NASA Astrophysics Data System (ADS)
Trushin, Egor; Betzinger, Markus; Blügel, Stefan; Görling, Andreas
2016-08-01
An approach to calculate fundamental band gaps, ionization energies, and electron affinities of periodic electron systems is explored. Starting from total energies obtained with the help of the adiabatic-connection fluctuation-dissipation (ACFD) theorem, these physical observables are calculated according to their basic definition by differences of the total energies of the N -, (N -1 ) -, and (N +1 ) -electron system. The response functions entering the ACFD theorem are approximated here by the direct random phase approximation (dRPA). For a set of prototypical semiconductors and insulators it is shown that even with this quite drastic approximation the resulting band gaps are very close to experiment and of a similar quality to those from the computationally more involved G W approximation. By going beyond the dRPA in the future the accuracy of the calculated band gaps may be significantly improved further.
Adiabatic Hyperspherical Analysis of Realistic Nuclear Potentials
NASA Astrophysics Data System (ADS)
Daily, K. M.; Kievsky, Alejandro; Greene, Chris H.
2015-12-01
Using the hyperspherical adiabatic method with the realistic nuclear potentials Argonne V14, Argonne V18, and Argonne V18 with the Urbana IX three-body potential, we calculate the adiabatic potentials and the triton bound state energies. We find that a discrete variable representation with the slow variable discretization method along the hyperradial degree of freedom results in energies consistent with the literature. However, using a Laguerre basis results in missing energy, even when extrapolated to an infinite number of basis functions and channels. We do not include the isospin T = 3/2 contribution in our analysis.
Ionization potentials of seaborgium
Johnson, E.; Pershina, V.; Fricke, B.
1999-10-21
Multiconfiguration relativistic Dirac-Fock values were calculated for the first six ionization potentials of seaborgium and of the other group 6 elements. No experimental ionization potentials are available for seaborgium. Accurate experimental values are not available for all of the other ionization potentials. Ionic radii for the 4+ through 6+ ions of seaborgium are also presented. The ionization potentials and ionic radii obtained will be used to predict some physiochemical properties of seaborgium and its compounds.
Theoretical determinations of ionization potentials of dopamine
NASA Astrophysics Data System (ADS)
Lu, J. F.; Yu, Z. Y.
2013-04-01
Adiabatic and vertical ionization potentials (IPs) of nine conformers of dopamine in the gas phase are determined using density functional theory (DFT) B3LYP, B3P86, B3PW91 methods and high level ab initio HF method with 6-311++G** basis set, respectively. And the nine stable cationic states have been found in the ionization process of dopamine. Vertical ionization potentials of nine conformers of dopamine are calculated using the older outer-valence Green's function (OVGF) calculations at 6-311++G** basis set. Vibrational frequencies and infrared spectrum intensities of G1b and G1b+ at B3LYP/6-311++G** level are discussed.
Superequilibrium ionization during adiabatic expansion of a relaxing gas
NASA Astrophysics Data System (ADS)
Achasov, O. V.; Zhdanok, S. A.; Soloukhin, R. I.; Fomin, N. A.
1980-08-01
A superequilibrium method for the generation of a weakly ionized plasma in a molecular gas is proposed; the method involves the production of a superequilibrium electron density in a thermally excited and vibrationally frozen molecular gas during expansion in supersonic flow. Experimental results are presented for the case of nitrogen. This method has applications in molecular and laser physics, including preionization in a fast-flow gas-discharge laser, and the study of energy losses in gasdynamic lasers.
NASA Astrophysics Data System (ADS)
Hofmann, C.; Zimmermann, T.; Zielinski, A.; Landsman, A. S.
2016-04-01
The validity of the adiabatic approximation in strong field ionization under typical experimental conditions has recently become a topic of great interest. Experimental results have been inconclusive, in part, due to the uncertainty in experimental calibration of intensity. Here we turn to the time-dependent Schrödinger equation, where all the laser parameters are known exactly. We find that the centre of the electron momentum distribution (typically used for calibration of elliptically and circularly polarized light) is sensitive to non-adiabatic effects, leading to intensity shifts in experimental data that can significantly affect the interpretation of results. On the other hand, the transverse momentum spread in the plane of polarization is relatively insensitive to such effects, even in the Keldysh parameter regime approaching γ ≈ 3. This suggests the transverse momentum spread in the plane of polarization as a good alternative to the usual calibration method, particularly for experimental investigation of non-adiabatic effects using circularly polarized light.
The lowest ionization potentials of Al2
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Barnes, Leslie A.; Taylor, Peter R.
1988-01-01
Potential curves for the lowest two electronic states (X 2 sigma g + and A 2 pi u) of Al2(+) were computed using complete active space SCF/multireference CI wave functions and large Gaussian basis sets. The lowest observable vertical ionization potential (to Al2(+) X 2 sigma g +) of the Al2 X 3 pi u ground state is calculated to occur around 6.1 eV, in excellent agreement with the experimental range of 6.0 to 6.42 eV obtained in recent cluster ionization studies by Cox and co-workers. The second vertical ionization potential (to Al2(+) A 2 pi u) occurs near 6.4 eV, also within the experimental range. The adiabatic IP of 5.90 eV is in good agreement with the value of 5.8 to 6.1 eV deduced by Hanley and co-workers from the difference in thresholds between collision induced dissociation processes of Al3(+). The computed IP values are somewhat larger than those deduced from branching ratios in cluster fragmentation experiments by Jarrold and co-workers. The observation of an ionization threshold below 6.42 eV is shown to be incompatible with an Al2 ground electronic state assignment of 3 sigma g -, but the separation between the two lowest states of Al2 is so small that it is likely that both are populated in the experiments, so that this does not provide unambiguous support for the recent theoretical assignment of the ground state as 3 pi u.
Ionization Potentials for Isoelectronic Series.
ERIC Educational Resources Information Center
Agmon, Noam
1988-01-01
Presents a quantitative treatment of ionization potentials of isoelectronic atoms. By looking at the single-electron view of calculating the total energy of an atom, trends in the screening and effective quantum number parameters are examined. Approaches the question of determining electron affinities. (CW)
Innocenti, Fabrizio; Eypper, Marie; Lee, Edmond P F; Stranges, Stefano; Mok, Daniel K W; Chau, Foo-tim; King, George C; Dyke, John M
2008-01-01
The first photoelectron band of difluorocarbene CF(2), has been studied by threshold photoelectron (TPE) spectroscopy. CF(2) was prepared by microwave discharge of a flowing mixture of hexafluoropropene, C(3)F(6), and argon. A vibrationally resolved band was observed in which at least twenty-two components were observed. In the first PE band of CF(2), the adiabatic ionization energy differs significantly from the vertical ionization energy because, for the ionization CF(2) (+) (X(2)A(1))+e(-) <-- CF(2) (X(1)A(1)), there is an increase in the FCF bond angle (by approximately 20 degrees ) and a decrease in the C--F bond length (by approximately 0.7 A). The adiabatic component was not observed in the experimental TPE spectrum. However, on comparing this spectrum with an ab initio/Franck-Condon simulation of this band, using results from high-level ab initio calculations, the structure associated with the vibrational components could be assigned. This led to alignment of the experimental TPE spectrum and the computed Franck-Condon envelope, and a determination of the first adiabatic ionization energy of CF(2) as (11.362+/-0.005) eV. From the assignment of the vibrational structure, values were obtained for the harmonic and fundamental frequencies of the symmetric stretching mode (nu(1)') and symmetric bending mode (nu(2)') in CF(2) (+) (X(2)A(1)). PMID:19006171
Recent developments in trapping and manipulation of atoms with adiabatic potentials
NASA Astrophysics Data System (ADS)
Garraway, Barry M.; Perrin, Hélène
2016-09-01
A combination of static and oscillating magnetic fields can be used to ‘dress’ atoms with radio-frequency (RF), or microwave, radiation. The spatial variation of these fields can be used to create an enormous variety of traps for ultra-cold atoms and quantum gases. This article reviews the type and character of these adiabatic traps and the applications which include atom interferometry and the study of low-dimensional quantum systems. We introduce the main concepts of magnetic traps leading to adiabatic dressed traps. The concept of adiabaticity is discussed in the context of the Landau-Zener model. The first bubble trap experiment is reviewed together with the method used for loading it. Experiments based on atom chips show the production of double wells and ring traps. Dressed atom traps can be evaporatively cooled with an additional RF field, and a weak RF field can be used to probe the spectroscopy of the adiabatic potentials. Several approaches to ring traps formed from adiabatic potentials are discussed, including those based on atom chips, time-averaged adiabatic potentials and induction methods. Several proposals for adiabatic lattices with dressed atoms are also reviewed.
Geometric phase of an atom inside an adiabatic radio-frequency potential
Zhang, P.; You, L.
2007-09-15
We investigate the geometric phase of an atom inside an adiabatic radio-frequency (rf) potential created from a static magnetic field (B field) and a time-dependent rf field. The spatial motion of the atomic center of mass is shown to give rise to a geometric phase, or Berry's phase, in the adiabatically evolving atomic hyperfine spin along the local B field. This phase is found to depend on both the static B field along the semiclassical trajectory of the atomic center of mass and an effective magnetic field consisting of the total B field, including the oscillating rf field. Specific calculations are provided for several recent atom interferometry experiments and proposals utilizing adiabatic rf potentials.
Dressed adiabatic and diabatic potentials to study conical intersections for F + H2
NASA Astrophysics Data System (ADS)
Das, Anita; Sahoo, Tapas; Mukhopadhyay, Debasis; Adhikari, Satrajit; Baer, Michael
2012-02-01
We follow a suggestion by Lipoff and Herschbach [Mol. Phys. 108, 1133 (2010), 10.1080/00268971003662912] and compare dressed and bare adiabatic potentials to get insight regarding the low-energy dynamics (e.g., cold reaction) taking place in molecular systems. In this particular case, we are interested to study the effect of conical intersections (ci) on the interacting atoms. For this purpose, we consider vibrational dressed adiabatic and vibrational dressed diabatic potentials in the entrance channel of reactive systems. According to our study, the most one should expect, in case of F + H2, is a mild effect of the (1, 2) ci on its reactive/exchange process-an outcome also supported by experiment. This happens although the corresponding dressed and bare potential barriers (and the corresponding van der Waals potential wells) differ significantly from each other.
Non-classical role of potential energy in adiabatic quantum annealing
NASA Astrophysics Data System (ADS)
Das, Arnab
2009-12-01
Adiabatic quantum annealing is a paradigm of analog quantum computation, where a given computational job is converted to the task of finding the global minimum of some classical potential energy function and the search for the global potential minimum is performed by employing external kinetic quantum fluctuations and subsequent slow reduction (annealing) of them. In this method, the entire potential energy landscape (PEL) may be accessed simultaneously through a delocalized wave-function, in contrast to a classical search, where the searcher has to visit different points in the landscape (i.e., individual classical configurations) sequentially. Thus in such searches, the role of the potential energy might be significantly different in the two cases. Here we discuss this in the context of searching of a single isolated hole (potential minimum) in a golf-course type gradient free PEL. We show, that the quantum particle would be able to locate the hole faster if the hole is deeper, while the classical particle of course would have no scope to exploit the depth of the hole. We also discuss the effect of the underlying quantum phase transition on the adiabatic dynamics.
Calibration-quality adiabatic potential energy surfaces for H3+ and its isotopologues
NASA Astrophysics Data System (ADS)
Pavanello, Michele; Adamowicz, Ludwik; Alijah, Alexander; Zobov, Nikolai F.; Mizus, Irina I.; Polyansky, Oleg L.; Tennyson, Jonathan; Szidarovszky, Tamás; Császár, Attila G.
2012-05-01
Calibration-quality ab initio adiabatic potential energy surfaces (PES) have been determined for all isotopologues of the molecular ion H_3^+. The underlying Born-Oppenheimer electronic structure computations used optimized explicitly correlated shifted Gaussian functions. The surfaces include diagonal Born-Oppenheimer corrections computed from the accurate electronic wave functions. A fit to the 41 655 ab initio points is presented which gives a standard deviation better than 0.1 cm-1 when restricted to the points up to 6000 cm-1 above the first dissociation asymptote. Nuclear motion calculations utilizing this PES, called GLH3P, and an exact kinetic energy operator given in orthogonal internal coordinates are presented. The ro-vibrational transition frequencies for H_3^+, H2D+, and HD_2^+ are compared with high resolution measurements. The most sophisticated and complete procedure employed to compute ro-vibrational energy levels, which makes explicit allowance for the inclusion of non-adiabatic effects, reproduces all the known ro-vibrational levels of the H_3^+ isotopologues considered to better than 0.2 cm-1. This represents a significant (order-of-magnitude) improvement compared to previous studies of transitions in the visible. Careful treatment of linear geometries is important for high frequency transitions and leads to new assignments for some of the previously observed lines. Prospects for further investigations of non-adiabatic effects in the H_3^+ isotopologues are discussed. In short, the paper presents (a) an extremely accurate global potential energy surface of H_3^+ resulting from high accuracy ab initio computations and global fit, (b) very accurate nuclear motion calculations of all available experimental line data up to 16 000 cm-1, and (c) results suggest that we can predict accurately the lines of H_3^+ towards dissociation and thus facilitate their experimental observation.
Diffusion of a massive particle in a periodic potential: Application to adiabatic ratchets
NASA Astrophysics Data System (ADS)
Rozenbaum, Viktor M.; Makhnovskii, Yurii A.; Shapochkina, Irina V.; Sheu, Sheh-Yi; Yang, Dah-Yen; Lin, Sheng Hsien
2015-12-01
We generalize a theory of diffusion of a massive particle by the way in which transport characteristics are described by analytical expressions that formally coincide with those for the overdamped massless case but contain a factor comprising the particle mass which can be calculated in terms of Risken's matrix continued fraction method (MCFM). Using this generalization, we aim to elucidate how large gradients of a periodic potential affect the current in a tilted periodic potential and the average current of adiabatically driven on-off flashing ratchets. For this reason, we perform calculations for a sawtooth potential of the period L with an arbitrary sawtooth length (l
Diffusion of a massive particle in a periodic potential: Application to adiabatic ratchets.
Rozenbaum, Viktor M; Makhnovskii, Yurii A; Shapochkina, Irina V; Sheu, Sheh-Yi; Yang, Dah-Yen; Lin, Sheng Hsien
2015-12-01
We generalize a theory of diffusion of a massive particle by the way in which transport characteristics are described by analytical expressions that formally coincide with those for the overdamped massless case but contain a factor comprising the particle mass which can be calculated in terms of Risken's matrix continued fraction method (MCFM). Using this generalization, we aim to elucidate how large gradients of a periodic potential affect the current in a tilted periodic potential and the average current of adiabatically driven on-off flashing ratchets. For this reason, we perform calculations for a sawtooth potential of the period L with an arbitrary sawtooth length (l
Ottaviani, C.; Corbalan, R.; Mompart, J.; Ahufinger, V.
2010-04-15
We show that the adiabatic dynamics of a Bose-Einstein condensate (BEC) in a double-well potential can be described in terms of a dark variable resulting from the combination of the population imbalance and the spatial atomic coherence between the two wells. By means of this dark variable, we extend, to the nonlinear matter-wave case, the recent proposal by Vitanov and Shore [Phys. Rev. A 73, 053402 (2006)] on adiabatic passage techniques to coherently control the population of two internal levels of an atom or molecule. We investigate the conditions to adiabatically split or transport a BEC as well as to prepare an adiabatic self-trapping state by the optimal delayed temporal variation of the tunneling rate via either the energy bias between the two wells or the BEC nonlinearity. The emergence of nonlinear eigenstates and unstable stationary solutions of the system as well as their role in the breaking down of the adiabatic dynamics is investigated in detail.
Rotational excitation of H2O by para-H2 from an adiabatically reduced dimensional potential
NASA Astrophysics Data System (ADS)
Scribano, Yohann; Faure, Alexandre; Lauvergnat, David
2012-03-01
Cross sections and rate coefficients for low lying rotational transitions in H2O colliding with para-hydrogen pH2 are computed using an adiabatic approximation which reduces the dimensional dynamics from a 5D to a 3D problem. Calculations have been performed at the close-coupling level using the recent potential of Valiron et al. [J. Chem. Phys. 129, 134306 (2008), 10.1063/1.2988314]. A good agreement is found between the reduced adiabatic calculations and the 5D exact calculations, with an impressive time saving and memory gain. This adiabatic reduction of dimensionality seems very promising for scattering studies involving the excitation of a heavy target molecule by a light molecular projectile.
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.
Measurement of the first ionization potential of astatine by laser ionization spectroscopy.
Rothe, S; Andreyev, A N; Antalic, S; Borschevsky, A; Capponi, L; Cocolios, T E; De Witte, H; Eliav, E; Fedorov, D V; Fedosseev, V N; Fink, D A; Fritzsche, S; Ghys, L; Huyse, M; Imai, N; Kaldor, U; Kudryavtsev, Yuri; Köster, U; Lane, J F W; Lassen, J; Liberati, V; Lynch, K M; Marsh, B A; Nishio, K; Pauwels, D; Pershina, V; Popescu, L; Procter, T J; Radulov, D; Raeder, S; Rajabali, M M; Rapisarda, E; Rossel, R E; Sandhu, K; Seliverstov, M D; Sjödin, A M; Van den Bergh, P; Van Duppen, P; Venhart, M; Wakabayashi, Y; Wendt, K D A
2013-01-01
The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine. PMID:23673620
Measurement of the first ionization potential of astatine by laser ionization spectroscopy
Rothe, S.; Andreyev, A. N.; Antalic, S.; Borschevsky, A.; Capponi, L.; Cocolios, T. E.; De Witte, H.; Eliav, E.; Fedorov, D. V.; Fedosseev, V. N.; Fink, D. A.; Fritzsche, S.; Ghys, L.; Huyse, M.; Imai, N.; Kaldor, U.; Kudryavtsev, Yuri; Köster, U.; Lane, J. F. W.; Lassen, J.; Liberati, V.; Lynch, K. M.; Marsh, B. A.; Nishio, K.; Pauwels, D.; Pershina, V.; Popescu, L.; Procter, T. J.; Radulov, D.; Raeder, S.; Rajabali, M. M.; Rapisarda, E.; Rossel, R. E.; Sandhu, K.; Seliverstov, M. D.; Sjödin, A. M.; Van den Bergh, P.; Van Duppen, P.; Venhart, M.; Wakabayashi, Y.; Wendt, K. D. A.
2013-01-01
The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine. PMID:23673620
Measurement of the first ionization potential of astatine by laser ionization spectroscopy.
Rothe, S; Andreyev, A N; Antalic, S; Borschevsky, A; Capponi, L; Cocolios, T E; De Witte, H; Eliav, E; Fedorov, D V; Fedosseev, V N; Fink, D A; Fritzsche, S; Ghys, L; Huyse, M; Imai, N; Kaldor, U; Kudryavtsev, Yuri; Köster, U; Lane, J F W; Lassen, J; Liberati, V; Lynch, K M; Marsh, B A; Nishio, K; Pauwels, D; Pershina, V; Popescu, L; Procter, T J; Radulov, D; Raeder, S; Rajabali, M M; Rapisarda, E; Rossel, R E; Sandhu, K; Seliverstov, M D; Sjödin, A M; Van den Bergh, P; Van Duppen, P; Venhart, M; Wakabayashi, Y; Wendt, K D A
2013-01-01
The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine.
Measurement of the first ionization potential of astatine by laser ionization spectroscopy
NASA Astrophysics Data System (ADS)
Rothe, S.; Andreyev, A. N.; Antalic, S.; Borschevsky, A.; Capponi, L.; Cocolios, T. E.; de Witte, H.; Eliav, E.; Fedorov, D. V.; Fedosseev, V. N.; Fink, D. A.; Fritzsche, S.; Ghys, L.; Huyse, M.; Imai, N.; Kaldor, U.; Kudryavtsev, Yuri; Köster, U.; Lane, J. F. W.; Lassen, J.; Liberati, V.; Lynch, K. M.; Marsh, B. A.; Nishio, K.; Pauwels, D.; Pershina, V.; Popescu, L.; Procter, T. J.; Radulov, D.; Raeder, S.; Rajabali, M. M.; Rapisarda, E.; Rossel, R. E.; Sandhu, K.; Seliverstov, M. D.; Sjödin, A. M.; van den Bergh, P.; van Duppen, P.; Venhart, M.; Wakabayashi, Y.; Wendt, K. D. A.
2013-05-01
The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine.
Determination of the first ionization potential of actinium
NASA Astrophysics Data System (ADS)
Roßnagel, J.; Raeder, S.; Hakimi, A.; Ferrer, R.; Trautmann, N.; Wendt, K.
2012-01-01
Using resonance ionization spectroscopy the first-ionization potential of actinium has been determined by analyzing different Rydberg series in two-color resonant laser excitation. Three individual Rydberg series were investigated, converging toward the ionic ground state and toward the first- and second-excited state of the actinium ion, respectively. A combined analysis of the convergence limits leads to a consistent value for the first-ionization potential of Ac of 43394.45(19)cm-1, equivalent to 5.380226(24) eV.
Ionizing potential waves and high-voltage breakdown streamers.
NASA Technical Reports Server (NTRS)
Albright, N. W.; Tidman, D. A.
1972-01-01
The structure of ionizing potential waves driven by a strong electric field in a dense gas is discussed. Negative breakdown waves are found to propagate with a velocity proportional to the electric field normal to the wavefront. This causes a curved ionizing potential wavefront to focus down into a filamentary structure, and may provide the reason why breakdown in dense gases propagates in the form of a narrow leader streamer instead of a broad wavefront.
Determination of the first ionization potential of technetium
Mattolat, C.; Gottwald, T.; Raeder, S.; Rothe, S.; Schwellnus, F.; Wendt, K.; Thoerle-Pospiech, P.; Trautmann, N.
2010-05-15
The first ionization potential (IP) of technetium (Tc) has been determined by evaluating Rydberg convergences toward the first ionization potential as well as toward two low-lying excited states of the singly charged Tc ion. The Rydberg states were excited and detected by applying multiphoton resonance ionization mass spectrometry (RIMS) on the long-lived isotope {sup 99g}Tc using a three-color excitation scheme. The observed Rydberg convergences yield a result for the first ionization potential of Tc V{sub IP}(Tc)=7.119380(32) eV. This precise value for V{sub IP}(Tc) is somewhat lower than the so far published data of 7.23 eV or 7.28 eV, dating back to the 1950s.
Kato, Tsuyoshi; Ide, Yoshihiro; Yamanouchi, Kaoru
2015-12-31
We first calculate the ground-state molecular wave function of 1D model H{sub 2} molecule by solving the coupled equations of motion formulated in the extended multi-configuration time-dependent Hartree-Fock (MCTDHF) method by the imaginary time propagation. From the comparisons with the results obtained by the Born-Huang (BH) expansion method as well as with the exact wave function, we observe that the memory size required in the extended MCTDHF method is about two orders of magnitude smaller than in the BH expansion method to achieve the same accuracy for the total energy. Second, in order to provide a theoretical means to understand dynamical behavior of the wave function, we propose to define effective adiabatic potential functions and compare them with the conventional adiabatic electronic potentials, although the notion of the adiabatic potentials is not used in the extended MCTDHF approach. From the comparison, we conclude that by calculating the effective potentials we may be able to predict the energy differences among electronic states even for a time-dependent system, e.g., time-dependent excitation energies, which would be difficult to be estimated within the BH expansion approach.
NASA Astrophysics Data System (ADS)
Fishman, S.; Soffer, A.
2016-07-01
We employ the recently developed multi-time scale averaging method to study the large time behavior of slowly changing (in time) Hamiltonians. We treat some known cases in a new way, such as the Zener problem, and we give another proof of the adiabatic theorem in the gapless case. We prove a new uniform ergodic theorem for slowly changing unitary operators. This theorem is then used to derive the adiabatic theorem, do the scattering theory for such Hamiltonians, and prove some classical propagation estimates and asymptotic completeness.
NASA Astrophysics Data System (ADS)
Yarkony, David
2015-03-01
The construction of fit single state potential energy surfaces (PESs), analytic representations of ab initio electronic energies and energy gradients, is now well established. These single state PESs, which are essential for accurate quantum dynamics and have found wide application in more approximate quasi-classical treatments, have revolutionized adiabatic dynamics. The situation for nonadiabatic processes involving dissociative and large amplitude motion is less sanguine. In these cases, compared to single electronic state dynamics, both the electronic structure data and the representation are more challenging to determine. We describe the recent development and applications of algorithms that enable description of multiple adiabatic electronic potential energy surfaces coupled by conical intersections in their full dimensionality using coupled quasi-diabatic states. These representations are demonstrably quasi-diabatic, provide accurate representations of conical intersection seams and can smooth out the discontinuities in electronic structure energies due to changing active orbital spaces that routinely afflict global multistate representations.
NASA Astrophysics Data System (ADS)
Dharmasena, Kushlani Chandima
1997-07-01
We observed Resonance Enhanced Multiphoton Ionization (REMPI) spectra of nf2ΠΩ Rydberg states of CO2 for n=4 to 8. In addition, we also did a laser power dependence study of these states for n=5 to 7. We compared our results to two other studies by Johnson and coworkers and Dobber and coworkers. In the present study we observed that dissociation rate increased with increasing frequency. Also, we observed a clear difference in rates of dissociation for the two spin-orbit components of each nf state. This difference was not consistent, in some states the /Omega=1/2 component dissociated more while in the others /Omega=3/2 dissociated more. When comparing with Dobber and coworkers' REMPI-Photoelectron Spectra (REMPI-PES), a good correlation between the observed symmetric vibrational progressions and our dissociation rates was noticed. We also found that these rates stayed remarkably constant for different powers of the laser even though the production of CO+ ions required more photons than CO2+ ions. From this observation we came to the conclusion that the two-photon transition was saturated. What was surprising was, the amount of CO2+ ions observed despite the fact that the two-photon transition X 2Πg/to/to[ C]2Σg+ was saturated. The observed ratio of CO+/CO2+ ratio never was lower than 6. These observations led us to believe that CO+ ions were predominantly made by predissociation rather than direct dissociation. We propose that the two- photon transition is X 2Πg/to/to[ C]2Σg+ followed by predissociation of the C2ΣG+ state. In our model, predissociation must occur through a potential barrier in the C2Σg+ state which is on the order of an electron volt above the dissociation limit. We estimated the mean lifetime of this state to be about 600 psec by using the ratio of CO+/CO2+ from our spectra. This model explains two other phenomena observed in REMPI spectra. First is the observation of increased dissociation with increasing principal quantum number in the
NASA Astrophysics Data System (ADS)
Nakata, Shunji; Katagiri, Yoshitada; Matsuno, Shun-ichi
2007-02-01
This paper considers the energy consumed by charging and discharging a width-variable capacitor. The capacitor with plate distance d is coupled with repulsive mechanical potential energy, which is proportional to 1/dn. In this capacitor model, there is a stable point between attractive electrical force and repulsive mechanical force. All energies, including the electrostatic energy, potential energy, and energy dissipation, are proportional not to the ordinary value V2 but to V2/(n-1)+2, where V is the abrupt power supply voltage. We apply N-stepwise adiabatic charging to the width-variable capacitor system. It is shown that the energy consumption after charging and discharging (or recycling) can be 1/N times smaller than that of the conventional abrupt operation. By increasing the step number N, the adiabatic operation can ideally charge and discharge the width-variable capacitor system with absolutely no energy dissipation, although the voltage dependence of energies is quite different from the usual one. Adiabatic charging is very promising for realizing dissipationless operation in the proposed system.
NASA Astrophysics Data System (ADS)
Köhler, S.; Albus, F.; Dibenberger, R.; Erdmann, N.; Funk, H.; Hasse, H.-U.; Herrmann, G.; Huber, G.; Kluge, H.-J.; Nunnemann, M.; Passler, G.; Rao, P. M.; Riegel, J.; Trautmann, N.; Urban, F.-J.
1995-04-01
Resonance ionization mass spectroscopy (RIMS) is used for the precise determination of the first ionization potential of transuranium elements. The first ionization potentials (IP) of americium and curium have been measured for the first time to IPAm=5.9738(2) and IPCm=5.9913(8) eV, respectively, using only 1012 atoms of 243Am and 248Cm. The same technique was applied to thorium, neptunium, and plutonium yielding IPTH=6.3067(2), IPNP=6.2655(2), and IPPu=6.0257(8) eV. The good agreement of our results with the literature data proves the precision of the method which was additionally confirmed by the analysis of Rydberg seris of americium measured by RIMS.
NASA Astrophysics Data System (ADS)
George, D. X. F.; Kumar, Sanjay
2010-08-01
Ab initio global adiabatic as well as quasidiabatic potential energy surfaces for the ground and the first excited electronic states of the H + + CO system have been computed as a function of the Jacobi coordinates ( R, r, γ) using Dunning's cc-pVTZ basis set at the internally contracted multi-reference (single and double) configuration interaction level of accuracy. In addition, nonadiabatic coupling matrix elements arising from radial motion, mixing angle and coupling potential have been computed using the ab initio procedure [Simah et al. (1999) [66
The Adiabatic Ionization Energy and Triplet T1 Energy of Jet-Cooled Keto-Amino Cytosine.
Lobsiger, Simon; Leutwyler, Samuel
2012-12-01
Gas-phase cytosine exists in five different tautomer/rotamer forms 1, 2a, 2b, 3a, and 3b. We determine the threshold ionization energy (IE) of the keto-amino tautomer 1 as 8.73 ± 0.02 eV, using resonant two-photon ionization mass spectrometry in a supersonic molecular beam via the (1)ππ* excited state. This is the first IE threshold measurement for the biologically relevant tautomer 1. The IE of the thermal gas-phase mixture of cytosine has been measured as 8.60 ± 0.05 eV by Kostko et al. using single-photon VUV photoionization [Phys. Chem. Chem. Phys., 2010, 12, 2860]. Given the tautomer distribution and ionization energies calculated in that work, our determination of the keto-amino tautomer IE implies that the IE measured by Kostko et al. is dominated by the enol-amino tautomers 2a and 2b. Upon excitation of keto-amino cytosine to its (1)ππ* state, relaxation occurs to a lower-lying long-lived state. The IE threshold measured via this state places its energy about 0.69 eV below the (1)ππ* state, in good agreement with the triplet T1 energy of keto-amino cytosine calculated by several high-level ab initio methods. The identification of keto-amino cytosine T1 is the basis for characterizing the intersystem crossing rates into and the photochemical reactions of this long-lived state.
NASA Astrophysics Data System (ADS)
Haruyama, Jun; Suzuki, Takahiro; Hu, Chunping; Watanabe, Kazuyuki
2012-01-01
We present a simple and computationally efficient method to calculate excited-state nuclear forces on adiabatic potential-energy surfaces (APES) from linear-response time-dependent density-functional theory within a real-space framework. The Casida ansatz, which has been validated for computing first-order nonadiabatic couplings in previous studies, was applied to the calculation of the excited-state forces. Our method is validated by the consistency of results in the lower excited states, which reproduce well those obtained by the numerical derivative of each APES. We emphasize the usefulness of this technique by demonstrating the excited-state molecular-dynamics simulation.
NASA Astrophysics Data System (ADS)
Xavier, F. George D.; Kumar, Sanjay
2010-10-01
Ab initio global adiabatic and quasidiabatic potential energy surfaces of lowest four electronic (1-4 A3″) states of the H++O2 system have been computed in the Jacobi coordinates (R,r,γ) using Dunning's cc-pVTZ basis set at the internally contracted multireference (single and double) configuration interaction level of accuracy, which are relevant to the dynamics studies of inelastic vibrational and charge transfer processes observed in the scattering experiments. The computed equilibrium geometry parameters of the bound [HO2]+ ion in the ground electronic state and other parameters for the transition state for the isomerization process, HOO+⇌OOH+ are in good quantitative agreement with those available from the high level ab initio calculations, thus lending credence to the accuracy of the potential energy surfaces. The nonadiabatic couplings between the electronic states have been analyzed in both the adiabatic and quasidiabatic frameworks by computing the nonadiabatic coupling matrix elements and the coupling potentials, respectively. It is inferred that the dynamics of energy transfer processes in the scattering experiments carried out in the range of 9.5-23 eV would involve all the four electronic states.
New estimates of ionization potentials of four DIB molecular carriers.
Sonnentrucker, P; Foing, B H; Ehrenfreund, P
1999-01-01
We present a study of the behaviour and ionization properties of four Diffuse Interstellar Bands (DIBs) at lambda lambda 5780, 5797, 6379 and 6613 angstroms. In the lambda lambda 5797, 6379 and 6613 angstrom DIBs, substructures have recently been detected, indicating large gaseous molecular carriers. Studying DIBs in regions with different physical properties in terms of UV flux and density enables us to monitor the behaviour of the carriers and hence to constrain their nature. As a follow-up of Sonnentrucker et al. (1997), we add new lines of sight and generalize the results for lines of sight with 2 or 3 clouds. This refines the Ionization Potential estimates which are between 10 and 13 eV, hence reminiscent of PAH or fullerene cations for those DIBs.
NASA Astrophysics Data System (ADS)
Petrović, V. M.; Miladinović, T. B.
2016-05-01
Within the framework of the Ammosov-Delone-Krainov theory, we consider the angular and energy distribution of outgoing electrons due to ionization by a circularly polarized electromagnetic field. A correction of the ground ionization potential by the ponderomotive and Stark shift is incorporated in both distributions. Spatial dependence is analyzed.
Ionization potential depression for non equilibrated aluminum plasmas
NASA Astrophysics Data System (ADS)
Calisti, A.; Ferri, S.; Talin, B.
2015-11-01
A classical molecular dynamics simulation model, designed to simulate neutral plasmas with various charge states of a given atom together with electrons, is used to investigate the ionization potential depression (IPD) in dense plasmas. The IPD is discussed for aluminum plasma at and out of equilibrium. The simulation results are compared with those of earlier theoretical models and with experimental data obtained in the framework of x-ray free-electron laser experiments. The model proposed in this work appears as an important tool to provide data for further discussion on IPD models.
Ionization potential for excited S states of the lithium atom
Puchalski, M.; KePdziera, D.; Pachucki, K.
2010-12-15
Nonrelativistic, relativistic, quantum electrodynamic, and finite nuclear mass corrections to the energy levels are obtained for the nS{sub 1/2},n=3,...,9 states of the lithium atom. Computational approach is based on the explicitly correlated Hylleraas functions with the analytic integration and recursion relations. Theoretical predictions for the ionization potential of nS{sub 1/2} states and transition energies nS{sub 1/2{yields}}2S{sub 1/2} are compared to known experimental values for {sup 6,7}Li isotopes.
Nonsequential double ionization of molecules
Prauzner-Bechcicki, Jakub S.; Sacha, Krzysztof; Zakrzewski, Jakub; Eckhardt, Bruno
2005-03-01
Double ionization of diatomic molecules by short linearly polarized laser pulses is analyzed. We consider the final stage of the ionization process, that is the decay of a highly excited two electron molecule, which is formed after rescattering. The saddles of the effective adiabatic potential energy close to which simultaneous escape of electrons takes place are identified. Numerical simulations of the ionization of molecules show that the process can be dominated by either sequential or nonsequential events. In order to increase the ratio of nonsequential to sequential ionizations very short laser pulses should be applied.
Ionization potential optimized double-hybrid density functional approximations
NASA Astrophysics Data System (ADS)
Margraf, Johannes T.; Verma, Prakash; Bartlett, Rodney J.
2016-09-01
Double-hybrid density functional approximations (DH-DFAs) provide an accurate description of the electronic structure of molecules by semiempirically mixing density functional and wavefunction theory. In this paper, we investigate the properties of the potential used in such approximations. By using the optimized effective potential approach, the consistent Kohn-Sham (KS) potential for a double-hybrid functional (including the second-order perturbational contribution) can be generated. This potential is shown to provide an improved description of orbital energies as vertical ionization potentials (IPs), relative to the perturbation-free KS potential typically used. Based on this observation, we suggest that DH-DFAs should be constructed in such a way that the potential provides accurate orbital energies. As a proof of principle, the B2-PLYP functional is reparameterized to obtain the IP-optimized B2IP-PLYP functional, using a small set of vertical IPs and atomization energies as reference data. This functional is shown to outperform B2-PLYP in a wide range of benchmarks and is en par with the related B2GP-PLYP. In particular, it is shown to be the most reliable choice in electronically difficult and multireference cases.
Ionization potential optimized double-hybrid density functional approximations.
Margraf, Johannes T; Verma, Prakash; Bartlett, Rodney J
2016-09-14
Double-hybrid density functional approximations (DH-DFAs) provide an accurate description of the electronic structure of molecules by semiempirically mixing density functional and wavefunction theory. In this paper, we investigate the properties of the potential used in such approximations. By using the optimized effective potential approach, the consistent Kohn-Sham (KS) potential for a double-hybrid functional (including the second-order perturbational contribution) can be generated. This potential is shown to provide an improved description of orbital energies as vertical ionization potentials (IPs), relative to the perturbation-free KS potential typically used. Based on this observation, we suggest that DH-DFAs should be constructed in such a way that the potential provides accurate orbital energies. As a proof of principle, the B2-PLYP functional is reparameterized to obtain the IP-optimized B2IP-PLYP functional, using a small set of vertical IPs and atomization energies as reference data. This functional is shown to outperform B2-PLYP in a wide range of benchmarks and is en par with the related B2GP-PLYP. In particular, it is shown to be the most reliable choice in electronically difficult and multireference cases. PMID:27634250
The Nanoflare Origins of the First Ionization Potential Effect
NASA Astrophysics Data System (ADS)
Laming, J. M.; Dahlburg, R. B.; Taylor, B. D.
2015-12-01
The First Ionization Potential (FIP) Effect is the by now well known abundance anomaly in the solar coronaand slow speed solar wind. Elements which are predominantly ionized in the chromosphere, i.e. those with FIP less than about 10 eV, are enhanced in abundance in the corona by a factor of about 3-4, while elements that are predominantly neutral are essentially unchanged (although He and Ne can be further depleted). A compelling explanation for this phenomenon invokes the ponderomotive force associated with Alfven or fast mode waves propagating through or reflecting from the chromosphere. The usual solar FIP effect, and most of its variations, are best modeled by waves resonant with the coronal loop on which they propagate, and therefore most plausibly have a coronal origin.We report on 3D compressible MHD simulations of coronal loop heating with the HYPERION code. A ponderomotive force of the correct sign and magnitude is produced naturally as a by-product of coronal heating processes that also produce a 1-3 MK corona loop, reinforcing our conjecture above. We argue that coronal element abundance anomalies, and the waves that produce them, offer a novel but hitherto largely untried approach to the problem of coronal heating.
Calculation of the Ionization Potentials and Electron Affinities for Atoms
NASA Astrophysics Data System (ADS)
Chen, Jiqiang; Krieger, J. B.; Iafrate, G. J.; Savin, A.
1998-03-01
The method employing the self-interaction-corrected correlation energy functional obtained from the homogeneous electron gas with a gap is extended to atoms and ions with non-zero spin polarization. As in the case for atoms and ions with ζ=3D0, the error in the calculated Ec is significantly smaller than in the LSD approximation with zero gap for atoms and ions with Z<=18. Comparison of the resulting ionization potentials and electron affinities with experimental values will also be presented. Finally, we will discuss the possibility of obtaining saturation for Ec for the He, Li, N, O, F and Ne isoelectronic series, but a divergent Ec for the Be, B and C isoelectronic series, in the large Z limit.
Assemblage of Superalkali Complexes with Ever Low-Ionization Potentials.
Paduani, C; Rappe, Andrew M
2016-08-18
A simple recipe is proposed for the obtention of new molecules with even lower vertical ionization potential (VIP): to decorate an atom of an electronegative element with superalkali species in number that exceeds its formal valence by one. For instance, density functional theory calculations show that by using the superalkali Li3O cluster (VIP = 3.83 eV) as building blocks decorating the O atom one obtains VIP = 3.33 eV for the Li9O4 cluster, which is lower than the calculated VIP for Cs (3.89 eV) and Li (5.39 eV). This feature is systematic, as confirmed by calculated results on Li-F and Li-S clusters as well. The calculated binding energy per atom of the large-sized species exceeds by far that of LiF (134.7 kcal/mol). PMID:27463269
A plea for a reexamination of ionization potential depression measurements
NASA Astrophysics Data System (ADS)
Iglesias, Carlos A.
2014-09-01
Experiments at the Linac Coherent Light Source determined the ionization potential depression (IPD) in dense plasmas by measuring the Kα fluorescence associated with K-shell holes created by the X-ray free-electron laser. The analysis of the experimental spectrum found a significantly larger IPD than predicted by the widely used Stewart-Pyatt model. It is shown, however, that a more accurate treatment of atomic levels than used in the analysis has additional channels reducing the threshold laser energy for creating Kα photons without invoking an increase in the IPD. Thus, it is argued that a simulation of the Kα fluorescence using improved atomic data could impact the interpretation of the experimental results.
Imaging cellular membrane potential through ionization of quantum dots
NASA Astrophysics Data System (ADS)
Rowland, Clare E.; Susumu, Kimihiro; Stewart, Michael H.; Oh, Eunkeu; Mäkinen, Antti J.; O'Shaughnessy, Thomas J.; Kushto, Gary; Wolak, Mason A.; Erickson, Jeffrey S.; Efros, Alexander L.; Huston, Alan L.; Delehanty, James B.
2016-03-01
Recent interest in quantum dots (QDs) stems from the plethora of potential applications that arises from their tunable absorption and emission profiles, high absorption cross sections, resistance to photobleaching, functionalizable surfaces, and physical robustness. The emergent use of QDs in biological imaging exploits these and other intrinsic properties. For example, quantum confined Stark effect (QCSE), which describes changes in the photoluminescence (PL) of QDs driven by the application of an electric field, provides an inherent means of detecting changes in electric fields by monitoring QD emission and thus points to a ready mean of imaging membrane potential (and action potentials) in electrically active cells. Here we examine the changing PL of various QDs subjected to electric fields comparable to those found across a cellular membrane. By pairing static and timeresolved PL measurements, we attempt to understand the mechanism driving electric-field-induced PL quenching and ultimately conclude that ionization plays a substantial role in initiating PL changes in systems where QCSE has traditionally been credited. Expanding on these findings, we explore the rapidity of response of the QD PL to applied electric fields and demonstrate changes amply able to capture the millisecond timescale of cellular action potentials.
Kneller, James P.; McLaughlin, Gail C.
2009-09-01
We discuss the three neutrino flavor evolution problem with general, flavor-diagonal, matter potentials and a fully parametrized mixing matrix that includes CP violation, and derive expressions for the eigenvalues, mixing angles, and phases. We demonstrate that, in the limit that the mu and tau potentials are equal, the eigenvalues and matter mixing angles {theta}-tilde{sub 12} and {theta}-tilde{sub 13} are independent of the CP phase, although {theta}-tilde{sub 23} does have CP dependence. Since we are interested in developing a framework that can be used for S matrix calculations of neutrino flavor transformation, it is useful to work in a basis that contains only off-diagonal entries in the Hamiltonian. We derive the 'nonadiabaticity' parameters that appear in the Hamiltonian in this basis. We then introduce the neutrino S matrix, derive its evolution equation and the integral solution. We find that this new Hamiltonian, and therefore the S matrix, in the limit that the {mu} and {tau} neutrino potentials are the same, is independent of both {theta}-tilde{sub 23} and the CP violating phase. In this limit, any CP violation in the flavor basis can only be introduced via the rotation matrices, and so effects which derive from the CP phase are then straightforward to determine. We then show explicitly that the electron neutrino and electron antineutrino survival probability is independent of the CP phase in this limit. Conversely, if the CP phase is nonzero and mu and tau matter potentials are not equal, then the electron neutrino survival probability cannot be independent of the CP phase.
Monte Carlo simulations of ionization potential depression in dense plasmas
NASA Astrophysics Data System (ADS)
Stransky, M.
2016-01-01
A particle-particle grand canonical Monte Carlo model with Coulomb pair potential interaction was used to simulate modification of ionization potentials by electrostatic microfields. The Barnes-Hut tree algorithm [J. Barnes and P. Hut, Nature 324, 446 (1986)] was used to speed up calculations of electric potential. Atomic levels were approximated to be independent of the microfields as was assumed in the original paper by Ecker and Kröll [Phys. Fluids 6, 62 (1963)]; however, the available levels were limited by the corresponding mean inter-particle distance. The code was tested on hydrogen and dense aluminum plasmas. The amount of depression was up to 50% higher in the Debye-Hückel regime for hydrogen plasmas, in the high density limit, reasonable agreement was found with the Ecker-Kröll model for hydrogen plasmas and with the Stewart-Pyatt model [J. Stewart and K. Pyatt, Jr., Astrophys. J. 144, 1203 (1966)] for aluminum plasmas. Our 3D code is an improvement over the spherically symmetric simplifications of the Ecker-Kröll and Stewart-Pyatt models and is also not limited to high atomic numbers as is the underlying Thomas-Fermi model used in the Stewart-Pyatt model.
NASA Technical Reports Server (NTRS)
Vidal, C. R.; Stwalley, W. C.
1982-01-01
The molecular constants and their adiabatic corrections have been determined for the (A 1 Sigma +) - (X 1 Sigma +) system of the isotopic lithium hydrides: (Li-6)H, (Li-7)H, (Li-6)D, and (Li-7)D. Using a fully quantum mechanical variational method, the potential energy curves (IPA potentials) are determined. Extending the variational method, we have obtained for the first time adiabatic corrections of potential energy curves from isotopic spectroscopic data. A significant difference between the potential energy curves of the lithium hydrides and the lithium deuterides has been observed. When Li-6 was replaced by Li-7, a significant difference was only observed for the (A 1 Sigma +) state, but not for the (X 1 Sigma +) state.
Topology of the Adiabatic Potential Energy Surfaces for theResonance States of the Water Anion
Haxton, Daniel J.; Rescigno, Thomas N.; McCurdy, C. William
2005-04-15
The potential energy surfaces corresponding to the long-lived fixed-nuclei electron scattering resonances of H{sub 2}O relevant to the dissociative electron attachment process are examined using a combination of ab initio scattering and bound-state calculations. These surfaces have a rich topology, characterized by three main features: a conical intersection between the {sup 2}A{sub 1} and {sup 2}B{sub 2} Feshbach resonance states; charge-transfer behavior in the OH ({sup 2}{Pi}) + H{sup -} asymptote of the {sup 2}B{sub 1} and {sup 2}A{sub 1} resonances; and an inherent double-valuedness of the surface for the {sup 2}B{sub 2} state the C{sub 2v} geometry, arising from a branch-point degeneracy with a {sup 2}B{sub 2} shape resonance. In total, eight individual seams of degeneracy among these resonances are located.
Accurate ionization potential of semiconductors from efficient density functional calculations
NASA Astrophysics Data System (ADS)
Ye, Lin-Hui
2016-07-01
Despite its huge successes in total-energy-related applications, the Kohn-Sham scheme of density functional theory cannot get reliable single-particle excitation energies for solids. In particular, it has not been able to calculate the ionization potential (IP), one of the most important material parameters, for semiconductors. We illustrate that an approximate exact-exchange optimized effective potential (EXX-OEP), the Becke-Johnson exchange, can be used to largely solve this long-standing problem. For a group of 17 semiconductors, we have obtained the IPs to an accuracy similar to that of the much more sophisticated G W approximation (GWA), with the computational cost of only local-density approximation/generalized gradient approximation. The EXX-OEP, therefore, is likely as useful for solids as for finite systems. For solid surfaces, the asymptotic behavior of the vx c has effects similar to those of finite systems which, when neglected, typically cause the semiconductor IPs to be underestimated. This may partially explain why standard GWA systematically underestimates the IPs and why using the same GWA procedures has not been able to get an accurate IP and band gap at the same time.
Cencek, Wojciech; Przybytek, Michał; Komasa, Jacek; Mehl, James B; Jeziorski, Bogumił; Szalewicz, Krzysztof
2012-06-14
The adiabatic, relativistic, and quantum electrodynamics (QED) contributions to the pair potential of helium were computed, fitted separately, and applied, together with the nonrelativistic Born-Oppenheimer (BO) potential, in calculations of thermophysical properties of helium and of the properties of the helium dimer. An analysis of the convergence patterns of the calculations with increasing basis set sizes allowed us to estimate the uncertainties of the total interaction energy to be below 50 ppm for interatomic separations R smaller than 4 bohrs and for the distance R = 5.6 bohrs. For other separations, the relative uncertainties are up to an order of magnitude larger (and obviously still larger near R = 4.8 bohrs where the potential crosses zero) and are dominated by the uncertainties of the nonrelativistic BO component. These estimates also include the contributions from the neglected relativistic and QED terms proportional to the fourth and higher powers of the fine-structure constant α. To obtain such high accuracy, it was necessary to employ explicitly correlated Gaussian expansions containing up to 2400 terms for smaller R (all R in the case of a QED component) and optimized orbital bases up to the cardinal number X = 7 for larger R. Near-exact asymptotic constants were used to describe the large-R behavior of all components. The fitted potential, exhibiting the minimum of -10.996 ± 0.004 K at R = 5.608 0 ± 0.000 1 bohr, was used to determine properties of the very weakly bound (4)He(2) dimer and thermophysical properties of gaseous helium. It is shown that the Casimir-Polder retardation effect, increasing the dimer size by about 2 Å relative to the nonrelativistic BO value, is almost completely accounted for by the inclusion of the Breit-interaction and the Araki-Sucher contributions to the potential, of the order α(2) and α(3), respectively. The remaining retardation effect, of the order of α(4) and higher, is practically negligible for the bound
Seto, Kunimasa; Nakayama, Tatsushi; Uno, Bunji
2013-09-19
Formal redox potentials E°' involving neutral species R and radical anions R(•-) in ionic liquids (ILs) composed of ammonium, pyridinium, and imidazolium cations are discussed from the point of view of the adiabatic electron affinity as a molecular property. The dependence of the 1,4-benzoquinone (BQ)/BQ(•-) redox process in CH2Cl2 and CH3CN is primarily investigated over a wide concentration range of ILs as the supporting electrolyte. A logarithmic relationship involving a positive shift of E°' with increasing concentration is obtained when the concentration is changed from 0.01 to 1.0 M. The relationship of E°' at IL concentrations greater than 1.0 M gradually reaches a plateau and remains there even for the neat ILs. It is found that the E°' values in the neat ILs are not influenced by the measurement conditions, and that they remain considerably dependent on the nature and concentration of the electrolyte when measured using the traditional method involving molecular solvents combined with a supporting electrolyte (0.1-0.5 M). The difference in the E°' values observed in the ammonium and pyridinium ILs is only several millivolts. In addition, ESR and self-consistent isodensity polarized continuum model calculation results reveal that the potential shift toward positive values upon the transition from molecular solvents containing ILs to neat ILs is adequately accounted for by changes in the electrostatic interaction of R(•-) taken into the cavity composed of the solvent and IL. On the other hand, the first reduction waves of quinones, electron-accepting molecules, and polynuclear aromatic hydrocarbons are reversibly or quasi-reversibly observed in the ILs. The electrochemical stability of the ILs is exploited in the facile measurement of these quasi-reversible waves at quite negative potentials, such as for the naphthalene (NP)/NP(•-) couple. Notably, the E°' values obtained in the ammonium ILs correlate well with the calculated standard redox
Seto, Kunimasa; Nakayama, Tatsushi; Uno, Bunji
2013-09-19
Formal redox potentials E°' involving neutral species R and radical anions R(•-) in ionic liquids (ILs) composed of ammonium, pyridinium, and imidazolium cations are discussed from the point of view of the adiabatic electron affinity as a molecular property. The dependence of the 1,4-benzoquinone (BQ)/BQ(•-) redox process in CH2Cl2 and CH3CN is primarily investigated over a wide concentration range of ILs as the supporting electrolyte. A logarithmic relationship involving a positive shift of E°' with increasing concentration is obtained when the concentration is changed from 0.01 to 1.0 M. The relationship of E°' at IL concentrations greater than 1.0 M gradually reaches a plateau and remains there even for the neat ILs. It is found that the E°' values in the neat ILs are not influenced by the measurement conditions, and that they remain considerably dependent on the nature and concentration of the electrolyte when measured using the traditional method involving molecular solvents combined with a supporting electrolyte (0.1-0.5 M). The difference in the E°' values observed in the ammonium and pyridinium ILs is only several millivolts. In addition, ESR and self-consistent isodensity polarized continuum model calculation results reveal that the potential shift toward positive values upon the transition from molecular solvents containing ILs to neat ILs is adequately accounted for by changes in the electrostatic interaction of R(•-) taken into the cavity composed of the solvent and IL. On the other hand, the first reduction waves of quinones, electron-accepting molecules, and polynuclear aromatic hydrocarbons are reversibly or quasi-reversibly observed in the ILs. The electrochemical stability of the ILs is exploited in the facile measurement of these quasi-reversible waves at quite negative potentials, such as for the naphthalene (NP)/NP(•-) couple. Notably, the E°' values obtained in the ammonium ILs correlate well with the calculated standard redox
Measurement of the first ionization potential of lawrencium, element 103.
