such phenomena is in its infancy. We have developed a novel dynamic self-consistent field (DSCF) theory that makes possible a detailed computational study of such phenomena. Our DSCF theory couples the time evolution of chain conformation statistics with probabilistic transport equations for volume fractions and momenta, based on local conservation laws formulated on a segmental scale. To generate chain conformation statistics, we are using a modification of the lattice random walk formalism of Scheutjens and Fleer. Their static SCF theory is limited to equilibrium systems, since probability distributions are obtained by free energy minimization, assuming isotropic Gaussian chain conformations. In contrast, our DSCF approach accounts for explicit time evolution of the segmental and (anisotropic) conditional stepping probabilities used for generating chain conformations. We have applied the DSCF model to a variety of isothermal inhomogenous fluids containing homopolymers, block copolymers and colloidal particles. In all the simulations, the system is equilibrated before the onset of a steady shear at the walls. Our results suggest that, on short time scales, the velocity evolution resembles shock wave propagation. In the course of time, the amplitude of the shock waves is viscously damped, giving rise to a Couette-like steady state velocity profile. This is also reflected in the temporal evolution of the tensor of the second moment of the end-to-end vector and the dissipative stress tensor. The two- and three-component polymer blends (with a diblock copolymer as the third component) exhibit the interfacial velocity and viscosity slip. The addition of a diblock copolymer suppresses the velocity, and therefore the viscosity slip. Colloidal particles suspended in a simple fluid exhibit layering near the walls

  15. 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

  16. 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.

  17. [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.

  18. Bi-functional nonlinearities in monodisperse ZnO nano-grains – Self-consistent transport and random lasing

    SciTech Connect

    Lubatsch, Andreas; Frank, Regine

    2014-08-20

    We report a quantum field theoretical description of light transport and random lasing. The Bethe-Salpeter equation is solved including maximally crossed diagrams and non-elastic scattering. This is the first theoretical framework that combines so called off-shell scattering and lasing in random media. We present results for the self-consistent scattering mean free path that varies over the width of the sample. Further we discuss the density dependent correlation length of self-consistent transport in disordered media composed of semi-conductor Mie scatterers.

  19. 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.

  20. Testing variations of the GW approximation on strongly correlated transition metal oxides: hematite (α-Fe2O3) as a benchmark.

    PubMed

    Liao, Peilin; Carter, Emily A

    2011-09-01

    Quantitative characterization of low-lying excited electronic states in materials is critical for the development of solar energy conversion materials. The many-body Green's function method known as the GW approximation (GWA) directly probes states corresponding to photoemission and inverse photoemission experiments, thereby determining the associated band structure. Several versions of the GW approximation with different levels of self-consistency exist in the field. While the GWA based on density functional theory (DFT) works well for conventional semiconductors, less is known about its reliability for strongly correlated semiconducting materials. Here we present a systematic study of the GWA using hematite (α-Fe(2)O(3)) as the benchmark material. We analyze its performance in terms of the calculated photoemission/inverse photoemission band gaps, densities of states, and dielectric functions. Overall, a non-self-consistent G(0)W(0) using input from DFT+U theory produces physical observables in best agreement with experiments.

  1. 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

  2. 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.

  3. First-principles DFT +GW study of oxygen vacancies in rutile TiO2

    NASA Astrophysics Data System (ADS)

    Malashevich, Andrei; Jain, Manish; Louie, Steven G.

    2014-02-01

    We perform first-principles calculations of the quasiparticle defect states, charge transition levels, and formation energies of oxygen vacancies in rutile titanium dioxide. The calculations are done within the recently developed combined DFT +GW formalism, including the necessary electrostatic corrections for the supercells with charged defects. We find the oxygen vacancy to be a negative U defect, where U is the defect electron addition energy. For Fermi level values below ˜2.8 eV (relative to the valence-band maximum), we find the +2 charge state of the vacancy to be the most stable, while above 2.8 eV we find that the neutral charge state is the most stable.

  4. Quasiparticle-continuum level repulsion in a quantum magnet

    DOE PAGESBeta

    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; et al

    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

  5. 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.

  6. Quasiparticle-continuum level repulsion in a quantum magnet

    NASA Astrophysics Data System (ADS)

    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

    2016-03-01

    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. However, 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. In our fine-resolution neutron spectroscopy study of magnetic quasiparticles in the frustrated quantum magnet BiCu2PO6, we observe a renormalization of the quasiparticle dispersion relation due to the presence of the continuum of multi-quasiparticle states.

  7. Environment-Dependent Quasiparticle Bandgap of Monolayer MoS2

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Sung; Noh, Ji-Young; Kim, Hanchul; Park, Minkyu; Santosh, K. C.; Cho, K. J.

    2015-03-01

    2D semiconductors are manifested by strong Coulomb interaction inside. The strong Coulomb interaction gives remarkable effects on various properties of the 2D semiconductors, including (i) large exciton binding energy (electron-hole), (ii) large quasi-particle self-energy (electron-electron), (iii) large scattering cross section in carrier transports by charged defects (electron-charged defects), (iv) deep defect transition level (bound electron-charged defects), and (v) strong interaction between charged defects (charged defects-charged defects). The ground state, optical, and transport properties are then largely affected by the dielectric environments surrounding the 2D semiconductors, because the Coulomb interaction is effectively screened by the dielectrics. We investigate the electronic band structures of a single-layer MoS2, as a prototype 2D semiconductor, with a variety of dielectric environments by using density-functional-theory (DFT) and GW calculations.

  8. 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.