Sato, T K; Asai, M; Borschevsky, A; Stora, T; Sato, N; Kaneya, Y; Tsukada, K; Düllmann, Ch E; Eberhardt, K; Eliav, E; Ichikawa, S; Kaldor, U; Kratz, J V; Miyashita, S; Nagame, Y; Ooe, K; Osa, A; Renisch, D; Runke, J; Schädel, M; Thörle-Pospiech, P; Toyoshima, A; Trautmann, N
2015-04-01
The chemical properties of an element are primarily governed by the configuration of electrons in the valence shell. Relativistic effects influence the electronic structure of heavy elements in the sixth row of the periodic table, and these effects increase dramatically in the seventh row--including the actinides--even affecting ground-state configurations. Atomic s and p1/2 orbitals are stabilized by relativistic effects, whereas p3/2, d and f orbitals are destabilized, so that ground-state configurations of heavy elements may differ from those of lighter elements in the same group. The first ionization potential (IP1) is a measure of the energy required to remove one valence electron from a neutral atom, and is an atomic property that reflects the outermost electronic configuration. Precise and accurate experimental determination of IP1 gives information on the binding energy of valence electrons, and also, therefore, on the degree of relativistic stabilization. However, such measurements are hampered by the difficulty in obtaining the heaviest elements on scales of more than one atom at a time. Here we report that the experimentally obtained IP1 of the heaviest actinide, lawrencium (Lr, atomic number 103), is 4.96(+0.08)(-0.07) electronvolts. The IP1 of Lr was measured with (256)Lr (half-life 27 seconds) using an efficient surface ion-source and a radioisotope detection system coupled to a mass separator. The measured IP1 is in excellent agreement with the value of 4.963(15) electronvolts predicted here by state-of-the-art relativistic calculations. The present work provides a reliable benchmark for theoretical calculations and also opens the way for IP1 measurements of superheavy elements (that is, transactinides) on an atom-at-a-time scale.
Measurement of the first ionization potential of lawrencium, element 103
NASA Astrophysics Data System (ADS)
Sato, T. K.; Asai, M.; Borschevsky, A.; Stora, T.; Sato, N.; Kaneya, Y.; Tsukada, K.; Düllmann, Ch. E.; Eberhardt, K.; Eliav, E.; Ichikawa, S.; Kaldor, U.; Kratz, J. V.; Miyashita, S.; Nagame, Y.; Ooe, K.; Osa, A.; Renisch, D.; Runke, J.; Schädel, M.; Thörle-Pospiech, P.; Toyoshima, A.; Trautmann, N.
2015-04-01
The chemical properties of an element are primarily governed by the configuration of electrons in the valence shell. Relativistic effects influence the electronic structure of heavy elements in the sixth row of the periodic table, and these effects increase dramatically in the seventh row--including the actinides--even affecting ground-state configurations. Atomic s and p1/2 orbitals are stabilized by relativistic effects, whereas p3/2, d and f orbitals are destabilized, so that ground-state configurations of heavy elements may differ from those of lighter elements in the same group. The first ionization potential (IP1) is a measure of the energy required to remove one valence electron from a neutral atom, and is an atomic property that reflects the outermost electronic configuration. Precise and accurate experimental determination of IP1 gives information on the binding energy of valence electrons, and also, therefore, on the degree of relativistic stabilization. However, such measurements are hampered by the difficulty in obtaining the heaviest elements on scales of more than one atom at a time. Here we report that the experimentally obtained IP1 of the heaviest actinide, lawrencium (Lr, atomic number 103), is electronvolts. The IP1 of Lr was measured with 256Lr (half-life 27 seconds) using an efficient surface ion-source and a radioisotope detection system coupled to a mass separator. The measured IP1 is in excellent agreement with the value of 4.963(15) electronvolts predicted here by state-of-the-art relativistic calculations. The present work provides a reliable benchmark for theoretical calculations and also opens the way for IP1 measurements of superheavy elements (that is, transactinides) on an atom-at-a-time scale.
Measurement of the first ionization potential of lawrencium, element 103.
Sato, T K; Asai, M; Borschevsky, A; Stora, T; Sato, N; Kaneya, Y; Tsukada, K; Düllmann, Ch E; Eberhardt, K; Eliav, E; Ichikawa, S; Kaldor, U; Kratz, J V; Miyashita, S; Nagame, Y; Ooe, K; Osa, A; Renisch, D; Runke, J; Schädel, M; Thörle-Pospiech, P; Toyoshima, A; Trautmann, N
2015-04-01
The chemical properties of an element are primarily governed by the configuration of electrons in the valence shell. Relativistic effects influence the electronic structure of heavy elements in the sixth row of the periodic table, and these effects increase dramatically in the seventh row--including the actinides--even affecting ground-state configurations. Atomic s and p1/2 orbitals are stabilized by relativistic effects, whereas p3/2, d and f orbitals are destabilized, so that ground-state configurations of heavy elements may differ from those of lighter elements in the same group. The first ionization potential (IP1) is a measure of the energy required to remove one valence electron from a neutral atom, and is an atomic property that reflects the outermost electronic configuration. Precise and accurate experimental determination of IP1 gives information on the binding energy of valence electrons, and also, therefore, on the degree of relativistic stabilization. However, such measurements are hampered by the difficulty in obtaining the heaviest elements on scales of more than one atom at a time. Here we report that the experimentally obtained IP1 of the heaviest actinide, lawrencium (Lr, atomic number 103), is 4.96(+0.08)(-0.07) electronvolts. The IP1 of Lr was measured with (256)Lr (half-life 27 seconds) using an efficient surface ion-source and a radioisotope detection system coupled to a mass separator. The measured IP1 is in excellent agreement with the value of 4.963(15) electronvolts predicted here by state-of-the-art relativistic calculations. The present work provides a reliable benchmark for theoretical calculations and also opens the way for IP1 measurements of superheavy elements (that is, transactinides) on an atom-at-a-time scale. PMID:25855457
Accurate potential energy functions, non-adiabatic and spin-orbit couplings in the ZnH(+) system.
Liang, Guiying; Liu, Xiaoting; Zhang, Xiaomei; Xu, Haifeng; Yan, Bing
2016-03-01
A high-level ab initio calculation on the ZnH(+) cation has been carried out with the multi-reference configuration interaction method plus Davison correction (MRCI+Q). The scalar relativistic effect is included by using the Douglas-Kroll-Hess (DKH) method. The calculated potential energy curves (PECs) of the 7 Λ-S states are associated with the dissociation limits of Zn(+)((2)Sg)+H((2)Sg), Zn((1)Sg)+H(+)((1)Sg), and Zn(+)((2)Pu)+H((2)Sg), respectively (The Λ-S state is labeled as (2S+1)Λ, in which Λ is the quantum number for the projection along the internuclear axis of the total electronic orbital angular momentum and S is the total electron spin). The spectroscopic constants of the bound states are determined and in good agreement with the available theoretical and experimental results. The permanent dipole moments (PDMs) of Λ-S states and the spin-orbit (SO) matrix elements between Λ-S states are also computed. The results show that the abrupt changes of the PDMs and SO matrix elements come into being for the reason of the avoided crossing between the states with the same symmetry. In addition, the non-adiabatic couplings matrix elements between Λ-S states are also evaluated. Finally, the spin-orbit couplings (SOCs) for the low-lying states are considered with Breit-Pauli operator. The SOC effect makes the 7 Λ-S states of the ZnH(+) cation split into 12 Ω states (Ω=Λ+Sz, in which Sz is projection of the total electron spin S along the internuclear Z-axis). For the (3)0(+) state, the two energy minima exhibit in the potential, which could be attributed to the formation of the new avoided crossing point. The transition dipole moments (TDMs), Franck-Condon factors, and the radiative lifetimes of the selected transitions (2)0(+)-X0(+), (3)0(+)-X0(+), (2)1-X0(+) and (3)1-X0(+) have been reported.
Accurate potential energy functions, non-adiabatic and spin-orbit couplings in the ZnH+ system
NASA Astrophysics Data System (ADS)
Liang, Guiying; Liu, Xiaoting; Zhang, Xiaomei; Xu, Haifeng; Yan, Bing
2016-03-01
A high-level ab initio calculation on the ZnH+ cation has been carried out with the multi-reference configuration interaction method plus Davison correction (MRCI + Q). The scalar relativistic effect is included by using the Douglas-Kroll-Hess (DKH) method. The calculated potential energy curves (PECs) of the 7 Λ-S states are associated with the dissociation limits of Zn+(2Sg) + H(2Sg), Zn(1Sg) + H+(1Sg), and Zn+(2Pu) + H(2Sg), respectively (The Λ-S state is labeled as 2S + 1Λ, in which Λ is the quantum number for the projection along the internuclear axis of the total electronic orbital angular momentum and S is the total electron spin). The spectroscopic constants of the bound states are determined and in good agreement with the available theoretical and experimental results. The permanent dipole moments (PDMs) of Λ-S states and the spin-orbit (SO) matrix elements between Λ-S states are also computed. The results show that the abrupt changes of the PDMs and SO matrix elements come into being for the reason of the avoided crossing between the states with the same symmetry. In addition, the non-adiabatic couplings matrix elements between Λ-S states are also evaluated. Finally, the spin-orbit couplings (SOCs) for the low-lying states are considered with Breit-Pauli operator. The SOC effect makes the 7 Λ-S states of the ZnH+ cation split into 12 Ω states (Ω = Λ + Sz, in which Sz is projection of the total electron spin S along the internuclear Z-axis). For the (3)0+ state, the two energy minima exhibit in the potential, which could be attributed to the formation of the new avoided crossing point. The transition dipole moments (TDMs), Franck-Condon factors, and the radiative lifetimes of the selected transitions (2)0+-X0+, (3)0+-X0+, (2)1-X0+ and (3)1-X0+ have been reported.
NASA Astrophysics Data System (ADS)
Saheer, V. C.; Kumar, Sanjay
2016-01-01
The global ground and first three excited electronic state adiabatic as well as the corresponding quasidiabatic potential energy surfaces is reported as a function of nuclear geometries in the Jacobi coordinates ( R → , r → , γ ) using Dunning's cc-pVTZ basis set at the internally contracted multi-reference (single and double) configuration interaction level of accuracy. Nonadiabatic couplings, arising out of relative motion of proton and the vibrational motion of CO, are also reported in terms of coupling potentials. The quasidiabatic potential energy surfaces and the coupling potentials have been obtained using the ab initio procedure [Simah et al., J. Chem. Phys. 111, 4523 (1999)] for the purpose of dynamics studies.
Shoulder, J M; Alderman, N S; Breneman, C M; Nyman, M C
2013-08-01
Property-Encoded Surface Translator (PEST) descriptors were found to be correlated with the degradation rates of polycyclic aromatic hydrocarbons (PAHs) by the peroxy-acid process. Reaction rate constants (k) in hr(-1) for nine PAHs (acenaphthene, anthracene, benzo[a]pyrene, benzo[k]fluoranthene, fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene) were determined by a peroxy-acid treatment method that utilized acetic acid, hydrogen peroxide, and a sulphuric acid catalyst to degrade the polyaromatic structures. Molecular properties of the selected nine PAHs were derived from structures optimized at B3LYP/6-31G(d) and HF/6-31G(d) levels of theory. Properties of adiabatic and vertical ionization potential (IP), highest occupied molecular orbitals (HOMO), HOMO/lowest unoccupied molecular orbital (LUMO) gap energies and HOMO/singly occupied molecular orbital (SOMO) gap energies were not correlated with rates of peroxy-acid reaction. PEST descriptors were calculated from B3LYP/6-31G(d) optimized structures and found to have significant levels of correlation with k. PIP Min described the minimum local IP on the surface of the molecule and was found to be related to k. PEST technology appears to be an accurate method in predicting reactivity and could prove to be a valuable asset in building treatment models and in remediation design for PAHs and other organic contaminants in the environment. PMID:23734862
Ionization potentials of cobalt and nickel ions in the local-spin-density approximation
Dhar, S. ); Kestner, N.R. )
1990-06-15
In this article we report on the ionization potentials of all configurations of the Co{sup {ital n}+} and Ni{sup {ital n}+} ions obtained via transition-state calculations using local-spin-density (LSD) potentials. The calculations were performed numerically with and without modifications of the local exchange potential for fractional occupation numbers. When the exchange potential is corrected for noninteger occupation numbers, a more consistent picture of the ionization process is obtained than that given by the LSD Kohn-Sham exchange. The agreement with experimental results is also significantly improved.
Laser-induced resonance states as dynamic suppressors of ionization in high-frequency short pulses
Barash, Danny; Orel, Ann E.; Baer, Roi
2000-01-01
An adiabatic-Floquet formalism is used to study the suppression of ionization in short laser pulses. In the high-frequency limit the adiabatic equations involve only the pulse envelope where transitions are purely ramp effects. For a short-ranged potential having a single-bound state we show that ionization suppression is caused by the appearance of a laser-induced resonance state, which is coupled by the pulse ramp to the ground state and acts to trap ionizing flux. (c) 1999 The American Physical Society.
Absorptive potentials due to ionization and thermal diffuse scattering by fast electrons in crystals
Allen, L.J. ); Rossouw, C.J. )
1990-12-15
An expression for the Fourier coefficients of the absorptive potential due to electron-impact ionization in crystals is derived and the cross section is given in terms of these Fourier components. Absorptive potentials due to {ital K}-shell ionization and thermal diffuse scattering (TDS) are calculated with use of a hydrogenic model and an Einstein model, respectively. Inelastic potentials require integration over all states of the scattered electron and, for {ital K}-shell ionization, integration over all states of the ejected electron. These potentials are thus dependent on incident-beam energy, in contrast with the elastic potential. The projected spatial distribution of these potentials are plotted and compared with the elastic potential for CdTe, GaAs, Si, and diamond. The delocalization of the ionization absorptive potential is similar to that expected from classical impact-parameter arguments. The form of the TDS potential is substantially different from that due to elastic scattering, being extremely peaked on atomic positions with no absorption in the channels between atomic planes.
Analysis of hyperspherical adiabatic curves of helium: A classical dynamics study
NASA Astrophysics Data System (ADS)
Simonović, N. S.; Solov'ev, E. A.
2013-05-01
The hyperspherical adiabatic curves (adiabatic eigenenergies as functions of the hyperradius R) of helium for zero total angular momentum are analyzed by studying the underlying classical dynamics which in the adiabatic treatment reduces to constrained two-electron motion on a hypersphere. This dynamics supports five characteristic classical configurations which can be represented by five types of short periodic orbits: the frozen planet (FP), the inverted frozen planet (IFP), the asymmetric stretch (AS), the asynchronous (ASC), and the Langmuir periodic orbit (PO). These POs are considered as fundamental modes of the two-electron motion on a hypersphere which, after quantization, give five families of so-called adiabatic lines (adiabatic energies related to these POs as functions of R). It is found that multiplets, each of them consisting of adiabatic curves which converge to the same ionization threshold, are at large values of R delimited from the bottom and from the top by the adiabatic lines which are related to the IFP and stable AS POs and to the FP PO, respectively. At smaller values of R, where the AS PO becomes unstable, the curves move to the area between the ASC (bottom) and AS (top) lines by crossing the latter. Therefore, at different values of R the lower limiting line of the multiplet is related to the three types of PO (IFP, AS, and ASC), which are all stable in the negative-energy part of this line. As a consequence, the quantum states of helium in principle are not related individually to a single classical configuration on the hypersphere. In addition, it is demonstrated that “unstable parts” of adiabatic lines (the so-called diabatic curves) determine the positions and type of avoided and hidden crossings between hyperspherical adiabatic curves. Two clearly visible classes of avoided crossings are related to the AS and ASC POs. In addition, a number of avoided crossings of the adiabatic curves is observed at the positions where the
Radioprotective Potential of Plants and Herbs against the Effects of Ionizing Radiation.
C Jagetia, Ganesh
2007-03-01
Ionizing radiations produce deleterious effects in the living organisms and the rapid technological advancement has increased human exposure to ionizing radiations enormously. There is a need to protect humans against such effects of ionizing radiation. Attempts to protect against the deleterious effects of ionizing radiations by pharmacological intervention were made as early as 1949 and efforts are continued to search radioprotectors, which may be of great help for human application. This review mainly dwells on the radioprotective potential of plant and herbal extracts. The results obtained from in vitro and in vivo studies indicate that several botanicals such as Gingko biloba, Centella asiatica, Hippophae rhamnoides, Ocimum sanctum, Panax ginseng, Podophyllum hexandrum, Amaranthus paniculatus, Emblica officinalis, Phyllanthus amarus, Piper longum, Tinospora cordifoila, Mentha arvensis, Mentha piperita, Syzygium cumini, Zingiber officinale, Ageratum conyzoides, Aegle marmelos and Aphanamixis polystachya protect against radiation-induced lethality, lipid peroxidation and DNA damage. The fractionation-guided evaluation may help to develop new radioprotectors of desired activities. PMID:18188408
Radioprotective Potential of Plants and Herbs against the Effects of Ionizing Radiation
C. Jagetia, Ganesh
2007-01-01
Ionizing radiations produce deleterious effects in the living organisms and the rapid technological advancement has increased human exposure to ionizing radiations enormously. There is a need to protect humans against such effects of ionizing radiation. Attempts to protect against the deleterious effects of ionizing radiations by pharmacological intervention were made as early as 1949 and efforts are continued to search radioprotectors, which may be of great help for human application. This review mainly dwells on the radioprotective potential of plant and herbal extracts. The results obtained from in vitro and in vivo studies indicate that several botanicals such as Gingko biloba, Centella asiatica, Hippophae rhamnoides, Ocimum sanctum, Panax ginseng, Podophyllum hexandrum, Amaranthus paniculatus, Emblica officinalis, Phyllanthus amarus, Piper longum, Tinospora cordifoila, Mentha arvensis, Mentha piperita, Syzygium cumini, Zingiber officinale, Ageratum conyzoides, Aegle marmelos and Aphanamixis polystachya protect against radiation-induced lethality, lipid peroxidation and DNA damage. The fractionation-guided evaluation may help to develop new radioprotectors of desired activities. PMID:18188408
Energy balance for a sonoluminescence bubble yields a measure of ionization potential lowering.
Kappus, B; Bataller, A; Putterman, S J
2013-12-01
Application of energy conservation between input sound and the microplasma which forms at the moment of sonoluminescence places bounds on the process, whereby the gas is ionized. Detailed pulsed Mie scattering measurements of the radius versus time for a xenon bubble in sulfuric acid provide a complete characterization of the hydrodynamics and minimum radius. For a range of emission intensities, the blackbody spectrum emitted during collapse matches the minimum bubble radius, implying opaque conditions are attained. This requires a degree of ionization >36%. Analysis reveals only 2.1±0.6 eV/atom of energy available during light emission. In order to unbind enough charge, collective processes must therefore reduce the ionization potential by at least 75%. We interpret this as evidence that a phase transition to a highly ionized plasma is occurring during sonoluminescence.
Variation in Surface Ionization Potentials of Pristine and Hydrated BiVO4
2015-01-01
Bismuth vanadate (BiVO4) is a promising material for photoelectrochemical water splitting and photocatalytic degradation of organic moieties. We evaluate the ionization potentials of the (010) surface termination of BiVO4 using first-principles simulations. The electron removal energy of the pristine termination (7.2 eV) validates recent experimental reports. The effect of water absorption on the ionization potentials is considered using static models as well as structures obtained from molecular dynamics simulations. Owing to the large molecular dipole of H2O, adsorption stabilizes the valence band edge (downward band bending), thereby increasing the ionization potentials. These results provide new understanding to the role of polar layers on complex oxide semiconductors, with importance for the design of efficient photoelectrodes for water splitting. PMID:26191376
Variation in Surface Ionization Potentials of Pristine and Hydrated BiVO4.
Crespo-Otero, Rachel; Walsh, Aron
2015-06-18
Bismuth vanadate (BiVO4) is a promising material for photoelectrochemical water splitting and photocatalytic degradation of organic moieties. We evaluate the ionization potentials of the (010) surface termination of BiVO4 using first-principles simulations. The electron removal energy of the pristine termination (7.2 eV) validates recent experimental reports. The effect of water absorption on the ionization potentials is considered using static models as well as structures obtained from molecular dynamics simulations. Owing to the large molecular dipole of H2O, adsorption stabilizes the valence band edge (downward band bending), thereby increasing the ionization potentials. These results provide new understanding to the role of polar layers on complex oxide semiconductors, with importance for the design of efficient photoelectrodes for water splitting. PMID:26191376
Density-functional errors in ionization potential with increasing system size
Whittleton, Sarah R.; Sosa Vazquez, Xochitl A.; Isborn, Christine M.; Johnson, Erin R.
2015-05-14
This work investigates the effects of molecular size on the accuracy of density-functional ionization potentials for a set of 28 hydrocarbons, including series of alkanes, alkenes, and oligoacenes. As the system size increases, delocalization error introduces a systematic underestimation of the ionization potential, which is rationalized by considering the fractional-charge behavior of the electronic energies. The computation of the ionization potential with many density-functional approximations is not size-extensive due to excessive delocalization of the incipient positive charge. While inclusion of exact exchange reduces the observed errors, system-specific tuning of long-range corrected functionals does not generally improve accuracy. These results emphasize that good performance of a functional for small molecules is not necessarily transferable to larger systems.
NASA Astrophysics Data System (ADS)
Zhu, Xiaolei; Yarkony, David R.
2012-05-01
In two previous papers we have introduced a method to generate coupled quasi-diabatic Hamiltonians (Hd) that are capable of representing adiabatic energies, energy gradients, and derivative couplings over a wide range of geometries including seams of conical intersection. In this work, two new synergistic features are introduced. Firstly, the functional form of Hd is generalized. Rather than requiring there to be a low energy point of high symmetry to serve as the unique origin, functions centered on points distributed in nuclear coordinate space are used in the polynomials that comprise the matrix elements in Hd. The use of functions with distributed origins, allows reproduction of the ab initio data with lower order expansions, and offers the possibility of describing multichannel dissociation. The fitting algorithm is combined with a three-step procedure in which the domain of Hd is extended from a core set of nuclear configurations to a region of nuclear coordinate space appropriate for nuclear dynamics, with a prescribed accuracy. This significant extension of the domain of definition compared to our original work, which is facilitated by the distributed origin approach, is achieved largely through the use of surface hopping trajectories. The 1,21A states of NH3, which provide an archetypical example of nonadiabatic dynamics, are used to demonstrate the utility of this approach. The representation describes 21 points on the 11A-21A seam of conical intersection and their local topography flawlessly and on the entire domain, the electronic structure data is represented to an accuracy of 77.00 (46.90) cm-1, as measured by the root mean square (mean unsigned) error for energies lower than 50 000 cm-1. This error is a factor of 10 lower than that of the most accurate representation of high quality ab initio data, on a comparable domain, previously reported for this system.
NASA Astrophysics Data System (ADS)
Cremers, C.; Degen, J.
1998-11-01
Coexistence of Jahn-Teller minima resulting from the coupling to different accepting modes within the adiabatic potential energy surface (APES) is not possible within the framework of linear vibronic coupling theory. For the lowest exited triplet state 3T1u of inorganic complexes with s2 electronic ground-state configuration, such a coexistence, due to quadratic coupling effects, is discussed. As a direct experimental evidence two vibronic progressions with different accepting modes in the emission spectra resulting from a single electronic state are observed in the emission spectra of the title compounds. The observation of vibronic finestructure in the emission spectra of [TeCl6]2- is reported for the first time.
Ultrafast ionization and fragmentation of molecular silane
Sayres, Scott G.; Ross, Matt W.; Castleman, A. W. Jr.
2010-09-15
The ionization and fragmentation of molecular silane is examined here with laser intensities ranging between 7x10{sup 12} and 1x10{sup 15} W/cm{sup 2} at 624 nm. The ionization potential of silane determined using both multiphoton ionization (MPI) and tunneling ionization (TI) models agrees with the vertical ionization potential of the molecule. In addition, the application of the tunneling ionization model is extended here to the fragments of silane to determine their appearance potentials. MPI values for SiH{sub 3}{sup +}, SiH{sub 2}{sup +}, SiH{sup +}, Si{sup +}, as well as H{sub 2}{sup +} and H{sup +} are consistent with vertical potentials, whereas the TI measurements are found to be in accord with adiabatic potentials. The tunneling appearance potentials observed for the fragments H{sub 2}{sup +} and H{sup +} are lower than reported for other techniques. In fact, the appearance potential measurements for these species resulting from silane are lower than their ionization potentials. The fragmentation rate of silane is determined to be nearly 20 times larger than the ionization rate. The main precursor for producing amorphous silicon (a-Si:H) thin films, SiH{sub 3}{sup +} is the dominant fragmentation product making up roughly a third of the total ion yield, a substantial increase from other techniques.
Schramm, E; Mühlberger, F; Mitschke, S; Reichardt, G; Schulte-Ladbeck, R; Pütz, M; Zimmermann, R
2008-02-01
Several ionization potentials (IPs) of security relevant substances were determined with single photon ionization time of flight mass spectrometry (SPI-TOFMS) using monochromatized synchrotron radiation from the "Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung" (BESSY). In detail, the IPs of nine explosives and related compounds, seven narcotics and narcotics precursors, and one chemical warfare agent (CWA) precursor were determined, whereas six IPs already known from the literature were verified correctly. From seven other substances, including one CWA precursor, the IP could not be determined as the molecule ion peak could not be detected. For these substances the appearance energy (AE) of a main fragment was determined. The analyzed security-relevant substances showed IPs significantly below the IPs of common matrix compounds such as nitrogen and oxygen. Therefore, it is possible to find photon energies in between, whereby the molecules of interest can be detected with SPI in very low concentrations due to the shielding of the matrix. All determined IPs except the one of the explosive EGDN were below 10.5 eV. Hence, laser-generated 118 nm photons can be applied for detecting almost all security-relevant substances by, e.g., SPI-TOFMS. PMID:18284801
EOMIP-CCSD(2)*: an efficient method for the calculation of ionization potentials.
Dutta, Achintya Kumar; Vaval, Nayana; Pal, Sourav
2015-06-01
A new approximation within the domain of EOMIP-CC method is proposed. The proposed scheme is based on the perturbative truncation of the similarity transformed effective Hamiltonian matrix. We call it the EOMIP-CCSD(2)* method, which scales as noniterative N(6) and its storage requirement is very less, compared to the conventional EOMIP-CCSD method. The existing EOMIP-CCSD(2) method has a tendency to overestimate the ionization potential (IP) values. On the other hand, our new strategy corrects for the problem of such an overestimation, which is evident from the excellent agreement achieved with the experimental values. Furthermore, not only the ionization potential but also geometry and IR frequencies of problematic double radicals are estimated correctly, and the results are comparable to the CCSD(T) method, obviously at lesser computational cost. The EOMIP-CCSD(2)* method works even for the core ionization and satellite IP, where the earlier EOMIP-CCSD(2) approximation dramatically fails.
Andreev, S.V.; Mishin, V.I.; Letokhov, V.S.
1988-10-01
A highly sensitive method of detecting atoms in samples has been used for spectral investigations of the rare radioactive element Fr. The method is based on laser-resonance photoionization of Fr atoms in a hot quasi-enclosed cavity. The investigations have been carried out with samples in which short-lived radioactive /sup 221/Fr atoms formed at a rate of approximately 10/sup 3/ atoms/sec. The data obtained, to our knowledge for the first time, on the energies of the high-lying Rydberg levels of the /sup 2/S/sub 1/2/ and /sup 2/D series have made it possible to determine the electron binding energy of the 7p /sup 2/P/sub 3/2/ state and to establish the ionization potential of Fr accurately.
Size-dependent error of the density functional theory ionization potential in vacuum and solution
Sosa Vazquez, Xochitl A.; Isborn, Christine M.
2015-12-28
Density functional theory is often the method of choice for modeling the energetics of large molecules and including explicit solvation effects. It is preferable to use a method that treats systems of different sizes and with different amounts of explicit solvent on equal footing. However, recent work suggests that approximate density functional theory has a size-dependent error in the computation of the ionization potential. We here investigate the lack of size-intensivity of the ionization potential computed with approximate density functionals in vacuum and solution. We show that local and semi-local approximations to exchange do not yield a constant ionization potential for an increasing number of identical isolated molecules in vacuum. Instead, as the number of molecules increases, the total energy required to ionize the system decreases. Rather surprisingly, we find that this is still the case in solution, whether using a polarizable continuum model or with explicit solvent that breaks the degeneracy of each solute, and we find that explicit solvent in the calculation can exacerbate the size-dependent delocalization error. We demonstrate that increasing the amount of exact exchange changes the character of the polarization of the solvent molecules; for small amounts of exact exchange the solvent molecules contribute a fraction of their electron density to the ionized electron, but for larger amounts of exact exchange they properly polarize in response to the cationic solute. In vacuum and explicit solvent, the ionization potential can be made size-intensive by optimally tuning a long-range corrected hybrid functional.
Size-dependent error of the density functional theory ionization potential in vacuum and solution
Sosa Vazquez, Xochitl A.; Isborn, Christine M.
2015-12-22
Density functional theory is often the method of choice for modeling the energetics of large molecules and including explicit solvation effects. It is preferable to use a method that treats systems of different sizes and with different amounts of explicit solvent on equal footing. However, recent work suggests that approximate density functional theory has a size-dependent error in the computation of the ionization potential. We here investigate the lack of size-intensivity of the ionization potential computed with approximate density functionals in vacuum and solution. We show that local and semi-local approximations to exchange do not yield a constant ionization potential for an increasing number of identical isolated molecules in vacuum. Instead, as the number of molecules increases, the total energy required to ionize the system decreases. Rather surprisingly, we find that this is still the case in solution, whether using a polarizable continuum model or with explicit solvent that breaks the degeneracy of each solute, and we find that explicit solvent in the calculation can exacerbate the size-dependent delocalization error. We demonstrate that increasing the amount of exact exchange changes the character of the polarization of the solvent molecules; for small amounts of exact exchange the solvent molecules contribute a fraction of their electron density to the ionized electron, but for larger amounts of exact exchange they properly polarize in response to the cationic solute. As a result, in vacuum and explicit solvent, the ionization potential can be made size-intensive by optimally tuning a long-range corrected hybrid functional.
NASA Technical Reports Server (NTRS)
Huo, Winifred M.; Kim, Yong-Ki
1999-01-01
Based on the Binary-Encounter-Bethe (BEB) model, the advantage of using relativistic effective core potentials (RECP) in the calculation of total ionization cross sections of heavy atoms or molecules containing heavy atoms is discussed. Numerical examples for Ar, Kr, Xe, and WF6 are presented.
Size-dependent error of the density functional theory ionization potential in vacuum and solution
Sosa Vazquez, Xochitl A.; Isborn, Christine M.
2015-12-22
Density functional theory is often the method of choice for modeling the energetics of large molecules and including explicit solvation effects. It is preferable to use a method that treats systems of different sizes and with different amounts of explicit solvent on equal footing. However, recent work suggests that approximate density functional theory has a size-dependent error in the computation of the ionization potential. We here investigate the lack of size-intensivity of the ionization potential computed with approximate density functionals in vacuum and solution. We show that local and semi-local approximations to exchange do not yield a constant ionization potentialmore » for an increasing number of identical isolated molecules in vacuum. Instead, as the number of molecules increases, the total energy required to ionize the system decreases. Rather surprisingly, we find that this is still the case in solution, whether using a polarizable continuum model or with explicit solvent that breaks the degeneracy of each solute, and we find that explicit solvent in the calculation can exacerbate the size-dependent delocalization error. We demonstrate that increasing the amount of exact exchange changes the character of the polarization of the solvent molecules; for small amounts of exact exchange the solvent molecules contribute a fraction of their electron density to the ionized electron, but for larger amounts of exact exchange they properly polarize in response to the cationic solute. As a result, in vacuum and explicit solvent, the ionization potential can be made size-intensive by optimally tuning a long-range corrected hybrid functional.« less
NASA Technical Reports Server (NTRS)
Goodrich, C. C.; Scudder, J. D.
1984-01-01
The adiabatic energy gain of electrons in the stationary electric and magnetic field structure of collisionless shock waves was examined analytically in reference to conditions of the earth's bow shock. The study was performed to characterize the behavior of electrons interacting with the cross-shock potential. A normal incidence frame (NIF) was adopted in order to calculate the reversible energy change across a time stationary shock, and comparisons were made with predictions made by the de Hoffman-Teller (HT) model (1950). The electron energy gain, about 20-50 eV, is demonstrated to be consistent with a 200-500 eV potential jump in the bow shock quasi-perpendicular geometry. The electrons lose energy working against the solar wind motional electric field. The reversible energy process is close to that modeled by HT, which predicts that the motional electric field vanishes and the electron energy gain from the electric potential is equated to the ion energy loss to the potential.
Elementary examples of adiabatic invariance
NASA Astrophysics Data System (ADS)
Crawford, Frank S.
1990-04-01
Simple classical one-dimensional systems subject to adiabatic (gradual) perturbations are examined. The first examples are well known: the adiabatic invariance of the product Eτ of energy E and period τ for the simple pendulum and for the simple harmonic oscillator. Next, the adiabatic invariants of the vertical bouncer are found—a ball bouncing elastically from the floor of a rising elevator having slowly varying velocity and acceleration. These examples lead to consideration of adiabatic invariance for one-dimensional systems with potentials of the form V=axn, with a=a(t) slowly varying in time. Then, the horizontal bouncer is considered—a mass sliding on a smooth floor, bouncing back and forth between two impenetrable walls, one of which is slowly moving. This example is generalized to a particle in a bound state of a general potential with one slowly moving ``turning point.'' Finally, circular motion of a charged particle in a magnetic field slowly varying in time under three different configurations is considered: (a) a free particle in a uniform field; (b) a free particle in a nonuniform ``betatron'' field; and (c) a particle constrained to a circular orbit in a uniform field.
HF echoes from ionization potentially produced by high-altitude discharges
Roussel-Dupre, R.; Fitzgerald, T.J.; Symbalisty, E.
1997-04-01
In this paper the authors report on recent radar measurements taken during the month of October 1994 with the LDG HF radar in the Ivory Coast, Africa as part of the International Equatorial Electrojet Year. The purpose of this experimental effort in part was to study the effects of thunderstorms on the ionosphere. At the same time, the authors decided to carry out a set of experiments of an exploratory nature to look for echoes that could potentially arise from ionization produced in the mesosphere. The two leading candidates for producing transient ionization in the mesosphere are meteors and high-altitude discharges. Each is discussed in the context of these measurements.
NASA Astrophysics Data System (ADS)
Song, Xiaohong; Lin, Cheng; Sheng, Zhihao; Liu, Peng; Chen, Zhangjin; Yang, Weifeng; Hu, Shilin; Lin, C. D.; Chen, Jing
2016-06-01
Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back and scatters off the ion(the signal wave). The interference hologram of the two waves may be used to extract target information embedded in the collision process. Unlike conventional optical holography, however, propagation of the electron wave packet is affected by the Coulomb potential as well as by the laser field. In addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. We showed that photoelectron hologram can be well described only when the effect of nonadiabatic ionization is accounted for, and Coulomb potential can be neglected only in the tunnel ionization regime. Our results help paving the way for establishing photoelectron holography for probing spatial and dynamic properties of atoms and molecules.
Song, Xiaohong; Lin, Cheng; Sheng, Zhihao; Liu, Peng; Chen, Zhangjin; Yang, Weifeng; Hu, Shilin; Lin, C. D.; Chen, Jing
2016-01-01
Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back and scatters off the ion(the signal wave). The interference hologram of the two waves may be used to extract target information embedded in the collision process. Unlike conventional optical holography, however, propagation of the electron wave packet is affected by the Coulomb potential as well as by the laser field. In addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. We showed that photoelectron hologram can be well described only when the effect of nonadiabatic ionization is accounted for, and Coulomb potential can be neglected only in the tunnel ionization regime. Our results help paving the way for establishing photoelectron holography for probing spatial and dynamic properties of atoms and molecules. PMID:27329071
Song, Xiaohong; Lin, Cheng; Sheng, Zhihao; Liu, Peng; Chen, Zhangjin; Yang, Weifeng; Hu, Shilin; Lin, C D; Chen, Jing
2016-01-01
Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back and scatters off the ion(the signal wave). The interference hologram of the two waves may be used to extract target information embedded in the collision process. Unlike conventional optical holography, however, propagation of the electron wave packet is affected by the Coulomb potential as well as by the laser field. In addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. We showed that photoelectron hologram can be well described only when the effect of nonadiabatic ionization is accounted for, and Coulomb potential can be neglected only in the tunnel ionization regime. Our results help paving the way for establishing photoelectron holography for probing spatial and dynamic properties of atoms and molecules. PMID:27329071
Song, Xiaohong; Lin, Cheng; Sheng, Zhihao; Liu, Peng; Chen, Zhangjin; Yang, Weifeng; Hu, Shilin; Lin, C. D.; Chen, Jing
2016-06-22
Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back and scatters off the ion(the signal wave). The interference hologram of the two waves may be used to extract target information embedded in the collision process. Unlike conventional optical holography, however, propagation of the electron wave packet is affected by the Coulomb potential as well as by the laser field. Inmore » addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. Here, we showed that photoelectron hologram can be well described only when the effect of nonadiabatic ionization is accounted for, and Coulomb potential can be neglected only in the tunnel ionization regime. Our results help paving the way for establishing photoelectron holography for probing spatial and dynamic properties of atoms and molecules.« less
Isothermal and Adiabatic Measurements.
ERIC Educational Resources Information Center
McNairy, William W.
1996-01-01
Describes the working of the Adiabatic Gas Law Apparatus, a useful tool for measuring the pressure, temperature, and volume of a variety of gases undergoing compressions and expansions. Describes the adaptation of this apparatus to perform isothermal measurements and discusses the theory behind the adiabatic and isothermal processes. (JRH)
NASA Astrophysics Data System (ADS)
Yonehara, Takehiro; Takatsuka, Kazuo
2012-12-01
We develop a theory and the method of its application for chemical dynamics in systems, in which the adiabatic potential energy hyper-surfaces (PES) are densely quasi-degenerate to each other in a wide range of molecular geometry. Such adiabatic electronic states tend to couple each other through strong nonadiabatic interactions. Technically, therefore, it is often extremely hard to accurately single out the individual PES in those systems. Moreover, due to the mutual nonadiabatic couplings that may spread wide in space and due to the energy-time uncertainty relation, the notion of the isolated and well-defined potential energy surface should lose the sense. On the other hand, such dense electronic states should offer a very interesting molecular field in which chemical reactions to proceed in characteristic manners. However, to treat these systems, the standard theoretical framework of chemical reaction dynamics, which starts from the Born-Oppenheimer approximation and ends up with quantum nuclear wavepacket dynamics, is not very useful. We here explore this problem with our developed nonadiabatic electron wavepacket theory, which we call the phase-space averaging and natural branching (PSANB) method [T. Yonehara and K. Takatsuka, J. Chem. Phys. 129, 134109 (2008)], 10.1063/1.2987302, or branching-path representation, in which the packets are propagated in time along the non-Born-Oppenheimer branching paths. In this paper, after outlining the basic theory, we examine using a one-dimensional model how well the PSANB method works with such densely quasi-degenerate nonadiabatic systems. To do so, we compare the performance of PSANB with the full quantum mechanical results and those given by the fewest switches surface hopping (FSSH) method, which is known to be one of the most reliable and flexible methods to date. It turns out that the PSANB electron wavepacket approach actually yields very good results with far fewer initial sampling paths. Then we apply the
Yonehara, Takehiro; Takatsuka, Kazuo
2012-12-14
We develop a theory and the method of its application for chemical dynamics in systems, in which the adiabatic potential energy hyper-surfaces (PES) are densely quasi-degenerate to each other in a wide range of molecular geometry. Such adiabatic electronic states tend to couple each other through strong nonadiabatic interactions. Technically, therefore, it is often extremely hard to accurately single out the individual PES in those systems. Moreover, due to the mutual nonadiabatic couplings that may spread wide in space and due to the energy-time uncertainty relation, the notion of the isolated and well-defined potential energy surface should lose the sense. On the other hand, such dense electronic states should offer a very interesting molecular field in which chemical reactions to proceed in characteristic manners. However, to treat these systems, the standard theoretical framework of chemical reaction dynamics, which starts from the Born-Oppenheimer approximation and ends up with quantum nuclear wavepacket dynamics, is not very useful. We here explore this problem with our developed nonadiabatic electron wavepacket theory, which we call the phase-space averaging and natural branching (PSANB) method [T. Yonehara and K. Takatsuka, J. Chem. Phys. 129, 134109 (2008)], or branching-path representation, in which the packets are propagated in time along the non-Born-Oppenheimer branching paths. In this paper, after outlining the basic theory, we examine using a one-dimensional model how well the PSANB method works with such densely quasi-degenerate nonadiabatic systems. To do so, we compare the performance of PSANB with the full quantum mechanical results and those given by the fewest switches surface hopping (FSSH) method, which is known to be one of the most reliable and flexible methods to date. It turns out that the PSANB electron wavepacket approach actually yields very good results with far fewer initial sampling paths. Then we apply the electron wavepacket
Bo, Iselin M. Th.; Esser, Ruth; Lie-Svendsen, Oystein E-mail: ruth.esser@uit.no
2013-05-20
We model the effect of gravitational settling in the upper chromosphere on O, Fe, Si, and Ne, studying whether Coulomb collisions between ionized low First Ionization Potential (FIP) elements and protons is sufficient to cause abundance enhancements relative to oxygen. We find that low-FIP abundance enhancements comparable to observed values can be obtained provided the hydrogen ionization degree lies in the approximate range 10%-30%, which agrees with chromospheric models. Lower or higher hydrogen ionization causes the FIP-effect to become smaller or absent (depletion of all heavy elements). Iron must be almost fully ionized in order to become enriched relative to high-FIP elements, and this requires a high iron photoionization rate. The time scale necessary to produce the enrichment increases rapidly with increasing H ionization. For iron in a background from a semiempirical chromospheric model, with an H ion fraction of the order of 30%-40% in the upper chromosphere, 1-2 hr of settling is required to produce enhancements comparable to observations. The absolute abundance (relative to H), which monotonically decreases with time during settling, has by that time decreased by less than 50% in the same altitude region. With the same background conditions, the silicon abundance is more strongly enhanced by the settling than the iron abundance. The high-FIP element neon is depleted, relative to O and low-FIP elements, in the same background and altitude region where iron is enhanced, typically by 50% or more relative to O after 1-2 hr of settling.
Adiabatic invariance of oscillons/I -balls
NASA Astrophysics Data System (ADS)
Kawasaki, Masahiro; Takahashi, Fuminobu; Takeda, Naoyuki
2015-11-01
Real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or I -balls. We prove the adiabatic invariance of the oscillons/I -balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We show that such a potential is uniquely determined to be the quadratic one with a logarithmic correction, for which the oscillons/I -balls are absolutely stable. For slightly different forms of the scalar potential dominated by the quadratic one, the oscillons/I -balls are only quasistable, because the adiabatic charge is only approximately conserved. We check the conservation of the adiabatic charge of the I -balls in numerical simulation by slowly varying the coefficient of logarithmic corrections. This unambiguously shows that the longevity of oscillons/I -balls is due to the adiabatic invariance.
Gelb, Lev D; Chakraborty, Somendra Nath
2011-12-14
The normal boiling points are obtained for a series of metals as described by the "quantum-corrected Sutton Chen" (qSC) potentials [S.-N. Luo, T. J. Ahrens, T. Çağın, A. Strachan, W. A. Goddard III, and D. C. Swift, Phys. Rev. B 68, 134206 (2003)]. Instead of conventional Monte Carlo simulations in an isothermal or expanded ensemble, simulations were done in the constant-NPH adabatic variant of the Gibbs ensemble technique as proposed by Kristóf and Liszi [Chem. Phys. Lett. 261, 620 (1996)]. This simulation technique is shown to be a precise tool for direct calculation of boiling temperatures in high-boiling fluids, with results that are almost completely insensitive to system size or other arbitrary parameters as long as the potential truncation is handled correctly. Results obtained were validated using conventional NVT-Gibbs ensemble Monte Carlo simulations. The qSC predictions for boiling temperatures are found to be reasonably accurate, but substantially underestimate the enthalpies of vaporization in all cases. This appears to be largely due to the systematic overestimation of dimer binding energies by this family of potentials, which leads to an unsatisfactory description of the vapor phase.
Zimmerman, J.A.; Bach, S.B.H.; Watson, C.H.; Eyler, J.R. )
1991-01-10
Ionization potentials (IP's) for arsenic and phosphorus clusters (As{sub n}, n = 1-5; P{sub n}, n = 1-4) have been determined by gas-phase charge-transfer reactions. Arsenic and phosphorus cluster ions were generated by pulsed CO{sub 2} laser desorption from GaAs and InP substrates, mass-selected, thermalized, and allowed to react with compounds of known ionization potential in a Fourier transform ion cyclotron resonance mass spectrometer. The IP's for As{sub 3} and As{sub 5} previously unreported, as well as more accurate IP values for several of the other clusters, have been determined. Products and rate coefficients of some interesting reactions of the cluster ions with the charge-transfer agents are also reported.
Bhaskaran-Nair, Kiran; Kowalski, Karol; Jarrell, Mark; Moreno, Juana; Shelton, William A.
2015-11-05
Polyacenes have attracted considerable attention due to their use in organic based optoelectronic materials. Polyacenes are polycyclic aromatic hydrocarbons composed of fused benzene rings. Key to understanding and design of new functional materials is an understanding of their excited state properties starting with their electron affinity (EA) and ionization potential (IP). We have developed a highly accurate and com- putationally e*fficient EA/IP equation of motion coupled cluster singles and doubles (EA/IP-EOMCCSD) method that is capable of treating large systems and large basis set. In this study we employ the EA/IP-EOMCCSD method to calculate the electron affinity and ionization potential of naphthalene, anthracene, tetracene, pentacene, hex- acene and heptacene. We have compared our results with other previous theoretical studies and experimental data. Our EA/IP results are in very good agreement with experiment and when compared with the other theoretical investigations our results represent the most accurate calculations as compared to experiment.
The ionization potential of aqueous hydroxide computed using many-body perturbation theory
Opalka, Daniel Sprik, Michiel; Pham, Tuan Anh; Galli, Giulia
2014-07-21
The ionization potentials of electrolyte solutions provide important information about the electronic structure of liquids and solute-solvent interactions. We analyzed the positions of solute and solvent bands of aqueous hydroxide and the influence of the solvent environment on the ionization potential of hydroxide ions. We used the concept of a computational hydrogen electrode to define absolute band positions with respect to vacuum. We found that many-body perturbation theory in the G{sub 0} W{sub 0} approximation substantially improves the relative and absolute positions of the band edges of solute and solvent with respect to those obtained within Density Functional Theory, using semi-local functionals, yielding results in satisfactory agreement with recent experiments.
NASA Astrophysics Data System (ADS)
Bross, David H.; Parmar, Payal; Peterson, Kirk A.
2015-11-01
The first 6 ionization potentials (IPs) of the uranium atom have been calculated using multireference configuration interaction (MRCI+Q) with extrapolations to the complete basis set limit using new all-electron correlation consistent basis sets. The latter was carried out with the third-order Douglas-Kroll-Hess Hamiltonian. Correlation down through the 5s5p5d electrons has been taken into account, as well as contributions to the IPs due to the Lamb shift. Spin-orbit coupling contributions calculated at the 4-component Kramers restricted configuration interaction level, as well as the Gaunt term computed at the Dirac-Hartree-Fock level, were added to the best scalar relativistic results. The final ionization potentials are expected to be accurate to at least 5 kcal/mol (0.2 eV) and thus more reliable than the current experimental values of IP3 through IP6.
Bross, David H.; Parmar, Payal; Peterson, Kirk A.
2015-11-14
The first 6 ionization potentials (IPs) of the uranium atom have been calculated using multireference configuration interaction (MRCI+Q) with extrapolations to the complete basis set limit using new all-electron correlation consistent basis sets. The latter was carried out with the third-order Douglas-Kroll-Hess Hamiltonian. Correlation down through the 5s5p5d electrons has been taken into account, as well as contributions to the IPs due to the Lamb shift. Spin-orbit coupling contributions calculated at the 4-component Kramers restricted configuration interaction level, as well as the Gaunt term computed at the Dirac-Hartree-Fock level, were added to the best scalar relativistic results. The final ionization potentials are expected to be accurate to at least 5 kcal/mol (0.2 eV) and thus more reliable than the current experimental values of IP{sub 3} through IP{sub 6}.
Borovkov, V I; Beregovaya, I V; Shchegoleva, L N; Potashov, P A; Bagryansky, V A; Molin, Y N
2012-09-14
Paramagnetic spin-lattice relaxation (SLR) in radical cations (RCs) of the cycloalkane series in liquid solution was studied and analyzed from the point of view of the correlation between the relaxation rate and the structure of the adiabatic potential energy surface (PES) of the RCs. SLR rates in the RCs formed in x-ray irradiated n-hexane solutions of the cycloalkanes studied were measured with the method of time-resolved magnetic field effect in the recombination fluorescence of spin-correlated radical ion pairs. Temperature and, for some cycloalkanes, magnetic field dependences of the relaxation rate were determined. It was found that the conventional Redfield theory of the paramagnetic relaxation as applied to the results on cyclohexane RC, gave a value of about 0.2 ps for the correlation time of the perturbation together with an unrealistically high value of 0.1 T in field units for the matrix element of the relaxation transition. The PES structure was obtained with the DFT quantum-chemical calculations. It was found that for all of the cycloalkanes RCs considered, including low symmetric alkyl-substituted ones, the adiabatic PESes were surfaces of pseudorotation due to avoided crossing. In the RCs studied, a correlation between the SLR rate and the calculated barrier height to the pseudorotation was revealed. For RCs with a higher relaxation rate, the apparent activation energies for the SLR were similar to the calculated heights of the barrier. To rationalize the data obtained it was assumed that the vibronic states degeneracy, which is specific for Jahn-Teller active cyclohexane RC, was approximately kept in the RCs of substituted cycloalkanes for the vibronic states with the energies above and close to the barrier height to the pseudorotation. It was proposed that the effective spin-lattice relaxation in a radical with nearly degenerate low-lying vibronic states originated from stochastic crossings of the vibronic levels that occur due to fluctuations of
Zhu, Xiaolei; Malbon, Christopher L; Yarkony, David R
2016-03-28
In a recent work we constructed a quasi-diabatic representation, H(d), of the 1, 2, 3(1)A adiabatic states of phenol from high level multireference single and double excitation configuration interaction electronic structure data, energies, energy gradients, and derivative couplings. That H(d) accurately describes surface minima, saddle points, and also regions of strong nonadiabatic interactions, reproducing the locus of conical intersection seams and the coordinate dependence of the derivative couplings. The present work determines the accuracy of H(d) for describing phenol photodissociation. Additionally, we demonstrate that a modest energetic shift of two diabats yields a quantifiably more accurate H(d) compared with experimental energetics. The analysis shows that in favorable circumstances it is possible to use single point energies obtained from the most reliable electronic structure methods available, including methods for which the energy gradients and derivative couplings are not available, to improve the quality of a global representation of several coupled potential energy surfaces. Our data suggest an alternative interpretation of kinetic energy release measurements near λphot ∼ 248 nm.
NASA Astrophysics Data System (ADS)
Zhu, Xiaolei; Malbon, Christopher L.; Yarkony, David R.
2016-03-01
In a recent work we constructed a quasi-diabatic representation, Hd, of the 1, 2, 31A adiabatic states of phenol from high level multireference single and double excitation configuration interaction electronic structure data, energies, energy gradients, and derivative couplings. That Hd accurately describes surface minima, saddle points, and also regions of strong nonadiabatic interactions, reproducing the locus of conical intersection seams and the coordinate dependence of the derivative couplings. The present work determines the accuracy of Hd for describing phenol photodissociation. Additionally, we demonstrate that a modest energetic shift of two diabats yields a quantifiably more accurate Hd compared with experimental energetics. The analysis shows that in favorable circumstances it is possible to use single point energies obtained from the most reliable electronic structure methods available, including methods for which the energy gradients and derivative couplings are not available, to improve the quality of a global representation of several coupled potential energy surfaces. Our data suggest an alternative interpretation of kinetic energy release measurements near λphot ˜ 248 nm.
Alonso, J L; Castro, A; Clemente-Gallardo, J; Echenique, P; Mazo, J J; Polo, V; Rubio, A; Zueco, D
2012-12-14
At non-zero temperature and when a system has low-lying excited electronic states, the ground-state Born-Oppenheimer approximation breaks down and the low-lying electronic states are involved in any chemical process. In this work, we use a temperature-dependent effective potential for the nuclei which can accommodate the influence of an arbitrary number of electronic states in a simple way, while at the same time producing the correct Boltzmann equilibrium distribution for the electronic part. With the help of this effective potential, we show that thermally activated low-lying electronic states can have a significant effect in molecular properties for which electronic excitations are oftentimes ignored. We study the thermal expansion of the Manganese dimer, Mn(2), where we find that the average bond length experiences a change larger than the present experimental accuracy upon the inclusion of the excited states into the picture. We also show that, when these states are taken into account, reaction-rate constants are modified. In particular, we study the opening of the ozone molecule, O(3), and show that in this case the rate is modified as much as a 20% with respect to the ground-state Born-Oppenheimer prediction.
Wireless adiabatic power transfer
Rangelov, A.A.; Suchowski, H.; Silberberg, Y.; Vitanov, N.V.
2011-03-15
Research Highlights: > Efficient and robust mid-range wireless energy transfer between two coils. > The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. > Wireless energy transfer is insensitive to any resonant constraints. > Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.
NASA Astrophysics Data System (ADS)
Homayoon, Zahra; Bowman, Joel M.
2014-10-01
A semi-global, permutationally invariant potential energy surface for NO3 is constructed from a subset of roughly 5000 Multi-State CASPT2 calculations (MS-CAS(17e,13o)PT2/aug-cc-pVTZ) reported by Morokuma and co-workers [H. Xiao, S. Maeda, and K. Morokuma, J. Chem. Theory Comput. 8, 2600 (2012)]. The PES, with empirical adjustments to modify the energies of two fundamentals and a hot-band transition, is used in full-dimensional vibrational self-consistent field/virtual state configuration interaction calculations using the code MULTIMODE. Vibrational energies and assignments are given for the fundamentals and low-lying combination states, including two that have been the focus of some controversy. Energies of a number of overtone and combinations are shown to be in good agreement with experiment and previous calculations using a model vibronic Hamiltonian [C. S. Simmons, T. Ichino, and J. F. Stanton, J. Phys. Chem. Lett. 3, 1946 (2012)]. Notably, the fundamental v3 is calculated to be at 1099 cm-1 in accord with the prediction from the vibronic analysis, although roughly 30 cm-1 higher. The state at 1493 cm-1 is assigned as v3 + v4, which is also in agreement with the vibronic analysis and some experiments. Vibrational energies for 15NO3 are also presented and these are also in good agreement with experiment.
NASA Technical Reports Server (NTRS)
Stallcop, James R.; Partridge, Harry; Levin, Eugene; Langhoff, Stephen R. (Technical Monitor)
1995-01-01
Collision integrals are fundamental quantities required to determine the transport properties of the environment surrounding aerospace vehicles in the upper atmosphere. These collision integrals can be determined as a function of temperature from the potential energy curves describing the atomic and molecular collisions. Ab initio calculations provide a practical method of computing the required interaction potentials. In this work we will discuss recent advances in scattering calculations with an emphasis on the accuracy that is obtainable. Results for interactions of the atoms and ionized atoms of nitrogen and oxygen will be reviewed and their application to the determination of transport properties, such as diffusion and viscosity coefficients, will be examined.
Gu, Quanli; Tang, Zhen; Su, Peifeng; Wu, Wei; Yang, Zhijun; Trindle, Carl O; Knee, Joseph L
2016-08-01
The ionization potential (IP) of the aromatic alpha hydroxy carboxylic acid, 9-hydroxy-9-fluorene carboxylic acid (9HFCA), is shifted by complexation with hydrogen bonding ligands such as water and formic acid. Generalized Kohn-Sham energy decomposition analysis decomposes the intermolecular binding energies into a frozen energy term, polarization, correlation, and/or dispersion energy terms, as well as terms of geometric relaxation and zero point energy. We observe that in each dimer the attractive polarization always increases upon ionization, enhancing binding in the cation and shifting the IP toward the red. For 9HFCA-H2O, a substantial decrease of the repulsive frozen energy in cation further shifts the IP toward red. For 9HFCA-HCOOH, the increase of the frozen energy actually occurs in the cation and shifts the IP toward blue. Consistent with the experimental measurements, our analysis provides new, non-intuitive perspectives on multiple hydrogen bonds interactions in carboxylic acids and water complexes.
NASA Astrophysics Data System (ADS)
Gu, Quanli; Tang, Zhen; Su, Peifeng; Wu, Wei; Yang, Zhijun; Trindle, Carl O.; Knee, Joseph L.
2016-08-01
The ionization potential (IP) of the aromatic alpha hydroxy carboxylic acid, 9-hydroxy-9-fluorene carboxylic acid (9HFCA), is shifted by complexation with hydrogen bonding ligands such as water and formic acid. Generalized Kohn-Sham energy decomposition analysis decomposes the intermolecular binding energies into a frozen energy term, polarization, correlation, and/or dispersion energy terms, as well as terms of geometric relaxation and zero point energy. We observe that in each dimer the attractive polarization always increases upon ionization, enhancing binding in the cation and shifting the IP toward the red. For 9HFCA—H2O, a substantial decrease of the repulsive frozen energy in cation further shifts the IP toward red. For 9HFCA—HCOOH, the increase of the frozen energy actually occurs in the cation and shifts the IP toward blue. Consistent with the experimental measurements, our analysis provides new, non-intuitive perspectives on multiple hydrogen bonds interactions in carboxylic acids and water complexes.
Amendt, Peter Ross, J. Steven; Milovich, Jose L.; Schneider, Marilyn; Storm, Erik; Callahan, Debra A.; Hinkel, Denise; Lasinski, Barbara; Meeker, Don; Michel, Pierre; Moody, John; Strozzi, David
2014-11-15
Rugby-shaped gold hohlraums driven by a nominal low-adiabat laser pulse shape have been tested on the National Ignition Facility. The rugby affords a higher coupling efficiency than a comparably sized cylinder hohlraum or, alternatively, improved drive symmetry and laser beam clearances for a larger hohlraum with similar cylinder wall area and laser energy. A first (large rugby hohlraum) shot at low energy (0.75 MJ) to test laser backscatter resulted in a moderately oblate CH capsule implosion, followed by a high energy shot (1.3 MJ) that gave a highly oblate compressed core according to both time-integrated and –resolved x-ray images. These implosions used low wavelength separation (1.0 Å) between the outer and inner cones to provide an alternative platform free of significant cross-beam energy transfer for simplified hohlraum dynamics. Post-shot 2- and 3-D radiation-hydrodynamic simulations using the high-flux model [M. D. Rosen et al., High Energy Density Phys. 7, 180 (2011)], however, give nearly round implosions for both shots, in striking contrast with observations. An analytic assessment of Rayleigh-Taylor hydrodynamic instability growth on the gold–helium gas-fill interface shows the potential for significant linear growth, saturation and transition to a highly nonlinear state. Candidate seeds for instability growth include laser speckle during the early-time laser picket episode in the presence of only partial temporal beam smoothing (1-D smoothing by spectral dispersion and polarization smoothing) and intensity modulations from quad-to-quad and beam overlap. Radiation-hydrodynamic 2-D simulations adapted to include a dynamic fall-line mix model across the unstable Au-He interface show good agreement with the observed implosion symmetry for both shots using an interface-to-fall-line penetration fraction of 100%. Physically, the potential development of an instability layer in a rugby hohlraum is tantamount to an enhanced wall motion leading to
NASA Astrophysics Data System (ADS)
Amendt, Peter; Ross, J. Steven; Milovich, Jose L.; Schneider, Marilyn; Storm, Erik; Callahan, Debra A.; Hinkel, Denise; Lasinski, Barbara; Meeker, Don; Michel, Pierre; Moody, John; Strozzi, David
2014-11-01
Rugby-shaped gold hohlraums driven by a nominal low-adiabat laser pulse shape have been tested on the National Ignition Facility. The rugby affords a higher coupling efficiency than a comparably sized cylinder hohlraum or, alternatively, improved drive symmetry and laser beam clearances for a larger hohlraum with similar cylinder wall area and laser energy. A first (large rugby hohlraum) shot at low energy (0.75 MJ) to test laser backscatter resulted in a moderately oblate CH capsule implosion, followed by a high energy shot (1.3 MJ) that gave a highly oblate compressed core according to both time-integrated and -resolved x-ray images. These implosions used low wavelength separation (1.0 Å) between the outer and inner cones to provide an alternative platform free of significant cross-beam energy transfer for simplified hohlraum dynamics. Post-shot 2- and 3-D radiation-hydrodynamic simulations using the high-flux model [M. D. Rosen et al., High Energy Density Phys. 7, 180 (2011)], however, give nearly round implosions for both shots, in striking contrast with observations. An analytic assessment of Rayleigh-Taylor hydrodynamic instability growth on the gold-helium gas-fill interface shows the potential for significant linear growth, saturation and transition to a highly nonlinear state. Candidate seeds for instability growth include laser speckle during the early-time laser picket episode in the presence of only partial temporal beam smoothing (1-D smoothing by spectral dispersion and polarization smoothing) and intensity modulations from quad-to-quad and beam overlap. Radiation-hydrodynamic 2-D simulations adapted to include a dynamic fall-line mix model across the unstable Au-He interface show good agreement with the observed implosion symmetry for both shots using an interface-to-fall-line penetration fraction of 100%. Physically, the potential development of an instability layer in a rugby hohlraum is tantamount to an enhanced wall motion leading to hindered
NASA Astrophysics Data System (ADS)
Song, Shu-Na; Liang, Hao; Peng, Liang-You; Jiang, Hong-Bing
2016-09-01
We theoretically investigate the low energy part of the photoelectron spectra in the tunneling ionization regime by numerically solving the time-dependent Schrdinger equation for different atomic potentials at various wavelengths. We find that the shift of the first above-threshold ionization (ATI) peak is closely related to the interferences between electron wave packets, which are controlled by the laser field and largely independent of the potential. By gradually changing the short-range potential to the long-range Coulomb potential, we show that the long-range potential’s effect is mainly to focus the electrons along the laser’s polarization and to generate the spider structure by enhancing the rescattering process with the parent ion. In addition, we find that the intermediate transitions and the Rydberg states have important influences on the number and the shape of the lobes near the threshold. Project supported by the National Natural Science Foundation of China (Grant Nos. 11322437 and 11574010) and the National Basic Research Program of China (Grant No. 2013CB922402).
Parallelizable adiabatic gate teleportation
NASA Astrophysics Data System (ADS)
Nakago, Kosuke; Hajdušek, Michal; Nakayama, Shojun; Murao, Mio
2015-12-01
To investigate how a temporally ordered gate sequence can be parallelized in adiabatic implementations of quantum computation, we modify adiabatic gate teleportation, a model of quantum computation proposed by Bacon and Flammia [Phys. Rev. Lett. 103, 120504 (2009), 10.1103/PhysRevLett.103.120504], to a form deterministically simulating parallelized gate teleportation, which is achievable only by postselection. We introduce a twisted Heisenberg-type interaction Hamiltonian, a Heisenberg-type spin interaction where the coordinates of the second qubit are twisted according to a unitary gate. We develop parallelizable adiabatic gate teleportation (PAGT) where a sequence of unitary gates is performed in a single step of the adiabatic process. In PAGT, numeric calculations suggest the necessary time for the adiabatic evolution implementing a sequence of L unitary gates increases at most as O (L5) . However, we show that it has the interesting property that it can map the temporal order of gates to the spatial order of interactions specified by the final Hamiltonian. Using this property, we present a controlled-PAGT scheme to manipulate the order of gates by a control qubit. In the controlled-PAGT scheme, two differently ordered sequential unitary gates F G and G F are coherently performed depending on the state of a control qubit by simultaneously applying the twisted Heisenberg-type interaction Hamiltonians implementing unitary gates F and G . We investigate why the twisted Heisenberg-type interaction Hamiltonian allows PAGT. We show that the twisted Heisenberg-type interaction Hamiltonian has an ability to perform a transposed unitary gate by just modifying the space ordering of the final Hamiltonian implementing a unitary gate in adiabatic gate teleportation. The dynamics generated by the time-reversed Hamiltonian represented by the transposed unitary gate enables deterministic simulation of a postselected event of parallelized gate teleportation in adiabatic
NASA Astrophysics Data System (ADS)
Chuluunbaatar, O.; Gusev, A. A.; Gerdt, V. P.; Rostovtsev, V. A.; Vinitsky, S. I.; Abrashkevich, A. G.; Kaschiev, M. S.; Serov, V. V.
2008-02-01
A FORTRAN 77 program is presented which calculates with the relative machine precision potential curves and matrix elements of the coupled adiabatic radial equations for a hydrogen-like atom in a homogeneous magnetic field. The potential curves are eigenvalues corresponding to the angular oblate spheroidal functions that compose adiabatic basis which depends on the radial variable as a parameter. The matrix elements of radial coupling are integrals in angular variables of the following two types: product of angular functions and the first derivative of angular functions in parameter, and product of the first derivatives of angular functions in parameter, respectively. The program calculates also the angular part of the dipole transition matrix elements (in the length form) expressed as integrals in angular variables involving product of a dipole operator and angular functions. Moreover, the program calculates asymptotic regular and irregular matrix solutions of the coupled adiabatic radial equations at the end of interval in radial variable needed for solving a multi-channel scattering problem by the generalized R-matrix method. Potential curves and radial matrix elements computed by the POTHMF program can be used for solving the bound state and multi-channel scattering problems. As a test desk, the program is applied to the calculation of the energy values, a short-range reaction matrix and corresponding wave functions with the help of the KANTBP program. Benchmark calculations for the known photoionization cross-sections are presented. Program summaryProgram title:POTHMF Catalogue identifier:AEAA_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAA_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.:8123 No. of bytes in distributed program, including test data
NASA Astrophysics Data System (ADS)
Bhaskaran-Nair, Kiran; Kowalski, Karol; Jarrell, Mark; Moreno, Juana; Shelton, William A.
2015-11-01
Polyacenes have attracted considerable attention due to their various applications in organic optoelectronic materials. This study focuses on linear polyacenes and their electron affinity (EA) and ionization potential (IP) properties. We have employed our recent implementation of EA/IP equation of motion coupled cluster singles and doubles (EA/IP-EOMCCSD) methods which are accurate, computationally efficient and are capable of treating large systems employing reasonable basis sets size. The EA/IP results obtained for naphthalene, anthracene, tetracene, pentacene, hexacene and heptacene are in a good agreement with experiment. Comparison between quality of excitation energies obtained from IP-EOMCCSD and EE-EOMCCSD formalisms were also studied.
Hohm, Uwe; Thakkar, Ajit J
2012-01-12
The atomic dipole polarizability α of the 101 elements from He to No is related to the second ionization potential I₂ and the Waber-Cromer radius r(WC). Our recommended model is the function α = P₁·I₂⁻⁴ + P₂·r(WC)(3) I₂(y). With the parameters P₁ = 2.26, P₂ = 3.912, and y = 0.439, it reproduces the polarizabilities of all 101 elements with a mean absolute deviation of 7.5 au.
Optical potential approach to the electron-atom impact ionization threshold problem
NASA Technical Reports Server (NTRS)
Temkin, A.; Hahn, Y.
1973-01-01
The problem of the threshold law for electron-atom impact ionization is reconsidered as an extrapolation of inelastic cross sections through the ionization threshold. The cross sections are evaluated from a distorted wave matrix element, the final state of which describes the scattering from the Nth excited state of the target atom. The actual calculation is carried for the e-H system, and a model is introduced which is shown to preserve the essential properties of the problem while at the same time reducing the dimensionability of the Schrodinger equation. Nevertheless, the scattering equation is still very complex. It is dominated by the optical potential which is expanded in terms of eigen-spectrum of QHQ. It is shown by actual calculation that the lower eigenvalues of this spectrum descend below the relevant inelastic thresholds; it follows rigorously that the optical potential contains repulsive terms. Analytical solutions of the final state wave function are obtained with several approximations of the optical potential.
Adiabatic capture and debunching
Ng, K.Y.; /Fermilab
2012-03-01
In the study of beam preparation for the g-2 experiment, adiabatic debunching and adiabatic capture are revisited. The voltage programs for these adiabbatic processes are derived and their properties discussed. Comparison is made with some other form of adiabatic capture program. The muon g-2 experiment at Fermilab calls for intense proton bunches for the creation of muons. A booster batch of 84 bunches is injected into the Recycler Ring, where it is debunched and captured into 4 intense bunches with the 2.5-MHz rf. The experiment requires short bunches with total width less than 100 ns. The transport line from the Recycler to the muon-production target has a low momentum aperture of {approx} {+-}22 MeV. Thus each of the 4 intense proton bunches required to have an emittance less than {approx} 3.46 eVs. The incoming booster bunches have total emittance {approx} 8.4 eVs, or each one with an emittance {approx} 0.1 eVs. However, there is always emittance increase when the 84 booster bunches are debunched. There will be even larger emittance increase during adiabatic capture into the buckets of the 2.5-MHz rf. In addition, the incoming booster bunches may have emittances larger than 0.1 eVs. In this article, we will concentrate on the analysis of the adiabatic capture process with the intention of preserving the beam emittance as much as possible. At this moment, beam preparation experiment is being performed at the Main Injector. Since the Main Injector and the Recycler Ring have roughly the same lattice properties, we are referring to adiabatic capture in the Main Injector instead in our discussions.
Bacon, Dave; Flammia, Steven T
2009-09-18
The difficulty in producing precisely timed and controlled quantum gates is a significant source of error in many physical implementations of quantum computers. Here we introduce a simple universal primitive, adiabatic gate teleportation, which is robust to timing errors and many control errors and maintains a constant energy gap throughout the computation above a degenerate ground state space. This construction allows for geometric robustness based upon the control of two independent qubit interactions. Further, our piecewise adiabatic evolution easily relates to the quantum circuit model, enabling the use of standard methods from fault-tolerance theory for establishing thresholds.
Śmiga, Szymon; Della Sala, Fabio; Buksztel, Adam; Grabowski, Ireneusz; Fabiano, Eduardo
2016-08-15
One important property of Kohn-Sham (KS) density functional theory is the exact equality of the energy of the highest occupied KS orbital (HOMO) with the negative ionization potential of the system. This exact feature is out of reach for standard density-dependent semilocal functionals. Conversely, accurate results can be obtained using orbital-dependent functionals in the optimized effective potential (OEP) approach. In this article, we investigate the performance, in this context, of some advanced OEP methods, with special emphasis on the recently proposed scaled-opposite-spin OEP functional. Moreover, we analyze the impact of the so-called HOMO condition on the final quality of the HOMO energy. Results are compared to reference data obtained at the CCSD(T) level of theory. © 2016 Wiley Periodicals, Inc.
A hierarchy of local coupled cluster singles and doubles response methods for ionization potentials.
Wälz, Gero; Usvyat, Denis; Korona, Tatiana; Schütz, Martin
2016-02-28
We present a hierarchy of local coupled cluster (CC) linear response (LR) methods to calculate ionization potentials (IPs), i.e., excited states with one electron annihilated relative to a ground state reference. The time-dependent perturbation operator V(t), as well as the operators related to the first-order (with respect to V(t)) amplitudes and multipliers, thus are not number conserving and have half-integer particle rank m. Apart from calculating IPs of neutral molecules, the method offers also the possibility to study ground and excited states of neutral radicals as ionized states of closed-shell anions. It turns out that for comparable accuracy IPs require a higher-order treatment than excitation energies; an IP-CC LR method corresponding to CC2 LR or the algebraic diagrammatic construction scheme through second order performs rather poorly. We therefore systematically extended the order with respect to the fluctuation potential of the IP-CC2 LR Jacobian up to IP-CCSD LR, keeping the excitation space of the first-order (with respect to V(t)) cluster operator restricted to the m=½⊕3/2 subspace and the accuracy of the zero-order (ground-state) amplitudes at the level of CC2 or MP2. For the more expensive diagrams beyond the IP-CC2 LR Jacobian, we employ local approximations. The implemented methods are capable of treating large molecular systems with hundred atoms or more.
Bross, David H.; Parmar, Payal; Peterson, Kirk A.
2015-11-12
The first 6 ionization potentials (IPs) of the uranium atom have been calculated using multireference configuration interaction (MRCI+Q) with extrapolations to the complete basis set (CBS) limit using new all-electron correlation consistent basis sets. The latter were carried out with the third-order Douglas-Kroll-Hess Hamiltonian. Correlation down through the 5s5p5d electrons have been taken into account, as well as contributions to the IPs due to the Lamb shift. Spin-orbit coupling contributions calculated at the 4-component Kramers restricted configuration interaction level, as well as the Gaunt term computed at the Dirac-Hartree-Fock level, were added to the best scalar relativistic results. As amore » result, the final ionization potentials are expected to be accurate to at least 5 kcal/mol (0.2 eV), and thus more reliable than the current experimental values of IP3 through IP6.« less
Bross, David H.; Parmar, Payal; Peterson, Kirk A.
2015-11-12
The first 6 ionization potentials (IPs) of the uranium atom have been calculated using multireference configuration interaction (MRCI+Q) with extrapolations to the complete basis set (CBS) limit using new all-electron correlation consistent basis sets. The latter were carried out with the third-order Douglas-Kroll-Hess Hamiltonian. Correlation down through the 5s5p5d electrons have been taken into account, as well as contributions to the IPs due to the Lamb shift. Spin-orbit coupling contributions calculated at the 4-component Kramers restricted configuration interaction level, as well as the Gaunt term computed at the Dirac-Hartree-Fock level, were added to the best scalar relativistic results. As a result, the final ionization potentials are expected to be accurate to at least 5 kcal/mol (0.2 eV), and thus more reliable than the current experimental values of IP_{3} through IP_{6}.
Giardi, Maria Teresa; Touloupakis, Eleftherios; Bertolotto, Delfina; Mascetti, Gabriele
2013-01-01
Humans are constantly exposed to ionizing radiation deriving from outer space sources or activities related to medical care. Absorption of ionizing radiation doses over a prolonged period of time can result in oxidative damage and cellular dysfunction inducing several diseases, especially in ageing subjects. In this report, we analyze the effects of ionizing radiation, particularly at low doses, in relation to a variety of human pathologies, including cancer, and cardiovascular and retinal diseases. We discuss scientific data in support of protection strategies by safe antioxidant formulations that can provide preventive or potential therapeutic value in response to long-term diseases that may develop following exposure. PMID:23965979
NASA Astrophysics Data System (ADS)
Zhevstovskikh, I. V.; Bersuker, I. B.; Gudkov, V. V.; Averkiev, N. S.; Sarychev, M. N.; Zherlitsyn, S.; Yasin, S.; Shakurov, G. S.; Ulanov, V. A.; Surikov, V. T.
2016-06-01
A methodology is worked out to retrieve the numerical values of all the main parameters of the six-dimensional adiabatic potential energy surface (APES) of a polyatomic system with a quadratic T-term Jahn-Teller effect (JTE) from the ultrasound experiments. The method is based on a verified assumption that ultrasound attenuation and speed encounter anomalies when the direction of propagation and polarization of its wave of strain coincides with the characteristic directions of symmetry breaking in the JTE. For the SrF2:Cr crystal, employed as a basic example, we observed anomaly peaks in the temperature dependence of attenuation of ultrasound at frequencies of 50-160 MHz in the temperature interval of 40-60 K for the wave propagating along the [110] direction, for both the longitudinal and the shear modes, the latter with two polarizations along the [001] and [1 1 ¯ 0 ] axes, respectively. We show that these anomalies are due to the ultrasound relaxation by the system of non-interacting Cr2+ JT centers with orthorhombic local distortions. The interpretation of the experimental findings is based on the T2 g⊗(eg+t2 g) JTE problem including the linear and the quadratic terms of vibronic interactions in the Hamiltonian and the same-symmetry modes reduced to one interaction mode. Combining the experimental results with a theoretical analysis, we show that on the complicated six-dimensional APES of this system with three tetragonal, four trigonal, and six orthorhombic extrema points, the latter are global minima, while the former are saddle points, and we estimate numerically all the main parameters of this surface, including the linear and quadratic vibronic coupling constants, the primary force constants, the coordinates of all the extrema points and their energies, the energy barrier between the orthorhombic minima, and the tunneling splitting of the ground vibrational states. To our knowledge, such a based-on-experimental-data numerical reconstruction of the APES
Adiabatic processes in monatomic gases
NASA Astrophysics Data System (ADS)
Carrera-Patiño, Martin E.
1988-08-01
A kinetic model is used to predict the temperature evolution of a monatomic ideal gas undergoing an adiabatic expansion or compression at a constant finite rate, and it is then generalized to treat real gases. The effects of interatomic forces are considered, using as examples the gas with the square-well potential and the van der Waals gas. The model is integrated into a Carnot cycle operating at a finite rate to compare the efficiency's rate-dependent behavior with the reversible result. Limitations of the model, rate penalties, and their importance are discussed.
Adiabatically implementing quantum gates
Sun, Jie; Lu, Songfeng Liu, Fang
2014-06-14
We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process.
Entanglement and adiabatic quantum computation
NASA Astrophysics Data System (ADS)
Ahrensmeier, D.
2006-06-01
Adiabatic quantum computation provides an alternative approach to quantum computation using a time-dependent Hamiltonian. The time evolution of entanglement during the adiabatic quantum search algorithm is studied, and its relevance as a resource is discussed.
Gu, Quanli; Tang, Zhen; Su, Peifeng; Wu, Wei; Yang, Zhijun; Trindle, Carl O; Knee, Joseph L
2016-08-01
The ionization potential (IP) of the aromatic alpha hydroxy carboxylic acid, 9-hydroxy-9-fluorene carboxylic acid (9HFCA), is shifted by complexation with hydrogen bonding ligands such as water and formic acid. Generalized Kohn-Sham energy decomposition analysis decomposes the intermolecular binding energies into a frozen energy term, polarization, correlation, and/or dispersion energy terms, as well as terms of geometric relaxation and zero point energy. We observe that in each dimer the attractive polarization always increases upon ionization, enhancing binding in the cation and shifting the IP toward the red. For 9HFCA-H2O, a substantial decrease of the repulsive frozen energy in cation further shifts the IP toward red. For 9HFCA-HCOOH, the increase of the frozen energy actually occurs in the cation and shifts the IP toward blue. Consistent with the experimental measurements, our analysis provides new, non-intuitive perspectives on multiple hydrogen bonds interactions in carboxylic acids and water complexes. PMID:27497532
NON-WKB MODELS OF THE FIRST IONIZATION POTENTIAL EFFECT: THE ROLE OF SLOW MODE WAVES
Laming, J. Martin
2012-01-10
A model for element abundance fractionation between the solar chromosphere and corona is further developed. The ponderomotive force due to Alfven waves propagating through or reflecting from the chromosphere in solar conditions generally accelerates chromospheric ions, but not neutrals, into the corona. This gives rise to what has become known as the first ionization potential effect. We incorporate new physical processes into the model. The chromospheric ionization balance is improved and the effect of different approximations is discussed. We also treat the parametric generation of slow mode waves by the parallel propagating Alfven waves. This is also an effect of the ponderomotive force, arising from the periodic variation of the magnetic pressure driving an acoustic mode, which adds to the background longitudinal pressure. This can have subtle effects on the fractionation, rendering it quasi-mass independent in the lower regions of the chromosphere. We also briefly discuss the change in the fractionation with Alfven wave frequency, relative to the frequency of the overlying coronal loop resonance.
High-field plasma acceleration in a high-ionization-potential gas
NASA Astrophysics Data System (ADS)
Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.
2016-06-01
Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ~150 GV m-1, over ~20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources.
High-field plasma acceleration in a high-ionization-potential gas
Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; et al
2016-06-17
Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. In our research, we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by upmore » to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ~150 GV m-1, over ~20 cm. Lastly, the results open new possibilities for the design of particle beam drivers and plasma sources.« less
NASA Technical Reports Server (NTRS)
Laming, J. Martin; Drake, J. J.; Widing, Kenneth G.
1995-01-01
In this paper we reanalayze the full-disk quiet-sun spectrum of Mallinovsky & Heroux (1973) with modern atomic data. The purposes of this are to check our atomic data and methods in other investigations using data from nearby stars obtained with the NASA Extreme Ultraviolet Explorer (EUVE) satellite, and to confirm that the solar first ionization potential (FIP) effect investigated by previous authors studying discrete solar regions is the same as that found in full-disk spectra. We recover the usual solar FIP effect of a coronal abundance enhancement of elements with a low FIP of a factor approximately 3-4 for lines formed at temperatures greater than approximately 10(exp 6) K. For lower temperatures, the FIP effect seems to be substantially smaller, in qualitative agreement with other data. Comparing our full-disk result with those from discrete solar structures suggest that the FIP effect is a function of altitude, with the lower temperature full-disk emission being dominated by the super-granulation network. We also compare the recent ionization balance of Arnaud & Raymond (1992) with that of Arnaud & Rothenflug (1985).
High-field plasma acceleration in a high-ionization-potential gas
Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.
2016-01-01
Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ∼150 GV m−1, over ∼20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources. PMID:27312720
High-field plasma acceleration in a high-ionization-potential gas.
Corde, S; Adli, E; Allen, J M; An, W; Clarke, C I; Clausse, B; Clayton, C E; Delahaye, J P; Frederico, J; Gessner, S; Green, S Z; Hogan, M J; Joshi, C; Litos, M; Lu, W; Marsh, K A; Mori, W B; Vafaei-Najafabadi, N; Walz, D; Yakimenko, V
2016-01-01
Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ∼150 GV m(-1), over ∼20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources. PMID:27312720
Ionization potential of {sup 9}Be calculated including nuclear motion and relativistic corrections
Stanke, Monika; Kedziera, Dariusz; Bubin, Sergiy; Adamowicz, Ludwik
2007-05-15
Variational calculations employing explicitly correlated Gaussian functions have been performed for the ground states of {sup 9}Be and {sup 9}Be{sup +} including the nuclear motion [i.e., without assuming the Born-Oppenheimer (BO) approximation]. An approach based on the analytical energy gradient calculated with respect to the Gaussian exponential parameters was employed, leading to energies of the two systems noticeably improved over those found in the recent paper of Pachucki and Komasa [Phys. Rev. A 73, 052502 (2006)]. The non-BO wave functions were used to calculate the {alpha}{sup 2} relativistic corrections ({alpha}=e{sup 2}/({Dirac_h}/2{pi})c). With those corrections and the {alpha}{sup 3} and {alpha}{sup 4} corrections taken from Pachucki and Komasa, a new value of the ionization potential (IP) of {sup 9}Be was determined. It agrees very well with the most recent experimental IP.
NASA Astrophysics Data System (ADS)
Shestakova, L. I.
2015-04-01
Calculated results are presented for solar radiation pressure acting on atoms and first ions. For some of these particles, radiation pressure exceeds the gravitational attraction and can accelerate them to large velocities. A comparison of the results with ionization potentials shows that the maxima of radiation pressure on neutral atoms coincide with the minima of the first ionization potentials (FIPs). This relationship is even more apparent for first ions. The minima of the second ionization potentials (SIPs) coincide with the radiation pressure maxima for a number of ions such as Be II, Mg II, Ca II, and the neighboring elements. Thus, radiation pressure may serve as a possible mechanism of acceleration of pickup ions and energetic neutral atoms (ENA) coming from an inner source (zodiacal dust and sungrazing comets). These atoms and ions, which are not typical of the solar wind, are formed as a result of the disintegration of comets or meteor showers near the Sun and can accelerate and reach the Earth's orbit as part of the solar wind. Doubly ionized atoms have resonance lines in the UV range, where solar radiation pressure has no apparent impact on the particle dynamics; thus, the proposed acceleration mechanism can only be applied to neutral atoms and first ions with low potentials of the subsequent ionization.
NASA Astrophysics Data System (ADS)
García-Hernández, Erwin; Díaz-García, Cecilia; Vargas, Rubicelia; Garza, Jorge
2014-09-01
The best way to estimate ionization potentials (I) for confined atoms is by using the same Hamiltonian for the neutral and the corresponding hypothetical ionized atom. For this purpose, we have implemented the electron propagator to second order (EP2) by using parallel programming techniques on graphic processing units (GPUs). These programming techniques exploit the GPUs for the evaluation of two-electron integrals, which is required for a self- consistent process and because of the reduction involved in the four-index integral transformation. As an example, we present results for confined helium, beryllium and neon atoms, and these are contrasted with previously reported results. Although Koopmans’ theorem (KT) provides good estimates for ionization potentials, it is evident that EP2 corrects these estimates. Unfortunately, the correction made by EP2 does not reveal a trend for confined atoms because in the case of certain confinement regions KT overestimates, whereas for other regions, KT underestimates the ionization potential. The orbital crossing between unoccupied orbitals is responsible for this behavior. In particular, if the lowest unoccupied atomic orbital (LUMO) crosses a virtual orbital, the difference {{I}_{EP2}}-{{I}_{KT}} will change its sign. Thus, EP2 approximation is required when the ionization potential is estimated for confined atoms.
Adiabatic topological quantum computing
NASA Astrophysics Data System (ADS)
Cesare, Chris; Landahl, Andrew J.; Bacon, Dave; Flammia, Steven T.; Neels, Alice
2015-07-01
Topological quantum computing promises error-resistant quantum computation without active error correction. However, there is a worry that during the process of executing quantum gates by braiding anyons around each other, extra anyonic excitations will be created that will disorder the encoded quantum information. Here, we explore this question in detail by studying adiabatic code deformations on Hamiltonians based on topological codes, notably Kitaev's surface codes and the more recently discovered color codes. We develop protocols that enable universal quantum computing by adiabatic evolution in a way that keeps the energy gap of the system constant with respect to the computation size and introduces only simple local Hamiltonian interactions. This allows one to perform holonomic quantum computing with these topological quantum computing systems. The tools we develop allow one to go beyond numerical simulations and understand these processes analytically.
Accurate adiabatic correction in the hydrogen molecule
NASA Astrophysics Data System (ADS)
Pachucki, Krzysztof; Komasa, Jacek
2014-12-01
A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10-12 at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H2, HD, HT, D2, DT, and T2 has been determined. For the ground state of H2 the estimated precision is 3 × 10-7 cm-1, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.
Accurate adiabatic correction in the hydrogen molecule
Pachucki, Krzysztof; Komasa, Jacek
2014-12-14
A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10{sup −12} at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H{sub 2}, HD, HT, D{sub 2}, DT, and T{sub 2} has been determined. For the ground state of H{sub 2} the estimated precision is 3 × 10{sup −7} cm{sup −1}, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.
Accurate adiabatic correction in the hydrogen molecule.
Pachucki, Krzysztof; Komasa, Jacek
2014-12-14
A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10(-12) at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H2, HD, HT, D2, DT, and T2 has been determined. For the ground state of H2 the estimated precision is 3 × 10(-7) cm(-1), which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels. PMID:25494728
Anders, André; Ni, Pavel; Panjan, Matjaž; Franz, Robert; Andersson, Joakim
2013-09-30
Ion energy distribution functions measured for high power impulse magnetron sputtering show features, such as a broad peak at several 10 eV with an extended tail, as well as asymmetry with respect to E×B, where E and B are the local electric and magnetic field vectors, respectively. Here it is proposed that those features are due to the formation of a potential hump of several 10 V in each of the traveling ionization zones. Potential hump formation is associated with a negative-positive-negative space charge that naturally forms in ionization zones driven by energetic drifting electrons.
Technology Transfer Automated Retrieval System (TEKTRAN)
The administration of primaquine (PQ), an essential drug for treatment and radical cure of malaria, can lead to methemoglobin formation and life-threatening hemolysis for glucose-6-phosphate dehydrogenase deficient patients. The ionization potential (IP, a quantitative measure of the ability to lose...
Bazzani, A.; Turchetti, G.; Benedetti, C.; Rambaldi, S.; Servizi, G.
2005-06-08
In a high intensity circular accelerator the synchrotron dynamics introduces a slow modulation in the betatronic tune due to the space-charge tune depression. When the transverse motion is non-linear due to the presence of multipolar effects, resonance islands move in the phase space and change their amplitude. This effect introduces the trapping and detrapping phenomenon and a slow diffusion in the phase space. We apply the neo-adiabatic theory to describe this diffusion mechanism that can contribute to halo formation.
Quantum-Mechanical Calculation of Ionization-Potential Lowering in Dense Plasmas
NASA Astrophysics Data System (ADS)
Son, Sang-Kil; Thiele, Robert; Jurek, Zoltan; Ziaja, Beata; Santra, Robin
2014-07-01
The charged environment within a dense plasma leads to the phenomenon of ionization-potential depression (IPD) for ions embedded in the plasma. Accurate predictions of the IPD effect are of crucial importance for modeling atomic processes occurring within dense plasmas. Several theoretical models have been developed to describe the IPD effect, with frequently discrepant predictions. Only recently, first experiments on IPD in Al plasma have been performed with an x-ray free-electron laser, where their results were found to be in disagreement with the widely used IPD model by Stewart and Pyatt. Another experiment on Al, at the Orion laser, showed disagreement with the model by Ecker and Kröll. This controversy shows a strong need for a rigorous and consistent theoretical approach to calculate the IPD effect. Here, we propose such an approach: a two-step Hartree-Fock-Slater model. With this parameter-free model, we can accurately and efficiently describe the experimental Al data and validate the accuracy of standard IPD models. Our model can be a useful tool for calculating atomic properties within dense plasmas with wide-ranging applications to studies on warm dense matter, shock experiments, planetary science, inertial confinement fusion, and nonequilibrium plasmas created with x-ray free-electron lasers.
An integrated programming and development environment for adiabatic quantum optimization
NASA Astrophysics Data System (ADS)
Humble, T. S.; McCaskey, A. J.; Bennink, R. S.; Billings, J. J.; DʼAzevedo, E. F.; Sullivan, B. D.; Klymko, C. F.; Seddiqi, H.
2014-01-01
Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware has raised challenging questions about how to evaluate adiabatic quantum optimization (AQO) programs. Processor behavior depends on multiple steps to synthesize an adiabatic quantum program, which are each highly tunable. We present an integrated programming and development environment for AQO called Jade Adiabatic Development Environment (JADE) that provides control over all the steps taken during program synthesis. JADE captures the workflow needed to rigorously specify the AQO algorithm while allowing a variety of problem types, programming techniques, and processor configurations. We have also integrated JADE with a quantum simulation engine that enables program profiling using numerical calculation. The computational engine supports plug-ins for simulation methodologies tailored to various metrics and computing resources. We present the design, integration, and deployment of JADE and discuss its potential use for benchmarking AQO programs by the quantum computer science community.
Geometry of the Adiabatic Theorem
ERIC Educational Resources Information Center
Lobo, Augusto Cesar; Ribeiro, Rafael Antunes; Ribeiro, Clyffe de Assis; Dieguez, Pedro Ruas
2012-01-01
We present a simple and pedagogical derivation of the quantum adiabatic theorem for two-level systems (a single qubit) based on geometrical structures of quantum mechanics developed by Anandan and Aharonov, among others. We have chosen to use only the minimum geometric structure needed for the understanding of the adiabatic theorem for this case.…
Yu Daren; Song Maojiang; Liu Hui; Zhang Xu; Li Hong
2012-07-15
Similar to a single stage Hall thruster, the magnetic field, which controls electron trajectory and electric field distribution, is the most important factor determining the performance of a double stage Hall thruster. Especially, a potential well, which is helpful to reduce the ion loss on the thruster walls, is shaped in the ionization stage due to the existence of an annular magnetic field topology there. In this paper, the influence of magnetic field strength in the ionization stage on the potential well is researched with both experiments and particle-in-cell simulations. It is found that the depth of potential well increases with the magnetic field strength as a result of enhanced magnetic confinement and lowered electron conductivity. Consequently, the plasma density as well as the ion current entering the acceleration stage increases. However, an excessive magnetic field strength leads to an excess of ion loss on the walls of the acceleration stage. Therefore, there is an appropriate magnetic field strength in the ionization stage that results in a proper potential well and consequently an optimal performance of a double stage Hall thruster.
HF echoes from ionization potentially produced by high-altitude discharges
Roussel-Dupre, R.A.; Blanc, E.
1997-03-01
The presence of ionization associated with high-altitude discharges has been detected using an HF radar operating at 2.2, 2.5, and 2.8 MHz. On several occasions, oblique echoes lasting several hundred ms at night and 1{r_arrow}10s during the day were observed. The echoes turned on in several interpulse times of 70 ms and were generally correlated with strong lightning activity prior to onset. The angles of arrival of sferics detected at three goniometer stations were used to determine the distance to thunderstorms. The data are consistent with specular reflections from columns of ionization produced at 55{endash}65 km altitude and having minimum electron densities of 6{times}10{sup 4}{endash}10{sup 5}cm{sup {minus}3}. The source of the ionization is believed to be high-altitude discharges.{copyright} 1997 American Geophysical Union
NASA Astrophysics Data System (ADS)
Verma, Prakash; Bartlett, Rodney J.
2016-07-01
Core excitation energies are computed with time-dependent density functional theory (TD-DFT) using the ionization energy corrected exchange and correlation potential QTP(0,0). QTP(0,0) provides C, N, and O K-edge spectra to about an electron volt. A mean absolute error (MAE) of 0.77 and a maximum error of 2.6 eV is observed for QTP(0,0) for many small molecules. TD-DFT based on QTP (0,0) is then used to describe the core-excitation spectra of the 22 amino acids. TD-DFT with conventional functionals greatly underestimates core excitation energies, largely due to the significant error in the Kohn-Sham occupied eigenvalues. To the contrary, the ionization energy corrected potential, QTP(0,0), provides excellent approximations (MAE of 0.53 eV) for core ionization energies as eigenvalues of the Kohn-Sham equations. As a consequence, core excitation energies are accurately described with QTP(0,0), as are the core ionization energies important in X-ray photoionization spectra or electron spectroscopy for chemical analysis.
Falcinelli, Stefano; Rosi, Marzio; Pirani, Fernando; Stranges, Domenico; Vecchiocattivi, Franco
2016-07-14
In this work, we present and analyze in detail new and recent ionization cross section and mass spectrum determinations, collected in the case of He*, Ne*-H2O, -H2S, and -NH3 ionizing collisions. These sets of data, obtained under the same experimental conditions, are relevant to identify differences in the autoionization stereodynamics of the three hydrogenated molecules and on the selective role of the imaginary part of the optical potential. We demonstrate that in these autoionization processes hydrogen and halogen bonds are competing because they are controlling both real and imaginary components of the optical potential that drives the complete reaction dynamics. In particular, we found that both components critically depend on the angular and radial approach between the reagent partners in determining the collision dynamics.
Bhaskaran-Nair, Kiran; Kowalski, Karol; Moreno, Juana; Jarrell, Mark; Shelton, William A
2014-08-21
In both molecular and periodic solid-state systems there is a need for the accurate determination of the ionization potential and the electron affinity for systems ranging from light harvesting polymers and photocatalytic compounds to semiconductors. The development of a Green's function approach based on the coupled cluster (CC) formalism would be a valuable tool for addressing many properties involving many-body interactions along with their associated correlation functions. As a first step in this direction, we have developed an accurate and parallel efficient approach based on the equation of motion-CC technique. To demonstrate the high degree of accuracy and numerical efficiency of our approach we calculate the ionization potential and electron affinity for C60 and C70. Accurate predictions for these molecules are well beyond traditional molecular scale studies. We compare our results with experiments and both quantum Monte Carlo and GW calculations. PMID:25149783
NASA Astrophysics Data System (ADS)
Kłos, Jacek; Alexander, Millard H.; Kumar, Praveen; Poirier, Bill; Jiang, Bin; Guo, Hua
2016-05-01
We report new and more accurate adiabatic potential energy surfaces (PESs) for the ground X˜ 1A1 and electronically excited C˜ 1B2(21A') states of the SO2 molecule. Ab initio points are calculated using the explicitly correlated internally contracted multi-reference configuration interaction (icMRCI-F12) method. A second less accurate PES for the ground X ˜ state is also calculated using an explicitly correlated single-reference coupled-cluster method with single, double, and non-iterative triple excitations [CCSD(T)-F12]. With these new three-dimensional PESs, we determine energies of the vibrational bound states and compare these values to existing literature data and experiment.
Krause, Pascal; Schlegel, H Bernhard
2014-11-01
The strong field ionization rates for ethylene, trans 1,3-butadiene, and trans,trans 1,3,5-hexatriene have been calculated using time-dependent configuration interaction with single excitations and a complex absorbing potential (TDCIS-CAP). The calculations used the aug-cc-pVTZ basis set with a large set of diffuse functions (3 s, 2 p, 3 d, and 1 f) on each atom. The absorbing boundary was placed 3.5 times the van der Waals radius from each atom. The simulations employed a seven-cycle cosine squared pulse with a wavelength of 800 nm. Ionization rates were calculated for intensities ranging from 0.3 × 10(14) W/cm(2) to 3.5 × 10(14) W/cm(2). Ionization rates along the molecular axis increased markedly with increasing conjugation length. By contrast, ionization rates perpendicular to the molecular axis were almost independent of the conjugation length. PMID:25381499
Krause, Pascal; Schlegel, H. Bernhard
2014-11-07
The strong field ionization rates for ethylene, trans 1,3-butadiene, and trans,trans 1,3,5-hexatriene have been calculated using time-dependent configuration interaction with single excitations and a complex absorbing potential (TDCIS-CAP). The calculations used the aug-cc-pVTZ basis set with a large set of diffuse functions (3 s, 2 p, 3 d, and 1 f) on each atom. The absorbing boundary was placed 3.5 times the van der Waals radius from each atom. The simulations employed a seven-cycle cosine squared pulse with a wavelength of 800 nm. Ionization rates were calculated for intensities ranging from 0.3 × 10{sup 14} W/cm{sup 2} to 3.5 × 10{sup 14} W/cm{sup 2}. Ionization rates along the molecular axis increased markedly with increasing conjugation length. By contrast, ionization rates perpendicular to the molecular axis were almost independent of the conjugation length.
Adiabatic theory for anisotropic cold molecule collisions
Pawlak, Mariusz; Shagam, Yuval; Narevicius, Edvardas; Moiseyev, Nimrod
2015-08-21
We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment {sup 4}He(1s2s {sup 3}S) + HD(1s{sup 2}) → {sup 4}He(1s{sup 2}) + HD{sup +}(1s) + e{sup −} [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings.
Adiabatic Heating of Contracting Turbulent Fluids
NASA Astrophysics Data System (ADS)
Robertson, Brant; Goldreich, Peter
2012-05-01
Turbulence influences the behavior of many astrophysical systems, frequently by providing non-thermal pressure support through random bulk motions. Although turbulence is commonly studied in systems with constant volume and mean density, turbulent astrophysical gases often expand or contract under the influence of pressure or gravity. Here, we examine the behavior of turbulence in contracting volumes using idealized models of compressed gases. Employing numerical simulations and an analytical model, we identify a simple mechanism by which the turbulent motions of contracting gases "adiabatically heat," experiencing an increase in their random bulk velocities until the largest eddies in the gas circulate over a Hubble time of the contraction. Adiabatic heating provides a mechanism for sustaining turbulence in gases where no large-scale driving exists. We describe this mechanism in detail and discuss some potential applications to turbulence in astrophysical settings.
ADIABATIC HEATING OF CONTRACTING TURBULENT FLUIDS
Robertson, Brant; Goldreich, Peter
2012-05-10
Turbulence influences the behavior of many astrophysical systems, frequently by providing non-thermal pressure support through random bulk motions. Although turbulence is commonly studied in systems with constant volume and mean density, turbulent astrophysical gases often expand or contract under the influence of pressure or gravity. Here, we examine the behavior of turbulence in contracting volumes using idealized models of compressed gases. Employing numerical simulations and an analytical model, we identify a simple mechanism by which the turbulent motions of contracting gases 'adiabatically heat', experiencing an increase in their random bulk velocities until the largest eddies in the gas circulate over a Hubble time of the contraction. Adiabatic heating provides a mechanism for sustaining turbulence in gases where no large-scale driving exists. We describe this mechanism in detail and discuss some potential applications to turbulence in astrophysical settings.
Adiabatic and isocurvature perturbation projections in multi-field inflation
Gordon, Chris; Saffin, Paul M. E-mail: Paul.Saffin@nottingham.ac.uk
2013-08-01
Current data are in good agreement with the predictions of single field inflation. However, the hemispherical asymmetry, seen in the cosmic microwave background data, may hint at a potential problem. Generalizing to multi-field models may provide one possible explanation. A useful way of modeling perturbations in multi-field inflation is to investigate the projection of the perturbation along and perpendicular to the background fields' trajectory. These correspond to the adiabatic and isocurvature perturbations. However, it is important to note that in general there are no corresponding adiabatic and isocurvature fields. The purpose of this article is to highlight the distinction between a field redefinition and a perturbation projection. We provide a detailed derivation of the evolution of the isocurvature perturbation to show that no assumption of an adiabatic or isocurvature field is needed. We also show how this evolution equation is consistent with the field covariant evolution equations for the adiabatic perturbation in the flat field space limit.
Yamada, Atsushi; Okazaki, Susumu
2008-01-28
We present a quantum equation of motion for chemical reaction systems on an adiabatic double-well potential surface in solution in the framework of mixed quantum-classical molecular dynamics, where the reactant and product states are explicitly defined by dividing the double-well potential into the reactant and product wells. The equation can describe quantum reaction processes such as tunneling and thermal excitation and relaxation assisted by the solvent. Fluctuations of the zero-point energy level, the height of the barrier, and the curvature of the well are all included in the equation. Here, the equation was combined with the surface hopping technique in order to describe the motion of the classical solvent. Applying the present method to model systems, we show two numerical examples in order to demonstrate the potential power of the present method. The first example is a proton transfer by tunneling where the high-energy product state was stabilized very rapidly by solvation. The second example shows a thermal activation mechanism, i.e., the initial vibrational excitation in the reactant well followed by the reacting transition above the barrier and the final vibrational relaxation in the product well.