  9. Validity of virial theorem in all-electron mixed basis density functional, Hartree-Fock, and GW calculations.

    PubMed

    Kuwahara, Riichi; Tadokoro, Yoichi; Ohno, Kaoru

    2014-08-28

    In this paper, we calculate kinetic and potential energy contributions to the electronic ground-state total energy of several isolated atoms (He, Be, Ne, Mg, Ar, and Ca) by using the local density approximation (LDA) in density functional theory, the Hartree-Fock approximation (HFA), and the self-consistent GW approximation (GWA). To this end, we have implemented self-consistent HFA and GWA routines in our all-electron mixed basis code, TOMBO. We confirm that virial theorem is fairly well satisfied in all of these approximations, although the resulting eigenvalue of the highest occupied molecular orbital level, i.e., the negative of the ionization potential, is in excellent agreement only in the case of the GWA. We find that the wave function of the lowest unoccupied molecular orbital level of noble gas atoms is a resonating virtual bound state, and that of the GWA spreads wider than that of the LDA and thinner than that of the HFA.

  10. Validity of virial theorem in all-electron mixed basis density functional, Hartree–Fock, and GW calculations

    SciTech Connect

    Kuwahara, Riichi; Tadokoro, Yoichi; Ohno, Kaoru

    2014-08-28

    In this paper, we calculate kinetic and potential energy contributions to the electronic ground-state total energy of several isolated atoms (He, Be, Ne, Mg, Ar, and Ca) by using the local density approximation (LDA) in density functional theory, the Hartree–Fock approximation (HFA), and the self-consistent GW approximation (GWA). To this end, we have implemented self-consistent HFA and GWA routines in our all-electron mixed basis code, TOMBO. We confirm that virial theorem is fairly well satisfied in all of these approximations, although the resulting eigenvalue of the highest occupied molecular orbital level, i.e., the negative of the ionization potential, is in excellent agreement only in the case of the GWA. We find that the wave function of the lowest unoccupied molecular orbital level of noble gas atoms is a resonating virtual bound state, and that of the GWA spreads wider than that of the LDA and thinner than that of the HFA.

  11. Quasiparticle interactions in frustrated Heisenberg chains

    NASA Astrophysics Data System (ADS)

    Vanderstraeten, Laurens; Haegeman, Jutho; Verstraete, Frank; Poilblanc, Didier

    2016-06-01

    Interactions between elementary excitations in quasi-one-dimensional antiferromagnets are of experimental relevance and their quantitative theoretical treatment has been a theoretical challenge for many years. Using matrix product states, one can explicitly determine the wave functions of the one- and two-particle excitations, and, consequently, the contributions to dynamical correlations. We apply this framework to the (nonintegrable) frustrated dimerized spin-1/2 chain, a model for generic spin-Peierls systems, where low-energy quasiparticle excitations are bound states of topological solitons. The spin structure factor involving two quasiparticle scattering states is obtained in the thermodynamic limit with full momentum and frequency resolution. This allows very subtle features in the two-particle spectral function to be revealed which, we argue, could be seen, e.g., in inelastic neutron scattering of spin-Peierls compounds under a change of the external pressure.

  12. 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.

  13. Fourier transform-based scattering-rate method for self-consistent simulations of carrier transport in semiconductor heterostructures

    NASA Astrophysics Data System (ADS)

    Schrottke, L.; Lü, X.; Grahn, H. T.

    2015-04-01

    We present a self-consistent model for carrier transport in periodic semiconductor heterostructures completely formulated in the Fourier domain. In addition to the Hamiltonian for the layer system, all expressions for the scattering rates, the applied electric field, and the carrier distribution are treated in reciprocal space. In particular, for slowly converging cases of the self-consistent solution of the Schrödinger and Poisson equations, numerous transformations between real and reciprocal space during the iterations can be avoided by using the presented method, which results in a significant reduction of computation time. Therefore, it is a promising tool for the simulation and efficient design of complex heterostructures such as terahertz quantum-cascade lasers.

  14. Local conditions for the Pauli potential in order to yield self-consistent electron densities exhibiting proper atomic shell structure

    NASA Astrophysics Data System (ADS)

    Finzel, Kati

    2016-01-01

    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.

  15. Local conditions for the Pauli potential in order to yield self-consistent electron densities exhibiting proper atomic shell structure.

    PubMed

    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.

  16. 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.

  17. Self-consistent scheme for optical response of large hybrid networks of semiconductor quantum dots and plasmonic metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Hayati, L.; Lane, C.; Barbiellini, B.; Bansil, A.; Mosallaei, H.

    2016-06-01

    We discuss a self-consistent scheme for treating the optical response of large, hybrid networks of semiconducting quantum dots (SQDs) and plasmonic metallic nanoparticles (MNPs). Our method is efficient and scalable and becomes exact in the limiting case of weakly interacting SQDs. The self-consistent equations obtained for the steady state are analogous to the von Neumann equations of motion for the density matrix of a SQD placed in an effective electric field computed within the discrete dipole approximation. Illustrative applications of the theory to square and honeycomb SQD, MNP, and hybrid SDQ-MNP lattices as well as SQD-MNP dimers are presented. Our results demonstrate that hybrid SQD-MNP lattices can provide flexible platforms for light manipulation with tunable resonant characteristics.

  18. Fourier transform-based scattering-rate method for self-consistent simulations of carrier transport in semiconductor heterostructures

    SciTech Connect

    Schrottke, L. Lü, X.; Grahn, H. T.