Non-adiabatic dark fluid cosmology
Hipólito-Ricaldi, W.S.; Velten, H.E.S.; Zimdahl, W. E-mail: velten@cce.ufes.br
2009-06-01
We model the dark sector of the cosmic substratum by a viscous fluid with an equation of state p = −ζΘ, where Θ is the fluid-expansion scalar and ζ is the coefficient of bulk viscosity for which we assume a dependence ζ∝ρ{sup ν} on the energy density ρ. The homogeneous and isotropic background dynamics coincides with that of a generalized Chaplygin gas with equation of state p = −A/ρ{sup α}. The perturbation dynamics of the viscous model, however, is intrinsically non-adiabatic and qualitatively different from the Chaplygin-gas case. In particular, it avoids short-scale instabilities and/or oscillations which apparently have ruled out unified models of the Chaplygin-gas type. We calculate the matter power spectrum and demonstrate that the non-adiabatic model is compatible with the data from the 2dFGRS and the SDSS surveys. A χ{sup 2}-analysis shows, that for certain parameter combinations the viscous-dark-fluid (VDF) model is well competitive with the ΛCDM model. These results indicate that non-adiabatic unified models can be seen as potential contenders for a General-Relativity-based description of the cosmic substratum.
Bernstein, N. K.; Karimi-Busheri, F.; Rasouli-Nia, A.; Mani, R.; Dianov, G.; Glover, J. N. M.; Weinfeld, M.
2010-01-01
The cytotoxicity of many antineoplastic agents is due to their capacity to damage DNA and there is evidence indicating that DNA repair contributes to the cellular resistance to such agents. DNA strand breaks constitute a significant proportion of the lesions generated by a broad range of genotoxic agents, either directly, or during the course of DNA repair. Strand breaks that are caused by many agents including ionizing radiation, topoisomerase I inhibitors, and DNA repair glycosylases such as NEIL1 and NEIL2, often contain 5’-hydroxyl and/or 3’-phosphate termini. These ends must be converted to 5’-phosphate and 3’-hydroxyl termini in order to allow DNA polymerases and ligases to catalyze repair synthesis and strand rejoining. A key enzyme involved in this end-processing is polynucleotide kinase (PNK), which possesses two enzyme activities, a DNA 5’-kinase activity and a 3’-phosphatase activity. PNK participates in the single-strand break repair pathway and the non-homologous end joining pathway for double-strand break repair. RNAi-mediated down-regulation of PNK renders cells more sensitive to ionizing radiation and camptothecin, a topoisomerase I inhibitor. Structural analysis of PNK revealed the protein is composed of three domains, the kinase domain at the C-terminus, the phosphatase domain in the centre and a forkhead associated (FHA) domain at the N-terminus. The FHA domain plays a critical role in the binding of PNK to other DNA repair proteins. Thus each PNK domain may be a suitable target for small molecule inhibition to effectively reduce resistance to ionizing radiation and topoisomerase I inhibitors. PMID:18473721
Tupitsyn, I.I.
1988-03-01
The ionization potentials of the halogen group have been calculated. The calculations were carried out using the relativistic Hartree-Fock method taking into account correlation effects. Comparison of theoretical results with experimental data for the elements F, Cl, Br, and I allows an estimation of the accuracy and reliability of the method. The theoretical values of the ionization potential of astatine obtained here may be of definite interest for the chemistry of astatine.
Theory of warm ionized gases: equation of state and kinetic Schottky anomaly.
Capolupo, A; Giampaolo, S M; Illuminati, F
2013-10-01
Based on accurate Lennard-Jones-type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analog in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiments.
Theory of warm ionized gases: equation of state and kinetic Schottky anomaly.
Capolupo, A; Giampaolo, S M; Illuminati, F
2013-10-01
Based on accurate Lennard-Jones-type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analog in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiments. PMID:24229140
NASA Astrophysics Data System (ADS)
Rubiano, J. G.; Rodríguez, R.; Gil, J. M.; Martel, P.; Mínguez, E.
2002-01-01
In this work, the Saha equation is solved using atomic data provided by means of a new relativistic-screened hydrogenic model based on analytical potentials to calculate the ionization state and ion abundance for LTE iron plasmas. The plasma effects on the atomic structure are taken into account by including the classical continuum lowering correction of Stewart and Pyatt. For high density, the Saha equation is modified to consider the degeneration of free electrons using the Fermi Dirac statistics instead of the Maxwellian distribution commonly used. The results are compared with more sophisticated self-consistent codes.
Chang, Zhiwei; Li, Jiguang; Dong, Chenzhong
2010-12-30
Multiconfiguration Dirac-Fock (MCDF) method was employed to calculate the first five ionization potentials, electron affinities, resonance excitation energies, oscillator strengths, and radii for the element Uus and its homologue At. Main valence correlation effects were taken into account. The Breit interaction and QED effects were also estimated. The uncertainties of calculated IPs, EAs, and IR for Uus and At were reduced through an extrapolation procedure. The good consistency with available experimental and other theoretical values demonstrates the validity of the present results. These theoretical data therefore can be used to predict some unknown physicochemical properties of element Uus, Astatine, and their compounds. PMID:21141866
Bhaskaran-Nair, Kiran; Kowalski, Karol; Moreno, Juana; Jarrell, Mark; Shelton, William A.
2014-08-21
Discovery of fullerenes has opened a entirely new chapter in chemistry due to their wide range of properties which holds exciting applications in numerous disciplines of science. The Nobel Prize in Chemistry 1996 was awarded jointly to Robert F. Curl Jr., Sir Harold W. Kroto and Richard E. Smalley in recoginition for their discovery of this new carbon allotrope. In this letter we are reporting ionization potential and electron attachment studies on fullerenes (C60 and C70) obtained with novel parallel implementation of the EA-EOM-CCSD and IP-EOM-CCSD methods in NWChem program package.
Chang, Zhiwei; Li, Jiguang; Dong, Chenzhong
2010-12-30
Multiconfiguration Dirac-Fock (MCDF) method was employed to calculate the first five ionization potentials, electron affinities, resonance excitation energies, oscillator strengths, and radii for the element Uus and its homologue At. Main valence correlation effects were taken into account. The Breit interaction and QED effects were also estimated. The uncertainties of calculated IPs, EAs, and IR for Uus and At were reduced through an extrapolation procedure. The good consistency with available experimental and other theoretical values demonstrates the validity of the present results. These theoretical data therefore can be used to predict some unknown physicochemical properties of element Uus, Astatine, and their compounds.
NASA Astrophysics Data System (ADS)
Sapozhkov, S. B.; Burakova, E. M.
2016-08-01
Strength is one of the most important characteristics of a weld joint. Mechanical properties of a weld metal can be improved in a variety of ways. One of the possibilities is to add a nanopowder to the weld metal. Authors of the paper suggest changing the production process of MMA welding electrodes via adding nanopowder Ti, Zr, Cs to electrode components through liquid glass. Theoretical research into the nanopowder influence on the effective ionization potential (Ueff) of welding arc discharge is also necessitated. These measures support arcing stability, improve strength of a weld joint, as the consequence, ensure quality enhancing of a weld joint and the structure on the whole.
Kuś, Tomasz; Krylov, Anna I
2011-08-28
The charge-stabilization method is applied to double ionization potential equation-of-motion (EOM-DIP) calculations to stabilize unstable dianion reference functions. The auto-ionizing character of the dianionic reference states spoils the numeric performance of EOM-DIP limiting applications of this method. We demonstrate that reliable excitation energies can be computed by EOM-DIP using a stabilized resonance wave function instead of the lowest energy solution corresponding to the neutral + free electron(s) state of the system. The details of charge-stabilization procedure are discussed and illustrated by examples. The choice of optimal stabilizing Coulomb potential, which is strong enough to stabilize the dianion reference, yet, minimally perturbs the target states of the neutral, is the crux of the approach. Two algorithms of choosing optimal parameters of the stabilization potential are presented. One is based on the orbital energies, and another--on the basis set dependence of the total Hartree-Fock energy of the reference. Our benchmark calculations of the singlet-triplet energy gaps in several diradicals show a remarkable improvement of the EOM-DIP accuracy in problematic cases. Overall, the excitation energies in diradicals computed using the stabilized EOM-DIP are within 0.2 eV from the reference EOM spin-flip values.
Kulshrestha, Pankaj; Sukumar, N; Murray, Jane S; Giese, Rossman F; Wood, Troy D
2009-01-29
Enzyme linked immunosorbent assay (ELISA) was used for the analysis of tetracycline, chlortetracycline, oxytetracycline, and their transformed compounds in environmental water samples. The antibodies employed in ELISA showed high relative affinity for tetracycline, epitetracycline, chlortetracycline, and epichlortetracycline as compared to anhydrotetracycline, epianhydrotetracycline, and anhydrochlortetracycline. The specificity and crossreactivity of these antibodies are discussed in relation to the electrostatic potentials and average local ionization energies computed on the molecular surfaces of tetracycline antibiotics and their transformed compounds with an objective of identifying common features as well as differences that may be related to the experimentally observed variation in cross-reactivity values. The computations were performed at both the HF/STO-3G and HF/6-31+G* levels using the Gaussian 98 program. The results in this study are based upon molecular electrostatic potentials and local ionization energies computed on isodensity molecular surfaces. The surface electrostatic potentials are characterized in terms of a group of statistically defined quantities, which include the average deviation, the positive, negative, and total variances, positive and negative surface extrema, and a parameter indicating the degree of electrostatic balance.
Momot, A. I.
2013-07-15
The problem of grain screening is solved numerically for the case of weakly ionized plasma in the presence of an external magnetic field. The plasma dynamics is described within the drift-diffusion approximation under the assumption that the grain absorbs all encountered electrons and ions. We also assume that the plasma current through the grain surface is equal to zero in the stationary state. This condition is used to perform self-consistent calculations of the grain charge. The spatial distribution of the screened grain potential is studied and compared with the analytical estimates. It is shown that at the distances larger than the Debye length such potential has the Coulomb-like asymptotics with the effective charge dependent on the angle between the radius vector and the external magnetic field direction. The numerical solutions show that in the direction parallel to the external magnetic field the effective potential can have nonmonotonic behavior.
Revisiting The Brightest RV Tauri Star: First Ionization Potential (FIP) Effect in R Sct
NASA Astrophysics Data System (ADS)
Yolalan, Gizay; Sahin, Timur
2016-07-01
We have derived elemental abundances of the brightest RV Tauri star, R Sct. The abundance analysis of the star is based on high resolution and high quality (S/N>300) echelle spectra, mainly obtained for radial velocity study of a large sample of IRAS like RV Tau sample stars, from the McDonald Observatory (R~48,000). Our analysis is based on optical spectra obtained at only one phase of the variation. The standard 1D LTE analysis provided a fresh determination of the atmospheric parameters: Teff=5000 K, logg=1.05 cgs, and a microturbulence velocity ξ=3.4 km/s and [Fe/H] = -0.33. We report on chemical abundances of 10 neutral and ionized species identified over 4800 - 5600 A wavelength region. In an effort to explain observed deficiency in abundances, possible scenarios including FIP is investigated.
Adiabatic computation: A toy model
NASA Astrophysics Data System (ADS)
Ribeiro, Pedro; Mosseri, Rémy
2006-10-01
We discuss a toy model for adiabatic quantum computation which displays some phenomenological properties expected in more realistic implementations. This model has two free parameters: the adiabatic evolution parameter s and the α parameter, which emulates many-variable constraints in the classical computational problem. The proposed model presents, in the s-α plane, a line of first-order quantum phase transition that ends at a second-order point. The relation between computation complexity and the occurrence of quantum phase transitions is discussed. We analyze the behavior of the ground and first excited states near the quantum phase transition, the gap, and the entanglement content of the ground state.
Adiabatic computation: A toy model
Ribeiro, Pedro; Mosseri, Remy
2006-10-15
We discuss a toy model for adiabatic quantum computation which displays some phenomenological properties expected in more realistic implementations. This model has two free parameters: the adiabatic evolution parameter s and the {alpha} parameter, which emulates many-variable constraints in the classical computational problem. The proposed model presents, in the s-{alpha} plane, a line of first-order quantum phase transition that ends at a second-order point. The relation between computation complexity and the occurrence of quantum phase transitions is discussed. We analyze the behavior of the ground and first excited states near the quantum phase transition, the gap, and the entanglement content of the ground state.
Adiabatic evolution of plasma equilibrium
Grad, H.; Hu, P. N.; Stevens, D. C.
1975-01-01
A new theory of plasma equilibrium is introduced in which adiabatic constraints are specified. This leads to a mathematically nonstandard structure, as compared to the usual equilibrium theory, in which prescription of pressure and current profiles leads to an elliptic partial differential equation. Topologically complex configurations require further generalization of the concept of adiabaticity to allow irreversible mixing of plasma and magnetic flux among islands. Matching conditions across a boundary layer at the separatrix are obtained from appropriate conservation laws. Applications are made to configurations with planned islands (as in Doublet) and accidental islands (as in Tokamaks). Two-dimensional, axially symmetric, helically symmetric, and closed line equilibria are included. PMID:16578729
Byrdwell, W C; Neff, W E; List, G R
2001-01-01
Several margarine base stock candidates have previously been prepared for the purpose of finding better, more oxidatively stable food components: high-saturate vegetable oils, randomized vegetable oils, vegetable oil-hard stock blends, and interesterified vegetable oil-hard stock blends. Here are reported the triacylglycerol compositions of these products, determined using reverse-phase high-performance liquid chromatography (HPLC) coupled with a flame ionization detector or a quadrupole mass spectrometer with an atmospheric pressure chemical ionization source. Triacylglycerol percent composition results for samples of known composition (randomized and interesterified samples) exhibited less average error by HPLC coupled with a quadrupole mass spectrometer with an atmospheric pressure chemical ionization source, after application of response factors, than the results by HPLC coupled with a flame ionization detector. The fatty acid compositions calculated from the mass spectrometric data exhibited less average error than the fatty acid compositions resulting from the flame ionization detector data. The average error of the fatty acid compositions by the mass spectrometer was lowest for interesterified blend samples, next lowest for randomized samples, then followed by high-saturated fatty acid oils, normal oils, and blends. Analysis of the vegetable oil-hard stock blends by mass spectrometer required special treatment for calculation of response factors.
Bravaya, Ksenia B.; Kostko, Oleg; Dolgikh, Stanislav; Landau, Arie; Ahmed, Musahid; Krylov, Anna I.
2010-08-02
We report high-level ab initio calculations and single-photon ionization mass spectrometry study of ionization of adenine (A), thymine (T), cytosine (C) and guanine (G). For thymine and adenine, only the lowest-energy tautomers were considered, whereas for cytosine and guanine we characterized five lowest-energy tautomeric forms. The first adiabatic and several vertical ionization energies were computed using equation-of-motion coupled-cluster method for ionization potentials with single and double substitutions. Equilibrium structures of the cationic ground states were characterized by DFT with the {omega}B97X-D functional. The ionization-induced geometry changes of the bases are consistent with the shapes of the corresponding molecular orbitals. For the lowest-energy tautomers, the magnitude of the structural relaxation decreases in the following series G > C > A > T, the respective relaxation energies being 0.41, 0.32, 0.25 and 0.20 eV. The computed adiabatic ionization energies (8.13, 8.89, 8.51-8.67 and 7.75-7.87 eV for A,T,C and G, respectively) agree well with the onsets of the photoionization efficiency (PIE) curves (8.20 {+-} 0.05, 8.95 {+-} 0.05, 8.60 {+-} 0.05 and 7.75 {+-} 0.05 eV). Vibrational progressions for the S{sub 0}-D{sub 0} vibronic bands computed within double-harmonic approximation with Duschinsky rotations are compared with previously reported experimental photoelectron spectra.
Mielke, Steven L; Schwenke, David W; Schatz, George C; Garrett, Bruce C; Peterson, Kirk A
2009-04-23
Multireference configuration interaction (MRCI) calculations of the Born-Oppenheimer diagonal correction (BODC) for H(3) were performed at 1397 symmetry-unique configurations using the Handy-Yamaguchi-Schaefer approach; isotopic substitution leads to 4041 symmetry-unique configurations for the DH(2) mass combination. These results were then fit to a functional form that permits calculation of the BODC for any combination of isotopes. Mean unsigned fitting errors on a test grid of configurations not included in the fitting process were 0.14, 0.12, and 0.65 cm(-1) for the H(3), DH(2), and MuH(2) isotopomers, respectively. This representation can be combined with any Born-Oppenheimer potential energy surface (PES) to yield Born-Huang (BH) PESs; herein, we choose the CCI potential energy surface, the uncertainties of which ( approximately 0.01 kcal/mol) are much smaller than the magnitude of the BODC. Fortran routines to evaluate these BH surfaces are provided. Variational transition state theory calculations are presented comparing thermal rate constants for reactions on the BO and BH surfaces to provide an initial estimate of the significance of the diagonal correction for the dynamics. PMID:19290604
Shortcuts to adiabaticity in a time-dependent box
Campo, A. del; Boshier, M. G.
2012-01-01
A method is proposed to drive an ultrafast non-adiabatic dynamics of an ultracold gas trapped in a time-dependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical self-similar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting many-body systems. As illustrative examples we consider the ultrafast expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential. PMID:22970340
Shortcuts to adiabaticity in a time-dependent box.
del Campo, A; Boshier, M G
2012-01-01
A method is proposed to drive an ultrafast non-adiabatic dynamics of an ultracold gas trapped in a time-dependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical self-similar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting many-body systems. As illustrative examples we consider the ultrafast expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential.
Shortcuts to adiabaticity in a time-dependent box
NASA Astrophysics Data System (ADS)
Del Campo, A.; Boshier, M. G.
2012-09-01
A method is proposed to drive an ultrafast non-adiabatic dynamics of an ultracold gas trapped in a time-dependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical self-similar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting many-body systems. As illustrative examples we consider the ultrafast expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential.
Crystal, J.; Friesner, R.A.
2000-03-23
Ionization potentials (IP) and electron affinities (EA) are calculated for bacteriopheophytin (BPh) and bacteriochlorophyll (BChl) in the photosynthetic reaction center utilizing density functional methods implemented in a parallel version of the JAGUAR electronic structure code. These quantities are studied as a function of basis set size and molecular geometry. The results indicate the necessity of using large basis sets with diffuse functions in order to obtain reliable IP and EA in the gas phase. The relative reduction potentials of BChl and BPh in dimethylformamide solution are also calculated and compared with experimental results. Excellent agreement between theory and experiment is obtained when ligand binding of solvent molecules to the central Mg atom of BNhl is incorporated in the calculations.
Adiabatic Floquet model for the optical response in femtosecond filaments
NASA Astrophysics Data System (ADS)
Hofmann, Michael; Brée, Carsten
2016-10-01
The standard model of femtosecond filamentation is based on phenomenological assumptions which suggest that the ionization-induced carriers can be treated as a homogeneous, uncorrelated plasma according to the Drude model, while the nonlinear response of the bound carriers is responsible for the all-optical Kerr effect. Here, we demonstrate that the additional plasma generated at a multiphoton resonance dominates the saturation of the nonlinear refractive index. Since resonances are not captured by the standard model, we propose a modification of the latter in which ionization enhancements can be accounted for by an ionization rate obtained from non-Hermitian Floquet theory. In the adiabatic regime of long pulse envelopes, this augmented standard model is in excellent agreement with direct quantum mechanical simulations. Since our proposal maintains the structure of the standard model, it can be easily incorporated into existing codes for the numerical simulation of femtosecond filaments.
Local entanglement generation in the adiabatic regime
Cliche, M.; Veitia, Andrzej
2010-09-15
We study entanglement generation in a pair of qubits interacting with an initially correlated system. Using time-independent perturbation theory and the adiabatic theorem, we show conditions under which the qubits become entangled as the joint system evolves into the ground state of the interacting theory. We then apply these results to the case of qubits interacting with a scalar quantum field. We study three different variations of this setup; a quantum field subject to Dirichlet boundary conditions, a quantum field interacting with a classical potential, and a quantum field that starts in a thermal state.
Pressure Oscillations in Adiabatic Compression
ERIC Educational Resources Information Center
Stout, Roland
2011-01-01
After finding Moloney and McGarvey's modified adiabatic compression apparatus, I decided to insert this experiment into my physical chemistry laboratory at the last minute, replacing a problematic experiment. With insufficient time to build the apparatus, we placed a bottle between two thick textbooks and compressed it with a third textbook forced…
Transitionless driving on adiabatic search algorithm
Oh, Sangchul; Kais, Sabre
2014-12-14
We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.
Sanders, Charles L.
2012-01-01
Ultra-low doses and dose- rates of ionizing radiation are effective in preventing disease which suggests that they also may be effective in treating disease. Limited experimental and anecdotal evidence indicates that low radiation doses from radon in mines and spas, thorium-bearing monazite sands and enhanced radioactive uranium ore obtained from a natural geological reactor may be useful in treating many inflammatory conditions and proliferative disorders, including cancer. Optimal therapeutic applications were identified via a literature survey as dose-rates ranging from 7 to 11μGy/hr or 28 to 44 times world average background rates. Rocks from an abandoned uranium mine in Utah were considered for therapeutic application and were examined by γ-ray and laser-induced breakdown fluorescence spectroscopy. The rocks showed the presence of transuranics and fission products with a γ-ray energy profile similar to aged spent uranium nuclear fuel (93% dose due to β particles and 7% due to γ rays). Mud packs of pulverized uranium ore rock dust in sealed plastic bags delivering bag surface β,γ dose-rates of 10–450 μGy/h were used with apparent success to treat several inflammatory and proliferative conditions in humans. PMID:23304108
Bond selective chemistry beyond the adiabatic approximation
Butler, L.J.
1993-12-01
One of the most important challenges in chemistry is to develop predictive ability for the branching between energetically allowed chemical reaction pathways. Such predictive capability, coupled with a fundamental understanding of the important molecular interactions, is essential to the development and utilization of new fuels and the design of efficient combustion processes. Existing transition state and exact quantum theories successfully predict the branching between available product channels for systems in which each reaction coordinate can be adequately described by different paths along a single adiabatic potential energy surface. In particular, unimolecular dissociation following thermal, infrared multiphoton, or overtone excitation in the ground state yields a branching between energetically allowed product channels which can be successfully predicted by the application of statistical theories, i.e. the weakest bond breaks. (The predictions are particularly good for competing reactions in which when there is no saddle point along the reaction coordinates, as in simple bond fission reactions.) The predicted lack of bond selectivity results from the assumption of rapid internal vibrational energy redistribution and the implicit use of a single adiabatic Born-Oppenheimer potential energy surface for the reaction. However, the adiabatic approximation is not valid for the reaction of a wide variety of energetic materials and organic fuels; coupling between the electronic states of the reacting species play a a key role in determining the selectivity of the chemical reactions induced. The work described below investigated the central role played by coupling between electronic states in polyatomic molecules in determining the selective branching between energetically allowed fragmentation pathways in two key systems.
Studies in Chaotic adiabatic dynamics
Jarzynski, C.
1994-01-01
Chaotic adiabatic dynamics refers to the study of systems exhibiting chaotic evolution under slowly time-dependent equations of motion. In this dissertation the author restricts his attention to Hamiltonian chaotic adiabatic systems. The results presented are organized around a central theme, namely, that the energies of such systems evolve diffusively. He begins with a general analysis, in which he motivates and derives a Fokker-Planck equation governing this process of energy diffusion. He applies this equation to study the {open_quotes}goodness{close_quotes} of an adiabatic invariant associated with chaotic motion. This formalism is then applied to two specific examples. The first is that of a gas of noninteracting point particles inside a hard container that deforms slowly with time. Both the two- and three-dimensional cases are considered. The results are discussed in the context of the Wall Formula for one-body dissipation in nuclear physics, and it is shown that such a gas approaches, asymptotically with time, an exponential velocity distribution. The second example involves the Fermi mechanism for the acceleration of cosmic rays. Explicit evolution equations are obtained for the distribution of cosmic ray energies within this model, and the steady-state energy distribution that arises when this equation is modified to account for the injection and removal of cosmic rays is discussed. Finally, the author re-examines the multiple-time-scale approach as applied to the study of phase space evolution under a chaotic adiabatic Hamiltonian. This leads to a more rigorous derivation of the above-mentioned Fokker-Planck equation, and also to a new term which has relevance to the problem of chaotic adiabatic reaction forces (the forces acting on slow, heavy degrees of freedom due to their coupling to light, fast chaotic degrees).
Morgan, William F.; Sowa, Marianne B.
2015-01-01
Not-targeted effects represent a paradigm shift from the "DNA centric" view that ionizing radiation only elicits biological effects and subsequent health consequences as a result of an energy deposition event in the cell nucleus. While this is likely true at higher radiation doses (> 1Gy), at low doses (< 100mGy) non-targeted effects associated with radiation exposure might play a significant role. Here definitions of non-targeted effects are presented, the potential mechanisms for the communication of signals and signaling networks from irradiated cells/tissues are proposed, and the various effects of this intra- and intercellular signaling are described. We conclude with speculation on how these observations might lead to and impact long-term human health outcomes.
Su, Neil Qiang; Xu, Xin
2016-05-10
Recently, we have developed an integration approach for the calculations of ionization potentials (IPs) and electron affinities (EAs) of molecular systems at the level of second-order Møller-Plesset (MP2) (Su, N. Q.; Xu, X. J. Chem. Theory Comput. 11, 4677, 2015), where the full MP2 energy gradient with respect to the orbital occupation numbers was derived but only at integer occupations. The theory is completed here to cover the fractional occupation systems, such that Slater's transition state concept can be used to have accurate predictions of IPs and EAs. Antisymmetrized Goldstone diagrams have been employed for interpretations and better understanding of the derived equations, where two additional rules were introduced in the present work specifically for hole or particle lines with fractional occupation numbers.
Su, Neil Qiang; Xu, Xin
2016-05-10
Recently, we have developed an integration approach for the calculations of ionization potentials (IPs) and electron affinities (EAs) of molecular systems at the level of second-order Møller-Plesset (MP2) (Su, N. Q.; Xu, X. J. Chem. Theory Comput. 11, 4677, 2015), where the full MP2 energy gradient with respect to the orbital occupation numbers was derived but only at integer occupations. The theory is completed here to cover the fractional occupation systems, such that Slater's transition state concept can be used to have accurate predictions of IPs and EAs. Antisymmetrized Goldstone diagrams have been employed for interpretations and better understanding of the derived equations, where two additional rules were introduced in the present work specifically for hole or particle lines with fractional occupation numbers. PMID:27010405
Beste, Ariana; Vazquez-Mayagoitia, Alvaro; Ortiz, J. Vincent
2013-01-01
A direct method (D-Delta-MBPT(2)) to calculate second-order ionization potentials (IPs), electron affinities (EAs), and excitation energies is developed. The Delta-MBPT(2) method is defined as the correlated extension of the Delta-HF method. Energy differences are obtained by integrating the energy derivative with respect to occupation numbers over the appropriate parameter range. This is made possible by writing the second-order energy as a function of the occupation numbers. Relaxation effects are fully included at the SCF level. This is in contrast to linear response theory, which makes the D-Delta-MBPT(2) applicable not only to single excited but also higher excited states. We show the relationship of the D-Delta-MBPT(2) method for IPs and EAs to a second-order approximation of the effective Fock-space coupled-cluster Hamiltonian and a second-order electron propagator method. We also discuss the connection between the D-Delta-MBPT(2) method for excitation energies and the CIS-MP2 method. Finally, as a proof of principle, we apply our method to calculate ionization potentials and excitation energies of some small molecules. For IPs, the Delta-MBPT(2) results compare well to the second-order solution of the Dyson equation. For excitation energies, the deviation from EOM-CCSD increases when correlation becomes more important. When using the numerical integration technique, we encounter difficulties that prevented us from reaching the Delta-MBPT(2) values. Most importantly, relaxation beyond the Hartree Fock level is significant and needs to be included in future research.
Ding, Yuanqing; Liu, Haining; Tekwani, Babu L; Nanayakkara, N P Dhammika; Khan, Ikhlas A; Walker, Larry A; Doerksen, Robert J
2016-07-18
The administration of primaquine (PQ), an essential drug for the treatment and radical cure of malaria, can lead to methemoglobin formation and life-threatening hemolysis for glucose-6-phosphate dehydrogenase deficient patients. The ionization potential (IP, a quantitative measure of the ability to lose an electron) of the metabolites generated by antimalarial 8-aminoquinoline (8-AQ) drugs like PQ has been believed to be correlated in part to this methemoglobinemia hemotoxicity: the lower the IP of an 8-AQ derivative, the higher the concentration of methemoglobin generated. In this work, demethoxylated primaquine (AQ02) was employed as a model, by intensive computation at the B3LYP-SCRF(PCM)/6-311++G**//B3LYP/6-31G** level in water, to study the effects of hydroxylation at various positions on the ionization potential. Compared to the parent AQ02, the IPs of AQ02's metabolites hydroxylated at N1', C5, and C7 were lower by 61, 30, and 19 kJ/mol, respectively, while differences in the IP relative to PQ were small for hydroxylation at all other positions. The C6 position, at which the IP of the hydroxylated metabolite was greater than that of AQ02, by 2 kJ/mol, was found to be unique. Several literature and proposed 8-AQ analogues were studied to evaluate substituent effects on their potential to generate methemoglobin, with the finding that hydroxylations at N1' and C5 contribute the most to the potential hemotoxicity of PQ-based antimalarials, whereas hydroxylation at C7 has little effect. Phenoxylation at C5 in PQ-based 8-AQs can block the hydroxylation at C5 and reduce the potential for methemoglobin generation, while -CF3 and chlorines attached to the phenolic ring can further reduce the risk. The H-shift at N1' during the cationization of hydroxylated metabolites of 8-AQs sharply decreased their IPs, but this effect can be significantly reduced by the introduction of an electron-withdrawing group to the quinoline core. The results and this approach may be
Spatial adiabatic passage: a review of recent progress
NASA Astrophysics Data System (ADS)
Menchon-Enrich, R.; Benseny, A.; Ahufinger, V.; Greentree, A. D.; Busch, Th; Mompart, J.
2016-07-01
Adiabatic techniques are known to allow for engineering quantum states with high fidelity. This requirement is currently of large interest, as applications in quantum information require the preparation and manipulation of quantum states with minimal errors. Here we review recent progress on developing techniques for the preparation of spatial states through adiabatic passage, particularly focusing on three state systems. These techniques can be applied to matter waves in external potentials, such as cold atoms or electrons, and to classical waves in waveguides, such as light or sound.
Spatial adiabatic passage: a review of recent progress.
Menchon-Enrich, R; Benseny, A; Ahufinger, V; Greentree, A D; Busch, Th; Mompart, J
2016-07-01
Adiabatic techniques are known to allow for engineering quantum states with high fidelity. This requirement is currently of large interest, as applications in quantum information require the preparation and manipulation of quantum states with minimal errors. Here we review recent progress on developing techniques for the preparation of spatial states through adiabatic passage, particularly focusing on three state systems. These techniques can be applied to matter waves in external potentials, such as cold atoms or electrons, and to classical waves in waveguides, such as light or sound. PMID:27245462
NASA Astrophysics Data System (ADS)
Li, Dafa
2016-05-01
The adiabatic theorem was proposed about 90 years ago and has played an important role in quantum physics. The quantitative adiabatic condition constructed from eigenstates and eigenvalues of a Hamiltonian is a traditional tool to estimate adiabaticity and has proven to be the necessary and sufficient condition for adiabaticity. However, recently the condition has become a controversial subject. In this paper, we list some expressions to estimate the validity of the adiabatic approximation. We show that the quantitative adiabatic condition is invalid for the adiabatic approximation via the Euclidean distance between the adiabatic state and the evolution state. Furthermore, we deduce general necessary and sufficient conditions for the validity of the adiabatic approximation by different definitions.
Effect of the Heat Pipe Adiabatic Region.
Brahim, Taoufik; Jemni, Abdelmajid
2014-04-01
The main motivation of conducting this work is to present a rigorous analysis and investigation of the potential effect of the heat pipe adiabatic region on the flow and heat transfer performance of a heat pipe under varying evaporator and condenser conditions. A two-dimensional steady-state model for a cylindrical heat pipe coupling, for both regions, is presented, where the flow of the fluid in the porous structure is described by Darcy-Brinkman-Forchheimer model which accounts for the boundary and inertial effects. The model is solved numerically by using the finite volumes method, and a fortran code was developed to solve the system of equations obtained. The results show that a phase change can occur in the adiabatic region due to temperature gradient created in the porous structure as the heat input increases and the heat pipe boundary conditions change. A recirculation zone may be created at the condenser end section. The effect of the heat transfer rate on the vapor radial velocities and the performance of the heat pipe are discussed. PMID:24895467
Etalo, Desalegn W.; De Vos, Ric C.H.; Joosten, Matthieu H.A.J.; Hall, Robert D.
2015-01-01
Laser-ablation electrospray ionization (LAESI)-mass spectrometry imaging has been applied to contrasting plant organs to assess its potential as a procedure for performing in vivo metabolomics in plants. In a proof-of-concept experiment, purple/white segmented Phalaenopsis spp. petals were first analyzed using standard liquid chromatography-mass spectrometry analyses of separate extracts made specifically from the purple and white regions. Discriminatory compounds were defined and putatively annotated. LAESI analyses were then performed on living tissues, and these metabolites were then relocalized within the LAESI-generated data sets of similar tissues. Maps were made to illustrate their locations across the petals. Results revealed that, as expected, anthocyanins always mapped to the purple regions. Certain other (nonvisible) polyphenols were observed to colocalize with the anthocyanins, whereas others were found specifically within the white tissues. In a contrasting example, control and Cladosporium fulvum-infected tomato (Solanum lycopersicum) leaves were subjected to the same procedures, and it could be observed that the alkaloid tomatine has clear heterogeneous distribution across the tomato leaf lamina. Furthermore, LAESI analyses revealed perturbations in alkaloid content following pathogen infection. These results show the clear potential of LAESI-based imaging approaches as a convenient and rapid way to perform metabolomics analyses on living tissues. However, a range of limitations and factors have also been identified that must be taken into consideration when interpreting LAESI-derived data. Such aspects deserve further evaluation before this approach can be applied in a routine manner. PMID:26392264
Adiabatic Wankel type rotary engine
NASA Technical Reports Server (NTRS)
Kamo, R.; Badgley, P.; Doup, D.
1988-01-01
This SBIR Phase program accomplished the objective of advancing the technology of the Wankel type rotary engine for aircraft applications through the use of adiabatic engine technology. Based on the results of this program, technology is in place to provide a rotor and side and intermediate housings with thermal barrier coatings. A detailed cycle analysis of the NASA 1007R Direct Injection Stratified Charge (DISC) rotary engine was performed which concluded that applying thermal barrier coatings to the rotor should be successful and that it was unlikely that the rotor housing could be successfully run with thermal barrier coatings as the thermal stresses were extensive.
Adiabatic preparation of Floquet condensates
NASA Astrophysics Data System (ADS)
Heinisch, Christoph; Holthaus, Martin
2016-10-01
We argue that a Bose-Einstein condensate can be transformed into a Floquet condensate, that is, into a periodically time-dependent many-particle state possessing the coherence properties of a mesoscopically occupied single-particle Floquet state. Our reasoning is based on the observation that the denseness of the many-body system's quasienergy spectrum does not necessarily obstruct effectively adiabatic transport. Employing the idealized model of a driven bosonic Josephson junction, we demonstrate that only a small amount of Floquet entropy is generated when a driving force with judiciously chosen frequency and maximum amplitude is turned on smoothly.
Ionization Thresholds of Small Carbon Clusters: Tunable VUVExperiments and Theory
Belau, Leonid; Wheeler, Steven E.; Ticknor, Brian W.; Ahmed,Musahid; Leone, Stephen R.; Allen, Wesley D.; Schaefer III, Henry F.; Duncan, Michael A.
2007-07-31
Small carbon clusters (Cn, n = 2-15) are produced in amolecular beam by pulsed laser vaporization and studied with vacuumultraviolet (VUV) photoionization mass spectrometry. The required VUVradiation in the 8-12 eV range is provided by the Advanced Light Source(ALS) at the Lawrence Berkeley National Laboratory. Mass spectra atvarious ionization energies reveal the qualitative relative abundances ofthe neutral carbon clusters produced. By far the most abundant species isC3. Using the tunability of the ALS, ionization threshold spectra arerecorded for the clusters up to 15 atoms in size. The ionizationthresholds are compared to those measured previously with charge-transferbracketing methods. To interpret the ionization thresholds for differentcluster sizes, new ab initio calculations are carried out on the clustersfor n = 4-10. Geometric structures are optimized at the CCSD(T) levelwith cc-pVTZ (or cc-pVDZ) basis sets, and focal point extrapolations areapplied to both neutral and cation species to determine adiabatic andvertical ionization potentials. The comparison of computed and measuredionization potentials makes it possible to investigate the isomericstructures of the neutral clusters produced in this experiment. Themeasurements are inconclusive for the n = 4-6 species because ofunquenched excited electronic states. However, the data provide evidencefor the prominence of linear structures for the n = 7, 9, 11, 13 speciesand the presence of cyclic C10.
Pathak, Himadri; Sasmal, Sudip; Nayak, Malaya K; Vaval, Nayana; Pal, Sourav
2016-08-21
The open-shell reference relativistic equation-of-motion coupled-cluster method within its four-component description is successfully implemented with the consideration of single- and double- excitation approximations using the Dirac-Coulomb Hamiltonian. At the first attempt, the implemented method is employed to calculate ionization potential value of heavy atomic (Ag, Cs, Au, Fr, and Lr) and molecular (HgH and PbF) systems, where the effect of relativity does really matter to obtain highly accurate results. Not only the relativistic effect but also the effect of electron correlation is crucial in these heavy atomic and molecular systems. To justify the fact, we have taken two further approximations in the four-component relativistic equation-of-motion framework to quantify how the effect of electron correlation plays a role in the calculated values at different levels of theory. All these calculated results are compared with the available experimental data as well as with other theoretically calculated values to judge the extent of accuracy obtained in our calculations. PMID:27544090
On the question of adiabatic invariants
NASA Astrophysics Data System (ADS)
Mitropol'Skii, Iu. A.
Some aspects of the construction of adiabadic invariants for dynamic systems with a single degree of freedom are discussed. Adiabatic invariants are derived using classical principles and the method proposed by Djukic (1981). The discussion covers an adiabatic invariant for a dynamic system with slowly varying parameters; derivation of an expression for an adiabatic invariant by the Djukic method for a second-order equation with a variable mass; and derivation of an expression for the adiabatic invariant for a nearly integrable differential equation.
NASA Astrophysics Data System (ADS)
Kimura, Jun-Ichi; Kawabata, Hiroshi
2014-06-01
numerical mass balance calculation model for the adiabatic melting of a dry to hydrous peridotite has been programmed in order to simulate the trace element compositions of basalts from mid-ocean ridges, back-arc basins, ocean islands, and large igneous provinces. The Excel spreadsheet-based calculator, Hydrous Adiabatic Mantle Melting Simulator version 1 (HAMMS1) uses (1) a thermodynamic model of fractional adiabatic melting of mantle peridotite, with (2) the parameterized experimental melting relationships of primitive to depleted mantle sources in terms of pressure, temperature, water content, and degree of partial melting. The trace element composition of the model basalt is calculated from the accumulated incremental melts within the adiabatic melting regime, with consideration for source depletion. The mineralogic mode in the primitive to depleted source mantle in adiabat is calculated using parameterized experimental results. Partition coefficients of the trace elements of mantle minerals are parameterized to melt temperature mostly from a lattice strain model and are tested using the latest compilations of experimental results. The parameters that control the composition of trace elements in the model are as follows: (1) mantle potential temperature, (2) water content in the source mantle, (3) depth of termination of adiabatic melting, and (4) source mantle depletion. HAMMS1 enables us to obtain the above controlling parameters using Monte Carlo fitting calculations and by comparing the calculated basalt compositions to primary basalt compositions. Additionally, HAMMS1 compares melting parameters with a major element model, which uses petrogenetic grids formulated from experimental results, thus providing better constraints on the source conditions.
Failure of geometric electromagnetism in the adiabatic vector Kepler problem
Anglin, J.R.; Schmiedmayer, J.
2004-02-01
The magnetic moment of a particle orbiting a straight current-carrying wire may precess rapidly enough in the wire's magnetic field to justify an adiabatic approximation, eliminating the rapid time dependence of the magnetic moment and leaving only the particle position as a slow degree of freedom. To zeroth order in the adiabatic expansion, the orbits of the particle in the plane perpendicular to the wire are Keplerian ellipses. Higher-order postadiabatic corrections make the orbits precess, but recent analysis of this 'vector Kepler problem' has shown that the effective Hamiltonian incorporating a postadiabatic scalar potential ('geometric electromagnetism') fails to predict the precession correctly, while a heuristic alternative succeeds. In this paper we resolve the apparent failure of the postadiabatic approximation, by pointing out that the correct second-order analysis produces a third Hamiltonian, in which geometric electromagnetism is supplemented by a tensor potential. The heuristic Hamiltonian of Schmiedmayer and Scrinzi is then shown to be a canonical transformation of the correct adiabatic Hamiltonian, to second order. The transformation has the important advantage of removing a 1/r{sup 3} singularity which is an artifact of the adiabatic approximation.
Sliding seal materials for adiabatic engines
NASA Technical Reports Server (NTRS)
Lankford, J.
1985-01-01
The sliding friction coefficients and wear rates of promising carbide, oxide, and nitride materials were measured under temperature, environmental, velocity, loading conditions that are representative of the adiabatic engine environment. In order to provide guidance needed to improve materials for this application, the program stressed fundamental understanding of the mechanisms involved in friction and wear. Microhardness tests were performed on the candidate materials at elevated temperatures, and in atmospheres relevant to the piston seal application, and optical and electron microscopy were used to elucidate the micromechanisms of wear following wear testing. X-ray spectroscopy was used to evaluate interface/environment interactions which seemed to be important in the friction and wear process. Electrical effects in the friction and wear processes were explored in order to evaluate the potential usefulness of such effects in modifying the friction and wear rates in service. However, this factor was found to be of negligible significance in controlling friction and wear.
Goble, J.H. Jr.
1982-05-01
Three variations on the Dunham series expansion function of the potential of a diatomic molecule are compared. The differences among these expansions lie in the choice of the expansion variable, lambda. The functional form of these variables are lambda/sub s/ = l-r/sub e//r for the Simon-Parr-Finlan version, lambda/sub T/ - 1-(r/sub e//r)/sup p/ for that of Thakkar, and lambda/sub H/ = 1-exp(-rho(r/r/sub e/-1) for that of Huffaker. A wide selection of molecular systems are examined. It is found that, for potentials in excess of thirty kcal/mole, the Huffaker expansion provides the best description of the three, extrapolating at large internuclear separation to a value within 10% of the true dissociation energy. For potentials that result from the interaction of excited states, all series expansions show poor behavior away from the equilibrium internuclear separation of the molecule. The series representation of the potentials of weakly bound molecules are examined in more detail. The ground states of BeAr/sup +/, HeNe/sup +/, NaAr, and Ar/sub 2/ and the excited states of HeNe+, NaNe, and NaAr are best described by the Thakkar expansion. Finally, the observation of laser-assisted excitive Penning ionization in a flowing afterglow is reported. The reaction Ar(/sup 3/P/sub 2/) + Ca + h nu ..-->.. Ar + Ca/sup +/(5p /sup 2/P/sub J/) + e/sup -/ occurs when the photon energy, h nu, is approximately equal to the energy difference between the metastable argon and one of the fine structure levels of the ion's doublet. By monitoring the cascade fluorescence of the above reaction and comparing it to the flourescence from the field-free process Ar(/sup 3/P/sub 2/) + Ca ..-->.. Ar + Ca/sup +/(4p /sup 2/P/sub J/) + e/sup -/ a surprisingly large cross section of 6.7 x 10/sup 3/ A/sup 2/ is estimated.
Ionization photophysics and spectroscopy of cyanoacetylene
Leach, Sydney; Champion, Norbert; Garcia, Gustavo A.; Fray, Nicolas; Gaie-Levrel, François; Mahjoub, Ahmed; Bénilan, Yves; Gazeau, Marie-Claire; Schwell, Martin
2014-05-07
Photoionization of cyanoacetylene was studied using synchrotron radiation over the non-dissociative ionization excitation range 11–15.6 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of cyanoacetylene was measured as 11.573 ± 0.010 eV. A detailed analysis of photoelectron spectra of HC{sub 3}N involves new aspects and new assignments of the vibrational components to excitation of the A{sup 2}Σ{sup +} and B{sup 2}Π states of the cation. Some of the structured autoionization features observed in the 11.94 to 15.5 eV region of the total ion yield (TIY) spectrum were assigned to two Rydberg series converging to the B{sup 2}Π state of HC{sub 3}N{sup +}. A number of the measured TIY features are suggested to be vibrational components of Rydberg series converging to the C{sup 2}Σ{sup +} state of HC{sub 3}N{sup +} at ≈17.6 eV and others to valence shell transitions of cyanoacetylene in the 11.6–15 eV region. The results of quantum chemical calculations of the cation electronic state geometries, vibrational frequencies and energies, as well as of the C–H dissociation potential energy profiles of the ground and electronic excited states of the ion, are compared with experimental observations. Ionization quantum yields are evaluated and discussed and the problem of adequate calibration of photoionization cross-sections is raised.
Degenerate adiabatic perturbation theory: Foundations and applications
NASA Astrophysics Data System (ADS)
Rigolin, Gustavo; Ortiz, Gerardo
2014-08-01
We present details and expand on the framework leading to the recently introduced degenerate adiabatic perturbation theory [Phys. Rev. Lett. 104, 170406 (2010), 10.1103/PhysRevLett.104.170406], and on the formulation of the degenerate adiabatic theorem, along with its necessary and sufficient conditions [given in Phys. Rev. A 85, 062111 (2012), 10.1103/PhysRevA.85.062111]. We start with the adiabatic approximation for degenerate Hamiltonians that paves the way to a clear and rigorous statement of the associated degenerate adiabatic theorem, where the non-Abelian geometric phase (Wilczek-Zee phase) plays a central role to its quantitative formulation. We then describe the degenerate adiabatic perturbation theory, whose zeroth-order term is the degenerate adiabatic approximation, in its full generality. The parameter in the perturbative power-series expansion of the time-dependent wave function is directly associated to the inverse of the time it takes to drive the system from its initial to its final state. With the aid of the degenerate adiabatic perturbation theory we obtain rigorous necessary and sufficient conditions for the validity of the adiabatic theorem of quantum mechanics. Finally, to illustrate the power and wide scope of the methodology, we apply the framework to a degenerate Hamiltonian, whose closed-form time-dependent wave function is derived exactly, and also to other nonexactly solvable Hamiltonians whose solutions are numerically computed.
Zeitlin, Benjamin D.; Spalding, Aaron C.; Campos, Marcia S.; Ashimori, Naoki; Dong Zhihong; Wang Shaomeng; Lawrence, Theodore S.; Noer, Jacques E.
2010-11-01
Purpose: To investigate the effect of a metronomic (low-dose, high-frequency) small-molecule inhibitor of Bcl-2 (TW-37) in combination with radiotherapy on microvascular endothelial cells in vitro and in tumor angiogenesis in vivo. Methods and Materials: Primary human dermal microvascular endothelial cells were exposed to ionizing radiation and/or TW-37 and colony formation, as well as capillary sprouting in three-dimensional collagen matrices, was evaluated. Xenografts vascularized with human blood vessels were engineered by cotransplantation of human squamous cell carcinoma cells (OSCC3) and human dermal microvascular endothelial cells seeded in highly porous biodegradable scaffolds into the subcutaneous space of immunodeficient mice. Mice were treated with metronomic TW-37 and/or radiation, and tumor growth was evaluated. Results: Low-dose TW-37 sensitized primary endothelial cells to radiation-induced inhibition of colony formation. Low-dose TW-37 or radiation partially inhibited endothelial cell sprout formation, and in combination, these therapies abrogated new sprouting. Combination of metronomic TW-37 and low-dose radiation inhibited tumor growth and resulted in significant increase in time to failure compared with controls, whereas single agents did not. Notably, histopathologic analysis revealed that tumors treated with TW-37 (with or without radiation) are more differentiated and showed more cohesive invasive fronts, which is consistent with less aggressive phenotype. Conclusions: These results demonstrate that metronomic TW-37 potentiates the antitumor effects of radiotherapy and suggest that patients with head and neck cancer might benefit from the combination of small molecule inhibitor of Bcl-2 and radiation therapy.
On a Nonlinear Model in Adiabatic Evolutions
NASA Astrophysics Data System (ADS)
Sun, Jie; Lu, Song-Feng
2016-08-01
In this paper, we study a kind of nonlinear model of adiabatic evolution in quantum search problem. As will be seen here, for this problem, there always exists a possibility that this nonlinear model can successfully solve the problem, while the linear model can not. Also in the same setting, when the overlap between the initial state and the final stare is sufficiently large, a simple linear adiabatic evolution can achieve O(1) time efficiency, but infinite time complexity for the nonlinear model of adiabatic evolution is needed. This tells us, it is not always a wise choice to use nonlinear interpolations in adiabatic algorithms. Sometimes, simple linear adiabatic evolutions may be sufficient for using. Supported by the National Natural Science Foundation of China under Grant Nos. 61402188 and 61173050. The first author also gratefully acknowledges the support from the China Postdoctoral Science Foundation under Grant No. 2014M552041
Quantum and classical dynamics in adiabatic computation
NASA Astrophysics Data System (ADS)
Crowley, P. J. D.; Äńurić, T.; Vinci, W.; Warburton, P. A.; Green, A. G.
2014-10-01
Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialized state and then slowly changing its Hamiltonian, one may achieve quantum states that would otherwise be inaccessible. Moreover, a judicious choice of final Hamiltonian whose ground state encodes the solution to a problem allows adiabatic transport to be used for universal quantum computation. However, the dephasing effects of the environment limit the quantum correlations that an open system can support and degrade the power of such adiabatic computation. We quantify this effect by allowing the system to evolve over a restricted set of quantum states, providing a link between physically inspired classical optimization algorithms and quantum adiabatic optimization. This perspective allows us to develop benchmarks to bound the quantum correlations harnessed by an adiabatic computation. We apply these to the D-Wave Vesuvius machine with revealing—though inconclusive—results.
Modulated voltage metastable ionization detector
NASA Technical Reports Server (NTRS)
Carle, G. C.; Kojiro, D. R.; Humphrey, D. E. (Inventor)
1985-01-01
The output current from a metastable ionization detector (MID) is applied to a modulation voltage circuit. An adjustment is made to balance out the background current, and an output current, above background, is applied to an input of a strip chart recorder. For low level concentrations, i.e., low detected output current, the ionization potential will be at a maximum and the metastable ionization detector will operate at its most sensitive level. When the detected current from the metastable ionization detector increases above a predetermined threshold level, a voltage control circuit is activated which turns on a high voltage transistor which acts to reduce the ionization potential. The ionization potential applied to the metastable ionization detector is then varied so as to maintain the detected signal level constant. The variation in ionization potential is now related to the concentration of the constituent and a representative amplitude is applied to another input of said strip chart recorder.
Measurement of a release adiabat from {approx}8 Mbar in lead using magnetically driven flyer impact
Rothman, S.D.; Parker, K.; Robinson, C.; Knudson, M.D.
2004-12-01
Using magnetically driven aluminium flyers to generate {approx}8 Mbar shocks in lead, which were then transmitted into lower-impedance material samples, points on a lead release adiabat have been measured. The pressure-particle-velocity points were calculated from known sample principal Hugoniots and from shock velocities measured using arrays of fiber-optic active and passive shock breakout diagnostics, and point and line velocity interferometer for a surface of any reflectivity (VISARs). The measured points agree closely with adiabats calculated using models which do not include ionization, or do include it both with, and without, atomic shell effects. Though the data are not sufficient to discriminate between widely different models we may qualitatively identify errors within these models. This is the first attempt to measure a release adiabat from such high pressures.
Bhaskaran-Nair, Kiran; Kowalski, Karol; Moreno, Juana; Jarrell, Mark; Shelton, William A.
2014-08-21
In both molecular and periodic solid-state systems there is a need for the accurate determination of the ionization potential and the electron affinity for systems ranging from light harvesting polymers and photocatalytic compounds to semiconductors. The development of a Green's function approach based on the coupled cluster (CC) formalism would be a valuable tool for addressing many properties involving many-body interactions along with their associated correlation functions. As a first step in this direction, we have developed an accurate and parallel efficient approach based on the equation of motion-CC technique. To demonstrate the high degree of accuracy and numerical efficiency of our approach we calculate the ionization potential and electron affinity for C{sub 60} and C{sub 70}. Accurate predictions for these molecules are well beyond traditional molecular scale studies. We compare our results with experiments and both quantum Monte Carlo and GW calculations.
Attosecond control of dissociative ionization of O{sub 2} molecules
Siu, W.; Kelkensberg, F.; Gademann, G.; Rouzee, A.; Vrakking, M. J. J.; Johnsson, P.; Dowek, D.; Lucchini, M.; Calegari, F.; De Giovannini, U.; Rubio, A.; Lucchese, R. R.; Kono, H.; Lepine, F.
2011-12-15
We demonstrate that dissociative ionization of O{sub 2} can be controlled by the relative delay between an attosecond pulse train (APT) and a copropagating infrared (IR) field. Our experiments reveal a dependence of both the branching ratios between a range of electronic states and the fragment angular distributions on the extreme ultraviolet (XUV) to IR time delay. The observations go beyond adiabatic propagation of dissociative wave packets on IR-induced quasistatic potential energy curves and are understood in terms of an IR-induced coupling between electronic states in the molecular ion.
Isegawa, Miho; Neese, Frank; Pantazis, Dimitrios A
2016-05-10
The calculation of redox potentials involves large energetic terms arising from gas phase ionization energies, thermodynamic contributions, and solvation energies of the reduced and oxidized species. In this work we study the performance of a wide range of wave function and density functional theory methods for the prediction of ionization energies and aqueous one-electron oxidation potentials of a set of 19 organic molecules. Emphasis is placed on evaluating methods that employ the computationally efficient local pair natural orbital (LPNO) approach, as well as several implementations of coupled cluster theory and explicitly correlated F12 methods. The electronic energies are combined with implicit solvation models for the solvation energies. With the exception of MP2 and its variants, which suffer from enormous errors arising at least partially from the poor Hartree-Fock reference, ionization energies can be systematically predicted with average errors below 0.1 eV for most of the correlated wave function based methods studies here, provided basis set extrapolation is performed. LPNO methods are the most efficient way to achieve this type of accuracy. DFT methods show in general larger errors and suffer from inconsistent behavior. The only exception is the M06-2X functional which is found to be competitive with the best LPNO-based approaches for ionization energies. Importantly, the limiting factor for the calculation of accurate redox potentials is the solvation energy. The errors in the predicted solvation energies by all continuum solvation models tested in this work dominate the final computed reduction potential, resulting in average errors typically in excess of 0.3 V and hence obscuring the gains that arise from choosing a more accurate electronic structure method.
Adiabatic two-photon quantum gate operations using a long-range photonic bus
NASA Astrophysics Data System (ADS)
Hope, Anthony P.; Nguyen, Thach G.; Mitchell, Arnan; Greentree, Andrew D.
2015-03-01
Adiabatic techniques have much potential to realize practical and robust optical waveguide devices. Traditionally, photonic elements are limited to coupling schemes that rely on proximity to nearest neighbour elements. We combine adiabatic passage with a continuum based long-range optical bus to break free from such topological restraints and thereby outline a new approach to photonic quantum gate design. We explicitly show designs for adiabatic quantum gates that produce a Hadamard, 50:50 and 1/3:2/3 beam splitter, and non-deterministic controlled NOT gate based on planar thin, shallow ridge waveguides. Our calculations are performed under conditions of one and two-photon inputs.
Arbitrary Amplitude DIA and DA Solitary Waves in Adiabatic Dusty Plasmas
Mamun, A. A.; Jahan, N.; Shukla, P. K.
2008-10-15
The dust-ion-acoustic (DIA) as well as the dust-acoustic (DA) solitary waves (SWs) in an adiabatic dusty plasma are investigated by the pseudo-potential approach which is valid for arbitrary amplitude SWs. The role of the adiabaticity of electrons and ions in modifying the basic features (polarity, speed, amplitude and width) of arbitrary amplitude DIA and DA SWs are explicitly examined. It is found that the effects of the adiabaticity of electrons and ions significantly modify the basic features (polarity, speed, amplitude and width) of the DIA and DA SWs. The implications of our results in space and laboratory dusty plasmas are briefly discussed.
Green, K.M.
1997-01-01
A diagnostic which combines a quartz crystal microbalance and a gridded energy analyzer has been developed to measure the ion-to- neutral ratio and the plasma potential in a commercial dc magnetron sputtering device. Additional features of this sensor include an externally controlled shutter which protects the diagnostic when it is in the chamber, but it is not in use. The diagnostic is mounted on a linear motion feedthrough and embedded in a slot in the wafer chuck to allow for measuring uniformity in deposition and ionization throughout the plane of the wafer. RF power is introduced to ionize the Al particles. Using the quartz crystal microbalance and the gridded energy analyzer, the ion-to-neutral ratio and other parameters are determined. Comparing the total deposition rate with and without a bias that screens out the ions, but leaves the plasma undisturbed, allows for the determination of the ion-to-neutral ratio. By varying the voltage applied to the grids, the plasma potential is measured. For example, a magnetron configuration having a pressure of 35 mtorr, a dc power of 2 kW, and a net rf power of 310{+-}5 W yielded 78{+-}5% ionization and a plasma potential of 35{+-}1 V.
A geometric criterion for adiabatic chaos
Kaper, T.J. ); Kovacic, G. )
1994-03-01
Chaos in adiabatic Hamiltonian systems is a recent discovery and a pervasive phenomenon in physics. In this work, a geometric criterion is discussed based on the theory of action from classical mechanics to detect the existence of Smale horseshoe chaos in adiabatic systems. It is used to show that generic adiabatic planar Hamiltonian systems exhibit stochastic dynamics in large regions of phase space. To illustrate the method, results are obtained for three problems concerning relativistic particle dynamics, fluid mechanics, and passage through resonance, results which either could not be obtained with existing methods, or which were difficult and analytically impractical to obtain with them.
Heating and cooling in adiabatic mixing process
Zhou Jing; Zou Xubo; Guo Guangcan; Cai Zi
2010-12-15
We study the effect of interaction on the temperature change in the process of adiabatic mixing of two components of Fermi gases using the real-space Bogoliubov-de Gennes method. We find that in the process of adiabatic mixing, the competition between the adiabatic expansion and the attractive interaction makes it possible to cool or heat the system depending on the strength of the interaction and the initial temperature of the system. The changes of the temperature in a bulk system and in a trapped system are investigated.
Electron ionization of acetylene
NASA Astrophysics Data System (ADS)
King, Simon J.; Price, Stephen D.
2007-11-01
Relative partial ionization cross sections and precursor specific relative partial ionization cross sections for fragment ions formed by electron ionization of C2H2 have been measured using time-of-flight mass spectrometry coupled with a 2D ion-ion coincidence technique. We report data for the formation of H+, H2+, C2+, C+/C22+, CH +/C2H22+, CH2+, C2+, and C2H + relative to the formation of C2H2+, as a function of ionizing electron energy from 30-200eV. While excellent agreement is found between our data and one set of previously published absolute partial ionization cross sections, some discrepancies exist between the results presented here and two other recent determinations of these absolute partial ionization cross sections. We attribute these differences to the loss of some translationally energetic fragment ions in these earlier studies. Our relative precursor-specific partial ionization cross sections enable us, for the first time, to quantify the contribution to the yield of each fragment ion from single, double, and triple ionization. Analysis shows that at 50eV double ionization contributes 2% to the total ion yield, increasing to over 10% at an ionizing energy of 100eV. From our ion-ion coincidence data, we have derived branching ratios for charge separating dissociations of the acetylene dication. Comparison of our data to recent ab initio/RRKM calculations suggest that close to the double ionization potential C2H22+ dissociates predominantly on the ground triplet potential energy surface (Σg-3) with a much smaller contribution from dissociation via the lowest singlet potential energy surface (Δg1). Measurements of the kinetic energy released in the fragmentation reactions of C2H22+ have been used to obtain precursor state energies for the formation of product ion pairs, and are shown to be in good agreement with available experimental data and with theory.
Laming, J. Martin
2009-04-20
We revisit in more detail a model for element abundance fractionation in the solar chromosphere that gives rise to the 'first ionization potential (FIP) effect' in the solar corona and wind. Elements with first ionization potential below about 10 eV, i.e., those that are predominantly ionized in the chromosphere, are enriched in the corona by a factor of 3-4. We model the propagation of Alfven waves through the chromosphere using a non-WKB treatment, and evaluate the ponderomotive force associated with these waves. Under solar conditions, this is generally pointed upward in the chromosphere, and enhances the abundance of chromospheric ions in the corona. Our new approach captures the essentials of the solar coronal abundance anomalies, including the depletion of He relative to H, and also the putative depletion of Ne, recently discussed in the literature. We also argue that the FIP effect provides the strongest evidence to date for energy fluxes of Alfven waves sufficient to heat the corona. However, it appears that these waves must also be generated in the corona, in order to preserve the rather regular fractionation pattern without strong variations from loop to loop observed in the solar corona and slow-speed solar wind.
Analytical instruments, ionization sources, and ionization methods
Atkinson, David A.; Mottishaw, Paul
2006-04-11
Methods and apparatus for simultaneous vaporization and ionization of a sample in a spectrometer prior to introducing the sample into the drift tube of the analyzer are disclosed. The apparatus includes a vaporization/ionization source having an electrically conductive conduit configured to receive sample particulate which is conveyed to a discharge end of the conduit. Positioned proximate to the discharge end of the conduit is an electrically conductive reference device. The conduit and the reference device act as electrodes and have an electrical potential maintained between them sufficient to cause a corona effect, which will cause at least partial simultaneous ionization and vaporization of the sample particulate. The electrical potential can be maintained to establish a continuous corona, or can be held slightly below the breakdown potential such that arrival of particulate at the point of proximity of the electrodes disrupts the potential, causing arcing and the corona effect. The electrical potential can also be varied to cause periodic arcing between the electrodes such that particulate passing through the arc is simultaneously vaporized and ionized. The invention further includes a spectrometer containing the source. The invention is particularly useful for ion mobility spectrometers and atmospheric pressure ionization mass spectrometers.
Artemyev, Anton N.; Müller, Anne D.; Demekhin, Philipp V.; Hochstuhl, David
2015-06-28
A theoretical method to study the angle-resolved multiphoton ionization of polyatomic molecules is developed. It is based on the time-dependent formulation of the Single Center (TDSC) method and consists in the propagation of single-active-electron wave packets in the effective molecular potentials in the presence of intense laser pulses. For this purpose, the time-dependent Schrödinger equation for one electron, moving in a molecular field and interacting with an arbitrary laser pulse, is solved in spherical coordinates by an efficient numerical approach. As a test, the method is applied to the one- and two-photon ionizations of a model methane-like chiral system by circularly polarized short intense high-frequency laser pulses. Thereby, we analyze the photoelectron circular dichroism (PECD) in the momentum distribution. The considered model application illustrates the capability of the TDSC method to study multiphoton PECD in fixed-in-space and randomly oriented chiral molecules.
Simulation of periodically focused, adiabatic thermal beams
Chen, C.; Akylas, T. R.; Barton, T. J.; Field, D. M.; Lang, K. M.; Mok, R. V.
2012-12-21
Self-consistent particle-in-cell simulations are performed to verify earlier theoretical predictions of adiabatic thermal beams in a periodic solenoidal magnetic focusing field [K.R. Samokhvalova, J. Zhou and C. Chen, Phys. Plasma 14, 103102 (2007); J. Zhou, K.R. Samokhvalova and C. Chen, Phys. Plasma 15, 023102 (2008)]. In particular, results are obtained for adiabatic thermal beams that do not rotate in the Larmor frame. For such beams, the theoretical predictions of the rms beam envelope, the conservations of the rms thermal emittances, the adiabatic equation of state, and the Debye length are verified in the simulations. Furthermore, the adiabatic thermal beam is found be stable in the parameter regime where the simulations are performed.
Adiabatic Motion of Fault Tolerant Qubits
NASA Astrophysics Data System (ADS)
Drummond, David Edward
This work proposes and analyzes the adiabatic motion of fault tolerant qubits in two systems as candidates for the building blocks of a quantum computer. The first proposal examines a pair of electron spins in double quantum dots, finding that the leading source of decoherence, hyperfine dephasing, can be suppressed by adiabatic rotation of the dots in real space. The additional spin-orbit effects introduced by this motion are analyzed, simulated, and found to result in an infidelity below the error-correction threshold. The second proposal examines topological qubits formed by Majorana zero modes theorized to exist at the ends of semiconductor nanowires coupled to conventional superconductors. A model is developed to design adiabatic movements of the Majorana bound states to produce entangled qubits. Analysis and simulations indicate that these adiabatic operations can also be used to demonstrate entanglement experimentally by testing Bell's theorem.
General conditions for quantum adiabatic evolution
Comparat, Daniel
2009-07-15
Adiabaticity occurs when, during its evolution, a physical system remains in the instantaneous eigenstate of the Hamiltonian. Unfortunately, existing results, such as the quantum adiabatic theorem based on a slow down evolution [H({epsilon}t),{epsilon}{yields}0], are insufficient to describe an evolution driven by the Hamiltonian H(t) itself. Here we derive general criteria and exact bounds, for the state and its phase, ensuring an adiabatic evolution for any Hamiltonian H(t). As a corollary, we demonstrate that the commonly used condition of a slow Hamiltonian variation rate, compared to the spectral gap, is indeed sufficient to ensure adiabaticity but only when the Hamiltonian is real and nonoscillating (for instance, containing exponential or polynomial but no sinusoidal functions)
Adiabatic Quantum Search in Open Systems
NASA Astrophysics Data System (ADS)
Wild, Dominik S.; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y.; Lukin, Mikhail D.
2016-10-01
Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.
Experimental demonstration of composite adiabatic passage
NASA Astrophysics Data System (ADS)
Schraft, Daniel; Halfmann, Thomas; Genov, Genko T.; Vitanov, Nikolay V.
2013-12-01
We report an experimental demonstration of composite adiabatic passage (CAP) for robust and efficient manipulation of two-level systems. The technique represents a altered version of rapid adiabatic passage (RAP), driven by composite sequences of radiation pulses with appropriately chosen phases. We implement CAP with radio-frequency pulses to invert (i.e., to rephase) optically prepared spin coherences in a Pr3+:Y2SiO5 crystal. We perform systematic investigations of the efficiency of CAP and compare the results with conventional π pulses and RAP. The data clearly demonstrate the superior features of CAP with regard to robustness and efficiency, even under conditions of weakly fulfilled adiabaticity. The experimental demonstration of composite sequences to support adiabatic passage is of significant relevance whenever a high efficiency or robustness of coherent excitation processes need to be maintained, e.g., as required in quantum information technology.
Adiabatic limits on Riemannian Heisenberg manifolds
Yakovlev, A A
2008-02-28
An asymptotic formula is obtained for the distribution function of the spectrum of the Laplace operator, in the adiabatic limit for the foliation defined by the orbits of an invariant flow on a compact Riemannian Heisenberg manifold. Bibliography: 21 titles.
AB INITIO SIMULATIONS FOR MATERIAL PROPERTIES ALONG THE JUPITER ADIABAT
French, Martin; Becker, Andreas; Lorenzen, Winfried; Nettelmann, Nadine; Bethkenhagen, Mandy; Redmer, Ronald; Wicht, Johannes
2012-09-15
We determine basic thermodynamic and transport properties of hydrogen-helium-water mixtures for the extreme conditions along Jupiter's adiabat via ab initio simulations, which are compiled in an accurate and consistent data set. In particular, we calculate the electrical and thermal conductivity, the shear and longitudinal viscosity, and diffusion coefficients of the nuclei. We present results for associated quantities like the magnetic and thermal diffusivity and the kinematic shear viscosity along an adiabat that is taken from a state-of-the-art interior structure model. Furthermore, the heat capacities, the thermal expansion coefficient, the isothermal compressibility, the Grueneisen parameter, and the speed of sound are calculated. We find that the onset of dissociation and ionization of hydrogen at about 0.9 Jupiter radii marks a region where the material properties change drastically. In the deep interior, where the electrons are degenerate, many of the material properties remain relatively constant. Our ab initio data will serve as a robust foundation for applications that require accurate knowledge of the material properties in Jupiter's interior, e.g., models for the dynamo generation.
Impact of electron ionization on the generation of high-order harmonics from molecules
Brener, S.; Moiseyev, N.; Ivanov, M. V.
2003-08-01
When the laser frequency is tuned to be equal to the molecular electronic excitation, high-order harmonics are generated due to the electronic dipole transitions between the corresponding two potential-energy surfaces (PES). A natural, often taken, choice is the PES of the field-free molecular system. In this special choice the ionization phenomenon is not considered. Only the effect of the dissociation is considered. The method we developed enables one to remain within the framework of the 2-PES approximation and yet to include also the ionization effect in the calculations of molecular high-order harmonic generation spectra. In this approach the coupling between the electronic and nuclear motions is taken into consideration by using coupled complex adiabatic PES. As an illustrative numerical example, we calculated the high harmonic generation (HHG) spectra of H{sub 2}{sup +} in a 730-nm laser with the intensity of 8.77x10{sup 13} W/cm{sup 2}. The inclusion of the ionization in our approach not only enables the electrons to tunnel through the effective static potential barrier, but also apply an asymmetric force which accelerates the electron before ionization takes place. Therefore, indirectly the inclusion of the ionization by the laser field may lead eventually to an enhanced HHG spectra in comparison with the calculated one when the ''natural'' choice of the field-free 2PES is taken.
Ionized cluster beam deposition
NASA Astrophysics Data System (ADS)
Kirkpatrick, A. R.
1983-11-01
Ionized Cluster Beam (ICB) deposition, a new technique originated by Takagi of Kyoto University in Japan, offers a number of unique capabilities for thin film metallization as well as for deposition of active semiconductor materials. ICB allows average energy per deposited atom to be controlled and involves impact kinetics which result in high diffusion energies of atoms on the growth surface. To a greater degree than in other techniques, ICB involves quantitative process parameters which can be utilized to strongly control the characteristics of films being deposited. In the ICB deposition process, material to be deposited is vaporized into a vacuum chamber from a confinement crucible at high temperature. Crucible nozzle configuration and operating temperature are such that emerging vapor undergoes supercondensation following adiabatic expansion through the nozzle.
Ionized cluster beam deposition
NASA Technical Reports Server (NTRS)
Kirkpatrick, A. R.
1983-01-01
Ionized Cluster Beam (ICB) deposition, a new technique originated by Takagi of Kyoto University in Japan, offers a number of unique capabilities for thin film metallization as well as for deposition of active semiconductor materials. ICB allows average energy per deposited atom to be controlled and involves impact kinetics which result in high diffusion energies of atoms on the growth surface. To a greater degree than in other techniques, ICB involves quantitative process parameters which can be utilized to strongly control the characteristics of films being deposited. In the ICB deposition process, material to be deposited is vaporized into a vacuum chamber from a confinement crucible at high temperature. Crucible nozzle configuration and operating temperature are such that emerging vapor undergoes supercondensation following adiabatic expansion through the nozzle.
Adiabatic Demagnetization Cooler For Far Infrared Detector
NASA Astrophysics Data System (ADS)
Sato, Akio; Yazawa, Takashi; Yamamoto, Junya
1988-11-01
An small adiabatic demagnetization cooler for an astronomical far infrared detector has been built. Single crystals of manganese ammonium sulphate and chromium potassium alum, were prepared as magnetic substances. The superconducting magnet was indirectly cooled and operated by small current up to 13.3 A, the maximum field being 3.5 T. As a preliminary step, adiabatic demagnetization to zero field was implemented. The lowest temperature obtained was 0.5 K, for 5.0 K initial temperature.
A Frontier orbital energy approach to redox potentials
NASA Astrophysics Data System (ADS)
Conradie, Jeanet
2015-09-01
The prediction of the oxidation and reduction potentials of molecules is important in many research areas. A review of relationships obtained between frontier orbital energies (eV), the calculated ionization potentials (IP in eV), or adiabatic electron affinities (EA in eV) with the experimental oxidation and reduction potentials is presented, for selected series of β- diketones, rhodium-β-diketonato complexes, as well as metal-tris-β-diketonato complexes, with the metal Fe or Mn. The good linear relationships obtained for related series of complexes show that the oxidation and reduction potentials of these complexes can be predicted by their DFT-calculated energies.
Adiabatic molecular-dynamics-simulation-method studies of kinetic friction
NASA Astrophysics Data System (ADS)
Zhang, J.; Sokoloff, J. B.
2005-06-01
An adiabatic molecular-dynamics method is developed and used to study the Muser-Robbins model for dry friction (i.e., nonzero kinetic friction in the slow sliding speed limit). In this model, dry friction between two crystalline surfaces rotated with respect to each other is due to mobile molecules (i.e., dirt particles) adsorbed at the interface. Our adiabatic method allows us to quickly locate interface potential-well minima, which become unstable during sliding of the surfaces. Since dissipation due to friction in the slow sliding speed limit results from mobile molecules dropping out of such unstable wells, our method provides a way to calculate dry friction, which agrees extremely well with results found by conventional molecular dynamics for the same system, but our method is more than a factor of 10 faster.
Sales, Carlos; Portolés, Tania; Sancho, Juan Vicente; Abad, Esteban; Ábalos, Manuela; Sauló, Jordi; Fiedler, Heidelore; Gómara, Belén; Beltrán, Joaquim
2016-01-01
A fast method for the screening and quantification of hexabromocyclododecane (sum of all isomers) by gas chromatography using a triple quadrupole mass spectrometer with atmospheric pressure chemical ionization (GC-APCI-QqQ) is proposed. This novel procedure makes use of the soft atmospheric pressure chemical ionization source, which results in less fragmentation of the analyte than by conventional electron impact (EI) and chemical ionization (CI) sources, favoring the formation of the [M - Br](+) ion and, thus, enhancing sensitivity and selectivity. Detection was based on the consecutive loses of HBr from the [M - Br](+) ion to form the specific [M - H5Br6](+) and [M - H4Br5](+) ions, which were selected as quantitation (Q) and qualification (q) transitions, respectively. Parameters affecting ionization and MS/MS detection were studied. Method performance was also evaluated; calibration curves were found linear from 1 pg/μL to 100 pg/μL for the total HBCD concentration; instrumental detection limit was estimated to be 0.10 pg/μL; repeatability and reproducibility, expressed as relative standard deviation, were better than 7% in both cases. The application to different real samples [polyurethane foam disks (PUFs), food, and marine samples] pointed out a rapid way to identify and allow quantification of this compound together with a number of polybrominated diphenyl ethers (BDE congeners 28, 47, 66, 85, 99, 100, 153, 154, 183, 184, 191, 196, 197, and 209) and two other novel brominated flame retardants [i.e., decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE)] because of their presence in the same fraction when performing the usual sample treatment.
Sales, Carlos; Portolés, Tania; Sancho, Juan Vicente; Abad, Esteban; Ábalos, Manuela; Sauló, Jordi; Fiedler, Heidelore; Gómara, Belén; Beltrán, Joaquim
2016-01-01
A fast method for the screening and quantification of hexabromocyclododecane (sum of all isomers) by gas chromatography using a triple quadrupole mass spectrometer with atmospheric pressure chemical ionization (GC-APCI-QqQ) is proposed. This novel procedure makes use of the soft atmospheric pressure chemical ionization source, which results in less fragmentation of the analyte than by conventional electron impact (EI) and chemical ionization (CI) sources, favoring the formation of the [M - Br](+) ion and, thus, enhancing sensitivity and selectivity. Detection was based on the consecutive loses of HBr from the [M - Br](+) ion to form the specific [M - H5Br6](+) and [M - H4Br5](+) ions, which were selected as quantitation (Q) and qualification (q) transitions, respectively. Parameters affecting ionization and MS/MS detection were studied. Method performance was also evaluated; calibration curves were found linear from 1 pg/μL to 100 pg/μL for the total HBCD concentration; instrumental detection limit was estimated to be 0.10 pg/μL; repeatability and reproducibility, expressed as relative standard deviation, were better than 7% in both cases. The application to different real samples [polyurethane foam disks (PUFs), food, and marine samples] pointed out a rapid way to identify and allow quantification of this compound together with a number of polybrominated diphenyl ethers (BDE congeners 28, 47, 66, 85, 99, 100, 153, 154, 183, 184, 191, 196, 197, and 209) and two other novel brominated flame retardants [i.e., decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE)] because of their presence in the same fraction when performing the usual sample treatment. PMID:26554601
Symmetry of the Adiabatic Condition in the Piston Problem
ERIC Educational Resources Information Center
Anacleto, Joaquim; Ferreira, J. M.
2011-01-01
This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be…
Hierarchical theory of quantum adiabatic evolution
NASA Astrophysics Data System (ADS)
Zhang, Qi; Gong, Jiangbin; Wu, Biao
2014-12-01
Quantum adiabatic evolution is a dynamical evolution of a quantum system under slow external driving. According to the quantum adiabatic theorem, no transitions occur between nondegenerate instantaneous energy eigenstates in such a dynamical evolution. However, this is true only when the driving rate is infinitesimally small. For a small nonzero driving rate, there are generally small transition probabilities between the energy eigenstates. We develop a classical mechanics framework to address the small deviations from the quantum adiabatic theorem order by order. A hierarchy of Hamiltonians is constructed iteratively with the zeroth-order Hamiltonian being determined by the original system Hamiltonian. The kth-order deviations are governed by a kth-order Hamiltonian, which depends on the time derivatives of the adiabatic parameters up to the kth-order. Two simple examples, the Landau-Zener model and a spin-1/2 particle in a rotating magnetic field, are used to illustrate our hierarchical theory. Our analysis also exposes a deep, previously unknown connection between classical adiabatic theory and quantum adiabatic theory.
Laboratory Measurements of Adiabatic and Isothermal Processes
NASA Astrophysics Data System (ADS)
McNairy, W. W.
1997-04-01
Adiabatic and isothermal measurements on various of gases are made possible by using the Adiabatic Gas Law apparatus made by PASCO Scientific(Much of this work was published by the author in "The Physics Teacher", vol. 34, March 1996, p. 178-80.). By using a computer interface, undergraduates are able to data for monatomic, diatomic and polyatomic gases for both compression and expansion processes. Designed principally to obtain adiabatic data, the apparatus may be easily modified for use in isothermal processes. The various sets of data are imported into a spreadsheet program where fits may be made to the ideal gas law and the adiabatic gas law. Excellent results are obtained for the natural logarithm of pressure versus the natural logarithm of volume for both the isothermal data (expected slope equal to -1 in all cases) and the adiabatic data (slope equal to -1 times the ratio of specific heats for the particular gas). An overview of the lab procedure used at VMI will be presented along with data obtained for several adiabatic and isothermal processes.
Excitation energies along a range-separated adiabatic connection
Rebolini, Elisa Toulouse, Julien Savin, Andreas; Teale, Andrew M.; Helgaker, Trygve
2014-07-28
We present a study of the variation of total energies and excitation energies along a range-separated adiabatic connection. This connection links the non-interacting Kohn–Sham electronic system to the physical interacting system by progressively switching on the electron–electron interactions whilst simultaneously adjusting a one-electron effective potential so as to keep the ground-state density constant. The interactions are introduced in a range-dependent manner, first introducing predominantly long-range, and then all-range, interactions as the physical system is approached, as opposed to the conventional adiabatic connection where the interactions are introduced by globally scaling the standard Coulomb interaction. Reference data are reported for the He and Be atoms and the H{sub 2} molecule, obtained by calculating the short-range effective potential at the full configuration-interaction level using Lieb's Legendre-transform approach. As the strength of the electron–electron interactions increases, the excitation energies, calculated for the partially interacting systems along the adiabatic connection, offer increasingly accurate approximations to the exact excitation energies. Importantly, the excitation energies calculated at an intermediate point of the adiabatic connection are much better approximations to the exact excitation energies than are the corresponding Kohn–Sham excitation energies. This is particularly evident in situations involving strong static correlation effects and states with multiple excitation character, such as the dissociating H{sub 2} molecule. These results highlight the utility of long-range interacting reference systems as a starting point for the calculation of excitation energies and are of interest for developing and analyzing practical approximate range-separated density-functional methodologies.
Assessment of total efficiency in adiabatic engines
NASA Astrophysics Data System (ADS)
Mitianiec, W.
2016-09-01
The paper presents influence of ceramic coating in all surfaces of the combustion chamber of SI four-stroke engine on working parameters mainly on heat balance and total efficiency. Three cases of engine were considered: standard without ceramic coating, fully adiabatic combustion chamber and engine with different thickness of ceramic coating. Consideration of adiabatic or semi-adiabatic engine was connected with mathematical modelling of heat transfer from the cylinder gas to the cooling medium. This model takes into account changeable convection coefficient based on the experimental formulas of Woschni, heat conductivity of multi-layer walls and also small effect of radiation in SI engines. The simulation model was elaborated with full heat transfer to the cooling medium and unsteady gas flow in the engine intake and exhaust systems. The computer program taking into account 0D model of engine processes in the cylinder and 1D model of gas flow was elaborated for determination of many basic engine thermodynamic parameters for Suzuki DR-Z400S 400 cc SI engine. The paper presents calculation results of influence of the ceramic coating thickness on indicated pressure, specific fuel consumption, cooling and exhaust heat losses. Next it were presented comparisons of effective power, heat losses in the cooling and exhaust systems, total efficiency in function of engine rotational speed and also comparison of temperature inside the cylinder for standard, semi-adiabatic and full adiabatic engine. On the basis of the achieved results it was found higher total efficiency of adiabatic engines at 2500 rpm from 27% for standard engine to 37% for full adiabatic engine.
Graph isomorphism and adiabatic quantum computing
NASA Astrophysics Data System (ADS)
Gaitan, Frank; Clark, Lane
2014-02-01
In the graph isomorphism (GI) problem two N-vertex graphs G and G' are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and transforms G →G'. If yes, then G and G' are said to be isomorphic; otherwise they are nonisomorphic. The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. In this paper we present a quantum algorithm that solves arbitrary instances of GI and which also provides an approach to determining all automorphisms of a given graph. We show how the GI problem can be converted to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. We numerically simulate the algorithm's quantum dynamics and show that it correctly (i) distinguishes nonisomorphic graphs; (ii) recognizes isomorphic graphs and determines the permutation(s) that connect them; and (iii) finds the automorphism group of a given graph G. We then discuss the GI quantum algorithm's experimental implementation, and close by showing how it can be leveraged to give a quantum algorithm that solves arbitrary instances of the NP-complete subgraph isomorphism problem. The computational complexity of an adiabatic quantum algorithm is largely determined by the minimum energy gap Δ (N) separating the ground and first-excited states in the limit of large problem size N ≫1. Calculating Δ (N) in this limit is a fundamental open problem in adiabatic quantum computing, and so it is not possible to determine the computational complexity of adiabatic quantum algorithms in general, nor consequently, of the specific adiabatic quantum algorithms presented here. Adiabatic quantum computing has been shown to be equivalent to the circuit model of quantum computing, and so development of adiabatic quantum algorithms continues to be of great interest.
Goff, Julie P.; Shields, Donna S.; Wang, Hong; Skoda, Erin M.; Sprachman, Melissa M.; Wipf, Peter; Garapati, Venkata Krishna; Atkinson, Jeffrey; London, Barry; Lazo, John S.; Kagan, Valerian; Epperly, Michael W.; Greenberger, Joel S.
2013-01-01
We evaluated the use of colony formation (CFU-GM, BFU-E, and CFU-GEMM) by human umbilical cord blood (CB) hematopoietic progenitor cells for testing novel small molecule ionizing irradiation protectors and mitigators. Each of 11 compounds was added before (protection) or after (mitigation) ionizing irradiation including: GS-nitroxides (JP4-039 and XJB-5-131), the bifunctional sulfoxide MMS-350, the phosphoinositol-3-kinase inhibitor (LY294002), TPP-imidazole fatty acid, (TPP-IOA), the nitric oxide synthase inhibitor (MCF-201-89), the p53/mdm2/mdm4 inhibitor (BEB55), methoxamine, isoproterenol, propanolol, and the ATP sensitive potassium channel blocker (glyburide). The drugs XJB-5-131, JP4-039, and MMS-350 were radiation protectors for CFU-GM. JP4-039 was also a radiation protector for CFU-GEMM. The drugs, XJB-5-131, JP4-039, and MMS-350 were radiation mitigators for BFU-E, MMS-350 and JP4-039 were mitigators for CFU-GM, and MMS350 was a mitigator for CFU-GEMM. In contrast, other drugs that were effective in murine assays: TTP-IOA, LY294002, MCF201-89, BEB55, propranolol, isoproterenol, methoxamine, and glyburide showed no significant protection or mitigation in human CB assays. These data support testing of new candidate clinical radiation protectors and mitigators using human CB clonogenic assays early in the drug discovery process, reducing the need for animal experiments. PMID:23933481
Xu, Yanqi; Tzeng, Sheng Yuan; Takahashi, Kaito; Shivatare, Vidya; Zhang, Bing; Tzeng, Wen Bih
2015-03-28
We report the vibronic and cation spectra of four rotamers of m-methoxystyrene, recorded by using the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques. The excitation energies of the S{sub 1}← S{sub 0} electronic transition are found to be 32 767, 32 907, 33 222, and 33 281 cm{sup −1}, and the corresponding adiabatic ionization energies are 65 391, 64 977, 65 114, and 64 525 cm{sup −1} for these isomeric species. Most of the observed active vibrations in the electronically excited S{sub 1} and cationic ground D{sub 0} states involve in-plane ring deformation and substituent-sensitive bending motions. It is found that the relative orientation of the methoxyl with respect to the vinyl group does not influence the vibrational frequencies of the ring-substituent bending modes. The two dimensional potential energy surface calculations support our experimental finding that the isomerization is restricted in the S{sub 1} and D{sub 0} states.
Xu, Yanqi; Tzeng, Sheng Yuan; Shivatare, Vidya; Takahashi, Kaito; Zhang, Bing; Tzeng, Wen Bih
2015-03-28
We report the vibronic and cation spectra of four rotamers of m-methoxystyrene, recorded by using the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques. The excitation energies of the S1← S0 electronic transition are found to be 32 767, 32 907, 33 222, and 33 281 cm(-1), and the corresponding adiabatic ionization energies are 65 391, 64 977, 65 114, and 64 525 cm(-1) for these isomeric species. Most of the observed active vibrations in the electronically excited S1 and cationic ground D0 states involve in-plane ring deformation and substituent-sensitive bending motions. It is found that the relative orientation of the methoxyl with respect to the vinyl group does not influence the vibrational frequencies of the ring-substituent bending modes. The two dimensional potential energy surface calculations support our experimental finding that the isomerization is restricted in the S1 and D0 states.
Energy efficiency of adiabatic superconductor logic
NASA Astrophysics Data System (ADS)
Takeuchi, Naoki; Yamanashi, Yuki; Yoshikawa, Nobuyuki
2015-01-01
Adiabatic superconductor logic (ASL), including adiabatic quantum-flux-parametron (AQFP) logic, exhibits high energy efficiency because its bit energy can be decreased below the thermal energy through adiabatic switching operations. In the present paper, we present the general scaling laws of ASL and compare the energy efficiency of ASL with those of other energy-efficient logics. Also, we discuss the minimum energy-delay product (EDP) of ASL at finite temperature. Our study shows that there is a maximum temperature at which the EDP can reach the quantum limit given by ħ/2, which is dependent on the superconductor material and the Josephson junction quality, and that it is reasonable to operate ASL at cryogenic temperatures in order to achieve an EDP that approaches ħ/2.
Adiabatic approximation for the density matrix
NASA Astrophysics Data System (ADS)
Band, Yehuda B.
1992-05-01
An adiabatic approximation for the Liouville density-matrix equation which includes decay terms is developed. The adiabatic approximation employs the eigenvectors of the non-normal Liouville operator. The approximation is valid when there exists a complete set of eigenvectors of the non-normal Liouville operator (i.e., the eigenvectors span the density-matrix space), the time rate of change of the Liouville operator is small, and an auxiliary matrix is nonsingular. Numerical examples are presented involving efficient population transfer in a molecule by stimulated Raman scattering, with the intermediate level of the molecule decaying on a time scale that is fast compared with the pulse durations of the pump and Stokes fields. The adiabatic density-matrix approximation can be simply used to determine the density matrix for atomic or molecular systems interacting with cw electromagnetic fields when spontaneous emission or other decay mechanisms prevail.
Adiabaticity and viscosity in deep mantle convection
NASA Technical Reports Server (NTRS)
Quareni, F.; Yuen, D. A.; Saari, M. R.
1986-01-01
A study has been conducted of steady convection with adiabatic and viscous heating for variable viscosity in the Boussinesq limit using the mean-field theory. A strong nonlinear coupling is found between the thermodynamic constants governing adiabatic heating and the rheological parameters. The range of rheological values for which adiabaticity would occur throughout the mantle has been established. Too large an activation volume, greater than 6 cu cm/mol for the cases examined, would produce unreasonably high temperature at the bottom of the mantle (greater than 6000 K) and superadiabatic gradients, especially in the lower mantle. Radiogenic heating plays a profound role in controlling dynamically mantle temperatures. Present values for the averaged mantle heat production would yield objectionably high temperatures in the lower mantle.
Nonadiabatic exchange dynamics during adiabatic frequency sweeps
NASA Astrophysics Data System (ADS)
Barbara, Thomas M.
2016-04-01
A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging.
NASA Astrophysics Data System (ADS)
Magrini, Laura; Famiglini, Giorgio; Palma, Pierangela; Termopoli, Veronica; Cappiello, Achille
2016-01-01
Detection of target and non-target substances and their characterization in complex samples is a challenging task. Here we demonstrate that coating the electron ionization (EI) ion source of an LC-MS system with a sol-gel ceramic film can drastically improve the detection of high-molecular weight and high-boiling analytes. A new ion source coated with a ceramic material was developed and tested with a mixture of polycyclic aromatic hydrocarbons (PAH) with an increasing number of rings. Comparison of the results obtained with those for an uncoated stainless steel (SS) ion source shows a dramatic improvement in the MS signals, with a nearly 40-fold increase of the signal-to-noise ratio. We also demonstrate the ability of the new system to produce excellent chromatographic profiles for hard-to-detect hormones.
Goff, Julie P; Shields, Donna S; Wang, Hong; Skoda, Erin M; Sprachman, Melissa M; Wipf, Peter; Garapati, Venkata Krishna; Atkinson, Jeffrey; London, Barry; Lazo, John S; Kagan, Valerian; Epperly, Michael W; Greenberger, Joel S
2013-11-01
We evaluated the use of colony formation (colony-forming unit-granulocyte macrophage [CFU-GM], burst-forming unit erythroid [BFU-E], and colony-forming unit-granulocyte-erythroid-megakaryocyte-monocytes [CFU-GEMM]) by human umbilical cord blood (CB) hematopoietic progenitor cells for testing novel small molecule ionizing irradiation protectors and mitigators. The following compounds were added before (protection) or after (mitigation) ionizing irradiation: GS-nitroxides (JP4-039 and XJB-5-131), the bifunctional sulfoxide MMS-350, the phosphoinositol-3-kinase inhibitor LY29400, triphenylphosphonium-imidazole fatty acid, the nitric oxide synthase inhibitor (MCF-201-89), the p53/mdm2/mdm4 inhibitor (BEB55), methoxamine, isoproterenol, propranolol, and the adenosine triphosphate-sensitive potassium channel blocker (glyburide). The drugs XJB-5-131, JP4-039, and MMS-350 were radiation protectors for CFU-GM. JP4-039 was also a radiation protector for CFU-GEMM. The drugs XJB-5-131, JP4-039, and MMS-350 were radiation mitigators for BFU-E, MMS-350 and JP4-039 were mitigators for CFU-GM, and MMS350 was a mitigator for CFU-GEMM. In contrast, other drugs were effective in murine assays; TTP-IOA, LY294002, MCF201-89, BEB55, propranolol, isoproterenol, methoxamine, and glyburide but showed no significant protection or mitigation in human CB assays. These data support the testing of new candidate clinical radiation protectors and mitigators using human CB clonogenic assays early in the drug discovery process, thus reducing the need for animal experiments.
On adiabatic invariant in generalized Galileon theories
Ema, Yohei; Jinno, Ryusuke; Nakayama, Kazunori; Mukaida, Kyohei E-mail: jinno@hep-th.phys.s.u-tokyo.ac.jp E-mail: kazunori@hep-th.phys.s.u-tokyo.ac.jp
2015-10-01
We consider background dynamics of generalized Galileon theories in the context of inflation, where gravity and inflaton are non-minimally coupled to each other. In the inflaton oscillation regime, the Hubble parameter and energy density oscillate violently in many cases, in contrast to the Einstein gravity with minimally coupled inflaton. However, we find that there is an adiabatic invariant in the inflaton oscillation regime in any generalized Galileon theory. This adiabatic invariant is useful in estimating the expansion law of the universe and also the particle production rate due to the oscillation of the Hubble parameter.
Spontaneous emission in stimulated Raman adiabatic passage
Ivanov, P. A.; Vitanov, N. V.; Bergmann, K.
2005-11-15
This work explores the effect of spontaneous emission on the population transfer efficiency in stimulated Raman adiabatic passage (STIRAP). The approach uses adiabatic elimination of weakly coupled density matrix elements in the Liouville equation, from which a very accurate analytic approximation is derived. The loss of population transfer efficiency is found to decrease exponentially with the factor {omega}{sub 0}{sup 2}/{gamma}, where {gamma} is the spontaneous emission rate and {omega}{sub 0} is the peak Rabi frequency. The transfer efficiency increases with the pulse delay and reaches a steady value. For large pulse delay and large spontaneous emission rate STIRAP degenerates into optical pumping.
Complexity of the Quantum Adiabatic Algorithm
NASA Technical Reports Server (NTRS)
Hen, Itay
2013-01-01
The Quantum Adiabatic Algorithm (QAA) has been proposed as a mechanism for efficiently solving optimization problems on a quantum computer. Since adiabatic computation is analog in nature and does not require the design and use of quantum gates, it can be thought of as a simpler and perhaps more profound method for performing quantum computations that might also be easier to implement experimentally. While these features have generated substantial research in QAA, to date there is still a lack of solid evidence that the algorithm can outperform classical optimization algorithms.
Ionization Time and Exit Momentum in Strong-Field Tunnel Ionization.
Teeny, Nicolas; Yakaboylu, Enderalp; Bauke, Heiko; Keitel, Christoph H
2016-02-12
Tunnel ionization belongs to the fundamental processes of atomic physics. The so-called two-step model, which describes the ionization as instantaneous tunneling at the electric field maximum and classical motion afterwards with zero exit momentum, is commonly employed to describe tunnel ionization in adiabatic regimes. In this contribution, we show by solving numerically the time-dependent Schrödinger equation in one dimension and employing a virtual detector at the tunnel exit that there is a nonvanishing positive time delay between the electric field maximum and the instant of ionization. Moreover, we find a nonzero exit momentum in the direction of the electric field. To extract proper tunneling times from asymptotic momentum distributions of ionized electrons, it is essential to incorporate the electron's initial momentum in the direction of the external electric field.
Novel developments and applications of the classical adiabatic dynamics technique
NASA Astrophysics Data System (ADS)
Rosso, Lula
The present work aims to apply and develop modern molecular dynamics techniques based on a novel analysis of the classical adiabatic dynamics approach. In the first part of this thesis, Car-Parrinello ab-initio molecular dynamics, a successful technique based on adiabatic dynamics, is used to study the charge transport mechanism in solid ammonium perchlorate (AP) crystal exposed to an ammonia-rich environment. AP is a solid-state proton conductor composed of NH+4 and ClO-4 units that can undergo a decomposition process at high temperature, leading to its use such as rocket fuel. After computing IR spectra and carefully analysing the dynamics at different temperatures, we found that the charge transport mechanism in the pure crystal is dominated by diffusion of the ammonium ions and that the translational diffusion is strongly coupled to rotational diffusion of the two types of ions present. When the pure ammonium-perchlorate crystal is doped with neutral ammonia, another mechanism comes into play, namely, the Grotthuss proton hopping mechanism via short-lived N2H+7 complexes. In the second part of this thesis, adiabatic dynamics will be used to develop an alternative approach to the calculation of free energy profiles along reaction paths. The new method (AFED) is based on the creation of an adiabatic separation between the reaction coordinate subspace and the remaining degrees of freedom within a molecular dynamics run. This is achieved by associating with the reaction coordinate(s) a high temperature and large mass. These conditions allow the activated process to occur while permitting the remaining degrees of freedom to respond adiabatically. In this limit, by applying a formal multiple time scale Liouville operator factorization, it can be rigorously shown that the free energy profile is obtained directly from the probability distribution of the reaction coordinate subspace and, therefore, no postprocessing of the output data is required. The new method is
From Classical Nonlinear Integrable Systems to Quantum Shortcuts to Adiabaticity.
Okuyama, Manaka; Takahashi, Kazutaka
2016-08-12
Using shortcuts to adiabaticity, we solve the time-dependent Schrödinger equation that is reduced to a classical nonlinear integrable equation. For a given time-dependent Hamiltonian, the counterdiabatic term is introduced to prevent nonadiabatic transitions. Using the fact that the equation for the dynamical invariant is equivalent to the Lax equation in nonlinear integrable systems, we obtain the counterdiabatic term exactly. The counterdiabatic term is available when the corresponding Lax pair exists and the solvable systems are classified in a unified and systematic way. Multisoliton potentials obtained from the Korteweg-de Vries equation and isotropic XY spin chains from the Toda equations are studied in detail.
From Classical Nonlinear Integrable Systems to Quantum Shortcuts to Adiabaticity
NASA Astrophysics Data System (ADS)
Okuyama, Manaka; Takahashi, Kazutaka
2016-08-01
Using shortcuts to adiabaticity, we solve the time-dependent Schrödinger equation that is reduced to a classical nonlinear integrable equation. For a given time-dependent Hamiltonian, the counterdiabatic term is introduced to prevent nonadiabatic transitions. Using the fact that the equation for the dynamical invariant is equivalent to the Lax equation in nonlinear integrable systems, we obtain the counterdiabatic term exactly. The counterdiabatic term is available when the corresponding Lax pair exists and the solvable systems are classified in a unified and systematic way. Multisoliton potentials obtained from the Korteweg-de Vries equation and isotropic X Y spin chains from the Toda equations are studied in detail.
NASA Astrophysics Data System (ADS)
Thonnard, N.
1995-09-01
measure noble gases from fourteen individual "X" SiC grains, previously identified by ion microprobe analysis, was unsuccessful with the 2,000 132Xe atom detection limit of the mass spectrometer [12,13]. From the Kr concentration measurements of SiC particles KJF by Lewis et al. [6], a 2 micrometer diameter particle will on average contain 134 Kr atoms. If only 4% of the SiC grains contain the majority of the noble gas atoms, then a single gas rich grain will contain 3,350 Kr atoms, or 12, 75, 385, 398, 1910, and 580 atoms for 78Kr through 86Kr, respectively. The Xe single-grain abundances would be similar. Resonance ionization, an emerging laser-based element analysis technique, is being harnessed to a wide variety of problems in which minute quantities of a particular element need to be measured efficiently in the presence of an overwhelmingly larger background of other materials [14]. By utilizing lasers tuned to specific atomic energy levels of the analyte element, ions are produced selectively in a mass spectrometer with much higher efficiency than possible using conventional methods, such as electron bombardment, thermal ionization, or ion sputtering. In a static resonance ionization system for noble gases, the combination of high ionization efficiency and sample concentrator results in an extremely fast (~3 min. detection half-life vs. ~60 min. for conventional systems) analyzer with a detection limit of ~100 85Kr atoms [15]. In addition to the almost complete absence of interferences, the short analysis time significantly reduces the background contribution of outgassing in the mass spectrometer. Although using a less efficient laser scheme resulting in slightly slower analyses, a similar system has recently been completed and dedicated to extraterrestrial Xe measurements [16]. At the newly formed Institute for Rare Isotope Measurements [17], the noble gas equipment that had previously been at Atom Sciences [14,15] is being re-installed and upgraded to provide
Towards fault tolerant adiabatic quantum computation.
Lidar, Daniel A
2008-04-25
I show how to protect adiabatic quantum computation (AQC) against decoherence and certain control errors, using a hybrid methodology involving dynamical decoupling, subsystem and stabilizer codes, and energy gaps. Corresponding error bounds are derived. As an example, I show how to perform decoherence-protected AQC against local noise using at most two-body interactions.
Dynamical aspects of an adiabatic piston.
Munakata, T; Ogawa, H
2001-09-01
Dynamical aspects of an adiabatic piston are investigated, based on the mass ratio expansion of the master equation for the piston velocity distribution function. Simple theory for piston motion and relaxation of an ideal gas in a cylinder turns out to reproduce our numerical experiments quantitatively.
Adiabatic reversible compression: a molecular view
NASA Astrophysics Data System (ADS)
Miranda, E. N.
2002-07-01
The adiabatic compression (or expansion) of an ideal gas has been analysed. Using the kinetic theory of gases the usual relation between temperature and volume is obtained, while textbooks follow a thermodynamic approach. In this way we show, once again, the agreement between a macroscopic view (thermodynamics) and a microscopic one (kinetic theory).
Dynamical aspects of an adiabatic piston
NASA Astrophysics Data System (ADS)
Munakata, Toyonori; Ogawa, Hideki
2001-09-01
Dynamical aspects of an adiabatic piston are investigated, based on the mass ratio expansion of the master equation for the piston velocity distribution function. Simple theory for piston motion and relaxation of an ideal gas in a cylinder turns out to reproduce our numerical experiments quantitatively.
Adiabatic Compression in a Fire Syringe.
ERIC Educational Resources Information Center
Hayn, Carl H.; Baird, Scott C.
1985-01-01
Suggests using better materials in fire syringes to obtain more effective results during demonstrations which show the elevation in temperature upon a very rapid (adiabatic) compression of air. Also describes an experiment (using ignition temperatures) which introduces students to the use of thermocouples for high temperature measurements. (DH)
Time dependence of adiabatic particle number
NASA Astrophysics Data System (ADS)
Dabrowski, Robert; Dunne, Gerald V.
2016-09-01
We consider quantum field theoretic systems subject to a time-dependent perturbation, and discuss the question of defining a time-dependent particle number not just at asymptotic early and late times, but also during the perturbation. Naïvely, this is not a well-defined notion for such a nonequilibrium process, as the particle number at intermediate times depends on a basis choice of reference states with respect to which particles and antiparticles are defined, even though the final late-time particle number is independent of this basis choice. The basis choice is associated with a particular truncation of the adiabatic expansion. The adiabatic expansion is divergent, and we show that if this divergent expansion is truncated at its optimal order, a universal time dependence is obtained, confirming a general result of Dingle and Berry. This optimally truncated particle number provides a clear picture of quantum interference effects for perturbations with nontrivial temporal substructure. We illustrate these results using several equivalent definitions of adiabatic particle number: the Bogoliubov, Riccati, spectral function and Schrödinger picture approaches. In each approach, the particle number may be expressed in terms of the tiny deviations between the exact and adiabatic solutions of the Ermakov-Milne equation for the associated time-dependent oscillators.
Apparatus to Measure Adiabatic and Isothermal Processes.
ERIC Educational Resources Information Center
Lamb, D. W.; White, G. M.