    2015-04-21

    We present a self-consistent model for carrier transport in periodic semiconductor heterostructures completely formulated in the Fourier domain. In addition to the Hamiltonian for the layer system, all expressions for the scattering rates, the applied electric field, and the carrier distribution are treated in reciprocal space. In particular, for slowly converging cases of the self-consistent solution of the Schrödinger and Poisson equations, numerous transformations between real and reciprocal space during the iterations can be avoided by using the presented method, which results in a significant reduction of computation time. Therefore, it is a promising tool for the simulation and efficient design of complex heterostructures such as terahertz quantum-cascade lasers.

  19. Self consistent impedance determination in multiple circuit paths for resistive magnetohydrodynamic z-pinch flux compression simulations

    NASA Astrophysics Data System (ADS)

    Peterson, Kyle

    2004-12-01

    Electromagnetic boundary conditions can be troublesome in multi-dimensional magnetohydrodynamic simulations of systems containing complex geometries with multiple circuit paths. Accurate modeling of electromagnetic boundary conditions requires the feedback impedance of conducting plasmas in the computational domain to be modeled self consistently with external circuit boundaries. A new method is presented to dynamically calculate inductive and resistive impedance in multiple circuit paths and determine the electromagnetic boundary conditions in a self consistent manner. The new method was implemented into a two dimensional resistive magnetohydrodynamics code in order to simulate azimuthally opposed magnetic flux compression in a z-pinch configuration. Results of the flux compression simulations demonstrate excellent conservation of energy and circuit stability.

  20. 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.

  1. A self-consistent method for the determination of neutral density from X-ray impurity spectra

    NASA Astrophysics Data System (ADS)

    Rosmej, F. B.; Lisitsa, V. S.

    1998-07-01

    A new method for the determination of neutral densities and the electron lifetime from X-ray line spectra through charge exchange processes is proposed. The non-equilibrium population of neutrals and the charge exchange from their excited states in plasma regimes of high density and temperature have been calculated in a self-consistent manner through the introduction of an “effective diffusion rate”.

  2. 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.

  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. 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

  5. Theoretical Model to Explain Excess of Quasiparticles in Superconductors.

    PubMed

    Bespalov, Anton; Houzet, Manuel; Meyer, Julia S; Nazarov, Yuli V

    2016-09-01

    Experimentally, the concentration of quasiparticles in gapped superconductors always largely exceeds the equilibrium one at low temperatures. Since these quasiparticles are detrimental for many applications, it is important to understand theoretically the origin of the excess. We demonstrate in detail that the dynamics of quasiparticles localized at spatial fluctuations of the gap edge becomes exponentially slow. This gives rise to the observed excess in the presence of a vanishingly weak nonequilibrium agent. PMID:27661716

  6. 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.

  7. 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; 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; 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    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 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.

  8. Tests of General Relativity with GW150914.

    PubMed

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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; 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

    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 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. PMID:27314708

  9. Towards improved exact exchange functionals relying on G W quasiparticle methods for parametrization

    NASA Astrophysics Data System (ADS)

    Zólyomi, V.; Kürti, J.

    2015-07-01

    We use fully self-consistent GW calculations on diamond and silicon carbide to reparametrize the Heyd-Scuseria-Ernzerhof (HSE) exact exchange density functional for use in band structure calculations of semiconductors and insulators. We show that the thus modified functional is able to calculate the band structure of bulk Si, Ge, GaAs, and CdTe with good quantitative accuracy at a significantly reduced computational cost as compared to G W methods, and also gives significantly improved band gap predictions in wide-gap ionic crystals as compared to the HSE06 parametrization. We discuss the limitations of this functional in low dimensions by calculating the band structures of single-layer hexagonal BN and MoS2, and by demonstrating that the diameter scaling of curvature induced band gaps in single-walled carbon nanotubes is still physically incorrect using our functional; we consider possible remedies to this problem.

  10. Self-Consistent Model of Magnetospheric Ring Current and Electromagnetic Ion Cyclotron Waves: The May 2-7, 1998, Storm

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Jordanova, V. K.

    2003-01-01

    Complete description of a self-consistent model for 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 non steady-state conditions. In the paper by Khazanov et al. [2002] this self-consistent model has only been shortly outlined, and discussions of many the model related details have been omitted. For example, in present study for the first time a new algorithm for numerical finding of the resonant numbers for quasilinear wave-particle interaction is described, or it is demonstrated that in order to describe quasilinear interaction in a multi-ion thermal plasma correctly, both e and He(+) modes of electromagnetic ion cyclotron waves should be employed. The developed model is used to simulate the entire May 2-7, 1998 storm period. Trapped number fluxes of the ring current protons are calculated and presented along with their comparison with the data measured by the 3D hot plasma instrument Polar/HYDRA. Examining of the wave (MLT, L shell) distributions produced during the storm progress reveals an essential intensification of the wave emissions in about two days after main phase of storm. This result is well consistent with the earlier ground-based observations. Also the theoretical shapes and the occurrence rates for power spectral densities of electromagnetic ion cyclotron waves are studied. It is found that in about 2 days after the storm main phase on May 4, mainly non Gaussian shapes of power spectral densities are produced.

  11. 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.

  12. 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.

  13. 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.

  14. Radio-frequency plasmas in CF4: Self-consistent modeling of the plasma physics and chemistry

    NASA Astrophysics Data System (ADS)

    Mantzaris, Nikolaos V.; Boudouvis, Andreas; Gogolides, Evangelos

    1995-06-01

    A self-consistent, one-dimensional simulator for the physics and chemistry of radio frequency plasmas is developed and applied for CF4. The simulator consists of a fluid model for the discharge, a commercial Boltzmann code for calculations of electron energy distribution function (EEDF), a generalized plasma chemistry code, and an interface among the three models. Chemistry calculations are fed back into the physics model and the procedure is repeated until a self-consistent solution is obtained. The CF4 discharge shows an electronegative behavior with ten times more negative ions than electrons even at low pressures of 100 mTorr. The EEDF high energy tail lies between the Maxwell and Druyvensteyn distribution. The chemistry model predicts densities of 3.5×1012 cm-3 for CF3, 3×1012 cm-3 for CF2, 2.5×1013 cm-3 for F, and 0.7×1012 cm-3 for CF, in agreement with experimental data from a Japanese group. CF and to a lesser extent CF2, are consumed at the surface, and CF, CF2, and F densities and profiles are sensitive to the sticking coefficient and residence time. CF2 and CF are produced mainly from the parent gas CF4 and not its fragments. Finally, the chemistry results are fed back into the physics model and influence the discharge structure, mainly by changing electron densities and the width of the inner core of the positive-negative ion plasma. Thus, the importance of self-consistent plasma calculations is demonstrated and justified.

  15. Internal structure of hole quasiparticles in antiferromagnets

    NASA Astrophysics Data System (ADS)

    Simons, B. D.; Gunn, J. M. F.

    1990-04-01

    Holes in an Ising antiferromagnet give rise to quasiparticles with an internal structure associated with the distortion of the spin ordering. We show that the spectrum of excited states (of this internal structure) commences at a lower energy than previously thought, at an energy of the order of the exchange constant. The character of the corresponding states differ from those previously discussed in that the phases associated with the various spin configurations with the same number of spin flips differ. Moreover, these excited states dominate the optical absorption and may explain the experimental results of Thomas et al. [Phys. Rev. Lett. 61, 1313 (1988)].

  16. Finite quasiparticle lifetime in disordered superconductors

    NASA Astrophysics Data System (ADS)

    Žemlička, M.; Neilinger, P.; Trgala, M.; Rehák, M.; Manca, D.; Grajcar, M.; Szabó, P.; Samuely, P.; Gaži, Š.; Hübner, U.; Vinokur, V. M.; Il'ichev, E.

    2015-12-01

    We investigate the complex conductivity of a highly disordered MoC superconducting film with kFl ≈1 , where kF 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 Tc. We find that the original Mattis-Bardeen model with a finite quasiparticle lifetime, τ , offers a perfect description of the experimentally observed complex conductivity. We show that τ 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.

  17. Quasiparticle virtual orbitals in electron propagator calculations.

    PubMed

    Flores-Moreno, R; Ortiz, J V

    2008-04-28

    The computational limits of accurate electron propagator methods for the calculation of electron binding energies of large molecules are usually determined by the rank of the virtual orbital space. Electron density difference matrices that correspond to these transition energies in the second-order quasiparticle approximation may be used to obtain a virtual orbital space of reduced rank that introduces only minor deviations with respect to the results produced with the full, original set of virtual orbitals. Numerical tests show the superior accuracy and efficiency of this approach compared to the usual practice of omission of virtual orbitals with the highest energies.

  18. 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

  19. 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.

  20. Self-Consistent Calculation of Half-Harmonics Emission Generated by the Two-Plasmon-Decay Instability

    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.

    2014-10-01

    Half-harmonics emission can be used as an effective diagnostic tool for the two-plasmon-decay (TPD) instability. However, interpretation of the half-harmonics spectrum is difficult because of its complicated generation mechanism. We have developed a code that can calculate half-harmonics emission self-consistently with the TPD instability. The results would be useful to interpret experimental data and help design experiments. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  1. A charge self-consistent LDA+DMFT study of the spectral properties of hexagonal NiS

    NASA Astrophysics Data System (ADS)

    Panda, S. K.; Thunström, P.; Di Marco, I.; Schött, J.; Delin, A.; Dasgupta, I.; Eriksson, O.; Sarma, D. D.

    2014-09-01

    The electronic structure and spectral properties of hexagonal NiS have been studied in the high temperature paramagnetic phase and low temperature antiferromagnetic phase. The calculations have been performed using charge self-consistent density-functional theory in local density approximation combined with dynamical mean-field theory (LDA+DMFT). The photoemission spectra (PES) and optical properties have been computed and compared with the experimental data. Our results show that the dynamical correlation effects are important to understand the spectral and optical properties of NiS. These effects have been analyzed in detail by means of the computed real and imaginary part of the self-energy.

  2. Contribution to the theory of phase inversion. Temperature of hydrophilic-lipophilic balance in self-consistent field approximation

    SciTech Connect

    Kuz'min, V.L.; Rusanov, A.I.

    1988-05-01

    An analysis was made of the simplest statistical-mechanical lattice model for describing phase equilibria in three-component systems in the self-consistent field approximation. The range of parameters was defined for the possible appearance of a point or region of hydrophilic-lipophilic balance (HLB) on the phase diagram. That either a point or a region of HLB may exist was an indication that the phenomena occurs widely. Analysis of such a simple model was established as a necessary step in passing on to more complex models.

  3. 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

    2016-04-01

    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 %.

  4. 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.

  5. Theoretical prediction of the band offsets at the ZnO/anatase TiO2 and GaN/ZnO heterojunctions using the self-consistent ab initio DFT/GGA-1/2 method

    NASA Astrophysics Data System (ADS)

    Fang, D. Q.; Zhang, S. L.

    2016-01-01

    The band offsets of the ZnO/anatase TiO2 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 TiO2, 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 TiO2 heterojunction and show good agreement with the GW calculations for the GaN/ZnO heterojunction.

  6. Theoretical prediction of the band offsets at the ZnO/anatase TiO2 and GaN/ZnO heterojunctions using the self-consistent ab initio DFT/GGA-1/2 method.