1996-01-01
Describes a simple manual apparatus designed to serve as an effective demonstration of the differences between isothermal and adiabatic processes for the general or elementary physics student. Enables students to verify Boyle's law for slow processes and identify the departure from this law for rapid processes and can also be used to give a clear…
Adiabatic Mass Parameters for Spontaneous Fission
Baran, A.; Sheikh, J. A.; Nazarewicz, Witold
2009-01-01
The collective mass tensor derived from the adiabatic time-dependent Hartree-Fock-Bogoliubov theory, perturbative cranking approximation, and the Gaussian overlap approximation to the generator-coordinate method is discussed. Illustrative calculations are carried out for ^{252}Fm using the nuclear density functional theory with Skyrme interaction SkM* and seniority pairing.
NASA Astrophysics Data System (ADS)
Yang, Yue; Weaver, Michael N.; Merz, Kenneth M.
2009-08-01
Computational chemists have long demonstrated great interest in finding ways to reliably and accurately predict the molecular properties for transition-metal-containing complexes. This study is a continuation of our validation efforts of density functional theory (DFT) methods when applied to transition-metal-containing systems (Riley, K.E.; Merz, K. M., Jr. J. Phys. Chem. 2007, 111, 6044-6053). In our previous work we examined DFT using all-electron basis sets, but approaches incorporating effective core potentials (ECPs) are effective in reducing computational expense. With this in mind, our efforts were expanded to include evaluation of the performance of the basis set derived to approximate such an approach as well on the same set of density functionals. Indeed, employing an ECP basis such as LANL2DZ (Los Alamos National Laboratory 2 double ζ) for transition metals, while using all-electron basis sets for all other non-transition-metal atoms, has become more and more popular in computations on transition-metal-containing systems. In this study, we assess the performance of 12 different DFT functionals, from the GGA (generalized gradient approximation), hybrid-GGA, meta-GGA, and hybrid-meta-GGA classes, respectively, along with the 6-31+G** + LANL2DZ (on the transition metal) mixed basis set in predicting two important molecular properties, heats of formation and ionization potentials, for 94 and 58 systems containing first-row transition metals from Ti to Zn, which are all in the third row of the periodic table. An interesting note is that the inclusion of the exact exchange term in density functional methods generally increases the accuracy of ionization potential prediction for the hybrid-GGA methods but decreases the reliability of determining the heats of formation for transition-metal-containing complexes for all hybrid density functional methods. The hybrid-GGA functional B3LYP gives the best performance in predicting the ionization potentials, while the
Communication: Adiabatic and non-adiabatic electron-nuclear motion: Quantum and classical dynamics
NASA Astrophysics Data System (ADS)
Albert, Julian; Kaiser, Dustin; Engel, Volker
2016-05-01
Using a model for coupled electronic-nuclear motion we investigate the range from negligible to strong non-adiabatic coupling. In the adiabatic case, the quantum dynamics proceeds in a single electronic state, whereas for strong coupling a complete transition between two adiabatic electronic states takes place. It is shown that in all coupling regimes the short-time wave-packet dynamics can be described using ensembles of classical trajectories in the phase space spanned by electronic and nuclear degrees of freedom. We thus provide an example which documents that the quantum concept of non-adiabatic transitions is not necessarily needed if electronic and nuclear motion is treated on the same footing.
Communication: Adiabatic and non-adiabatic electron-nuclear motion: Quantum and classical dynamics.
Albert, Julian; Kaiser, Dustin; Engel, Volker
2016-05-01
Using a model for coupled electronic-nuclear motion we investigate the range from negligible to strong non-adiabatic coupling. In the adiabatic case, the quantum dynamics proceeds in a single electronic state, whereas for strong coupling a complete transition between two adiabatic electronic states takes place. It is shown that in all coupling regimes the short-time wave-packet dynamics can be described using ensembles of classical trajectories in the phase space spanned by electronic and nuclear degrees of freedom. We thus provide an example which documents that the quantum concept of non-adiabatic transitions is not necessarily needed if electronic and nuclear motion is treated on the same footing.
Transient Particle Energies in Shortcuts to Adiabatic Expansions of Harmonic Traps.
Cui, Yang-Yang; Chen, Xi; Muga, J G
2016-05-19
The expansion of a harmonic potential that holds a quantum particle may be realized without any final particle excitation but much faster than adiabatically via "shortcuts to adiabaticity" (STA). While ideally the process time can be reduced to zero, practical limitations and constraints impose minimal finite times for the externally controlled time-dependent frequency protocols. We examine the role of different time-averaged energies (total, kinetic, potential, nonadiabatic) and of the instantaneous power in characterizing or selecting different protocols. Specifically, we prove a virial theorem for STA processes, set minimal energies (or times) for given times (or energies), and discuss their realizability by means of Dirac impulses or otherwise.
Transient Particle Energies in Shortcuts to Adiabatic Expansions of Harmonic Traps.
Cui, Yang-Yang; Chen, Xi; Muga, J G
2016-05-19
The expansion of a harmonic potential that holds a quantum particle may be realized without any final particle excitation but much faster than adiabatically via "shortcuts to adiabaticity" (STA). While ideally the process time can be reduced to zero, practical limitations and constraints impose minimal finite times for the externally controlled time-dependent frequency protocols. We examine the role of different time-averaged energies (total, kinetic, potential, nonadiabatic) and of the instantaneous power in characterizing or selecting different protocols. Specifically, we prove a virial theorem for STA processes, set minimal energies (or times) for given times (or energies), and discuss their realizability by means of Dirac impulses or otherwise. PMID:26237328
The dynamic instability of adiabatic blast waves
NASA Technical Reports Server (NTRS)
Ryu, Dongsu; Vishniac, Ethan T.
1991-01-01
Adiabatic blastwaves, which have a total energy injected from the center E varies as t(sup q) and propagate through a preshock medium with a density rho(sub E) varies as r(sup -omega) are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.
Adiabatic burst evaporation from bicontinuous nanoporous membranes
Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk
2015-01-01
Evaporation of volatile liquids from nanoporous media with bicontinuous morphology and pore diameters of a few 10 nm is an ubiquitous process. For example, such drying processes occur during syntheses of nanoporous materials by sol–gel chemistry or by spinodal decomposition in the presence of solvents as well as during solution impregnation of nanoporous hosts with functional guests. It is commonly assumed that drying is endothermic and driven by non-equilibrium partial pressures of the evaporating species in the gas phase. We show that nearly half of the liquid evaporates in an adiabatic mode involving burst-like liquid-to-gas conversions. During single adiabatic burst evaporation events liquid volumes of up to 107 μm3 are converted to gas. The adiabatic liquid-to-gas conversions occur if air invasion fronts get unstable because of the built-up of high capillary pressures. Adiabatic evaporation bursts propagate avalanche-like through the nanopore systems until the air invasion fronts have reached new stable configurations. Adiabatic cavitation bursts thus compete with Haines jumps involving air invasion front relaxation by local liquid flow without enhanced mass transport out of the nanoporous medium and prevail if the mean pore diameter is in the range of a few 10 nm. The results reported here may help optimize membrane preparation via solvent-based approaches, solution-loading of nanopore systems with guest materials as well as routine use of nanoporous membranes with bicontinuous morphology and may contribute to better understanding of adsorption/desorption processes in nanoporous media. PMID:25926406
Transport of ultracold atoms between concentric traps via spatial adiabatic passage
NASA Astrophysics Data System (ADS)
Polo, J.; Benseny, A.; Busch, Th; Ahufinger, V.; Mompart, J.
2016-01-01
Spatial adiabatic passage processes for ultracold atoms trapped in tunnel-coupled cylindrically symmetric concentric potentials are investigated. Specifically, we discuss the matter-wave analog of the rapid adiabatic passage (RAP) technique for a high fidelity and robust loading of a single atom into a harmonic ring potential from a harmonic trap, and for its transport between two concentric rings. We also consider a system of three concentric rings and investigate the transport of a single atom between the innermost and the outermost rings making use of the matter-wave analog of the stimulated Raman adiabatic passage (STIRAP) technique. We describe the RAP-like and STIRAP-like dynamics by means of a two- and a three-state model, respectively, obtaining good agreement with the numerical simulations of the corresponding two-dimensional Schrödinger equation.
NASA Astrophysics Data System (ADS)
Kleinertz, S.; Eckhardt, K.-U.; Theisen, S.; Palm, H. W.; Leinweber, P.
2016-07-01
The present study represents the first molecular-chemical screening by pyrolysis-field ionization mass spectrometry applied on fish parasites. A total of 71 fishes from Balinese fish markets, 36 Auxis rochei (Risso, 1810) and 35 A. thazard (Lacepède, 1800), were studied for their acanthocephalan parasites. This is the first record of Rhadinorhynchus zhukovi in Balinese waters, Indonesia, and we describe for the first time A. rochei and A. thazard as R. zhukovi hosts. Using this method, small scale variations within the chemical compounds of acanthocephalans could be detected. Using this methodology it will be possible to generate additional, pollutant specific information from aquatic habitats in future with the potential of a new bioindicator application for parasite/host origin and/or environmental pollution.
Alkali metal ionization detector
Bauerle, James E.; Reed, William H.; Berkey, Edgar
1978-01-01
Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.
Benabbas, Abdelkrim; Salna, Bridget; Sage, J Timothy; Champion, Paul M
2015-03-21
Analytical models describing the temperature dependence of the deep tunneling rate, useful for proton, hydrogen, or hydride transfer in proteins, are developed and compared. Electronically adiabatic and non-adiabatic expressions are presented where the donor-acceptor (D-A) motion is treated either as a quantized vibration or as a classical "gating" distribution. We stress the importance of fitting experimental data on an absolute scale in the electronically adiabatic limit, which normally applies to these reactions, and find that vibrationally enhanced deep tunneling takes place on sub-ns timescales at room temperature for typical H-bonding distances. As noted previously, a small room temperature kinetic isotope effect (KIE) does not eliminate deep tunneling as a major transport channel. The quantum approach focuses on the vibrational sub-space composed of the D-A and hydrogen atom motions, where hydrogen bonding and protein restoring forces quantize the D-A vibration. A Duschinsky rotation is mandated between the normal modes of the reactant and product states and the rotation angle depends on the tunneling particle mass. This tunnel-mass dependent rotation contributes substantially to the KIE and its temperature dependence. The effect of the Duschinsky rotation is solved exactly to find the rate in the electronically non-adiabatic limit and compared to the Born-Oppenheimer (B-O) approximation approach. The B-O approximation is employed to find the rate in the electronically adiabatic limit, where we explore both harmonic and quartic double-well potentials for the hydrogen atom bound states. Both the electronically adiabatic and non-adiabatic rates are found to diverge at high temperature unless the proton coupling includes the often neglected quadratic term in the D-A displacement from equilibrium. A new expression is presented for the electronically adiabatic tunnel rate in the classical limit for D-A motion that should be useful to experimentalists working near
Benabbas, Abdelkrim; Salna, Bridget; Sage, J. Timothy; Champion, Paul M.
2015-03-21
Analytical models describing the temperature dependence of the deep tunneling rate, useful for proton, hydrogen, or hydride transfer in proteins, are developed and compared. Electronically adiabatic and non-adiabatic expressions are presented where the donor-acceptor (D-A) motion is treated either as a quantized vibration or as a classical “gating” distribution. We stress the importance of fitting experimental data on an absolute scale in the electronically adiabatic limit, which normally applies to these reactions, and find that vibrationally enhanced deep tunneling takes place on sub-ns timescales at room temperature for typical H-bonding distances. As noted previously, a small room temperature kinetic isotope effect (KIE) does not eliminate deep tunneling as a major transport channel. The quantum approach focuses on the vibrational sub-space composed of the D-A and hydrogen atom motions, where hydrogen bonding and protein restoring forces quantize the D-A vibration. A Duschinsky rotation is mandated between the normal modes of the reactant and product states and the rotation angle depends on the tunneling particle mass. This tunnel-mass dependent rotation contributes substantially to the KIE and its temperature dependence. The effect of the Duschinsky rotation is solved exactly to find the rate in the electronically non-adiabatic limit and compared to the Born-Oppenheimer (B-O) approximation approach. The B-O approximation is employed to find the rate in the electronically adiabatic limit, where we explore both harmonic and quartic double-well potentials for the hydrogen atom bound states. Both the electronically adiabatic and non-adiabatic rates are found to diverge at high temperature unless the proton coupling includes the often neglected quadratic term in the D-A displacement from equilibrium. A new expression is presented for the electronically adiabatic tunnel rate in the classical limit for D-A motion that should be useful to experimentalists working
Benabbas, Abdelkrim; Salna, Bridget; Sage, J Timothy; Champion, Paul M
2015-03-21
Analytical models describing the temperature dependence of the deep tunneling rate, useful for proton, hydrogen, or hydride transfer in proteins, are developed and compared. Electronically adiabatic and non-adiabatic expressions are presented where the donor-acceptor (D-A) motion is treated either as a quantized vibration or as a classical "gating" distribution. We stress the importance of fitting experimental data on an absolute scale in the electronically adiabatic limit, which normally applies to these reactions, and find that vibrationally enhanced deep tunneling takes place on sub-ns timescales at room temperature for typical H-bonding distances. As noted previously, a small room temperature kinetic isotope effect (KIE) does not eliminate deep tunneling as a major transport channel. The quantum approach focuses on the vibrational sub-space composed of the D-A and hydrogen atom motions, where hydrogen bonding and protein restoring forces quantize the D-A vibration. A Duschinsky rotation is mandated between the normal modes of the reactant and product states and the rotation angle depends on the tunneling particle mass. This tunnel-mass dependent rotation contributes substantially to the KIE and its temperature dependence. The effect of the Duschinsky rotation is solved exactly to find the rate in the electronically non-adiabatic limit and compared to the Born-Oppenheimer (B-O) approximation approach. The B-O approximation is employed to find the rate in the electronically adiabatic limit, where we explore both harmonic and quartic double-well potentials for the hydrogen atom bound states. Both the electronically adiabatic and non-adiabatic rates are found to diverge at high temperature unless the proton coupling includes the often neglected quadratic term in the D-A displacement from equilibrium. A new expression is presented for the electronically adiabatic tunnel rate in the classical limit for D-A motion that should be useful to experimentalists working near
Non-adiabatic perturbations in multi-component perfect fluids
Koshelev, N.A.
2011-04-01
The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models.
NASA Astrophysics Data System (ADS)
Araghi, Houshang; Zabihi, Zabiholah; Nayebi, Payman; Ehsani, Mohammad Mahdi
2016-10-01
II-VI semiconductor CdTe was grown on the Si(100) substrate surface by the ionized cluster beam (ICB) technique. In the ICB method, when vapors of solid materials such as CdTe were ejected through a nozzle of a heated crucible into a vacuum region, nanoclusters were created by an adiabatic expansion phenomenon. The clusters thus obtained were partially ionized by electron bombardment and then accelerated onto the silicon substrate at 473 K by high potentials. The cluster size was determined using a retarding field energy analyzer. The results of X-ray diffraction measurements indicate the cubic zinc blende (ZB) crystalline structure of the CdTe thin film on the silicon substrate. The CdTe thin film prepared by the ICB method had high crystalline quality. The microscopic processes involved in the ICB deposition technique, such as impact and coalescence processes, have been studied in detail by molecular dynamics (MD) simulation.
Adiabatic quantum simulation of quantum chemistry.
Babbush, Ryan; Love, Peter J; Aspuru-Guzik, Alán
2014-10-13
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.
Quantum adiabatic evolution with energy degeneracy levels
NASA Astrophysics Data System (ADS)
Zhang, Qi
2016-01-01
A classical-kind phase-space formalism is developed to address the tiny intrinsic dynamical deviation from what is predicted by Wilczek-Zee theorem during quantum adiabatic evolution on degeneracy levels. In this formalism, the Hilbert space and the aggregate of degenerate eigenstates become the classical-kind phase space and a high-dimensional subspace in the phase space, respectively. Compared with the previous analogous study by a different method, the current result is qualitatively different in that the first-order deviation derived here is always perpendicular to the degeneracy subspace. A tripod-scheme Hamiltonian with two degenerate dark states is employed to illustrate the adiabatic deviation with degeneracy levels.
Adiabatic quantum optimization for associative memory recall
Seddiqi, Hadayat; Humble, Travis S.
2014-12-22
Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are stored in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.
Adiabatic quantum optimization for associative memory recall
Seddiqi, Hadayat; Humble, Travis S.
2014-12-22
Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are storedmore » in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.« less
Trapped Ion Quantum Computation by Adiabatic Passage
Feng Xuni; Wu Chunfeng; Lai, C. H.; Oh, C. H.
2008-11-07
We propose a new universal quantum computation scheme for trapped ions in thermal motion via the technique of adiabatic passage, which incorporates the advantages of both the adiabatic passage and the model of trapped ions in thermal motion. Our scheme is immune from the decoherence due to spontaneous emission from excited states as the system in our scheme evolves along a dark state. In our scheme the vibrational degrees of freedom are not required to be cooled to their ground states because they are only virtually excited. It is shown that the fidelity of the resultant gate operation is still high even when the magnitude of the effective Rabi frequency moderately deviates from the desired value.
Ramsey numbers and adiabatic quantum computing.
Gaitan, Frank; Clark, Lane
2012-01-01
The graph-theoretic Ramsey numbers are notoriously difficult to calculate. In fact, for the two-color Ramsey numbers R(m,n) with m, n≥3, only nine are currently known. We present a quantum algorithm for the computation of the Ramsey numbers R(m,n). We show how the computation of R(m,n) can be mapped to a combinatorial optimization problem whose solution can be found using adiabatic quantum evolution. We numerically simulate this adiabatic quantum algorithm and show that it correctly determines the Ramsey numbers R(3,3) and R(2,s) for 5≤s≤7. We then discuss the algorithm's experimental implementation, and close by showing that Ramsey number computation belongs to the quantum complexity class quantum Merlin Arthur.
Adiabatic Quantum Simulation of Quantum Chemistry
NASA Astrophysics Data System (ADS)
Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán
2014-10-01
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.
Shortcuts to adiabaticity from linear response theory
Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian
2015-10-23
A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts to adiabaticity for specific and very short driving times.
Shortcuts to adiabaticity from linear response theory
Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian
2015-10-23
A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts tomore » adiabaticity for specific and very short driving times.« less
Sprecher, D; Beyer, M; Merkt, F
2013-01-01
Recent experiments are reviewed which have led to the determination of the ionization and dissociation energies of molecular hydrogen with a precision of 0.0007 cm(-)1 (8 mJ/mol or 20 MHz) using a procedure based on high-resolution spectroscopic measurements of high Rydberg states and the extrapolation of the Rydberg series to the ionization thresholds. Molecular hydrogen, with only two protons and two electrons, is the simplest molecule with which all aspects of a chemical bond, including electron correlation effects, can be studied. Highly precise values of its ionization and dissociation energies provide stringent tests of the precision of molecular quantum mechanics and of quantum-electrodynamics calculations in molecules. The comparison of experimental and theoretical values for these quantities enable one to quantify the contributions to a chemical bond that are neglected when making the Born-Oppenheimer approximation, i.e. adiabatic, nonadiabatic, relativistic, and radiative corrections. Ionization energies of a broad range of molecules can now be determined experimentally with high accuracy (i.e. about 0.01 cm(-1)). Calculations at similar accuracies are extremely challenging for systems containing more than two electrons. The combination of precision measurements of molecular ionization energies with highly accurateab initio calculations has the potential to provide, in future, fully reliable sets of thermochemical quantities for gas-phase reactions. PMID:23967701
Seiler, Ch.; Hogan, S. D.; Schmutz, H.; Agner, J. A.; Merkt, F.
2011-02-18
A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90 deg., decelerated to zero velocity in less than 25 {mu}s, and loaded into an electric trap. The deflection has allowed the suppression of collisions with atoms in the trailing part of the gas pulse. The processes leading to trap losses, i.e., fluorescence to the ground state, and transitions and ionization induced by blackbody radiation have been monitored over several milliseconds and quantitatively analyzed.
O'Brien, K.J.
1985-01-01
It is demonstrated that the cold Vlasov beam, the circle-limit of the warm Vlasov beam, the spread-mass model, and the energy-group model of a relativistic electron beam undergoing linear hose instability, are all formally equivalent. Therefore, the circle-orbit beam is the natural starting point for a higher order theory. Introducing the next order in non-circularity the author makes contact with the adiabatic theory for warm beams. The adiabatic theory is founded upon the existence of transverse action invariants that remain sufficiently well-defined, despite the nonaxisymmetric potential and the coupling resonances driven by linear hose instability. The existence of action invariants enables the elimination of a fast variable, analogous to gyro-motion, called vortex-gyration. One problem with adiabatic beam theory is that coupling resonances between the degrees of freedom could destroy the adiabatic invariants upon which the theory rests. KAM theory is employed here to study the destruction of action invariants due to linear hose instability. Nonaxisymmetric adiabatic beams are defined to be those for which KAM tori exist in the transverse phase space. For hose deflections of the magnitude considered in linear theory, KAM tori persist, preventing the destruction of the invariants.
Siphon flows in isolated magnetic flux tubes. II - Adiabatic flows
NASA Technical Reports Server (NTRS)
Montesinos, Benjamin; Thomas, John H.
1989-01-01
This paper extends the study of steady siphon flows in isolated magnetic flux tubes surrounded by field-free gas to the case of adiabatic flows. The basic equations governing steady adiabatic siphon flows in a thin, isolated magnetic flux tube are summarized, and qualitative features of adiabatic flows in elevated, arched flux tubes are discussed. The equations are then cast in nondimensional form and the results of numerical computations of adiabatic siphon flows in arched flux tubes are presented along with comparisons between isothermal and adiabatic flows. The effects of making the interior of the flux tube hotter or colder than the surrounding atmosphere at the upstream footpoint of the arch is considered. In this case, is it found that the adiabatic flows are qualitatively similar to the isothermal flows, with adiabatic cooling producing quantitative differences. Critical flows can produce a bulge point in the rising part of the arch and a concentration of magnetic flux above the bulge point.
Siphon flows in isolated magnetic flux tubes. II. Adiabatic flows
Montesinos, B.; Thomas, J.H.
1989-02-01
This paper extends the study of steady siphon flows in isolated magnetic flux tubes surrounded by field-free gas to the case of adiabatic flows. The basic equations governing steady adiabatic siphon flows in a thin, isolated magnetic flux tube are summarized, and qualitative features of adiabatic flows in elevated, arched flux tubes are discussed. The equations are then cast in nondimensional form and the results of numerical computations of adiabatic siphon flows in arched flux tubes are presented along with comparisons between isothermal and adiabatic flows. The effects of making the interior of the flux tube hotter or colder than the surrounding atmosphere at the upstream footpoint of the arch is considered. In this case, is it found that the adiabatic flows are qualitatively similar to the isothermal flows, with adiabatic cooling producing quantitative differences. Critical flows can produce a bulge point in the rising part of the arch and a concentration of magnetic flux above the bulge point. 15 references.
Hapka, Michał; Chałasiński, Grzegorz; Kłos, Jacek; Zuchowski, Piotr S
2013-07-01
We present new interaction potential curves, calculated from first-principles, for the He((3)S, 1s(1)2s(1))···H2 and He((3)S)···Ar systems, relevant in recent Penning ionization experiments of Henson et al. [Science 338, 234 (2012)]. Two different approaches were applied: supermolecular using coupled cluster (CC) theory and perturbational within symmetry-adapted perturbation theory (SAPT). Both methods gave consistent results, and the potentials were used to study the elastic scattering and determine the positions of shape resonances for low kinetic energy (up to 1 meV). We found a good agreement with the experiment. In addition, we investigated two other dimers composed of metastable Ne ((3)P, 2p(5)3s(1)) and ground state He and Ar atoms. For the Ne((3)P)···He system, a good agreement between CC and SAPT approaches was obtained. The Ne((3)P)···Ar dimer was described only with SAPT, as CC gave divergent results. Ne* systems exhibit extremely small electronic orbital angular momentum anisotropy of the potentials. We attribute this effect to screening of an open 2p shell by a singly occupied 3s shell.
Computer Code For Turbocompounded Adiabatic Diesel Engine
NASA Technical Reports Server (NTRS)
Assanis, D. N.; Heywood, J. B.
1988-01-01
Computer simulation developed to study advantages of increased exhaust enthalpy in adiabatic turbocompounded diesel engine. Subsytems of conceptual engine include compressor, reciprocator, turbocharger turbine, compounded turbine, ducting, and heat exchangers. Focus of simulation of total system is to define transfers of mass and energy, including release and transfer of heat and transfer of work in each subsystem, and relationship among subsystems. Written in FORTRAN IV.
Adiabatic charging of nickel-hydrogen batteries
NASA Astrophysics Data System (ADS)
Lurie, Chuck; Foroozan, S.; Brewer, Jeff; Jackson, Lorna
1995-02-01
Battery management during prelaunch activities has always required special attention and careful planning. The transition from nickel-cadium to nickel-hydrogen batteries, with their high self discharge rate and lower charge efficiency, as well as longer prelaunch scenarios, has made this aspect of spacecraft battery management even more challenging. The AXAF-I Program requires high battery state of charge at launch. The use of active cooling, to ensure efficient charging, was considered and proved to be difficult and expensive. Alternative approaches were evaluated. Optimized charging, in the absence of cooling, appeared promising and was investigated. Initial testing was conducted to demonstrate the feasibility of the 'Adiabatic Charging' approach. Feasibility was demonstrated and additional testing performed to provide a quantitative, parametric data base. The assumption that the battery is in an adiabatic environment during prelaunch charging is a conservative approximation because the battery will transfer some heat to its surroundings by convective air cooling. The amount is small compared to the heat dissipated during battery overcharge. Because the battery has a large thermal mass, substantial overcharge can occur before the cells get too hot to charge efficiently. The testing presented here simulates a true adiabatic environment. Accordingly the data base may be slightly conservative. The adiabatic charge methodology used in this investigation begins with stabilizing the cell at a given starting temperature. The cell is then fully insulated on all sides. Battery temperature is carefully monitored and the charge terminated when the cell temperature reaches 85 F. Charging has been evaluated with starting temperatures from 55 to 75 F.
Advanced Adiabatic Demagnetization Refrigerators for Continuous Cooling
NASA Technical Reports Server (NTRS)
Chu, Paul C. W.
2004-01-01
The research at Houston was focused on optimizing the design of superconducting magnets for advanced adiabatic demagnetization refrigerators (ADRs), assessing the feasibility of using high temperature superconducting (HTS) magnets in ADRs in the future, and developing techniques to deposit HTS thin and thick films on high strength, low thermal conductivity substrates for HTS magnet leads. Several approaches have been tested for the suggested superconducting magnets.
Random matrix model of adiabatic quantum computing
Mitchell, David R.; Adami, Christoph; Lue, Waynn; Williams, Colin P.
2005-05-15
We present an analysis of the quantum adiabatic algorithm for solving hard instances of 3-SAT (an NP-complete problem) in terms of random matrix theory (RMT). We determine the global regularity of the spectral fluctuations of the instantaneous Hamiltonians encountered during the interpolation between the starting Hamiltonians and the ones whose ground states encode the solutions to the computational problems of interest. At each interpolation point, we quantify the degree of regularity of the average spectral distribution via its Brody parameter, a measure that distinguishes regular (i.e., Poissonian) from chaotic (i.e., Wigner-type) distributions of normalized nearest-neighbor spacings. We find that for hard problem instances - i.e., those having a critical ratio of clauses to variables - the spectral fluctuations typically become irregular across a contiguous region of the interpolation parameter, while the spectrum is regular for easy instances. Within the hard region, RMT may be applied to obtain a mathematical model of the probability of avoided level crossings and concomitant failure rate of the adiabatic algorithm due to nonadiabatic Landau-Zener-type transitions. Our model predicts that if the interpolation is performed at a uniform rate, the average failure rate of the quantum adiabatic algorithm, when averaged over hard problem instances, scales exponentially with increasing problem size.
Shortcut to adiabaticity in full-wave optics for ultra-compact waveguide junctions
NASA Astrophysics Data System (ADS)
Della Valle, Giuseppe; Perozziello, Gerardo; Longhi, Stefano
2016-09-01
We extend the concept of shortcuts to adiabaticity to full-wave optics and provide an application to the design of an ultra-compact waveguide junction. In particular, we introduce a procedure allowing one to synthesize a purely dielectric optical potential that precisely compensates for non-adiabatic losses of the transverse electric fundamental mode in any (sufficiently regular) two-dimensional waveguide junction. Our results are corroborated by finite-element method numerical simulations in a Pöschl–Teller waveguide mode expander.
Protecting and accelerating adiabatic passage with time-delayed pulse sequences.
Sampedro, Pablo; Chang, Bo Y; Sola, Ignacio R
2016-05-21
Using numerical simulations of two-photon electronic absorption with femtosecond pulses in Na2 we show that: (i) it is possible to avoid the characteristic saturation or dumped Rabi oscillations in the yield of absorption by time-delaying the laser pulses; (ii) it is possible to accelerate the onset of adiabatic passage by using the vibrational coherence starting in a wave packet; and (iii) it is possible to prepare the initial wave packet in order to achieve full state-selective transitions with broadband pulses. The findings can be used, for instance, to achieve ultrafast adiabatic passage by light-induced potentials and understand its intrinsic robustness. PMID:27125342
Adiabatic response and quantum thermoelectrics for ac-driven quantum systems
NASA Astrophysics Data System (ADS)
Ludovico, María Florencia; Battista, Francesca; von Oppen, Felix; Arrachea, Liliana
2016-02-01
We generalize the theory of thermoelectrics to include coherent electron systems under adiabatic ac driving, accounting for quantum pumping of charge and heat, as well as for the work exchanged between the electron system and driving potentials. We derive the relevant response coefficients in the adiabatic regime and show that they obey generalized Onsager reciprocity relations. We analyze the consequences of our generalized thermoelectric framework for quantum motors, generators, heat engines, and heat pumps, characterizing them in terms of efficiencies and figures of merit. We illustrate these concepts in a model for a quantum pump.
Protecting and accelerating adiabatic passage with time-delayed pulse sequences.
Sampedro, Pablo; Chang, Bo Y; Sola, Ignacio R
2016-05-21
Using numerical simulations of two-photon electronic absorption with femtosecond pulses in Na2 we show that: (i) it is possible to avoid the characteristic saturation or dumped Rabi oscillations in the yield of absorption by time-delaying the laser pulses; (ii) it is possible to accelerate the onset of adiabatic passage by using the vibrational coherence starting in a wave packet; and (iii) it is possible to prepare the initial wave packet in order to achieve full state-selective transitions with broadband pulses. The findings can be used, for instance, to achieve ultrafast adiabatic passage by light-induced potentials and understand its intrinsic robustness.
Non-equilibrium scale invariance and shortcuts to adiabaticity in a one-dimensional Bose gas
Rohringer, W.; Fischer, D.; Steiner, F.; Mazets, I. E.; Schmiedmayer, J.; Trupke, M.
2015-01-01
We present experimental evidence for scale invariant behaviour of the excitation spectrum in phase-fluctuating quasi-1d Bose gases after a rapid change of the external trapping potential. Probing density correlations in free expansion, we find that the temperature of an initial thermal state scales with the spatial extension of the cloud as predicted by a model based on adiabatic rescaling of initial eigenmodes with conserved quasiparticle occupation numbers. Based on this result, we demonstrate that shortcuts to adiabaticity for the rapid expansion or compression of the gas do not induce additional heating. PMID:25867640
Non-equilibrium scale invariance and shortcuts to adiabaticity in a one-dimensional Bose gas
NASA Astrophysics Data System (ADS)
Rohringer, W.; Fischer, D.; Steiner, F.; Mazets, I. E.; Schmiedmayer, J.; Trupke, M.
2015-04-01
We present experimental evidence for scale invariant behaviour of the excitation spectrum in phase-fluctuating quasi-1d Bose gases after a rapid change of the external trapping potential. Probing density correlations in free expansion, we find that the temperature of an initial thermal state scales with the spatial extension of the cloud as predicted by a model based on adiabatic rescaling of initial eigenmodes with conserved quasiparticle occupation numbers. Based on this result, we demonstrate that shortcuts to adiabaticity for the rapid expansion or compression of the gas do not induce additional heating.
Non-equilibrium scale invariance and shortcuts to adiabaticity in a one-dimensional Bose gas.
Rohringer, W; Fischer, D; Steiner, F; Mazets, I E; Schmiedmayer, J; Trupke, M
2015-04-13
We present experimental evidence for scale invariant behaviour of the excitation spectrum in phase-fluctuating quasi-1d Bose gases after a rapid change of the external trapping potential. Probing density correlations in free expansion, we find that the temperature of an initial thermal state scales with the spatial extension of the cloud as predicted by a model based on adiabatic rescaling of initial eigenmodes with conserved quasiparticle occupation numbers. Based on this result, we demonstrate that shortcuts to adiabaticity for the rapid expansion or compression of the gas do not induce additional heating.
Mass analyzed threshold ionization spectroscopy of 4-aminobenzonitrile cation
NASA Astrophysics Data System (ADS)
Huang, L. C. L.; Lin, J. L.; Tzeng, W. B.
2000-11-01
Mass analyzed threshold ionization (MATI) and two-color resonant two-photon ionization (R2PI) methods were used to investigate the ionic properties of 4-aminobenzonitrile (4-ABN). The adiabatic ionization energy of this molecule was determined to be 66 493±4 cm -1 by the MATI spectroscopy and 66 494±7 cm -1 by the two-color R2PI spectroscopy. The active vibrations of the 4-ABN cation include the in-plane ring deformation, CC stretching, C-CN stretching, and CH bending motions. The present experimental results are well supported by our ab initio and density functional theory calculations.
Walenta, Albert H.
1981-01-01
An ionization chamber has separate drift and detection regions electrically isolated from each other by a fine wire grid. A relatively weak electric field can be maintained in the drift region when the grid and another electrode in the chamber are connected to a high voltage source. A much stronger electric field can be provided in the detection region by connecting wire electrodes therein to another high voltage source. The detection region can thus be operated in a proportional mode when a suitable gas is contained in the chamber. High resolution output pulse waveforms are provided across a resistor connected to the detection region anode, after ionizing radiation enters the drift region and ionize the gas.
Walenta, A.H.
An ionization chamber is described which has separate drift and detection regions electrically isolated from each other by a fine wire grid. A relatively weak electric field can be maintained in the drift region when the grid and another electrode in the chamber are connected to a high voltage source. A much stronger electric field can be provided in the detection region by connecting wire electrodes therein to another high voltage source. The detection region can thus be operated in a proportional mode when a suitable gas is contained in the chamber. High resolution output pulse waveforms are provided across a resistor connected to the detection region anode, after ionizing radiation enters the drift region and ionizes the gas.
Zhang, Lynn X; Manard, Benjamin T; Powell, Brian A; Marcus, R Kenneth
2015-07-21
The determination of metals, including the generation of metal-ligand speciation information, is essential across a myriad of biochemical, environmental, and industrial systems. Metal speciation is generally affected by the combination of some form of chromatographic separation (reflective of the metal-ligand chemistry) with element-specific detection for the quantification of the metal composing the chromatographic eluent. Thus, the identity of the metal-ligand is assigned by inference. Presented here, the liquid sampling-atmospheric pressure glow discharge (LS-APGD) is assessed as an ionization source for metal speciation, with the uranyl ion-acetate system used as a test system. Molecular mass spectra can be obtained from the same source by simple modification of the sustaining electrolyte solution. Specifically, chemical information pertaining to the degree of acetate complexation of uranyl ion (UO2(2+)) is assessed as a function of pH in the spectral abundance of three metallic species: inorganic (nonligated) uranyl, UO2Ac(H2O)n(MeOH)m(+), and UO2Ac2(H2O)n(MeOH)(m)H(+) (n = 1, 2, 3, ...; m = 1, 2, 3, ...). The product mass spectra are different from what are obtained from electrospray ionization sources that have been applied to this system. The resulting relationships between the speciation and pH values have been compared to calculated concentrations of the corresponding uranyl species: UO2(2+), UO2Ac(+), UO2Ac2. The capacity for the LS-APGD to affect both atomic mass spectra and structurally significant spectra for organometallic complexes is a unique and potentially powerful combination.
Jiang, Cheng; Cui, Yuanshun; Chen, Guibin
2016-01-01
We explore theoretically the dynamics of an optomechanical system in which a resonantly driven cavity mode is quadratically coupled to the displacement of a mechanical resonator. Considering the first order correction to adiabatic elimination, we obtain the analytical expression of optomechanical damping rate which is negative and depends on the position of the mechanical resonator. After comparing the numerical results between the full simulation of Langevin equations, adiabatic elimination, and first order correction to adiabatic elimination, we explain the dynamics of the system in terms of overall mechanical potential and optomechanical damping rate. The antidamping induced by radiation pressure can result in self-sustained oscillation of the mechanical resonator. Finally, we discuss the time evolution of the intracavity photon number, which also shows that the effect of first order correction cannot be neglected when the ratio of the cavity decay rate to the mechanical resonance frequency becomes smaller than a critical value. PMID:27752125
NASA Astrophysics Data System (ADS)
González, Leticia; Kröner, Dominik; Solá, Ignacio R.
2001-08-01
Different strategies to separate enantiomers from a racemate using analytical laser pulses in the ultraviolet frequency domain are proposed for the prototype model system H2POSH. Wave-packet propagations on ab initio ground- and electronic-excited state potentials show that it is possible to produce 100% of enantiomeric excess in a sub-picosecond time scale using a sequence of π and half-π pulses. Alternatively, the previous transitions can be substituted by adiabatic counterparts, using chirped laser pulses and a half-STIRAP (stimulated Raman adiabatic passage) method which only transfers half of the population between appropriate levels. Such an overall adiabatic mechanism gains stability concerning the pulse areas and frequencies at the expense of introducing new control variables, like the chirp and time delay.
Redman, W.C.; Shonka, F.R.
1958-02-18
This patent describes a novel ionization chamber which is well suited to measuring the radioactivity of the various portions of a wire as the wire is moved at a uniform speed, in order to produce the neutron flux traverse pattern of a reactor in which the wire was previously exposed to neutron radiation. The ionization chamber of the present invention is characterized by the construction wherein the wire is passed through a tubular, straight electrode and radiation shielding material is disposed along the wire except at an intermediate, narrow area where the second electrode of the chamber is located.
Determination of caloric values of agricultural crops and crop waste by Adiabatic Bomb Calorimetry
Technology Transfer Automated Retrieval System (TEKTRAN)
Calorific values of agricultural crops and their waste were measured by adiabatic bomb calorimetry. Sustainable farming techniques require that all potential sources of revenue be utilized. A wide variety of biomass is beginning to be used as alternative fuels all over the world. The energy potentia...
Shkol'nik, V M; Pogorelov, A V
1998-05-01
A clinical examination was done as was an investigation into polymodal evoked potentials (EP) of the brain in the group of 123 liquidators of the accident (LA) to the N 4 reactor unit of the Chernobyl nuclear power station. There was a steady decrease in the amplitude of auditory EP of the brain stem (AEPBS), somatosensory EP, visual EP and a great lengthening of latent periods (LP) of late cortical components H200, II300, H400. LP AEPBS appeared to be intact in 91.5% LA. Correlation was established between the hemodynamic and neurodynamic disorders suggesting to us that further postradiation nosology is brought about by morbid neuronal pattern, the formation of which is determined not only by radiation exposure but acquires the character of a multivariate process. PMID:9695553
Non-adiabatic effects in near-adiabatic mixed-field orientation and alignment
NASA Astrophysics Data System (ADS)
Maan, Anjali; Ahlawat, Dharamvir Singh; Prasad, Vinod
2016-11-01
We present a theoretical study of the impact of a pair of moderate electric fields tilted an angle with respect to one another on a molecule. As a prototype, we consider a molecule with large rotational constant (with corresponding small rotational period) and moderate dipole moment. Within rigid-rotor approximation, the time-dependent Schrodinger equation is solved using fourth-order Runge-Kutta method. We have analysed that lower rotational states are significantly influenced by variation in pulse durations, the tilt angle between the fields and also on the electric field strengths. We also suggest a control scheme of how the rotational dynamics, orientation and alignment of a molecule can be enhanced by a combination of near-adiabatic pulses in comparision to non-adiabatic or adiabatic pulses.
NASA Astrophysics Data System (ADS)
Saul, Lukas; Wurz, Peter; Kallenbach, Reinald
2009-09-01
Interstellar neutral gas enters the inner heliosphere where it is ionized and becomes the pickup ion population of the solar wind. It is often assumed that this population will subsequently cool adiabatically, like an expanding ideal gas due, to the divergent flow of the solar wind. Here, we report the first independent measure of the effective adiabatic cooling index in the inner heliosphere from SOHO CELIAS measurements of singly charged helium taken during times of perpendicular interplanetary magnetic field. We use a simple adiabatic transport model of interstellar pickup helium ions, valid for the upwind region of the inner heliosphere. The time averaged velocity spectrum of helium pickup ions measured by CELIAS/CTOF is fit to this model with a single free parameter which indicates an effective cooling rate with a power-law index of γ = 1.35 ± 0.2. While this average is consistent with the "ideal-gas" assumption of γ = 1.5, the analysis indicates that such an assumption will not apply in general, and that due to observational constraints further measurements are necessary to constrain the cooling process. Implications are discussed for understanding the transport processes in the inner heliosphere and improving this measurement technique.
Saul, Lukas; Wurz, Peter; Kallenbach, Reinald
2009-09-20
Interstellar neutral gas enters the inner heliosphere where it is ionized and becomes the pickup ion population of the solar wind. It is often assumed that this population will subsequently cool adiabatically, like an expanding ideal gas due, to the divergent flow of the solar wind. Here, we report the first independent measure of the effective adiabatic cooling index in the inner heliosphere from SOHO CELIAS measurements of singly charged helium taken during times of perpendicular interplanetary magnetic field. We use a simple adiabatic transport model of interstellar pickup helium ions, valid for the upwind region of the inner heliosphere. The time averaged velocity spectrum of helium pickup ions measured by CELIAS/CTOF is fit to this model with a single free parameter which indicates an effective cooling rate with a power-law index of gamma = 1.35 +- 0.2. While this average is consistent with the 'ideal-gas' assumption of gamma = 1.5, the analysis indicates that such an assumption will not apply in general, and that due to observational constraints further measurements are necessary to constrain the cooling process. Implications are discussed for understanding the transport processes in the inner heliosphere and improving this measurement technique.
Li, Y. Q.; Ma, F. C.; Sun, M. T.
2013-10-21
A full three-dimensional global potential energy surface is reported first time for the title system, which is important for the photodissociation processes. It is obtained using double many-body expansion theory and an extensive set of accurate ab initio energies extrapolated to the complete basis set limit. Such a work can be recommended for dynamics studies of the N({sup 2}D) + H{sub 2} reaction, a reliable theoretical treatment of the photodissociation dynamics and as building blocks for constructing the double many-body expansion potential energy surface of larger nitrogen/hydrogen containing systems. In turn, a preliminary theoretical study of the reaction N({sup 2}D)+H{sub 2}(X{sup 1}Σ{sub g}{sup +})(ν=0,j=0)→NH(a{sup 1}Δ)+H({sup 2}S) has been carried out with the method of quasi-classical trajectory on the new potential energy surface. Integral cross sections and thermal rate constants have been calculated, providing perhaps the most reliable estimate of the integral cross sections and the rate constants known thus far for such a reaction.
Timescales for adiabatic photodissociation dynamics from the {tilde A} state of ammonia
NASA Astrophysics Data System (ADS)
Chatterley, Adam S.; Roberts, Gareth M.; Stavros, Vasilios G.
2013-07-01
Photodissociation dynamics after excitation of the {tilde A} state ν'2 = 4 (umbrella) level of ammonia are investigated using ultrafast time-resolved velocity map ion imaging (TR-VMI). These studies extend upon previous TR-VMI measurements [K. L. Wells, G. Perriam, and V. G. Stavros, J. Chem. Phys. 130, 074308 (2009)], 10.1063/1.3072763, which reported the appearance timescales for ground state NH_2 {(tilde X)} + H photoproducts, born from non-adiabatic passage through an {tilde X/tilde A} state conical intersection (CI) at elongated H-NH2 bond distances. In particular, the present work sheds new light on the formation timescales for electronically excited NH_2 {(tilde A)} + H species, generated from NH3 parent molecules that avoid the CI and dissociate adiabatically. The results reveal a step-wise dynamical picture for the production of NH_2 {(tilde A)} + H products, where nascent dissociative flux can become temporarily trapped/impeded around the upper cone of the CI on the {tilde A} state potential energy surface (PES), while on course towards the adiabatic dissociation asymptote - this behavior contrasts the concerted mechanism previously observed for non-adiabatic dissociation into H-atoms associated with ro-vibrationally "cold" NH_2 {(tilde X)}. Initially, non-planar NH3 molecules (species which have the capacity to yield adiabatic photoproducts) are found to evolve out of the vertical Franck-Condon excitation region and towards the CI region of the {tilde A} state PES with a time-constant of 113 ± 46 fs. Subsequently, transient population encircling the CI then progresses to finally form NH_2 {(tilde A)} + H photoproducts from the CI region of the tildeA state PES with a slower time-constant of 415 ± 25 fs. Non-adiabatic dissociation into ro-vibrationally "hot" NH_2 {(tilde X)} radicals together with H-atoms is also evidenced to occur via a qualitatively similar process.
Timescales for adiabatic photodissociation dynamics from the Ã state of ammonia.
Chatterley, Adam S; Roberts, Gareth M; Stavros, Vasilios G
2013-07-21
Photodissociation dynamics after excitation of the Ã state ν'2 = 4 (umbrella) level of ammonia are investigated using ultrafast time-resolved velocity map ion imaging (TR-VMI). These studies extend upon previous TR-VMI measurements [K. L. Wells, G. Perriam, and V. G. Stavros, J. Chem. Phys. 130, 074308 (2009)], which reported the appearance timescales for ground state NH2(X̃)+H photoproducts, born from non-adiabatic passage through an X̃/Ã state conical intersection (CI) at elongated H-NH2 bond distances. In particular, the present work sheds new light on the formation timescales for electronically excited NH2(Ã)+H species, generated from NH3 parent molecules that avoid the CI and dissociate adiabatically. The results reveal a step-wise dynamical picture for the production of NH2(Ã)+H products, where nascent dissociative flux can become temporarily trapped∕impeded around the upper cone of the CI on the Ã state potential energy surface (PES), while on course towards the adiabatic dissociation asymptote - this behavior contrasts the concerted mechanism previously observed for non-adiabatic dissociation into H-atoms associated with ro-vibrationally "cold" NH2(X̃). Initially, non-planar NH3 molecules (species which have the capacity to yield adiabatic photoproducts) are found to evolve out of the vertical Franck-Condon excitation region and towards the CI region of the Ã state PES with a time-constant of 113 ± 46 fs. Subsequently, transient population encircling the CI then progresses to finally form NH2(Ã)+H photoproducts from the CI region of the Ã state PES with a slower time-constant of 415 ± 25 fs. Non-adiabatic dissociation into ro-vibrationally "hot" NH2(X̃) radicals together with H-atoms is also evidenced to occur via a qualitatively similar process. PMID:23883038
Shortcut to adiabaticity in spinor condensates
NASA Astrophysics Data System (ADS)
Sala, Arnau; Núñez, David López; Martorell, Joan; De Sarlo, Luigi; Zibold, Tilman; Gerbier, Fabrice; Polls, Artur; Juliá-Díaz, Bruno
2016-10-01
We devise a method to shortcut the adiabatic evolution of a spin-1 Bose gas with an external magnetic field as the control parameter. An initial many-body state with almost all bosons populating the Zeeman sublevel m =0 is evolved to a final state very close to a macroscopic spin-singlet condensate, a fragmented state with three macroscopically occupied Zeeman states. The shortcut protocol, obtained by an approximate mapping to a harmonic oscillator Hamiltonian, is compared to linear and exponential variations of the control parameter. We find a dramatic speedup of the dynamics when using the shortcut protocol.
On adiabatic perturbations in the ekpyrotic scenario
Linde, A.; Mukhanov, V.; Vikman, A. E-mail: Viatcheslav.Mukhanov@physik.uni-muenchen.de
2010-02-01
In a recent paper, Khoury and Steinhardt proposed a way to generate adiabatic cosmological perturbations with a nearly flat spectrum in a contracting Universe. To produce these perturbations they used a regime in which the equation of state exponentially rapidly changed during a short time interval. Leaving aside the singularity problem and the difficult question about the possibility to transmit these perturbations from a contracting Universe to the expanding phase, we will show that the methods used in Khoury are inapplicable for the description of the cosmological evolution and of the process of generation of perturbations in this scenario.
Generalized Ramsey numbers through adiabatic quantum optimization
NASA Astrophysics Data System (ADS)
Ranjbar, Mani; Macready, William G.; Clark, Lane; Gaitan, Frank
2016-09-01
Ramsey theory is an active research area in combinatorics whose central theme is the emergence of order in large disordered structures, with Ramsey numbers marking the threshold at which this order first appears. For generalized Ramsey numbers r( G, H), the emergent order is characterized by graphs G and H. In this paper we: (i) present a quantum algorithm for computing generalized Ramsey numbers by reformulating the computation as a combinatorial optimization problem which is solved using adiabatic quantum optimization; and (ii) determine the Ramsey numbers r({{T}}m,{{T}}n) for trees of order m,n = 6,7,8, most of which were previously unknown.
Cavity-state preparation using adiabatic transfer
NASA Astrophysics Data System (ADS)
Larson, Jonas; Andersson, Erika
2005-05-01
We show how to prepare a variety of cavity field states for multiple cavities. The state preparation technique used is related to the method of stimulated adiabatic Raman passage. The cavity modes are coupled by atoms, making it possible to transfer an arbitrary cavity field state from one cavity to another and also to prepare nontrivial cavity field states. In particular, we show how to prepare entangled states of two or more cavities, such as an Einstein-Podolsky-Rosen state and a W state, as well as various entangled superpositions of coherent states in different cavities, including Schrödinger cat states. The theoretical considerations are supported by numerical simulations.
Phase avalanches in near-adiabatic evolutions
Vertesi, T.; Englman, R.
2006-02-15
In the course of slow, nearly adiabatic motion of a system, relative changes in the slowness can cause abrupt and high magnitude phase changes, ''phase avalanches,'' superimposed on the ordinary geometric phases. The generality of this effect is examined for arbitrary Hamiltonians and multicomponent (>2) wave packets and is found to be connected (through the Blaschke term in the theory of analytic signals) to amplitude zeros in the lower half of the complex time plane. Motion on a nonmaximal circle on the Poincare-sphere suppresses the effect. A spectroscopic transition experiment can independently verify the phase-avalanche magnitudes.
An adiabatic demagnetization refrigerator for infrared bolometers
NASA Technical Reports Server (NTRS)
Britt, R. D.; Richards, P. L.
1981-01-01
Adiabatic demagnetization refrigerators have been built and installed in small portable liquid helium cryostats to test the feasibility of this method of cooling infrared bolometric detectors to temperatures below 0.3 K. Performance has been achieved which suggests that bolometer temperatures of 0.2 K can be maintained for periods of approximately 60 hours. Applications to sensitive infrared detection from ground-based telescopes and space satellites are discussed. Design data are given which permit the evaluation of refrigerator performance for a variety of design parameters.
Shil, Suranjan; Bhattacharya, Debojit; Sarkar, Sonali; Misra, Anirban
2013-06-13
We have computed and investigated the performance of Minnesota density functionals especially the M05, M06, and M08 suite of complementary density functionals for the prediction of the heat of formations (HOFs) and the ionization potentials (IPs) of various benchmark complexes containing nine different first row transition metals. The eight functionals of M0X family, namely, the M05, M05-2X, M06-L, M06, M06-2X, M06-HF, M08-SO, and M08-HX are taken for the computation of the above-mentioned physical properties of such metal complexes along with popular Los Alamos National Laboratory 2 double-ζ (LANL2DZ) basis set. Total 54 benchmark systems are taken for HOF calculation, whereas the 47 systems among these benchmark complexes are chosen for the calculation of IPs because of lack of experimental results on rest of the seven systems. The computed values of HOFs and IPs are compared with the experimental results obtained from the literature. The deviation of these computed values from the actual experimental results is calculated for each eight different M0X functionals to judge their performances in evaluating these properties. Finally, a clear relationship between the exchange correlation energy of eight M0X functionals and their efficiency are made to predict the different physical properties.