    PubMed

    Fang, D Q; Zhang, S L

    2016-01-01

    The band offsets of the ZnO/anatase TiO2 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 TiO2, 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 TiO2 heterojunction and show good agreement with the GW calculations for the GaN/ZnO heterojunction. PMID:26747815

  7. 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. PMID:26831071

  8. Nodal quasiparticle in pseudogapped colossal magnetoresistive manganites

    NASA Astrophysics Data System (ADS)

    Mannella, N.; Yang, W. L.; Zhou, X. J.; Tanaka, K.; Zheng, H.; Mitchell, J. F.; Zaanen, J.; Devereaux, T. P.; Nagaosa, N.; Hussain, Z.; Shen, Z. X.

    2006-03-01

    In this talk, the result of a recent angle-resolved photoemission spectroscopy (ARPES) investigation which allowed elucidating the controversial nature of the ferromagnetic metallic groundstate in the prototypical colossal magnetoresistive manganite bilayer compound La1.2Sr1.8Mn2O7 will be discussed [1]. The distribution of spectral weight in momentum space exhibits a nodal--antinodal dichotomous character. Quasiparticle excitations have been detected for the first time along the nodal direction (i.e. diagonal), and they are found to determine the metallic transport properties of this compound. The weight of the quasiparticle peak diminishes rapidly while crossing over to the antinodal (i.e. parallel to the Mn--O bonds) parallel sections of the Fermi surface, with the spectra strongly resembling those found in heavily underdoped cuprates high temperature superconductors (HTSC) such as Ca2-xNaxCuO2Cl2 [2]. This dichotomy between the electronic excitations along the nodal and antinodal directions in momentum space was so far considered a characteristic unique feature of the copper oxide HTSC. These findings therefore cast doubt on the assumption that the pseudogap state in the cuprate HTSC and the nodal-antinodal dichotomy are hallmarks of the superconductivity state. [1] N. Mannella et al., Nature 438, 474 (2005) [2] K. M Shen et al., Science 307, 901 (2005).

  9. Charge of a quasiparticle in a superconductor

    PubMed Central

    Ronen, Yuval; Cohen, Yonatan; Kang, Jung-Hyun; Haim, Arbel; Rieder, Maria-Theresa; Heiblum, Moty; Mahalu, Diana; Shtrikman, Hadas

    2016-01-01

    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. PMID:26831071

  10. 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.

  11. Self-consistent treatment of the sheath boundary conditions by introducing anisotropic ion temperatures and virtual divertor model

    NASA Astrophysics Data System (ADS)

    Togo, Satoshi; Takizuka, Tomonori; Nakamura, Makoto; Hoshino, Kazuo; Ibano, Kenzo; Lang, Tee Long; Ogawa, Yuichi

    2016-04-01

    One-dimensional SOL-divertor plasma fluid simulation code which considers anisotropy of ion temperature has been developed so as to deal with sheath theory self-consistently. In our fluid modeling, explicit use of boundary condition for Mach number M at divertor plate, e.g., M = 1, becomes unnecessary. In order to deal with the Bohm condition and the sheath heat transmission factors at divertor plate self-consistently, we introduced a virtual divertor (VD) model which sets an artificial region beyond divertor plates and artificial sinks for particle, momentum and energy there to model the effects of the sheath region in front of the divertor plate. Validity of our fluid model with VD model is confirmed by showing that simulation results agree well with those from a kinetic code regarding the Bohm condition, ion temperature anisotropy and supersonic flow. We also show that the strength of artificial sinks in VD region does not affect profiles in plasma region at least in the steady state and that sheath heat transmission factors can be adjusted to theoretical values by VD model. Validity of viscous flux is also investigated.

  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. Communication: The description of strong correlation within self-consistent Green's function second-order perturbation theory

    SciTech Connect

    Phillips, Jordan J. Zgid, Dominika

    2014-06-28

    We report an implementation of self-consistent Green's function many-body theory within a second-order approximation (GF2) for application with molecular systems. This is done by iterative solution of the Dyson equation expressed in matrix form in an atomic orbital basis, where the Green's function and self-energy are built on the imaginary frequency and imaginary time domain, respectively, and fast Fourier transform is used to efficiently transform these quantities as needed. We apply this method to several archetypical examples of strong correlation, such as a H{sub 32} finite lattice that displays a highly multireference electronic ground state even at equilibrium lattice spacing. In all cases, GF2 gives a physically meaningful description of the metal to insulator transition in these systems, without resorting to spin-symmetry breaking. Our results show that self-consistent Green's function many-body theory offers a viable route to describing strong correlations while remaining within a computationally tractable single-particle formalism.

  14. Communication: The description of strong correlation within self-consistent Green's function second-order perturbation theory

    NASA Astrophysics Data System (ADS)

    Phillips, Jordan J.; Zgid, Dominika

    2014-06-01

    We report an implementation of self-consistent Green's function many-body theory within a second-order approximation (GF2) for application with molecular systems. This is done by iterative solution of the Dyson equation expressed in matrix form in an atomic orbital basis, where the Green's function and self-energy are built on the imaginary frequency and imaginary time domain, respectively, and fast Fourier transform is used to efficiently transform these quantities as needed. We apply this method to several archetypical examples of strong correlation, such as a H32 finite lattice that displays a highly multireference electronic ground state even at equilibrium lattice spacing. In all cases, GF2 gives a physically meaningful description of the metal to insulator transition in these systems, without resorting to spin-symmetry breaking. Our results show that self-consistent Green's function many-body theory offers a viable route to describing strong correlations while remaining within a computationally tractable single-particle formalism.