NASA Astrophysics Data System (ADS)
DeYonker, Nathan J.; Peterson, Kirk A.
2013-04-01
Recent developments in ab initio coupled cluster (CC) theory and correlation consistent basis sets have ushered in an era of unprecedented accuracy when studying the spectroscopy and thermodynamics of molecules containing main group elements. These same developments have recently seen application to heavier inorganic or transition metal-containing species. The present work benchmarks conventional single reference coupled cluster theory (up to full configuration interaction for valence electron correlation and coupled cluster with up to full pentuple excitations (CCSDTQP) for core-valence correlation) and explicitly correlated coupled cluster methods [CC with single, double, and perturbative triple substitutions (CCSD(T)-F12)] for the atomic ionization potentials of the six 4p elements (Ga-Kr), a property with experimental error bars no greater than a few cm-1. When second-order spin orbit coupling effects are included, a composite methodology based on CCSD(T) calculations yielded a mean signed error of just -0.039 kcal mol-1 and a mean unsigned error of 0.043 kcal mol-1. Inclusion of post-CCSD(T) correlation corrections reduced both of these values to -0.008 kcal mol-1 and 0.025 kcal mol-1, respectively, with the latter corresponding to an average error of just 9 cm-1. The maximum signed error in the latter scheme was just -0.043 kcal mol-1 (15 cm-1).
NASA Astrophysics Data System (ADS)
Balabanov, Nikolai B.; Peterson, Kirk A.
2006-08-01
Recently developed correlation consistent basis sets for the first row transition metal elements Sc-Zn have been utilized to determine complete basis set (CBS) scalar relativistic electron affinities, ionization potentials, and 4s23dn -2-4s1dn -1 electronic excitation energies with single reference coupled cluster methods [CCSD(T), CCSDT, and CCSDTQ] and multireference configuration interaction with three reference spaces: 3d4s, 3d4s4p, and 3d4s4p3d'. The theoretical values calculated with the highest order coupled cluster techniques at the CBS limit, including extrapolations to full configuration interaction, are well within 1kcal/mol of the corresponding experimental data. For the early transition metal elements (Sc-Mn) the internally contracted multireference averaged coupled pair functional method yielded excellent agreement with experiment; however, the atomic properties for the late transition metals (Mn-Zn) proved to be much more difficult to describe with this level of theory, even with the largest reference function of the present work.
Naguib, Y.M.A.; Steel, C.; Cohen, S.G.; Young, M.A.
1987-05-21
Triplet benzophenone (/sup 4/K) abstracts a hydrogen from acetonitrile with a rate constant of 130 +/- 30 M/sup -1/ s/sup -1/. Despite this low rate constant acetonitrile is not really an inert solvent and at low light fluxes, where T-T annihilation is not a major fate of the triplet, a major decay path for /sup 4/K is hydrogen abstraction with resulting pinacol (K/sub 2/H/sub 2/) formation (phi/sub K/sub 2/H/sub 2/ approx. = 0.1 at t = 0). Both K/sub 2/H/sub 2/ formation and /sup 3/K lifetime rapidly decrease with irradiation due to the light absorbing transients (LAT's) which are formed along with K/sub 7/H/sub 2/ from ketyl radicals (KH). The rate constants per hydrogen (k/sub H/) for abstraction from R-H by the electrophilic /sup 3/K correlate well with the ionization potentials (IP) of the corresponding radicals (R).
Richard, Ryan M; Marshall, Michael S; Dolgounitcheva, O; Ortiz, J V; Brédas, Jean-Luc; Marom, Noa; Sherrill, C David
2016-02-01
In designing organic materials for electronics applications, particularly for organic photovoltaics (OPV), the ionization potential (IP) of the donor and the electron affinity (EA) of the acceptor play key roles. This makes OPV design an appealing application for computational chemistry since IPs and EAs are readily calculable from most electronic structure methods. Unfortunately reliable, high-accuracy wave function methods, such as coupled cluster theory with single, double, and perturbative triples [CCSD(T)] in the complete basis set (CBS) limit are too expensive for routine applications to this problem for any but the smallest of systems. One solution is to calibrate approximate, less computationally expensive methods against a database of high-accuracy IP/EA values; however, to our knowledge, no such database exists for systems related to OPV design. The present work is the first of a multipart study whose overarching goal is to determine which computational methods can be used to reliably compute IPs and EAs of electron acceptors. This part introduces a database of 24 known organic electron acceptors and provides high-accuracy vertical IP and EA values expected to be within ±0.03 eV of the true non-relativistic, vertical CCSD(T)/CBS limit. Convergence of IP and EA values toward the CBS limit is studied systematically for the Hartree-Fock, MP2 correlation, and beyond-MP2 coupled cluster contributions to the focal point estimates. PMID:26731487
Nucleon-deuteron scattering using the adiabatic projection method
NASA Astrophysics Data System (ADS)
Elhatisari, Serdar; Lee, Dean; Meißner, Ulf-G.; Rupak, Gautam
2016-06-01
In this paper we discuss the adiabatic projection method, a general framework for scattering and reaction calculations on the lattice. We also introduce several new techniques developed to study nucleus-nucleus scattering and reactions on the lattice. We present technical details of the method for large-scale problems. To estimate the systematic errors of the calculations we consider simple two-particle scattering on the lattice. Then we benchmark the accuracy and efficiency of the numerical methods by applying these to calculate fermion-dimer scattering in lattice effective field theory with and without a long-range Coulomb potential. The fermion-dimer calculations correspond to neutron-deuteron and proton-deuteron scattering in the spin-quartet channel at leading order in the pionless effective field theory.
From Classical Nonlinear Integrable Systems to Quantum Shortcuts to Adiabaticity.
Okuyama, Manaka; Takahashi, Kazutaka
2016-08-12
Using shortcuts to adiabaticity, we solve the time-dependent Schrödinger equation that is reduced to a classical nonlinear integrable equation. For a given time-dependent Hamiltonian, the counterdiabatic term is introduced to prevent nonadiabatic transitions. Using the fact that the equation for the dynamical invariant is equivalent to the Lax equation in nonlinear integrable systems, we obtain the counterdiabatic term exactly. The counterdiabatic term is available when the corresponding Lax pair exists and the solvable systems are classified in a unified and systematic way. Multisoliton potentials obtained from the Korteweg-de Vries equation and isotropic XY spin chains from the Toda equations are studied in detail. PMID:27563938
Adiabatic cooling of solar wind electrons
NASA Technical Reports Server (NTRS)
Sandbaek, Ornulf; Leer, Egil
1992-01-01
In thermally driven winds emanating from regions in the solar corona with base electron densities of n0 not less than 10 exp 8/cu cm, a substantial fraction of the heat conductive flux from the base is transfered into flow energy by the pressure gradient force. The adiabatic cooling of the electrons causes the electron temperature profile to fall off more rapidly than in heat conduction dominated flows. Alfven waves of solar origin, accelerating the basically thermally driven solar wind, lead to an increased mass flux and enhanced adiabatic cooling. The reduction in electron temperature may be significant also in the subsonic region of the flow and lead to a moderate increase of solar wind mass flux with increasing Alfven wave amplitude. In the solar wind model presented here the Alfven wave energy flux per unit mass is larger than that in models where the temperature in the subsonic flow is not reduced by the wave, and consequently the asymptotic flow speed is higher.
Quantum Adiabatic Algorithms and Large Spin Tunnelling
NASA Technical Reports Server (NTRS)
Boulatov, A.; Smelyanskiy, V. N.
2003-01-01
We provide a theoretical study of the quantum adiabatic evolution algorithm with different evolution paths proposed in this paper. The algorithm is applied to a random binary optimization problem (a version of the 3-Satisfiability problem) where the n-bit cost function is symmetric with respect to the permutation of individual bits. The evolution paths are produced, using the generic control Hamiltonians H (r) that preserve the bit symmetry of the underlying optimization problem. In the case where the ground state of H(0) coincides with the totally-symmetric state of an n-qubit system the algorithm dynamics is completely described in terms of the motion of a spin-n/2. We show that different control Hamiltonians can be parameterized by a set of independent parameters that are expansion coefficients of H (r) in a certain universal set of operators. Only one of these operators can be responsible for avoiding the tunnelling in the spin-n/2 system during the quantum adiabatic algorithm. We show that it is possible to select a coefficient for this operator that guarantees a polynomial complexity of the algorithm for all problem instances. We show that a successful evolution path of the algorithm always corresponds to the trajectory of a classical spin-n/2 and provide a complete characterization of such paths.
Ionization energies of argon clusters: A combined experimental and theoretical study
NASA Astrophysics Data System (ADS)
Echt, O.; Fiegele, T.; Rümmele, M.; Probst, M.; Matt-Leubner, S.; Urban, J.; Mach, P.; Leszczynski, J.; Scheier, P.; Märk, T. D.
2005-08-01
We have measured appearance energies of Arn+,n⩽30, by electron impact of gas phase clusters. Quantum-chemical calculations have been performed to determine the adiabatic and vertical ionization energies of argon clusters up to n =4 and 6, respectively. The experimental appearance energy of the dimer ion approaches, under suitable cluster source conditions, the adiabatic ionization energy. The agreement with values obtained by photoionization and threshold photoelectron-photoion coincidence (TPEPICO) spectra demonstrates that autoionizing Rydberg states are accessible by electron impact. Appearance energies of larger clusters, though, exceed the TPEPICO values by about 0.5 eV.
Vibrational dynamics of the bifluoride ion. II. Adiabatic separation and proton dynamics
NASA Astrophysics Data System (ADS)
Epa, V. C.; Thorson, W. R.
1990-01-01
Vibrational dynamics of the bifluoride ion FHF-, which exhibits strongly anharmonic and nonseparable vibrations, is studied using the extended ab initio model potential surface described in the first paper of this series. Adiabatic separation of the proton motion from the F-F (ν1) motion forms a zero-order basis for description, although strong coupling of adiabatic states by the ν1 motion is important in higher vibrational levels and must be considered to understand the spectrum. The adiabatic protonic eigenstates at F-F separations R from 3.75 to 6.40 a.u. have been determined using the self-consistent field approximation in prolate spheroidal coordinates to provide a basis set for configuration interaction expansion of the exact eigenstates. 78 SCF eigenstates (21 σg, 21 σu, 21 πu, and 15 πg) were computed by ``exact'' numerical solution of the SCF equations. The adiabatic CI eigenstates are shown to be converged in energy to better than 1.0 cm-1 for the ground state of each symmetry type and usually better than 10 cm-1 for the lowest three to five states, and pass critical tests of accuracy such as the Hellmann-Feynman theorem. The resulting CI potential energy curves closely resemble corresponding SCF energy curves and justify the concept of mode separation even in this very anharmonic system. The adiabatic CI potential energy curves explain most aspects of the dynamics relevant to the IR and Raman spectra of FHF- (e.g., in KHF2), and calculations of ν1 dynamics within the adiabatic approximation suffice to assign most of the observed IR spectrum of KHF2(s) (to about 6000 cm-1). States corresponding qualitatively to modal overtone and combination levels such as 3ν2 and (ν2+2ν3) however exhibit avoided crossings in the neighborhood of the equilibrium configuration and ``Fermi resonance'' involving interactions of two or more such adiabatic states via the ν1 motion must be treated by close-coupling to predict both frequencies and intensities in the
Adiabat Shaping of ICF Capsules Using Ramped Pressure Profiles
NASA Astrophysics Data System (ADS)
Anderson, K.; Betti, R.; Collins, T. J. B.; Marinak, M. M.; Haan, S. W.
2002-11-01
Target design of direct-drive ICF capsules has historically involved a compromise between high 1-D (clean) yield and capsule stability. Low-adiabat fuel is desirable to achieve high compression and, hence, high yield. A higher adiabat at the ablation front reduces the growth rate of the Raleigh--Taylor instability due to higher ablation velocity. An optimal target design will take advantage of both by shaping the adiabat of the capsule to allow for high adiabat in the material that is to be ablated and low adiabat in the remaining fuel. We present here a method of adiabat shaping using a low-intensity prepulse followed by laser shutoff before beginning the main drive pulse. This creates a decaying shock with a ramped pressure profile behind it. Since the prepulse is low intensity, the adiabat is not strongly affected by the prepulse. The main shock is then launched up this ramped pressure profile to set the adiabat. Because the main shock sees an increasing pressure profile, the effective strength of the shock decreases as it propagates through the shell, thus creating a smooth adiabat profile from high outer-shell adiabat to low inner-shell adiabat. Results of simulations using 1-D LILAC and 2-D DRACO (LLE), as well as 1-D and 2-D HYDRA (LLNL), are presented. This work was supported by the U.S. DOE Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460 and by the University of California LLNL under contract No. W-7405-Eng-48.
NASA Astrophysics Data System (ADS)
Mandrà, Salvatore; Guerreschi, Gian Giacomo; Aspuru-Guzik, Alán
2015-12-01
Adiabatic quantum optimization is a procedure to solve a vast class of optimization problems by slowly changing the Hamiltonian of a quantum system. The evolution time necessary for the algorithm to be successful scales inversely with the minimum energy gap encountered during the dynamics. Unfortunately, the direct calculation of the gap is strongly limited by the exponential growth in the dimensionality of the Hilbert space associated to the quantum system. Although many special-purpose methods have been devised to reduce the effective dimensionality, they are strongly limited to particular classes of problems with evident symmetries. Moreover, little is known about the computational power of adiabatic quantum optimizers in real-world conditions. Here we propose and implement a general purposes reduction method that does not rely on any explicit symmetry and which requires, under certain general conditions, only a polynomial amount of classical resources. Thanks to this method, we are able to analyze the performance of "nonideal" quantum adiabatic optimizers to solve the well-known Grover problem, namely the search of target entries in an unsorted database, in the presence of discrete local defects. In this case, we show that adiabatic quantum optimization, even if affected by random noise, is still potentially faster than any classical algorithm.
Tong, Xin; Cerný, Jirí; Müller-Dethlefs, Klaus; Dessent, Caroline E H
2008-07-01
Two conformational isomers of the aromatic hydrocarbon n-butylbenzene have been studied using two-color MATI (mass analyzed threshold ionization) spectroscopy to explore the effect of conformation on ionization dynamics. Cationic states of g auche-conformer III and anti- conformers IV were selectively produced by two-color excitation via the respective S 1 origins. Adiabatic ionization potentials of the gauche- and anti-conformations were determined to be 70146 and 69872 +/- 5 cm (-1) respectively. Spectral features and vibrational modes are interpreted with the aid of MP2/cc-pVDZ ab initio calculations, and ionization-induced changes in the molecular conformations are discussed. Complete basis set (CBS) ab initio studies at MP2 level reveal reliable energetics for all four n-butylbenzene conformers observed in earlier two-color REMPI (resonance enhanced multiphoton ionization) spectra. For the S 0 state, the energies of conformer III, IV and V are above conformer I by 130, 289, 73 cm (-1), respectively. Furthermore, the combination of the CBS calculations with the measured REMPI, MATI spectra allowed the determination of the energetics of all four conformers in the S 1 and D 0 states.
Tong, Xin; Cerný, Jirí; Müller-Dethlefs, Klaus; Dessent, Caroline E H
2008-07-01
Two conformational isomers of the aromatic hydrocarbon n-butylbenzene have been studied using two-color MATI (mass analyzed threshold ionization) spectroscopy to explore the effect of conformation on ionization dynamics. Cationic states of g auche-conformer III and anti- conformers IV were selectively produced by two-color excitation via the respective S 1 origins. Adiabatic ionization potentials of the gauche- and anti-conformations were determined to be 70146 and 69872 +/- 5 cm (-1) respectively. Spectral features and vibrational modes are interpreted with the aid of MP2/cc-pVDZ ab initio calculations, and ionization-induced changes in the molecular conformations are discussed. Complete basis set (CBS) ab initio studies at MP2 level reveal reliable energetics for all four n-butylbenzene conformers observed in earlier two-color REMPI (resonance enhanced multiphoton ionization) spectra. For the S 0 state, the energies of conformer III, IV and V are above conformer I by 130, 289, 73 cm (-1), respectively. Furthermore, the combination of the CBS calculations with the measured REMPI, MATI spectra allowed the determination of the energetics of all four conformers in the S 1 and D 0 states. PMID:18533642
The Adiabatic Invariance of the Action Variable in Classical Dynamics
ERIC Educational Resources Information Center
Wells, Clive G.; Siklos, Stephen T. C.
2007-01-01
We consider one-dimensional classical time-dependent Hamiltonian systems with quasi-periodic orbits. It is well known that such systems possess an adiabatic invariant which coincides with the action variable of the Hamiltonian formalism. We present a new proof of the adiabatic invariance of this quantity and illustrate our arguments by means of…
Generation of atomic NOON states via shortcuts to adiabatic passage
NASA Astrophysics Data System (ADS)
Song, Chong; Su, Shi-Lei; Bai, Cheng-Hua; Ji, Xin; Zhang, Shou
2016-10-01
Based on Lewis-Riesenfeld invariants and quantum Zeno dynamics, we propose an effective scheme for generating atomic NOON states via shortcuts to adiabatic passage. The photon losses are efficiently suppressed by engineering shortcuts to adiabatic passage in the scheme. The numerical simulation shows that the atomic NOON states can be generated with high fidelity.
Kinetic Theory Derivation of the Adiabatic Law for Ideal Gases.
ERIC Educational Resources Information Center
Sobel, Michael I.
1980-01-01
Discusses how the adiabatic law for ideal gases can be derived from the assumption of a Maxwell-Boltzmann (or any other) distribution of velocities--in contrast to the usual derivations from thermodynamics alone, and the higher-order effect that leads to one-body viscosity. An elementary derivation of the adiabatic law is given. (Author/DS)
Adiabat-shaping in indirect drive inertial confinement fusion
Baker, K. L.; Robey, H. F.; Milovich, J. L.; Jones, O. S.; Smalyuk, V. A.; Casey, D. T.; MacPhee, A. G.; Pak, A.; Celliers, P. M.; Clark, D. S.; Landen, O. L.; Peterson, J. L.; Berzak-Hopkins, L. F.; Weber, C. R.; Haan, S. W.; Döppner, T. D.; Dixit, S.; Hamza, A. V.; Jancaitis, K. S.; Kroll, J. J.; and others
2015-05-15
Adiabat-shaping techniques were investigated in indirect drive inertial confinement fusion experiments on the National Ignition Facility as a means to improve implosion stability, while still maintaining a low adiabat in the fuel. Adiabat-shaping was accomplished in these indirect drive experiments by altering the ratio of the picket and trough energies in the laser pulse shape, thus driving a decaying first shock in the ablator. This decaying first shock is designed to place the ablation front on a high adiabat while keeping the fuel on a low adiabat. These experiments were conducted using the keyhole experimental platform for both three and four shock laser pulses. This platform enabled direct measurement of the shock velocities driven in the glow-discharge polymer capsule and in the liquid deuterium, the surrogate fuel for a DT ignition target. The measured shock velocities and radiation drive histories are compared to previous three and four shock laser pulses. This comparison indicates that in the case of adiabat shaping the ablation front initially drives a high shock velocity, and therefore, a high shock pressure and adiabat. The shock then decays as it travels through the ablator to pressures similar to the original low-adiabat pulses when it reaches the fuel. This approach takes advantage of initial high ablation velocity, which favors stability, and high-compression, which favors high stagnation pressures.
NASA Astrophysics Data System (ADS)
Salom, Igor; Dmitrašinović, V.
2016-05-01
We construct the three-body permutation symmetric O (6) hyperspherical harmonics and use them to solve the non-relativistic three-body Schrödinger equation in three spatial dimensions. We label the states with eigenvalues of the U (1) ⊗ SO(3)rot ⊂ U (3) ⊂ O (6) chain of algebras, and we present the K ≤ 4 harmonics and tables of their matrix elements. That leads to closed algebraic form of low-K energy spectra in the adiabatic approximation for factorizable potentials with square-integrable hyper-angular parts. This includes homogeneous pairwise potentials of degree α ≥ - 1. More generally, a simplification is achieved in numerical calculations of non-adiabatic approximations to non-factorizable potentials by using our harmonics.
Decoherence and adiabatic transport in semiconductor quantum dots
NASA Astrophysics Data System (ADS)
Switkes, Michael
2000-10-01
I present research on ballistic electron transport in lateral GaAs/AlGaAs quantum dots connected to the environment with leads supporting one or more fully transmitting quantum modes. The first part of this dissertation examines electron the phenomena which mediate the transition from quantum mechanical to classical behavior in these quantum dots. Measurements of electron phase coherence time based on the magnitude of weak localization correction are presented as a function both of temperature and of applied bias. The coherence time is found to depend on temperature approximately as a sum of two power laws, tauφ ≈ AT-1 + BT-2, in agreement with the prediction for diffusive two dimensional systems but not with predictions for closed quantum dots or ballistic 2D systems. The effects of a large applied bias can be described with an elevated effective electron temperature calculated from the balance of Joule heating and cooling by Wiedemann-Franz out diffusion of hot electrons. The limits this imposes for quantum dot based technologies are examined through the detailed analysis of a quantum dot magnetometer. The second part of the work presented here focuses on a novel form of electron transport, adiabatic quantum electron pumping, in which a current is driven by cyclic changes in the wave function of a mesoscopic system rather than by an externally imposed bias. After a brief review of other mechanisms which produce a dc current from an ac excitation, measurements of adiabatic pumping are presented. The pumped current (or voltage) is sinusoidal in the phase difference between the two ac voltages deforming the dot potential and fluctuates in both magnitude and direction with small changes in external parameters such as magnetic field. Dependencies of pumping on the strength of the deformations, temperature, and breaking of time-reversal symmetry are also investigated.
Adiabatic principles in atom-diatom collisional energy transfer
Hovingh, W.J.
1993-01-01
This work describes the application of numerical methods to the solution of the time dependent Schroedinger equation for non-reactive atom-diatom collisions in which only one of the degrees of freedom has been removed. The basic method involves expanding the wave function in a basis set in two of the diatomic coordinates in a body-fixed frame (with respect to the triatomic complex) and defining the coefficients in that expansion as functions on a grid in the collision coordinate. The wave function is then propagated in time using a split operator method. The bulk of this work is devoted to the application of this formalism to the study of internal rotational predissociation in NeHF, in which quasibound states of the triatom predissociate through the transfer of energy from rotation of the diatom into translational energy in the atom-diatom separation coordinate. The author analyzes the computed time dependent wave functions to calculate the lifetimes for several quasibound states; these are in agreement with time independent quantum calculations using the same potential. Moreover, the time dependent behavior of the wave functions themselves sheds light on the dynamics of the predissociation processes. Finally, the partial cross sections of the products in those processes is determined with multiple exit channels. These show strong selectivity in the orbital angular momentum of the outgoing fragments, which the author explains with an adiabatic channel interpretation of the wave function's dynamics. The author also suggests that the same formalism might profitably be used to investigate the quantum dynamics of [open quotes]quasiresonant vibration-rotation transfer[close quotes], in which remarkably strong propensity rules in certain inelastic atom-diatom collision arise from classical adiabatic invariance theory.
An adiabatic demagnetization refrigerator for SIRTF
NASA Technical Reports Server (NTRS)
Timbie, P. T.; Bernstein, G. M.; Richards, P. L.
1989-01-01
An adiabatic demagnetization refrigerator (ADR) has been proposed to cool bolometric infrared detectors on the multiband imaging photometer of the Space Infrared Telescope Facility (SIRTF). One such refrigerator has been built which uses a ferric ammonium alum salt pill suspended by nylon threads in a 3-T solenoid. The resonant modes of this suspension are above 100 Hz. The heat leak to the salt pill is less than 0.5 microW. The system has a hold time at 0.1K of more than 12 h. The cold stage temperature is regulated with a feedback loop that controls the magnetic field. A second, similar refrigerator is being built at a SIRTF prototype to fly on a ballon-borne telescope. It will use a ferromagnetic shield. The possibility of using a high-Tc solenoid-actuated heat switch is also discussed.
An adiabatic demagnetization refrigerator for SIRTF
Timbie, P.T.; Bernstein, G.M.; Richards, P.L.
1989-02-01
An adiabatic demagnetization refrigerator (ADR) has been proposed to cool bolometric infrared detectors on the Multiband Imaging Photometer of the Space Infrared Telescope Facility (SIRTF). The authors have built one such refrigerator which employs a ferric ammonium alum salt pill suspended by nylon threads in a 3 Tesla solenoid. The resonant modes of this suspension are above 100 Hz. The heat leak to the salt pill is <0.5 ..mu..W. The system has a hold time at 0.1 /sup 0/K of >12 hours. The cold stage temperature is regulated with a feedback loop that controls the magnetic field. A second, similar refrigerator is being built as a SIRTF prototype to fly on a balloon-borne telescope. It will employ a ferromagnetic shield. The possibility of using high T/sub c/ leads to the superconducting magnet and a solenoid-actuated heat switch are also discussed.
The HAWC and SAFIRE Adiabatic Demagnetization Refrigerators
NASA Technical Reports Server (NTRS)
Tuttle, Jim; Shirron, Peter; DiPirro, Michael; Jackson, Michael; Behr, Jason; Kunes, Evan; Hait, Tom; Krebs, Carolyn (Technical Monitor)
2001-01-01
The High-Resolution Airborne Wide-band Camera (HAWC) and Submillimeter and Far Infrared Experiment (SAFIRE) are far-infrared experiments which will fly on the Stratospheric Observatory for Infrared Astronomy (SOFIA) aircraft. HAWC's detectors will operate at 0.2 Kelvin, while those of SAFIRE will be at 0.1 Kelvin. Each instrument will include an adiabatic demagnetization refrigerator (ADR) to cool its detector stage from the liquid helium bath temperature (HAWC's at 4.2 Kelvin and SAFIRE's pumped to about 1.3 Kelvin) to its operating temperature. Except for the magnets used to achieve the cooling and a slight difference in the heat switch design, the two ADRs are nearly identical. We describe the ADR design and present the results of performance testing.
Number Partitioning via Quantum Adiabatic Computation
NASA Technical Reports Server (NTRS)
Smelyanskiy, Vadim N.; Toussaint, Udo; Clancy, Daniel (Technical Monitor)
2002-01-01
We study both analytically and numerically the complexity of the adiabatic quantum evolution algorithm applied to random instances of combinatorial optimization problems. We use as an example the NP-complete set partition problem and obtain an asymptotic expression for the minimal gap separating the ground and exited states of a system during the execution of the algorithm. We show that for computationally hard problem instances the size of the minimal gap scales exponentially with the problem size. This result is in qualitative agreement with the direct numerical simulation of the algorithm for small instances of the set partition problem. We describe the statistical properties of the optimization problem that are responsible for the exponential behavior of the algorithm.
Differential topology of adiabatically controlled quantum processes
NASA Astrophysics Data System (ADS)
Jonckheere, Edmond A.; Rezakhani, Ali T.; Ahmad, Farooq
2013-03-01
It is shown that in a controlled adiabatic homotopy between two Hamiltonians, H 0 and H 1, the gap or "anti-crossing" phenomenon can be viewed as the development of cusps and swallow tails in the region of the complex plane where two critical value curves of the quadratic map associated with the numerical range of H 0 + i H 1 come close. The "near crossing" in the energy level plots happens to be a generic situation, in the sense that a crossing is a manifestation of the quadratic numerical range map being unstable in the sense of differential topology. The stable singularities that can develop are identified and it is shown that they could occur near the gap, making those singularities of paramount importance. Various applications, including the quantum random walk, are provided to illustrate this theory.
Quantum Adiabatic Optimization and Combinatorial Landscapes
NASA Technical Reports Server (NTRS)
Smelyanskiy, V. N.; Knysh, S.; Morris, R. D.
2003-01-01
In this paper we analyze the performance of the Quantum Adiabatic Evolution (QAE) algorithm on a variant of Satisfiability problem for an ensemble of random graphs parametrized by the ratio of clauses to variables, gamma = M / N. We introduce a set of macroscopic parameters (landscapes) and put forward an ansatz of universality for random bit flips. We then formulate the problem of finding the smallest eigenvalue and the excitation gap as a statistical mechanics problem. We use the so-called annealing approximation with a refinement that a finite set of macroscopic variables (verses only energy) is used, and are able to show the existence of a dynamic threshold gamma = gammad, beyond which QAE should take an exponentially long time to find a solution. We compare the results for extended and simplified sets of landscapes and provide numerical evidence in support of our universality ansatz.
Geometric Adiabatic Transport in Quantum Hall States.
Klevtsov, S; Wiegmann, P
2015-08-21
We argue that in addition to the Hall conductance and the nondissipative component of the viscous tensor, there exists a third independent transport coefficient, which is precisely quantized. It takes constant values along quantum Hall plateaus. We show that the new coefficient is the Chern number of a vector bundle over moduli space of surfaces of genus 2 or higher and therefore cannot change continuously along the plateau. As such, it does not transpire on a sphere or a torus. In the linear response theory, this coefficient determines intensive forces exerted on electronic fluid by adiabatic deformations of geometry and represents the effect of the gravitational anomaly. We also present the method of computing the transport coefficients for quantum Hall states. PMID:26340197
Geometric Adiabatic Transport in Quantum Hall States.
Klevtsov, S; Wiegmann, P
2015-08-21
We argue that in addition to the Hall conductance and the nondissipative component of the viscous tensor, there exists a third independent transport coefficient, which is precisely quantized. It takes constant values along quantum Hall plateaus. We show that the new coefficient is the Chern number of a vector bundle over moduli space of surfaces of genus 2 or higher and therefore cannot change continuously along the plateau. As such, it does not transpire on a sphere or a torus. In the linear response theory, this coefficient determines intensive forces exerted on electronic fluid by adiabatic deformations of geometry and represents the effect of the gravitational anomaly. We also present the method of computing the transport coefficients for quantum Hall states.
Adiabatic frequency conversion of ultrafast pulses
NASA Astrophysics Data System (ADS)
Suchowski, H.; Bruner, B. D.; Ganany-Padowicz, A.; Juwiler, I.; Arie, A.; Silberberg, Y.
2011-12-01
A new method for efficient, broadband sum and difference frequency generation of ultrafast pulses is demonstrated. The principles of the method follow from an analogy between frequency conversion and coherent optical excitation of a two-level system. For conversion of ultrafast pulses, the concepts of adiabatic conversion are developed further in order to account for dispersion and group velocity mismatch. The scheme was implemented using aperiodically poled nonlinear crystals and a single step nonlinear mixing process, leading to conversion of near-IR (˜790 nm) ultrafast pulses into the blue (˜450 nm) and mid-IR (˜3.15 μm) spectral regions. Conversion bandwidths up to 15 THz FWHM and efficiencies up to 50% are reported.
Stirling engine with one adiabatic cylinder
NASA Astrophysics Data System (ADS)
West, C. D.
1982-03-01
It is shown that integration around the P-V loop of a Stirling-like cycle with an adiabatic expansion or compression space is possible through careful application of the ideal gas laws. The result is a set of closed-form solutions or the work output, work input, and efficiency for ideal gases. Previous analyses yielded closed-form solutions only for machines in which all spaces behave isothermally, or that have other limitations that simplify the arithmetic but omit important aspects of real machines. The results of this analysis, although still far removed from the exact behavior of real, practical engines, yield important insights into the effects observed in computer models and experimental machines. These results are especially illuminating for machines intended to operate with fairly small temperature differences. Heat pumps and low-technology solar-powered engines might be included in this category.
Adiabatic connection at negative coupling strengths
Seidl, Michael; Gori-Giorgi, Paola
2010-01-15
The adiabatic connection of density functional theory (DFT) for electronic systems is generalized here to negative values of the coupling strength alpha (with attractive electrons). In the extreme limit alpha->-infinity a simple physical solution is presented and its implications for DFT (as well as its limitations) are discussed. For two-electron systems (a case in which the present solution can be calculated exactly), we find that an interpolation between the limit alpha->-infinity and the opposite limit of infinitely strong repulsion (alpha->+infinity) yields a rather accurate estimate of the second-order correlation energy E{sub c}{sup GL2}[rho] for several different densities rho, without using virtual orbitals. The same procedure is also applied to the Be isoelectronic series, analyzing the effects of near degeneracy.
Lattice Boltzmann method for adiabatic acoustics.
Li, Yanbing; Shan, Xiaowen
2011-06-13
The lattice Boltzmann method (LBM) has been proved to be a useful tool in many areas of computational fluid dynamics, including computational aero-acoustics (CAA). However, for historical reasons, its applications in CAA have been largely restricted to simulations of isothermal (Newtonian) sound waves. As the recent kinetic theory-based reformulation establishes a theoretical framework in which LBM can be extended to recover the full Navier-Stokes-Fourier (NS) equations and beyond, in this paper, we show that, at least at the low-frequency limit (sound frequency much less than molecular collision frequency), adiabatic sound waves can be accurately simulated by the LBM provided that the lattice and the distribution function ensure adequate recovery of the full NS equations.
An Integrated Development Environment for Adiabatic Quantum Programming
Humble, Travis S; McCaskey, Alex; Bennink, Ryan S; Billings, Jay Jay; D'Azevedo, Eduardo; Sullivan, Blair D; Klymko, Christine F; Seddiqi, Hadayat
2014-01-01
Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware raises the question of how well quantum programs perform. Benchmarking behavior is challenging since the multiple steps to synthesize an adiabatic quantum program are highly tunable. We present an adiabatic quantum programming environment called JADE that provides control over all the steps taken during program development. JADE captures the workflow needed to rigorously benchmark performance while also allowing a variety of problem types, programming techniques, and processor configurations. We have also integrated JADE with a quantum simulation engine that enables program profiling using numerical calculation. The computational engine supports plug-ins for simulation methodologies tailored to various metrics and computing resources. We present the design, integration, and deployment of JADE and discuss its use for benchmarking adiabatic quantum programs.
Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation
Zamstein, Noa; Tannor, David J.
2012-12-14
We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schroedinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.
Microwave remote sensing of ionized air.
Liao, S.; Gopalsami, N.; Heifetz, A.; Elmer, T.; Fiflis, P.; Koehl, E. R.; Chien, H. T.; Raptis, A. C.
2011-07-01
We present observations of microwave scattering from ambient room air ionized with a negative ion generator. The frequency dependence of the radar cross section of ionized air was measured from 26.5 to 40 GHz (Ka-band) in a bistatic mode with an Agilent PNA-X series (model N5245A) vector network analyzer. A detailed calibration scheme is provided to minimize the effect of the stray background field and system frequency response on the target reflection. The feasibility of detecting the microwave reflection from ionized air portends many potential applications such as remote sensing of atmospheric ionization and remote detection of radioactive ionization of air.
``Adiabatic-hindered-rotor'' treatment of the parahydrogen-water complex
NASA Astrophysics Data System (ADS)
Zeng, Tao; Li, Hui; Le Roy, Robert J.; Roy, Pierre-Nicholas
2011-09-01
Inspired by a recent successful adiabatic-hindered-rotor treatment for parahydrogen pH2 in CO2-H2 complexes [H. Li, P.-N. Roy, and R. J. Le Roy, J. Chem. Phys. 133, 104305 (2010); H. Li, R. J. Le Roy, P.-N. Roy, and A. R. W. McKellar, Phys. Rev. Lett. 105, 133401 (2010)], we apply the same approximation to the more challenging H2O-H2 system. This approximation reduces the dimension of the H2O-H2 potential from 5D to 3D and greatly enhances the computational efficiency. The global minimum of the original 5D potential is missing from the adiabatic 3D potential for reasons based on solution of the hindered-rotor Schrödinger equation of the pH2. Energies and wave functions of the discrete rovibrational levels of H2O-pH2 complexes obtained from the adiabatic 3D potential are in good agreement with the results from calculations with the full 5D potential. This comparison validates our approximation, although it is a relatively cruder treatment for pH2-H2O than it is for pH2-CO2. This adiabatic approximation makes large-scale simulations of H2O-pH2 systems possible via a pairwise additive interaction model in which pH2 is treated as a point-like particle. The poor performance of the diabatically spherical treatment of pH2 rotation excludes the possibility of approximating pH2 as a simple sphere in its interaction with H2O.
Zero-point energy, tunnelling, and vibrational adiabaticity in the Mu + H2 reaction
NASA Astrophysics Data System (ADS)
Mielke, Steven L.; Garrett, Bruce C.; Fleming, Donald G.; Truhlar, Donald G.
2015-01-01
Isotopic substitution of muonium for hydrogen provides an unparalleled opportunity to deepen our understanding of quantum mass effects on chemical reactions. A recent topical review in this journal of the thermal and vibrationally state-selected reaction of Mu with H2 raises a number of issues that are addressed here. We show that some earlier quantum mechanical calculations of the Mu + H2 reaction, which are highlighted in this review, and which have been used to benchmark approximate methods, are in error by as much as 19% in the low-temperature limit. We demonstrate that an approximate treatment of the Born-Oppenheimer diagonal correction that was used in some recent studies is not valid for treating the vibrationally state-selected reaction. We also discuss why vibrationally adiabatic potentials that neglect bend zero-point energy are not a useful analytical tool for understanding reaction rates, and why vibrationally non-adiabatic transitions cannot be understood by considering tunnelling through vibrationally adiabatic potentials. Finally, we present calculations on a hierarchical family of potential energy surfaces to assess the sensitivity of rate constants to the quality of the potential surface.
Exploiting initial-state dependence to improve the performance of adiabatic TDDFT
NASA Astrophysics Data System (ADS)
Fuks, Johanna I.; Nielsen, Soeren E. B.; Ruggenthaler, Michael; Maitra, Neepa T.; Hunter college City University of New York Collaboration; Max-Planck-Institut für Struktur und Dynamik der Materie, Hamburg Collaboration
Although time-dependent density functional theory (TDDFT) descriptions of dynamics in non-equilibrium situations have seen exciting successes recently, there have also been studies that throw into doubt the reliability of the approximate exchange-correlation functionals to accurately describe the dynamics. Here we study exact exchange-correlation potentials for few electron systems, found using the global fixed-point iteration method [NRL]. We find that the size of dynamical correlation features that are missing in the currently-used adiabatic approximations depend strongly on the choice of the initial Kohn-Sham wavefunction. With a judicious choice, the dynamical effects can be small over a finite time duration, but sometimes they can get large at longer times. We also examine different starting points, in particular an orbital-dependent potential directly obtained from the Kohn-Sham hole [LFSEM14], for approximate xc functionals: instead of building on an adiabatic approximation.
Temperature gradients due to adiabatic plasma expansion in a magnetic nozzle
NASA Astrophysics Data System (ADS)
Sheehan, J. P.; Longmier, B. W.; Bering, E. A.; Olsen, C. S.; Squire, J. P.; Ballenger, M. G.; Carter, M. D.; Cassady, L. D.; Díaz, F. R. Chang; Glover, T. W.; Ilin, A. V.
2014-08-01
A mechanism for ambipolar ion acceleration in a magnetic nozzle is proposed. The plasma is adiabatic (i.e., does not exchange energy with its surroundings) in the diverging section of a magnetic nozzle so any energy lost by the electrons must be transferred to the ions via the electric field. Fluid theory indicates that the change in plasma potential is proportional to the change in average electron energy. These predictions were compared to measurements in the VX-200 experiment which has conditions conducive to ambipolar ion acceleration. A planar Langmuir probe was used to measure the plasma potential, electron density, and electron temperature for a range of mass flow rates and power levels. Axial profiles of those parameters were also measured, showing consistency with the adiabatic ambipolar fluid theory.
Rydberg atom spectroscopy enabled by blackbody radiation ionization
Lu Xiaoxu; Sun Yuan; Metcalf, Harold
2011-09-15
We have excited helium atoms from their metastable 2 {sup 3} S state to Rydberg states in the range 13
Electron-impact ionization and dissociative ionization of biomolecules
NASA Astrophysics Data System (ADS)
Huo, Winifred
2006-05-01
Oxidative damages by ionizing radiation are the source of radiation-induced damages to human health. It is recognized that secondary electrons play a role in the damage process, particularly important is the damage of DNA by electrons, potentially leading to mutagenesis. The damage can be direct, by creating a DNA lesion, or indirect, by producing radicals that attack the DNA. Molecular-level study of electron interaction with DNA provides information on the damage pathways and dominant mechanisms. This investigation focuses on ionization and dissociative ionization (DI) of DNA fragments by electron-impact. For ionization we use the improved binary-encounter dipole (iBED) model [W.M. Huo, Phys. Rev. A64, 042719-1 (2001)]. For DI it is assumed that electron motion is much faster than nuclear motion, allowing DI to be treated as a two-step process and the DI cross section given by the product of the ionization cross section and dissociation probability. The ionization study covers DNA bases, sugar phosphate backbone, and nucleotides. An additivity principle is observed. For example, the sum of the ionization cross sections of the separate deoxyribose and phosphate fragments is in close agreement with the C3'- and C5'-deoxyribose-phospate cross sections, differing by less than 5%. The result implies that certain properties of the DNA, like the total ionization cross section, are localized properties and an additivity principle may apply. This allows us to obtain properties of a larger molecular system built up from the results of smaller subsystem fragments. The DI of guanine and cytosine has been studied. For guanine, a proton is produced from the channel where the ionized electron originates from a molecular orbital with significant charge density along the N(1)-H bond. The interaction of the proton with cytosine was also studied.
Effects of EOS adiabat on hot spot dynamics
NASA Astrophysics Data System (ADS)
Cheng, Baolian; Kwan, Thomas; Wang, Yi-Ming; Batha, Steven
2013-10-01
Equation of state (EOS) and adiabat of the pusher play significant roles in the dynamics and formation of the hot spot of an ignition capsule. For given imploding energy, they uniquely determine the partition of internal energy, mass, and volume between the pusher and the hot spot. In this work, we apply the new scaling laws recently derived by Cheng et al. to the National Ignition Campaign (NIC) ignition capsules and study the impacts of EOS and adiabat of the pusher on the hot spot dynamics by using the EOS adiabat index as an adjustable model parameter. We compare our analysis with the NIC data, specifically, for shots N120321 and N120205, and with the numerical simulations of these shots. The predictions from our theoretical model are in good agreements with the NIC data when a hot adiabat was used for the pusher, and with code simulations when a cold adiabat was used for the pusher. Our analysis indicates that the actual adiabat of the pusher in NIC experiments may well be higher than the adiabat assumed in the simulations. This analysis provides a physical and systematic explanation to the ongoing disagreements between the NIC experimental results and the multi-dimensional numerical simulations. This work was performed under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under contract number W-7405-ENG-36.
Angeletti, R; Gioacchini, A M; Seraglia, R; Piro, R; Traldi, P
1998-06-01
Adulteration by addition of bovine milk to water buffalo milk employed for mozzarella cheese production is often observed. Water buffalo milk and mozzarella cheese were analysed by matrix-assisted laser desorption/ionization mass spectrometry in order to achieve their rapid and accurate characterization and to evaluate possible fraudulence in mozzarella cheese production.
NOVAE EJECTA AS DISCRETE ADIABATICALLY EXPANDING GLOBULES
Williams, Robert
2013-09-15
Available data for novae show that the X-ray and visible spectral regions correlate with each other as they evolve. Large differences in ionization exist simultaneously in the two wavelength regimes, and a straightforward model is proposed that explains the characteristics observed in both spectral regimes. Its key features are (1) ejected blobs of very high density gas from the white dwarf (WD) that expand to create within each clump a wide range of emitting density, ionization, and velocity, and (2) a more homogeneous circumbinary envelope of gas that is produced by secondary star mass loss. The relative mass loss rates from the two stars determine whether the He/N or the Fe II visible spectrum predominates during decline, when hard X-rays are detected, and when the WD can be detected as a super soft X-ray source.
Novae Ejecta as Discrete Adiabatically Expanding Globules
NASA Astrophysics Data System (ADS)
Williams, Robert
2013-09-01
Available data for novae show that the X-ray and visible spectral regions correlate with each other as they evolve. Large differences in ionization exist simultaneously in the two wavelength regimes, and a straightforward model is proposed that explains the characteristics observed in both spectral regimes. Its key features are (1) ejected blobs of very high density gas from the white dwarf (WD) that expand to create within each clump a wide range of emitting density, ionization, and velocity, and (2) a more homogeneous circumbinary envelope of gas that is produced by secondary star mass loss. The relative mass loss rates from the two stars determine whether the He/N or the Fe II visible spectrum predominates during decline, when hard X-rays are detected, and when the WD can be detected as a super soft X-ray source.
Adiabatic optical bus for long-range coupling between silicon photonic waveguides
NASA Astrophysics Data System (ADS)
Hope, A. P.; Nguyen, T. G.; Greentree, A. D.; Mitchell, A.
2014-05-01
We present a new approach to planar photonic interconnects based on spatial adiabatic passage between thin ridge silicon waveguides. Our approach provides robust coupling between arbitrary pairs of well-separated waveguides across a single chip, potentially bypassing intermediate waveguides and structures. This new technique presents opportunities for waveguide routing and device topologies that cannot be achieved using traditional evanescent coupling, while remaining compatible with conventional CMOS fabrication techniques.
Optimality of partial adiabatic search and its circuit model
NASA Astrophysics Data System (ADS)
Mei, Ying; Sun, Jie; Lu, Songfeng; Gao, Chao
2014-08-01
In this paper, we first uncover a fact that a partial adiabatic quantum search with time complexity is in fact optimal, in which is the total number of elements in an unstructured database, and () of them are the marked ones(one) . We then discuss how to implement a partial adiabatic search algorithm on the quantum circuit model. From the implementing procedure on the circuit model, we can find out that the approximating steps needed are always in the same order of the time complexity of the adiabatic algorithm.
Adiabatic control of atomic dressed states for transport and sensing
NASA Astrophysics Data System (ADS)
Cooper, N. R.; Rey, A. M.
2015-08-01
We describe forms of adiabatic transport that arise for dressed-state atoms in optical lattices. Focusing on the limit of weak tunnel-coupling between nearest-neighbor lattice sites, we explain how adiabatic variation of optical dressing allows control of atomic motion between lattice sites: allowing adiabatic particle transport in a direction that depends on the internal state, and force measurements via spectroscopic preparation and readout. For uniformly filled bands these systems display topologically quantized particle transport. An implementation of the dressing scheme using optical transitions in alkaline-earth atoms is discussed as well as its favorable features for precise force sensing.
Topological States and Adiabatic Pumping in Quasicrystals
NASA Astrophysics Data System (ADS)
Kraus, Yaakov; Lahini, Yoav; Ringel, Zohar; Verbin, Mor; Zilberberg, Oded
2012-02-01
We find a connection between quasicrystals and topological matter, namely that quasicrystals exhibit non-trivial topological phases attributed to dimensions higher than their own [1]. Quasicrystals are materials which are neither ordered nor disordered, i.e. they exhibit only long-range order [2]. This long-range order is usually expressed as a projection from a higher dimensional ordered system. Recently, the unrelated discovery of Topological Insulators [3] defined a new type of materials classified by their topology. We show theoretically and experimentally using photonic lattices, that one-dimensional quasicrystals exhibit topologically-protected boundary states equivalent to the edge states of the two-dimensional Integer Quantum Hall Effect. We harness this property to adiabatically pump light across the quasicrystal, and generalize our results to higher dimensional systems. Hence, quasicrystals offer a new platform for the study of topological phases while their topology may better explain their surface properties.[4pt] [1] Y. E. Kraus, Y. Lahini, Z. Ringel, M. Verbin, and O. Zilberberg, arXiv:1109.5983 (2011).[0pt] [2] C. Janot, Quasicrystals (Clarendon, Oxford, 1994), 2nd ed.[0pt] [3] M. Z. Hasan and C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010).
On the persistence of adiabatic shear bands
NASA Astrophysics Data System (ADS)
Boakye-Yiadom, S.; Bassim, M. N.; Al-Ameeri, S.
2012-08-01
It is generally agreed that the initiation and development of adiabatic shear bands (ASBs) are manifestations of damage in metallic materials subjected to high strain rates and large strains as those due to impact in a Hopkinson Bar system. Models for evolution of these bands have been described in the literature. One question that has not received attention is how persistent these bands are and whether their presence and effect can be reversed or eliminated by using a process of thermal (heat treatment) or thermo-mechanical treatment that would relieve the material from the high strain associated with ASBs and their role as precursors to crack initiation and subsequent failure. Since ASBs are more prevalent and more defined in BCC metals including steels, a study was conducted to investigate the best conditions of generating ASBs in a heat treatable steel, followed by determining the best conditions for heat treatment of specimens already damaged by the presence of ASBs in order to relieve the strains due to ASBs and restore the material to an apparent microstructure without the "scars" due to the previous presence of ASBs. It was found that heat treatment achieves the curing from ASBs. This presentation documents the process undertaken to achieve this objective.
Adiabatic quantum algorithm for search engine ranking.
Garnerone, Silvano; Zanardi, Paolo; Lidar, Daniel A
2012-06-01
We propose an adiabatic quantum algorithm for generating a quantum pure state encoding of the PageRank vector, the most widely used tool in ranking the relative importance of internet pages. We present extensive numerical simulations which provide evidence that this algorithm can prepare the quantum PageRank state in a time which, on average, scales polylogarithmically in the number of web pages. We argue that the main topological feature of the underlying web graph allowing for such a scaling is the out-degree distribution. The top-ranked log(n) entries of the quantum PageRank state can then be estimated with a polynomial quantum speed-up. Moreover, the quantum PageRank state can be used in "q-sampling" protocols for testing properties of distributions, which require exponentially fewer measurements than all classical schemes designed for the same task. This can be used to decide whether to run a classical update of the PageRank. PMID:23003933
Graph isomorphism and adiabatic quantum computing
NASA Astrophysics Data System (ADS)
Gaitan, Frank; Clark, Lane
2014-03-01
In the Graph Isomorphism (GI) problem two N-vertex graphs G and G' are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and maps G --> G'. If yes (no), then G and G' are said to be isomorphic (non-isomorphic). The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. We present a quantum algorithm that solves arbitrary instances of GI, and which provides a novel approach to determining all automorphisms of a graph. The algorithm converts a GI instance to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. Numerical simulation of the algorithm's quantum dynamics shows that it correctly distinguishes non-isomorphic graphs; recognizes isomorphic graphs; and finds the automorphism group of a graph. We also discuss the algorithm's experimental implementation and show how it can be leveraged to solve arbitrary instances of the NP-Complete Sub-Graph Isomorphism problem.
Design of the PIXIE Adiabatic Demagnetization Refrigerators
NASA Technical Reports Server (NTRS)
Shirron, Peter J.; Kimball, Mark Oliver; Fixsen, Dale J.; Kogut, Alan J.; Li, Xiaoyi; DiPirro, Michael
2012-01-01
The Primordial Inflation Explorer (PIXIE) is a proposed mission to densely map the polarization of the cosmic microwave background. It will operate in a scanning mode from a sun-synchronous orbit, using low temperature detectors (at 0.1 K) and located inside a teslescope that is cooled to approximately 2.73 K - to match the background temperature. A mechanical cryocooler operating at 4.5 K establishes a low base temperature from which two adiabatic demagnetization refrigerator (ADR) assemblies will cool the telescope and detectors. To achieve continuous scanning capability, the ADRs must operate continuously. Complicating the design are two factors: 1) the need to systematically vary the temperature of various telescope components in order to separate the small polarization signal variations from those that may arise from temperature drifts and changing gradients within the telescope, and 2) the orbital and monthly variations in lunar irradiance into the telescope barrels. These factors require the telescope ADR to reject quasi-continuous heat loads of 2-3 millwatts, while maintaining a peak heat reject rate of less than 12 milliwatts. The detector heat load at 0.1 K is comparatively small at 1-2 microwatts. This paper will describe the 3-stage and 2-stage continuous ADRs that will be used to meet the cooling power and temperature stability requirements of the PIXIE detectors and telescope.