  15. Landau Damping and Anomalous Skin Effect in Low-pressure Gas Discharges: Self-consistent Treatment of Collisionless Heating

    SciTech Connect

    Igor D. Kaganovich; Oleg V. Polomarov; Constantine E. Theodosiou

    2004-01-30

    In low-pressure discharges, where the electron mean free path is larger or comparable with the discharge length, the electron dynamics is essentially nonlocal. Moreover, the electron energy distribution function (EEDF) deviates considerably from a Maxwellian. Therefore, an accurate kinetic description of the low-pressure discharges requires knowledge of the nonlocal conductivity operator and calculation of the non-Maxwellian EEDF. The previous treatments made use of simplifying assumptions: a uniform density profile and a Maxwellian EEDF. In the present study a self-consistent system of equations for the kinetic description of nonlocal, nonuniform, nearly collisionless plasmas of low-pressure discharges is reported. It consists of the nonlocal conductivity operator and the averaged kinetic equation for calculation of the non-Maxwellian EEDF. This system was applied to the calculation of collisionless heating in capacitively and inductively coupled plasmas. In particular, the importance of accounting for the nonuniform plasma density profile for computing the current density profile and the EEDF is demonstrated. The enhancement of collisionless heating due to the bounce resonance between the electron motion in the potential well and the external radio-frequency electric field is investigated. It is shown that a nonlinear and self-consistent treatment is necessary for the correct description of collisionless heating.

  16. 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.

  17. 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

  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. Normal-metal quasiparticle traps for superconducting qubits

    NASA Astrophysics Data System (ADS)

    Riwar, R.-P.; Hosseinkhani, A.; Burkhart, L. D.; Gao, Y. Y.; Schoelkopf, R. J.; Glazman, L. I.; Catelani, G.

    2016-09-01

    The presence of quasiparticles in superconducting qubits emerges as an intrinsic constraint on their coherence. While it is difficult to prevent the generation of quasiparticles, keeping them away from active elements of the qubit provides a viable way of improving the device performance. Here we develop theoretically and validate experimentally a model for the effect of a single small trap on the dynamics of the excess quasiparticles injected in a transmon-type qubit. The model allows one to evaluate the time it takes to evacuate the injected quasiparticles from the transmon as a function of trap parameters. With the increase of the trap size, this time decreases monotonically, saturating at the level determined by the quasiparticles diffusion constant and the qubit geometry. We determine the characteristic trap size needed for the relaxation time to approach that saturation value.

  20. 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)

  1. Coherent Suppression of Quasiparticle Dissipation in Superconducting Artificial Atom

    NASA Astrophysics Data System (ADS)

    Pop, Ioan M.

    2015-03-01

    We demonstrate immunity to quasiparticle dissipation in a Josephson junction. At the foundation of this protection rests a prediction by Brian Josephson from fifty years ago: the particle-hole interference of superconducting quasiparticles when tunneling across a Josephson junction. The junction under study is the central element of a fluxonium artificial atom, which we place in an extremely low loss environment and measure using radio-frequency dispersive techniques. Furthermore, by using a quantum limited amplifier (a Josephson Parametric Converter) we can observe quantum jumps between the 0 and 1 states of the qubit in thermal equilibrium with the environment. The distribution of the times in-between the quantum jumps reveals quantitative information about the population and dynamics of quasiparticles. The data is entirely consistent with the hypothesis that our system is sensitive to single quasiparticle excitations, which opens new perspectives for quasiparticle monitoring in low temperature devices. Work supported by: IARPA, ARO, and ONR.

  2. Hubbard physics in the PAW GW approximation.

    PubMed

    Booth, J M; Drumm, D W; Casey, P S; Smith, J S; Russo, S P

    2016-06-28

    It is demonstrated that the signatures of the Hubbard Model in the strongly interacting regime can be simulated by modifying the screening in the limit of zero wavevector in Projector-Augmented Wave GW calculations for systems without significant nesting. This modification, when applied to the Mott insulator CuO, results in the opening of the Mott gap by the splitting of states at the Fermi level into upper and lower Hubbard bands, and exhibits a giant transfer of spectral weight upon electron doping. The method is also employed to clearly illustrate that the M1 and M2 forms of vanadium dioxide are fundamentally different types of insulator. Standard GW calculations are sufficient to open a gap in M1 VO2, which arise from the Peierls pairing filling the valence band, creating homopolar bonds. The valence band wavefunctions are stabilized with respect to the conduction band, reducing polarizability and pushing the conduction band eigenvalues to higher energy. The M2 structure, however, opens a gap from strong on-site interactions; it is a Mott insulator.

  3. Hubbard physics in the PAW GW approximation

    NASA Astrophysics Data System (ADS)

    Booth, J. M.; Drumm, D. W.; Casey, P. S.; Smith, J. S.; Russo, S. P.

    2016-06-01

    It is demonstrated that the signatures of the Hubbard Model in the strongly interacting regime can be simulated by modifying the screening in the limit of zero wavevector in Projector-Augmented Wave GW calculations for systems without significant nesting. This modification, when applied to the Mott insulator CuO, results in the opening of the Mott gap by the splitting of states at the Fermi level into upper and lower Hubbard bands, and exhibits a giant transfer of spectral weight upon electron doping. The method is also employed to clearly illustrate that the M1 and M2 forms of vanadium dioxide are fundamentally different types of insulator. Standard GW calculations are sufficient to open a gap in M1 VO2, which arise from the Peierls pairing filling the valence band, creating homopolar bonds. The valence band wavefunctions are stabilized with respect to the conduction band, reducing polarizability and pushing the conduction band eigenvalues to higher energy. The M2 structure, however, opens a gap from strong on-site interactions; it is a Mott insulator.

  4. Did GW150914 produce a rotating gravastar?

    NASA Astrophysics Data System (ADS)

    Chirenti, Cecilia; Rezzolla, Luciano

    2016-10-01

    The interferometric LIGO detectors have recently measured the first direct gravitational-wave signal from what has been interpreted as the inspiral, merger and ringdown of a binary system of black holes. The signal-to-noise ratio of the measured signal is large enough to leave little doubt that it does refer to the inspiral of two massive and ultracompact objects, whose merger yields a rotating black hole. Yet, the quality of the data is such that some room is left for alternative interpretations that do not involve black holes, but other objects that, within classical general relativity, can be equally massive and compact, namely, gravastars. We here consider the hypothesis that the merging objects were indeed gravastars and explore whether the merged object could therefore be not a black hole but a rotating gravastar. After comparing the real and imaginary parts of the ringdown signal of GW150914 with the corresponding quantities for a variety of gravastars, and notwithstanding the very limited knowledge of the perturbative response of rotating gravastars, we conclude it is not possible to model the measured ringdown of GW150914 as due to a rotating gravastar.

  5. Hubbard physics in the PAW GW approximation.

    PubMed

    Booth, J M; Drumm, D W; Casey, P S; Smith, J S; Russo, S P

    2016-06-28

    It is demonstrated that the signatures of the Hubbard Model in the strongly interacting regime can be simulated by modifying the screening in the limit of zero wavevector in Projector-Augmented Wave GW calculations for systems without significant nesting. This modification, when applied to the Mott insulator CuO, results in the opening of the Mott gap by the splitting of states at the Fermi level into upper and lower Hubbard bands, and exhibits a giant transfer of spectral weight upon electron doping. The method is also employed to clearly illustrate that the M1 and M2 forms of vanadium dioxide are fundamentally different types of insulator. Standard GW calculations are sufficient to open a gap in M1 VO2, which arise from the Peierls pairing filling the valence band, creating homopolar bonds. The valence band wavefunctions are stabilized with respect to the conduction band, reducing polarizability and pushing the conduction band eigenvalues to higher energy. The M2 structure, however, opens a gap from strong on-site interactions; it is a Mott insulator. PMID:27369500

  6. Quasiparticle interference, quasiparticle interactions, and the origin of the charge density wave in 2H-NbSe2.

    PubMed

    Arguello, C J; Rosenthal, E P; Andrade, E F; Jin, W; Yeh, P C; Zaki, N; Jia, S; Cava, R J; Fernandes, R M; Millis, A J; Valla, T; Osgood, R M; Pasupathy, A N

    2015-01-23

    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. 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 wave vector and energy dependence of the important electronic scattering processes thereby obtaining direct information both about the fermiology and the interactions. In 2H-NbSe2, we use this combination to confirm 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 charge density wave ordering wave vector.

  7. Quasiparticle interference, quasiparticle interactions, and the origin of the charge density wave in 2H–NbSe2

    DOE PAGESBeta

    Arguello, C. J.; Rosenthal, E. P.; Andrade, E. F.; Jin, W.; Yeh, P. C.; Zaki, N.; Jia, S.; Cava, R. J.; Fernandes, R. M.; Millis, A. J.; et al

    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

  8. 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.

  9. Solvent effects in time-dependent self-consistent field methods. II. Variational formulations and analytical gradients.

    PubMed

    Bjorgaard, J A; Velizhanin, K A; Tretiak, S

    2015-08-01

    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 solvent models are examined. Enforcing a variational ground state energy 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 semiempirical model chemistry, the variational expressions are verified by numerical and analytical differentiation with respect to a static external electric field. Analytical gradients are further tested by performing microcanonical excited state molecular dynamics with p-nitroaniline. PMID:26254651

  10. 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.

  11. Self-consistent spectra from GRMHD simulations with radiative cooling: A link to reality for Sgr A

    NASA Astrophysics Data System (ADS)

    Drappeau, S.; Dibi, S.; Dexter, J.; Markoff, S.; Fragile, P. C.

    2011-12-01

    Cosmos++ (Anninos et al., 2005) is one of the first fully relativistic magneto-hydro-dynamical (MHD) codes that can self-consistently account for radiative cooling, in the optically thin regime. As the code combines a total energy conservation formulation with a radiative cooling function, we have now the possibility to produce spectra energy density from these simulations and compare them to data. In this paper, we present preliminary results of spectra calculated using the same cooling functions from 2D Cosmos++ simulations of the accretion flow around Sgr A*. The simulation parameters were designed to roughly reproduce Sgr A*'s behavior at very low ( 10^{-8}-10^{-7} M_{⊙}/yr) accretion rate, but only via spectra can we test that this has been achieved.

  12. Self-consistent spectra from GRMHD simulations with radiative cooling A link to reality for Sgr A*

    NASA Astrophysics Data System (ADS)

    Drappeau, Samia; Dibi, Salomé; Markoff, Sera; Fragile, Chris

    2011-02-01

    Cosmos++ (Anninos et al. 2005) is one of the first fully relativistic magneto-hydro-dynamical (MHD) codes that can self-consistently account for radiative cooling, in the optically thin regime. As the code combines a total energy conservation formulation with a radiative cooling function, we have now the possibility to produce spectra energy density from these simulations and compare them to data. In this paper, we present preliminary results of spectra calculated using the same cooling functions from 2D Cosmos++ simulations of the accretion flow around Sgr A*. The simulation parameters were designed to roughly reproduce Sgr A*'s behavior at very low (10-8-10-7 Msolar/yr) accretion rate, but only via spectra can we test that this has been achieved.

  13. Modeling the Adsorption of Hydrophobic Ethoxylated Urethane (HEUR) Thickeners onto Latex Surfaces using Self-Consistent Field Theory

    NASA Astrophysics Data System (ADS)

    Ginzburg, Valeriy; van Dyk, Antony; Chatterjee, Tirtha; Wang, Shihu; Larson, Ronald

    2015-03-01

    Hydrophobic Ethoxylated Urethane (HEUR) polymers are widely used as rheology modifiers (thickeners) in waterborne latex paints. Recently, it has been shown that the thickening effect of HEURs in paints is largely determined by their adsorption onto latex surfaces, this adsorption being a function of polymer structure, latex surface chemistry, and total available latex surface. Here, we describe the application of Self-Consistent Field Theory (SCFT) to calculate adsorption isotherms of several model HEURs onto ideal hydrophobic latex surfaces. Unlike earlier SCFT studies of adsorption, we explicitly take into account the role of HEUR micelles and competition between adsorption and micellization. The results are compared with experimental data and coarse-grained molecular dynamic (CG-MD) simulations, and good qualitative and semi-quantitative agreement is found. This work was supported by The Dow Chemical Company.

  14. A self-consistent regime of generation of terahertz radiation by an optical pulse with a tilted intensity front

    SciTech Connect

    Bugai, A N; Sazonov, S V; Shashkov, Andrei Yu

    2012-11-30

    We derived a self-consistent system of nonlinear wave equations describing the terahertz generation in dielectric uniaxial crystals by optical pulsed radiation with a tilted wavefront. The numerical analysis of the system of equations showed that the generation of a broadband one-period terahertz signal is accompanied by a red shift of the carrier frequency of the optical pulse, the magnitude of the shift being proportional to the pulse intensity. The generation efficiency with respect to energy reached a maximum at a certain distance of propagation in the crystal, after which the efficiency decreased. A satisfactory agreement was obtained between theoretical calculations and experimental data of other investigations. (generation of terahertz radiation)

  15. Combining physical resist modeling and self-consistent field theory for pattern simulation in directed self-assembly

    NASA Astrophysics Data System (ADS)

    Reilly, Michael; Ginzburg, Valeriy; Smith, Mark D.

    2013-03-01

    In this presentation, we describe multi-scale modeling method combining PROLITH lithography simulation with Self-Consistent Field Theory (SCFT) computation of the block copolymer Directed Self-Assembly (DSA). Within this method, we utilize PROLITH to predict the shape of a lithographic feature as function of process conditions. The results of that calculation are then used as input into SCFT simulation to predict the distribution of the matrix and etchable blocks of the DSA polymers (such as PS-b-PDMS or PS-b- PMMA) inside that feature. This method is applied to simple cases (e.g., rectangular trench and cylindrical contact hole), and the self-assembly of various polymers is investigated as a function of their compositions. The new tool could therefore be applied to rapidly design and screen lithographic process conditions together with polymers used to shrink or rectify the features within the DSA technology.

  16. 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.

  17. Use of emission-line intensities for a self-consistent determination of the particle densities in a transient plasma.

    PubMed

    Gregorian, L; Bernshtam, V A; Kroupp, E; Davara, G; Maron, Y

    2003-01-01

    A method for a self-consistent determination of the time history of the electron density, electron temperature, and ionic charge-state composition in a multicomponent plasma, using time-dependent measurements and calculations of absolute emission-line intensities, is presented. The method is applied for studying the properties of an imploding gas-puff Z-pinch plasma that contains several oxygen ions up to the fifth ionization stage. Furthermore, by using intensity ratios of lines from different ion species, the electron temperature was determined with a much improved accuracy, in comparison to previous spectroscopic studies of the same plasma. The ion-density history obtained, together with the known time-dependent radial boundaries of the plasma shell, allowed for tracking the rise in time of the mass swept by the magnetic field during the implosion. PMID:12636608

  18. 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].

  19. Self-consistent iteration procedure in analyzing reflectivity and spectroscopic ellipsometry data of multilayered materials and their interfaces

    SciTech Connect

    Asmara, T. C.; Rusydi, A.; Santoso, I.

    2014-12-15

    For multilayered materials, reflectivity depends on the complex dielectric function of all the constituent layers, and a detailed analysis is required to separate them. Furthermore, for some cases, new quantum states can occur at the interface which may change the optical properties of the material. In this paper, we discuss various aspects of such analysis, and present a self-consistent iteration procedure, a versatile method to extract and separate the complex dielectric function of each individual layer of a multilayered system. As a case study, we apply this method to LaAlO{sub 3}/SrTiO{sub 3} heterostructure in which we are able to separate the effects of the interface from the LaAlO{sub 3} film and the SrTiO{sub 3} substrate. Our method can be applied to other complex multilayered systems with various numbers of layers.

  20. Analytical gradients of the state-average complete active space self-consistent field method with density fitting

    SciTech Connect

    Delcey, Mickaël G.; Pedersen, Thomas Bondo; Aquilante, Francesco; Lindh, Roland

    2015-07-28

    An efficient implementation of the state-averaged complete active space self-consistent field (SA-CASSCF) gradients employing density fitting (DF) is presented. The DF allows a reduction both in scaling and prefactors of the different steps involved. The performance of the algorithm is demonstrated on a set of molecules ranging up to an iron-Heme b complex which with its 79 atoms and 811 basis functions is to our knowledge the largest SA-CASSCF gradient computed. For smaller systems where the conventional code could still be used as a reference, both the linear response calculation and the gradient formation showed a clear timing reduction and the overall cost of a geometry optimization is typically reduced by more than one order of magnitude while the accuracy loss is negligible.