Adiabaticity and spectral splits in collective neutrino transformations
Raffelt, Georg G.; Smirnov, Alexei Yu.
2007-12-15
Neutrinos streaming off a supernova core transform collectively by neutrino-neutrino interactions, leading to 'spectral splits' where an energy E{sub split} divides the transformed spectrum sharply into parts of almost pure but different flavors. We present a detailed description of the spectral-split phenomenon which is conceptually and quantitatively understood in an adiabatic treatment of neutrino-neutrino effects. Central to this theory is a self-consistency condition in the form of two sum rules (integrals over the neutrino spectra that must equal certain conserved quantities). We provide explicit analytic and numerical solutions for various neutrino spectra. We introduce the concept of the adiabatic reference frame and elaborate on the relative adiabatic evolution. Violating adiabaticity leads to the spectral split being 'washed out'. The sharpness of the split appears to be represented by a surprisingly universal function.
Adiabatic rotation, quantum search, and preparation of superposition states
NASA Astrophysics Data System (ADS)
Siu, M. Stewart
2007-06-01
We introduce the idea of using adiabatic rotation to generate superpositions of a large class of quantum states. For quantum computing this is an interesting alternative to the well-studied “straight line” adiabatic evolution. In ways that complement recent results, we show how to efficiently prepare three types of states: Kitaev’s toric code state, the cluster state of the measurement-based computation model, and the history state used in the adiabatic simulation of a quantum circuit. We also show that the method, when adapted for quantum search, provides quadratic speedup as other optimal methods do with the advantages that the problem Hamiltonian is time independent and that the energy gap above the ground state is strictly nondecreasing with time. Likewise the method can be used for optimization as an alternative to the standard adiabatic algorithm.
Coherent transfer by adiabatic passage in two-dimensional lattices
Longhi, Stefano
2014-09-15
Coherent tunneling by adiabatic passage (CTAP) is a well-established technique for robust spatial transport of quantum particles in linear chains. Here we introduce two exactly-solvable models where the CTAP protocol can be extended to two-dimensional lattice geometries. Such bi-dimensional lattice models are synthesized from time-dependent second-quantization Hamiltonians, in which the bosonic field operators evolve adiabatically like in an ordinary three-level CTAP scheme thus ensuring adiabatic passage in Fock space. - Highlights: • New ways of coherent transport by adiabatic passage (CTAP) in 2D lattices. • Synthesis of exactly-solvable 2D lattices from a simple three-well model. • CTAP in 2D lattices can be exploited for quantum state transfer.
Ultrafast stimulated Raman parallel adiabatic passage by shaped pulses
Dridi, G.; Guerin, S.; Hakobyan, V.; Jauslin, H. R.; Eleuch, H.
2009-10-15
We present a general and versatile technique of population transfer based on parallel adiabatic passage by femtosecond shaped pulses. Their amplitude and phase are specifically designed to optimize the adiabatic passage corresponding to parallel eigenvalues at all times. We show that this technique allows the robust adiabatic population transfer in a Raman system with the total pulse area as low as 3{pi}, corresponding to a fluence of one order of magnitude below the conventional stimulated Raman adiabatic passage process. This process of short duration, typically picosecond and subpicosecond, is easily implementable with the modern pulse shaper technology and opens the possibility of ultrafast robust population transfer with interesting applications in quantum information processing.
NASA Astrophysics Data System (ADS)
Shaikin, A. P.; Galiev, I. R.
2016-08-01
We have considered the functional dependence of the ionization detector readings (ion current) on the composition of the fuel-air mixture, adiabatic temperature, and the turbulent combustion zone width. Experiments on the engine show that, for an air excess factor of 0.75-1.15, the coincidence of the calculated and experimental data exceeds 90%. Our results can be used to predict and monitor the adiabatic temperature of the flame and the width of the turbulent combustion zone in the combustion changer of the internal combustion engine using the ionization detector.
Stimulated Raman adiabatic passage for improved performance of a cold-atom electron and ion source
NASA Astrophysics Data System (ADS)
Sparkes, B. M.; Murphy, D.; Taylor, R. J.; Speirs, R. W.; McCulloch, A. J.; Scholten, R. E.
2016-08-01
We implement high-efficiency coherent excitation to a Rydberg state using stimulated Raman adiabatic passage in a cold-atom electron and ion source. We achieve an efficiency of 60% averaged over the laser excitation volume with a peak efficiency of 82%, a 1.6 times improvement relative to incoherent pulsed-laser excitation. Using pulsed electric field ionization of the Rydberg atoms we create electron bunches with durations of 250 ps. High-efficiency excitation will increase source brightness, crucial for ultrafast electron diffraction experiments, and coherent excitation to high-lying Rydberg states could allow for the reduction of internal bunch heating and the creation of a high-speed single-ion source.
Extended adiabatic blast waves and a model of the soft X-ray background. [interstellar matter
NASA Technical Reports Server (NTRS)
Cox, D. P.; Anderson, P. R.
1981-01-01
An analytical approximation is generated which follows the development of an adiabatic spherical blast wave in a homogeneous ambient medium of finite pressure. An analytical approximation is also presented for the electron temperature distribution resulting from coulomb collisional heating. The dynamical, thermal, ionization, and spectral structures are calculated for blast waves of energy E sub 0 = 5 x 10 to the 50th power ergs in a hot low-density interstellar environment. A formula is presented for estimating the luminosity evolution of such explosions. The B and C bands of the soft X-ray background, it is shown, are reproduced by such a model explosion if the ambient density is about .000004 cm, the blast radius is roughly 100 pc, and the solar system is located inside the shocked region. Evolution in a pre-existing cavity with a strong density gradient may, it is suggested, remove both the M band and OVI discrepancies.
Adiabatic invariant value variation under shortwave band subcritical conditions
NASA Astrophysics Data System (ADS)
Svistunov, K. V.; Tinin, M. V.
1985-04-01
The possibility of significant variations of the adiabatic invariant is examined for the propagation of radio waves in an irregular Earth-ionosphere waveguide with a parabolic dependence of permittivity on height. Numerical and analytical results indicate that nonexponential deviations of the adiabatic invariant can occur not only when the characteristic size of horizontal irregularity decreases (e.g., during resonant beam excitation) but also in quasi-critical conditions and for smoothly irregular waveguides.
Shortcuts to adiabaticity for non-Hermitian systems
Ibanez, S.; Martinez-Garaot, S.; Torrontegui, E.; Muga, J. G.; Chen Xi
2011-08-15
Adiabatic processes driven by non-Hermitian, time-dependent Hamiltonians may be sped up by generalizing inverse engineering techniques based on counter-diabatic (transitionless driving) algorithms or on dynamical invariants. We work out the basic theory and examples described by two-level Hamiltonians: the acceleration of rapid adiabatic passage with a decaying excited level and of the dynamics of a classical particle on an expanding harmonic oscillator.
Heavy-Ion-Acoustic Solitary and Shock Waves in an Adiabatic Multi-Ion Plasma
NASA Astrophysics Data System (ADS)
Hossen, M. A.; Rahman, M. M.; Hossen, M. R.; Mamun, A. A.
2015-08-01
The standard reductive perturbation method has been employed to derive the Korteweg-deVries (K-dV) and Burgers (BG) equations to investigate the basic properties of heavy-ion-acoustic (HIA) waves in a plasma system which is supposed to be composed of nonthermal electrons, Boltzmann distributed light ions, and adiabatic positively charged inertial heavy ions. The HIA solitary and shock structures are found to exist with either positive or negative potential. It is found that the effects of adiabaticity of inertial heavy ions, nonthermality of electrons, and number densities of plasma components significantly modify the basic properties of the HIA solitary and shock waves. The implications of our results may be helpful in understanding the electrostatic perturbations in various laboratory and astrophysical plasma environments.
Quasi-classical theory of electronic flux density in electronically adiabatic molecular processes.
Diestler, D J
2012-11-26
The standard Born-Oppenheimer (BO) description of electronically adiabatic molecular processes predicts a vanishing electronic flux density (EFD). A previously proposed "coupled-channels" theory permits the extraction of the EFD from the BO wave function for one-electron diatomic systems, but attempts at generalization to many-electron polyatomic systems are frustrated by technical barriers. An alternative "quasi-classical" approach, which eliminates the explicit quantum dynamics of the electrons within a classical framework, yet retains the quantum character of the nuclear motion, appears capable of yielding EFDs for arbitrarily complex systems. Quasi-classical formulas for the EFD in simple systems agree with corresponding coupled-channels formulas. Results of the application of the new quasi-classical formula for the EFD to a model triatomic system indicate the potential of the quasi-classical scheme to elucidate the dynamical role of electrons in electronically adiabatic processes in more complex multiparticle systems.
Romero-Redondo, C.; Garrido, E.; Barletta, P.; Kievsky, A.; Viviani, M.
2011-02-15
In this work we investigate 1+2 reactions within the framework of the hyperspherical adiabatic expansion method. With this aim two integral relations, derived from the Kohn variational principle, are used. A detailed derivation of these relations is shown. The expressions derived are general, not restricted to relative s partial waves, and with applicability in multichannel reactions. The convergence of the K matrix in terms of the adiabatic potentials is investigated. Together with a simple model case used as a test for the method, we show results for the collision of a {sup 4}He atom on a {sup 4}He{sub 2} dimer (only the elastic channel open), and for collisions involving a {sup 6}Li and two {sup 4}He atoms (two channels open).
Ionized cluster beam technology for material science
NASA Astrophysics Data System (ADS)
Takagi, Toshinori
1997-06-01
The most suitable kinetic energy range of ionized materials in film formation and epitaxial growth is from a few eV to a few hundreds eV, especially, less than about 100eV, when ions are used as a host. The main roles of ions in film formation are the effects due to their kinetic energy and the electronic charge effects which involve the effect to active film formation and the effect acceleration of chemical reactions. Therefore, it is important to develope the technology to transport large volume of a flux of ionized particles with an extremely low incident energy without any troubles due to the space charge effects and charge up problems on the surface. This is the exact motivation for us to have been developing the Ionized Cluster Beam (ICB) technology since 1972. By ICB technology materials (actually wide varieties of materials such as metal, semiconductor, magnetic material, insulator, organic material, etc.) are vaporized and ejected through a small hole nozzle into a high vacuum, where the vaporized material condenses into clusters with loosely coupled atoms with the sizes about from 100 to a few 1000 atoms (mainly 100-2000 atoms) by supercondensation phenomena due to the adiabatic expansion in this evaporation process through a small hole nozzle. In the ICB technology an atom in each cluster is ionized by irradiated by electron shower, and the ionized clusters are accelerated by electric field onto a substrate. The ionized clusters with neutral clusters impinged onto a substrate are spreaded separately into atoms migrating over the substrate, so that the surface migration energy of the impinged atoms, that is, surface diffusion energy are controlled by an incident energy of a cluster. In this report the theoretical and also experimental results of ICB technology are summarized.
Mechanism of enhanced ionization of linear H+3 in intense laser fields
NASA Astrophysics Data System (ADS)
Kawata, I.; Kono, H.; Bandrauk, A. D.
2001-10-01
We investigate the mechanism of enhanced ionization that occurs at a critical internuclear distance Rc in the two-electron symmetric linear triatomic molecule H+3 subjected to an ultrashort, intense laser pulse by solving exactly the time-dependent Schrödinger equation for a one-dimensional model of H+3. Results of the simulations are analyzed by using three essential adiabatic field states \\|1>, \\|2>, and \\|3> that are adiabatically connected with the lowest three electronic states X1Σ+g, B1Σ+u, and E1Σ+g of the field free ion. We give also a simple MO (molecular orbital) picture in terms of these three states to illustrate the important electronic configurations in an intense field. The states \\|1>, \\|2>, and \\|3> are shown to be composed mainly of the configurations HHH+, HH+H, and H+HH, respectively in the presence of the field. We conclude that the overall level dynamics is governed mainly by transitions at the zero-field energy quasicrossings of these three states. The response of H+3 to a laser field can be classified into two regimes. In the adiabatic regime (R
Adiabatic calorimetric decomposition studies of 50 wt.% hydroxylamine/water.
Cisneros, L O; Rogers, W J; Mannan, M S
2001-03-19
Calorimetric data can provide a basis for determining potential hazards in reactions, storage, and transportation of process chemicals. This work provides calorimetric data for the thermal decomposition behavior in air of 50wt.% hydroxylamine/water (HA), both with and without added stabilizers, which was measured in closed cells with an automatic pressure tracking adiabatic calorimeter (APTAC). Among the data provided are onset temperatures, reaction order, activation energies, pressures of noncondensable products, thermal stability at 100 degrees C, and the effect of HA storage time. Discussed also are the catalytic effects of carbon steel, stainless steel, stainless steel with silica coating, inconel, titanium, and titanium with silica coating on the reaction self-heat rates and onset temperatures. In borosilicate glass cells, HA was relatively stable at temperatures up to 133 degrees C, where the HA decomposition self-heat rate reached 0.05 degrees C/min. The added stabilizers appeared to reduce HA decomposition rates in glass cells and at ambient temperatures. The tested metals and metal surfaces coated with silica acted as catalysts to lower the onset temperatures and increase the self-heat rates. PMID:11165058
Adiabatic calorimetric decomposition studies of 50 wt.% hydroxylamine/water.
Cisneros, L O; Rogers, W J; Mannan, M S
2001-03-19
Calorimetric data can provide a basis for determining potential hazards in reactions, storage, and transportation of process chemicals. This work provides calorimetric data for the thermal decomposition behavior in air of 50wt.% hydroxylamine/water (HA), both with and without added stabilizers, which was measured in closed cells with an automatic pressure tracking adiabatic calorimeter (APTAC). Among the data provided are onset temperatures, reaction order, activation energies, pressures of noncondensable products, thermal stability at 100 degrees C, and the effect of HA storage time. Discussed also are the catalytic effects of carbon steel, stainless steel, stainless steel with silica coating, inconel, titanium, and titanium with silica coating on the reaction self-heat rates and onset temperatures. In borosilicate glass cells, HA was relatively stable at temperatures up to 133 degrees C, where the HA decomposition self-heat rate reached 0.05 degrees C/min. The added stabilizers appeared to reduce HA decomposition rates in glass cells and at ambient temperatures. The tested metals and metal surfaces coated with silica acted as catalysts to lower the onset temperatures and increase the self-heat rates.
Evolution of f{sub NL} to the adiabatic limit
Elliston, Joseph; Mulryne, David J.; Tavakol, Reza; Seery, David E-mail: D.Mulryne@qmul.ac.uk E-mail: R.Tavakol@qmul.ac.uk
2011-11-01
We study inflationary perturbations in multiple-field models, for which ζ typically evolves until all isocurvature modes decay — the {sup a}diabatic limit{sup .} We use numerical methods to explore the sensitivity of the local-shape bispectrum to the process by which this limit is achieved, finding an appreciable dependence on model-specific data such as the time at which slow-roll breaks down or the timescale of reheating. In models with a sum-separable potential where the isocurvature modes decay before the end of the slow-roll phase we give an analytic criterion for the asymptotic value of f{sub NL} to be large. Other examples can be constructed using a waterfall field to terminate inflation while f{sub NL} is transiently large, caused by descent from a ridge or convergence into a valley. We show that these two types of evolution are distinguished by the sign of the bispectrum, and give approximate expressions for the peak f{sub NL}.
Bailey, Nicholas P.; Bøhling, Lasse; Veldhorst, Arno A.; Schrøder, Thomas B.; Dyre, Jeppe C.
2013-11-14
We derive exact results for the rate of change of thermodynamic quantities, in particular, the configurational specific heat at constant volume, C{sub V}, along configurational adiabats (curves of constant excess entropy S{sub ex}). Such curves are designated isomorphs for so-called Roskilde liquids, in view of the invariance of various structural and dynamical quantities along them. The slope of the isomorphs in a double logarithmic representation of the density-temperature phase diagram, γ, can be interpreted as one third of an effective inverse power-law potential exponent. We show that in liquids where γ increases (decreases) with density, the contours of C{sub V} have smaller (larger) slope than configurational adiabats. We clarify also the connection between γ and the pair potential. A fluctuation formula for the slope of the C{sub V}-contours is derived. The theoretical results are supported with data from computer simulations of two systems, the Lennard-Jones fluid, and the Girifalco fluid. The sign of dγ/dρ is thus a third key parameter in characterizing Roskilde liquids, after γ and the virial-potential energy correlation coefficient R. To go beyond isomorph theory we compare invariance of a dynamical quantity, the self-diffusion coefficient, along adiabats and C{sub V}-contours, finding it more invariant along adiabats.
Bailey, Nicholas P; Bøhling, Lasse; Veldhorst, Arno A; Schrøder, Thomas B; Dyre, Jeppe C
2013-11-14
We derive exact results for the rate of change of thermodynamic quantities, in particular, the configurational specific heat at constant volume, CV, along configurational adiabats (curves of constant excess entropy Sex). Such curves are designated isomorphs for so-called Roskilde liquids, in view of the invariance of various structural and dynamical quantities along them. The slope of the isomorphs in a double logarithmic representation of the density-temperature phase diagram, γ, can be interpreted as one third of an effective inverse power-law potential exponent. We show that in liquids where γ increases (decreases) with density, the contours of CV have smaller (larger) slope than configurational adiabats. We clarify also the connection between γ and the pair potential. A fluctuation formula for the slope of the CV-contours is derived. The theoretical results are supported with data from computer simulations of two systems, the Lennard-Jones fluid, and the Girifalco fluid. The sign of dγ∕dρ is thus a third key parameter in characterizing Roskilde liquids, after γ and the virial-potential energy correlation coefficient R. To go beyond isomorph theory we compare invariance of a dynamical quantity, the self-diffusion coefficient, along adiabats and CV-contours, finding it more invariant along adiabats.
Azizova, Tamara V.; Bazyka, Dimitry; Bouffler, Simon D.; Cardis, Elisabeth; Chekin, Sergey; Chumak, Vadim V.; Cucinotta, Francis A.; de Vathaire, Florent; Hall, Per; Harrison, John D.; Hildebrandt, Guido; Ivanov, Victor; Kashcheev, Valeriy V.; Klymenko, Sergiy V.; Kreuzer, Michaela; Laurent, Olivier; Ozasa, Kotaro; Schneider, Thierry; Tapio, Soile; Taylor, Andrew M.; Tzoulaki, Ioanna; Vandoolaeghe, Wendy L.; Wakeford, Richard; Zablotska, Lydia B.; Zhang, Wei; Lipshultz, Steven E.
2012-01-01
Background: Although high doses of ionizing radiation have long been linked to circulatory disease, evidence for an association at lower exposures remains controversial. However, recent analyses suggest excess relative risks at occupational exposure levels. Objectives: We performed a systematic review and meta-analysis to summarize information on circulatory disease risks associated with moderate- and low-level whole-body ionizing radiation exposures. Methods: We conducted PubMed/ISI Thomson searches of peer-reviewed papers published since 1990 using the terms “radiation” AND “heart” AND “disease,” OR “radiation” AND “stroke,” OR “radiation” AND “circulatory” AND “disease.” Radiation exposures had to be whole-body, with a cumulative mean dose of < 0.5 Sv, or at a low dose rate (< 10 mSv/day). We estimated population risks of circulatory disease from low-level radiation exposure using excess relative risk estimates from this meta-analysis and current mortality rates for nine major developed countries. Results: Estimated excess population risks for all circulatory diseases combined ranged from 2.5%/Sv [95% confidence interval (CI): 0.8, 4.2] for France to 8.5%/Sv (95% CI: 4.0, 13.0) for Russia. Conclusions: Our review supports an association between circulatory disease mortality and low and moderate doses of ionizing radiation. Our analysis was limited by heterogeneity among studies (particularly for noncardiac end points), the possibility of uncontrolled confounding in some occupational groups by lifestyle factors, and higher dose groups (> 0.5 Sv) generally driving the observed trends. If confirmed, our findings suggest that overall radiation-related mortality is about twice that currently estimated based on estimates for cancer end points alone (which range from 4.2% to 5.6%/Sv for these populations). PMID:22728254
Raro, M; Portolés, T; Pitarch, E; Sancho, J V; Hernández, F; Garrostas, L; Marcos, J; Ventura, R; Segura, J; Pozo, O J
2016-02-01
The atmospheric pressure chemical ionization (APCI) source for gas chromatography-mass spectrometry analysis has been evaluated for the screening of 16 exogenous androgenic anabolic steroids (AAS) in urine. The sample treatment is based on the strategy currently applied in doping control laboratories i.e. enzymatic hydrolysis, liquid-liquid extraction (LLE) and derivatization to form the trimethylsilyl ether-trimethylsilyl enol ether (TMS) derivatives. These TMS derivatives are then analyzed by gas chromatography tandem mass spectrometry using a triple quadrupole instrument (GC-QqQ MS/MS) under selected reaction monitoring (SRM) mode. The APCI promotes soft ionization with very little fragmentation resulting, in most cases, in abundant [M + H](+) or [M + H-2TMSOH](+) ions, which can be chosen as precursor ions for the SRM transitions, improving in this way the selectivity and sensitivity of the method. Specificity of the transitions is also of great relevance, as the presence of endogenous compounds can affect the measurements when using the most abundant ions. The method has been qualitatively validated by spiking six different urine samples at two concentration levels each. Precision was generally satisfactory with RSD values below 25 and 15% at the low and high concentration level, respectively. Most the limits of detection (LOD) were below 0.5 ng mL(-1). Validation results were compared with the commonly used method based on the electron ionization (EI) source. EI analysis was found to be slightly more repeatable whereas lower LODs were found for APCI. In addition, the applicability of the developed method has been tested in samples collected after the administration of 4-chloromethandienone. The highest sensitivity of the APCI method for this compound, allowed to increase the period in which its administration can be detected.
Raro, M; Portolés, T; Pitarch, E; Sancho, J V; Hernández, F; Garrostas, L; Marcos, J; Ventura, R; Segura, J; Pozo, O J
2016-02-01
The atmospheric pressure chemical ionization (APCI) source for gas chromatography-mass spectrometry analysis has been evaluated for the screening of 16 exogenous androgenic anabolic steroids (AAS) in urine. The sample treatment is based on the strategy currently applied in doping control laboratories i.e. enzymatic hydrolysis, liquid-liquid extraction (LLE) and derivatization to form the trimethylsilyl ether-trimethylsilyl enol ether (TMS) derivatives. These TMS derivatives are then analyzed by gas chromatography tandem mass spectrometry using a triple quadrupole instrument (GC-QqQ MS/MS) under selected reaction monitoring (SRM) mode. The APCI promotes soft ionization with very little fragmentation resulting, in most cases, in abundant [M + H](+) or [M + H-2TMSOH](+) ions, which can be chosen as precursor ions for the SRM transitions, improving in this way the selectivity and sensitivity of the method. Specificity of the transitions is also of great relevance, as the presence of endogenous compounds can affect the measurements when using the most abundant ions. The method has been qualitatively validated by spiking six different urine samples at two concentration levels each. Precision was generally satisfactory with RSD values below 25 and 15% at the low and high concentration level, respectively. Most the limits of detection (LOD) were below 0.5 ng mL(-1). Validation results were compared with the commonly used method based on the electron ionization (EI) source. EI analysis was found to be slightly more repeatable whereas lower LODs were found for APCI. In addition, the applicability of the developed method has been tested in samples collected after the administration of 4-chloromethandienone. The highest sensitivity of the APCI method for this compound, allowed to increase the period in which its administration can be detected. PMID:26772132
Adiabatic and diabatic invariants in ion-molecule reactions.
Lorquet, J C
2009-12-28
A point charge interacting with a dipole (either induced or permanent) constitutes a completely integrable dynamical subsystem characterized by three first integrals of the motion (E, p(phi), and either l(2) or a Hamilton-Jacobi separation constant beta). An ion-molecule reaction (capture or fragmentation) can be seen as an interaction between such a subsystem and a bath of oscillators. This interaction is a perturbation that destroys some of the first integrals. However, the perturbation depends on the separation between the fragments and the destruction is gradual. The mathematical simplicity of the long-range electrostatic interaction potential leads to useful simplifications. A first-order perturbation treatment based on the structured and regular nature of the multipole expansion is presented. The separating integrals valid in the asymptotic limit are found to subsist at intermediate distances, although in a weaker form. As the reaction coordinate decreases, i.e., as the fragments approach, the asymptotic range is followed by an outer region where (i) the azimuthal momentum p(phi) remains a constant of the motion; (ii) the square angular momentum l(2) or the separation constant beta transform into a diabatic invariant in regions of phase space characterized by a high value of the translational momentum p(r); (iii) for low values of p(r), it is advantageous to use the action integral contour integral(p(theta)d theta), which is an adiabatic invariant. The conditions under which an effective potential obtained by adding centrifugal repulsion to an electrostatic attractive term can be validly constructed are specified. In short, the dynamics of ion-molecule interactions is still regular in parts of phase space corresponding to a range of the reaction coordinate where the interaction potential deviates from its asymptotic shape. PMID:20059072
Ionization probes of molecular structure and chemistry
Johnson, P.M.
1993-12-01
Various photoionization processes provide very sensitive probes for the detection and understanding of the spectra of molecules relevant to combustion processes. The detection of ionization can be selective by using resonant multiphoton ionization or by exploiting the fact that different molecules have different sets of ionization potentials. Therefore, the structure and dynamics of individual molecules can be studied even in a mixed sample. The authors are continuing to develop methods for the selective spectroscopic detection of molecules by ionization, and to use these methods for the study of some molecules of combustion interest.
Coverage dependent non-adiabaticity of CO on a copper surface
Omiya, Takuma; Arnolds, Heike
2014-12-07
We have studied the coverage-dependent energy transfer dynamics between hot electrons and CO on Cu(110) with femtosecond visible pump, sum frequency probe spectroscopy. We find that transients of the C–O stretch frequency display a red shift, which increases from 3 cm{sup −1} at 0.1 ML to 9 cm{sup −1} at 0.77 ML. Analysis of the transients reveals that the non-adiabatic coupling between the adsorbate vibrational motion and the electrons becomes stronger with increasing coverage. This trend requires the frustrated rotational mode to be the cause of the non-adiabatic behavior, even for relatively weak laser excitation of the adsorbate. We attribute the coverage dependence to both an increase in the adsorbate electronic density of states and an increasingly anharmonic potential energy surface caused by repulsive interactions between neighboring CO adsorbates. This work thus reveals adsorbate-adsorbate interactions as a new way to control adsorbate non-adiabaticity.
Waste heat recovery from adiabatic diesel engines by exhaust-driven Brayton cycles
NASA Technical Reports Server (NTRS)
Khalifa, H. E.
1983-01-01
An evaluation of Bryton Bottoming Systems (BBS) as waste heat recovery devices for future adiabatic diesel engines in heavy duty trucks is presented. Parametric studies were performed to evaluate the influence of external and internal design parameters on BBS performance. Conceptual design and trade-off studies were undertaken to estimate the optimum configuration, size, and cost of major hardware components. The potential annual fuel savings of long-haul trucks equipped with BBS were estimated. The addition of a BBS to a turbocharged, nonaftercooled adiabatic engine would improve fuel economy by as much as 12%. In comparison with an aftercooled, turbocompound engine, the BBS-equipped turbocharged engine would offer a 4.4% fuel economy advantage. If installed in tandem with an aftercooled turbocompound engine, the BBS could effect a 7.2% fuel economy improvement. The cost of a mass-produced 38 Bhp BBS is estimated at about $6460 or 170/Bhp. Technical and economic barriers that hinder the commercial introduction of bottoming systems were identified. Related studies in the area of waste heat recovery from adiabatic diesel engines and NASA-CR-168255 (Steam Rankine) and CR-168256 (Organic Rankine).
Comment on ``Adiabatic quantum computation with a one-dimensional projector Hamiltonian''
NASA Astrophysics Data System (ADS)
Kay, Alastair
2013-10-01
The partial adiabatic search algorithm was introduced in Tulsi's paper [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.80.052328 80, 052328 (2009)] as a modification of the usual adiabatic algorithm for a quantum search with the idea that most of the interesting computation only happens over a very short range of the adiabatic path. By focusing on that restricted range, one can potentially gain an advantage by reducing the control requirements on the system, enabling a uniform rate of evolution. In this Comment, we point out an oversight in Tulsi's paper [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.80.052328 80, 052328 (2009)] that invalidates its proof. However, the argument can be corrected, and the calculations in Tulsi's paper [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.80.052328 80, 052328 (2009)] are then sufficient to show that the scheme still works. Nevertheless, subsequent works [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.82.034304 82, 034304 (2010), Chin. Phys. BCPBHAJ1674-105610.1088/1674-1056/20/4/040309 20, 040309 (2011), Chin. Phys. BCPBHAJ1674-105610.1088/1674-1056/21/1/010306 21, 010306 (2012), AASRI Procedia 1, 5862 (2012), and Quantum Inf. Process.10.1007/s11128-013-0557-1 12, 2689 (2013)] cannot all be recovered in the same way.
Exchange-Correlation Functionals via Local Interpolation along the Adiabatic Connection.
Vuckovic, Stefan; Irons, Tom J P; Savin, Andreas; Teale, Andrew M; Gori-Giorgi, Paola
2016-06-14
The construction of density-functional approximations is explored by modeling the adiabatic connection locally, using energy densities defined in terms of the electrostatic potential of the exchange-correlation hole. These local models are more amenable to the construction of size-consistent approximations than their global counterparts. In this work we use accurate input local ingredients to assess the accuracy of a range of local interpolation models against accurate exchange-correlation energy densities. The importance of the strictly correlated electrons (SCE) functional describing the strong coupling limit is emphasized, enabling the corresponding interpolated functionals to treat strong correlation effects. In addition to exploring the performance of such models numerically for the helium and beryllium isoelectronic series and the dissociation of the hydrogen molecule, an approximate analytic model is presented for the initial slope of the local adiabatic connection. Comparisons are made with approaches based on global models, and prospects for future approximations based on the local adiabatic connection are discussed. PMID:27116427
Exchange–Correlation Functionals via Local Interpolation along the Adiabatic Connection
2016-01-01
The construction of density-functional approximations is explored by modeling the adiabatic connection locally, using energy densities defined in terms of the electrostatic potential of the exchange–correlation hole. These local models are more amenable to the construction of size-consistent approximations than their global counterparts. In this work we use accurate input local ingredients to assess the accuracy of a range of local interpolation models against accurate exchange–correlation energy densities. The importance of the strictly correlated electrons (SCE) functional describing the strong coupling limit is emphasized, enabling the corresponding interpolated functionals to treat strong correlation effects. In addition to exploring the performance of such models numerically for the helium and beryllium isoelectronic series and the dissociation of the hydrogen molecule, an approximate analytic model is presented for the initial slope of the local adiabatic connection. Comparisons are made with approaches based on global models, and prospects for future approximations based on the local adiabatic connection are discussed. PMID:27116427
Pure spin current induced by adiabatic quantum pumping in zigzag-edged graphene nanoribbons
Souma, Satofumi Ogawa, Matsuto
2014-05-05
We show theoretically that pure spin current can be generated in zigzag edged graphene nanoribbons through the adiabatic pumping by edge selective pumping potentials. The origin of such pure spin current is the spin splitting of the edge localized states, which are oppositely spin polarized at opposite edges. In the proposed device, each edge of the ribbon is covered by two independent time-periodic local gate potentials with a definite phase difference, inducing the edge spin polarized current. When the pumping phase difference is opposite in sign between two edges, the total charge currents is zero and the pure edge spin current is generated.
Ionization of Atoms by Slow Heavy Particles, Including Dark Matter.
Roberts, B M; Flambaum, V V; Gribakin, G F
2016-01-15
Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9σ annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusplike behavior of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. We also show that electron relativistic effects actually give the dominant contribution to such a process, enhancing the differential cross section by up to 1000 times.
Ionization of Atoms by Slow Heavy Particles, Including Dark Matter
NASA Astrophysics Data System (ADS)
Roberts, B. M.; Flambaum, V. V.; Gribakin, G. F.
2016-01-01
Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9 σ annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusplike behavior of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. We also show that electron relativistic effects actually give the dominant contribution to such a process, enhancing the differential cross section by up to 1000 times.
LETTERS AND COMMENTS: Adiabatic process reversibility: microscopic and macroscopic views
NASA Astrophysics Data System (ADS)
Anacleto, Joaquim; Pereira, Mário G.
2009-05-01
The reversibility of adiabatic processes was recently addressed by two publications. In the first (Miranda 2008 Eur. J. Phys. 29 937-43), an equation was derived relating the initial and final volumes and temperatures for adiabatic expansions of an ideal gas, using a microscopic approach. In that relation the parameter r accounts for the process reversibility, ranging between 0 and 1, which corresponds to the free and reversible expansion, respectively. In the second (Anacleto and Pereira 2009 Eur. J. Phys. 30 177-83), the authors have shown that thermodynamics can effectively and efficiently be used to obtain the general law for adiabatic processes carried out by an ideal gas, including compressions, for which r \\ge 1. The present work integrates and extends the aforementioned studies, providing thus further insights into the analysis of the adiabatic process. It is shown that Miranda's work is wholly valid for compressions. In addition, it is demonstrated that the adiabatic reversibility coefficient given in terms of the piston velocity and the root mean square velocity of the gas particles is equivalent to the macroscopic description, given just by the quotient between surroundings and system pressure values.
Adiabatic continuity, wave-function overlap, and topological phase transitions
NASA Astrophysics Data System (ADS)
Gu, Jiahua; Sun, Kai
2016-09-01
In this paper, we study the relation between wave-function overlap and adiabatic continuity in gapped quantum systems. We show that for two band insulators, a scalar function can be defined in the momentum space, which characterizes the wave-function overlap between Bloch states in the two insulators. If this overlap is nonzero for all momentum points in the Brillouin zone, these two insulators are adiabatically connected, i.e., we can deform one insulator into the other smoothly without closing the band gap. In addition, we further prove that this adiabatic path preserves all the symmetries of the insulators. The existence of such an adiabatic path implies that two insulators with nonzero wave-function overlap belong to the same topological phase. This relation, between adiabatic continuity and wave-function overlap, can be further generalized to correlated systems. The generalized relation cannot be applied to study generic many-body systems in the thermodynamic limit, because of the orthogonality catastrophe. However, for certain interacting systems (e.g., quantum Hall systems), the quantum wave-function overlap can be utilized to distinguish different quantum states. Experimental implications are also discussed.
Adiabatic condition and the quantum hitting time of Markov chains
Krovi, Hari; Ozols, Maris; Roland, Jeremie
2010-08-15
We present an adiabatic quantum algorithm for the abstract problem of searching marked vertices in a graph, or spatial search. Given a random walk (or Markov chain) P on a graph with a set of unknown marked vertices, one can define a related absorbing walk P{sup '} where outgoing transitions from marked vertices are replaced by self-loops. We build a Hamiltonian H(s) from the interpolated Markov chain P(s)=(1-s)P+sP{sup '} and use it in an adiabatic quantum algorithm to drive an initial superposition over all vertices to a superposition over marked vertices. The adiabatic condition implies that, for any reversible Markov chain and any set of marked vertices, the running time of the adiabatic algorithm is given by the square root of the classical hitting time. This algorithm therefore demonstrates a novel connection between the adiabatic condition and the classical notion of hitting time of a random walk. It also significantly extends the scope of previous quantum algorithms for this problem, which could only obtain a full quadratic speedup for state-transitive reversible Markov chains with a unique marked vertex.
Nonadiabatic dynamics of floppy hydrogen bonded complexes: the case of the ionized ammonia dimer.
Chalabala, Jan; Slavíček, Petr
2016-07-27
In the case of the ammonia dimer, we address the following questions: how ultrafast ionization dynamics is controlled by hydrogen bonding and whether we can control the products via selective ionization of a specific electron. We use quantum chemical calculations and ab initio non-adiabatic molecular dynamics simulations to model the femtosecond dynamics of the ammonia dimer upon ionization. The role of nuclear quantum effects and thermal fluctuations in predicting the structure of the dimer is emphasized; it is shown that the minimum energy and vibrationally averaged structures are rather different. The ground state structure subsequently controls the ionization dynamics. We describe reaction pathways, electronic population transfers and reaction yields with respect to ionization from different molecular orbitals. The simulations showed that the ionized ammonia dimer is highly unstable and its decay rate is primarily driven by the position of the electron hole. In the case of ground state ionization (i.e. the HOMO electron is ionized), the decay is likely to be preceded by a proton transfer (PT) channel yielding NH4(+) and NH2˙ fragments. The PT is less intense and slower compared with the ionized water dimer. After ionizing deeper lying electrons, mainly NH3(+)˙ and NH3 fragments are formed. Overall, our results show that the ionization dynamics of the ammonia and water dimers differ due to the nature of the hydrogen bond in these systems. PMID:27402376
Effect of dephasing on stimulated Raman adiabatic passage
Ivanov, P.A.; Vitanov, N.V.; Bergmann, K.
2004-12-01
This work explores the effect of phase relaxation on the population transfer efficiency in stimulated Raman adiabatic passage (STIRAP). The study is based on the Liouville equation, which is solved analytically in the adiabatic limit. The transfer efficiency of STIRAP is found to decrease exponentially with the dephasing rate; this effect is stronger for shorter pulse delays and weaker for larger delays, since the transition time is found to be inversely proportional to the pulse delay. Moreover, it is found that the transfer efficiency of STIRAP in the presence of dephasing does not depend on the peak Rabi frequencies at all, as long as they are sufficiently large to enforce adiabatic evolution; hence increasing the field intensity cannot reduce the dephasing losses. It is shown also that for any dephasing rate, the final populations of the initial state and the intermediate state are equal. For strong dephasing all three populations tend to (1/3)
Design of a photonic lattice using shortcuts to adiabaticity
NASA Astrophysics Data System (ADS)
Stefanatos, Dionisis
2014-08-01
In this article we use the method of shortcuts to adiabaticity to design a photonic lattice (array of waveguides) which can drive the input light to a controlled location at the output. The output position in the array is determined by functions of the propagation distance along the waveguides, which modulate the lattice characteristics (index of refraction, and first- and second-neighbor couplings). The proposed coupler is expected to possess the robustness properties of the design method, coming from its adiabatic nature, and also to have a smaller footprint than purely adiabatic couplers. The present work provides a very interesting example where methods from quantum control can be exploited to design lattices with desired input-output properties.
Adiabatic Quantum Programming: Minor Embedding With Hard Faults
Klymko, Christine F; Sullivan, Blair D; Humble, Travis S
2013-01-01
Adiabatic quantum programming defines the time-dependent mapping of a quantum algorithm into the hardware or logical fabric. An essential programming step is the embedding of problem-specific information into the logical fabric to define the quantum computational transformation. We present algorithms for embedding arbitrary instances of the adiabatic quantum optimization algorithm into a square lattice of specialized unit cells. Our methods are shown to be extensible in fabric growth, linear in time, and quadratic in logical footprint. In addition, we provide methods for accommodating hard faults in the logical fabric without invoking approximations to the original problem. These hard fault-tolerant embedding algorithms are expected to prove useful for benchmarking the adiabatic quantum optimization algorithm on existing quantum logical hardware. We illustrate this versatility through numerical studies of embeddabilty versus hard fault rates in square lattices of complete bipartite unit cells.
Adiabatic Quantum Computation and the Theory of Quantum Phase Transitions
NASA Astrophysics Data System (ADS)
Kaminsky, William; Lloyd, Seth
2007-03-01
We present a general approach to determining the asymptotic scaling of adiabatic quantum computational resources (space, time, energy, and precision) on random instances of NP-complete graph theory problems. By utilizing the isomorphisms between certain NP-complete graph theory problems and certain frustrated spin models, we demonstrate that the asymptotic scaling of the minimum spectral gap that determines the asymptotic running time of adiabatic algorithms is itself determined by the presence and character of quantum phase transitions in these frustrated models. Most notably, we draw the conclusion that adiabatic quantum computers based on quantum Ising models are much less likely to be efficient than those based on quantum rotor or Heisenberg models. We then exhibit practical rotor and Heisenberg model based architectures using Josephson junction and quantum dot circuits.
Global adiabaticity and non-Gaussianity consistency condition
NASA Astrophysics Data System (ADS)
Romano, Antonio Enea; Mooij, Sander; Sasaki, Misao
2016-10-01
In the context of single-field inflation, the conservation of the curvature perturbation on comoving slices, Rc, on super-horizon scales is one of the assumptions necessary to derive the consistency condition between the squeezed limit of the bispectrum and the spectrum of the primordial curvature perturbation. However, the conservation of Rc holds only after the perturbation has reached the adiabatic limit where the constant mode of Rc dominates over the other (usually decaying) mode. In this case, the non-adiabatic pressure perturbation defined in the thermodynamic sense, δPnad ≡ δP - cw2 δρ where cw2 = P ˙ / ρ ˙ , usually becomes also negligible on superhorizon scales. Therefore one might think that the adiabatic limit is the same as thermodynamic adiabaticity. This is in fact not true. In other words, thermodynamic adiabaticity is not a sufficient condition for the conservation of Rc on super-horizon scales. In this paper, we consider models that satisfy δPnad = 0 on all scales, which we call global adiabaticity (GA), which is guaranteed if cw2 = cs2, where cs is the phase velocity of the propagation of the perturbation. A known example is the case of ultra-slow-roll (USR) inflation in which cw2 = cs2 = 1. In order to generalize USR we develop a method to find the Lagrangian of GA K-inflation models from the behavior of background quantities as functions of the scale factor. Applying this method we show that there indeed exists a wide class of GA models with cw2 = cs2, which allows Rc to grow on superhorizon scales, and hence violates the non-Gaussianity consistency condition.
Gravitational Chern-Simons and the adiabatic limit
NASA Astrophysics Data System (ADS)
McLellan, Brendan
2010-12-01
We compute the gravitational Chern-Simons term explicitly for an adiabatic family of metrics using standard methods in general relativity. We use the fact that our base three-manifold is a quasiregular K-contact manifold heavily in this computation. Our key observation is that this geometric assumption corresponds exactly to a Kaluza-Klein Ansatz for the metric tensor on our three-manifold, which allows us to translate our problem into the language of general relativity. Similar computations have been performed by Guralnik et al. [Ann. Phys. 308, 222 (2008)], although not in the adiabatic context.
Speeding up Adiabatic Quantum State Transfer by Using Dressed States
NASA Astrophysics Data System (ADS)
Baksic, Alexandre; Ribeiro, Hugo; Clerk, Aashish A.
2016-06-01
We develop new pulse schemes to significantly speed up adiabatic state transfer protocols. Our general strategy involves adding corrections to an initial control Hamiltonian that harness nonadiabatic transitions. These corrections define a set of dressed states that the system follows exactly during the state transfer. We apply this approach to stimulated Raman adiabatic passage protocols and show that a suitable choice of dressed states allows one to design fast protocols that do not require additional couplings, while simultaneously minimizing the occupancy of the "intermediate" level.
Quantum Adiabatic Pumping by Modulating Tunnel Phase in Quantum Dots
NASA Astrophysics Data System (ADS)
Taguchi, Masahiko; Nakajima, Satoshi; Kubo, Toshihiro; Tokura, Yasuhiro
2016-08-01
In a mesoscopic system, under zero bias voltage, a finite charge is transferred by quantum adiabatic pumping by adiabatically and periodically changing two or more control parameters. We obtained expressions for the pumped charge for a ring of three quantum dots (QDs) by choosing the magnetic flux penetrating the ring as one of the control parameters. We found that the pumped charge shows a steplike behavior with respect to the variance of the flux. The value of the step heights is not universal but depends on the trajectory of the control parameters. We discuss the physical origin of this behavior on the basis of the Fano resonant condition of the ring.
Classical nuclear motion coupled to electronic non-adiabatic transitions
Agostini, Federica; Abedi, Ali; Gross, E. K. U.
2014-12-07
Based on the exact factorization of the electron-nuclear wave function, we have recently proposed a mixed quantum-classical scheme [A. Abedi, F. Agostini, and E. K. U. Gross, Europhys. Lett. 106, 33001 (2014)] to deal with non-adiabatic processes. Here we present a comprehensive description of the formalism, including the full derivation of the equations of motion. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations.
Gravitational Chern-Simons and the adiabatic limit
McLellan, Brendan
2010-12-15
We compute the gravitational Chern-Simons term explicitly for an adiabatic family of metrics using standard methods in general relativity. We use the fact that our base three-manifold is a quasiregular K-contact manifold heavily in this computation. Our key observation is that this geometric assumption corresponds exactly to a Kaluza-Klein Ansatz for the metric tensor on our three-manifold, which allows us to translate our problem into the language of general relativity. Similar computations have been performed by Guralnik et al.[Ann. Phys. 308, 222 (2008)], although not in the adiabatic context.
Adiabatic fluctuations from cosmic strings in a contracting universe
Brandenberger, Robert H.; Takahashi, Tomo; Yamaguchi, Masahide E-mail: tomot@cc.saga-u.ac.jp
2009-07-01
We show that adiabatic, super-Hubble, and almost scale invariant density fluctuations are produced by cosmic strings in a contracting universe. An essential point is that isocurvature perturbations produced by topological defects such as cosmic strings on super-Hubble scales lead to a source term which seeds the growth of curvature fluctuations on these scales. Once the symmetry has been restored at high temperatures, the isocurvature seeds disappear, and the fluctuations evolve as adiabatic ones in the expanding phase. Thus, cosmic strings may be resurrected as a mechanism for generating the primordial density fluctuations observed today.
Adiabatic effects in the dynamics of Langmuir solitons
Astrelin, V.T.; Breizman, B.N.; Sedlacek, Z.; Jungwirth, K.
1988-06-01
The adiabatic slowness with which the plasma density profile is reconstructed from localized in large-amplitude Langmuir solitons is characteristic of such solitons. Several examples making use of this feature in the description of the soliton dynamics are given. Specifically, long-lived states in the form of composite solitons ar found. Additional limitations are found on the interaction of solitons with each other and with sound waves. The effect of the adiabatic nature on the formation of solitons from free plasmons is discussed.
Power-driven and adiabatic expansions into vacuum
NASA Astrophysics Data System (ADS)
Farnsworth, A. V., Jr.
1980-08-01
Analytical solutions are obtained for the planar, cylindrical, and spherical expansions into vacuum of matter initially concentrated at a plane, a line, or a point. Both power-driven and adiabatic expansions are considered, where in the power-driven case, the specific power is deposited uniformly in space, but may vary in time according to a power law. These problems are found to be self-similar. The non-self-similar motion of matter during the adiabatic expansion that follows a power pulse of finite duration has also been addressed and a solution has been obtained.
Adiabatic regularisation of power spectra in k-inflation
Alinea, Allan L.; Kubota, Takahiro; Nakanishi, Yukari; Naylor, Wade E-mail: kubota@celas.osaka-u.ac.jp E-mail: naylor@phys.sci.osaka-u.ac.jp
2015-06-01
We look at the question posed by Parker et al. about the effect of UV regularisation on the power spectrum for inflation. Focusing on the slow-roll k-inflation, we show that up to second order in the Hubble and sound flow parameters, the adiabatic regularisation of such model leads to no difference in the power spectrum apart from certain cases that violate near scale-invariant power spectra. Furthermore, extending to non-minimal k-inflation, we establish the equivalence of the subtraction terms in the adiabatic regularisation of the power spectrum in Jordan and Einstein frames.
Local control of non-adiabatic dissociation dynamics
NASA Astrophysics Data System (ADS)
Bomble, L.; Chenel, A.; Meier, C.; Desouter-Lecomte, M.
2011-05-01
We present a theoretical approach which consists of applying the strategy of local control to projectors based on asymptotic scattering states. This allows to optimize final state distributions upon laser excitation in cases where strong non-adiabatic effects are present. The approach, despite being based on a time-local formulation, can take non-adiabatic transitions that appear at later times fully into account and adopt a corresponding control strategy. As an example, we show various dissociation channels of HeH+, a system where the ultrafast dissociation dynamics is determined by strong non-Born-Oppenheimer effects.
Ionization Energies of Lanthanides
ERIC Educational Resources Information Center
Lang, Peter F.; Smith, Barry C.
2010-01-01
This article describes how data are used to analyze the pattern of ionization energies of the lanthanide elements. Different observed pathways of ionization between different ground states are discussed, and the effects of pairing, exchange, and orbital interactions on ionization energies of the lanthanides are evaluated. When all the above…
NASA Astrophysics Data System (ADS)
Fujisawa, Jun-ichi; Hanaya, Minoru
2016-06-01
Interfacial charge-transfer (ICT) transitions between inorganic semiconductors and π-conjugated molecules allow direct charge separation without loss of energy. This feature is potentially useful for efficient photovoltaic conversions. Charge-transferred complexes of TiO2 nanoparticles with 7,7,8,8-tetracyanoquinodimethane (TCNQ) and its analogues (TCNX) show strong ICT absorption in the visible region. The ICT band was reported to be significantly red-shifted with extension of the π-conjugated system of TCNX. In order to clarify the mechanism of the red-shift, in this work, we systematically study electronic structures of the TiO2-TCNX surface complexes (TCNX; TCNE, TCNQ, 2,6-TCNAQ) by ionization potential measurements and density functional theory (DFT) calculations.
Electron ionization and dissociation of aliphatic amino acids
NASA Astrophysics Data System (ADS)
Papp, P.; Shchukin, P.; Kočíšek, J.; Matejčík, Š.
2012-09-01
We present experimental and theoretical study of electron ionization and dissociative ionization to the gas phase amino acids valine, leucine, and isoleucine. A crossed electron/molecular beams technique equipped with quadrupole mass analyzer has been applied to measure mass spectra and ion efficiency curves for formation of particular ions. From experimental data the ionization energies of the molecules and the appearance energies of the fragment ions were determined. Ab initio calculations (Density Functional Theory and G3MP2 methods) were performed in order to calculate the fragmentation paths and interpret the experimental data. The experimental ionization energies of parent molecules [P]+ 8.91 ± 0.05, 8.85 ± 0.05, and 8.79 ± 0.05 eV and G3MP2 ionization energies (adiabatic) of 8.89, 8.88, and 8.81 eV were determined for valine, leucine, and isoleucine, respectively, as well as the experimental and theoretical threshold energies for dissociative ionization channels. The comparison of experimental data with calculations resulted in identification of the ions as well as the neutral fragments formed in the dissociative reactions. Around 15 mass/charge ratio fragments were identified from the mass spectra by comparison of experimental appearance energies with calculated reaction enthalpies for particular dissociative reactions.
Non-adiabatic dynamics around a conical intersection with surface-hopping coupled coherent states.
Humeniuk, Alexander; Mitrić, Roland
2016-06-21
A surface-hopping extension of the coupled coherent states-method [D. Shalashilin and M. Child, Chem. Phys. 304, 103-120 (2004)] for simulating non-adiabatic dynamics with quantum effects of the nuclei is put forward. The time-dependent Schrödinger equation for the motion of the nuclei is solved in a moving basis set. The basis set is guided by classical trajectories, which can hop stochastically between different electronic potential energy surfaces. The non-adiabatic transitions are modelled by a modified version of Tully's fewest switches algorithm. The trajectories consist of Gaussians in the phase space of the nuclei (coherent states) combined with amplitudes for an electronic wave function. The time-dependent matrix elements between different coherent states determine the amplitude of each trajectory in the total multistate wave function; the diagonal matrix elements determine the hopping probabilities and gradients. In this way, both interference effects and non-adiabatic transitions can be described in a very compact fashion, leading to the exact solution if convergence with respect to the number of trajectories is achieved and the potential energy surfaces are known globally. The method is tested on a 2D model for a conical intersection [A. Ferretti, J. Chem. Phys. 104, 5517 (1996)], where a nuclear wavepacket encircles the point of degeneracy between two potential energy surfaces and interferes with itself. These interference effects are absent in classical trajectory-based molecular dynamics but can be fully incorpo rated if trajectories are replaced by surface hopping coupled coherent states. PMID:27334155
Non-adiabatic dynamics around a conical intersection with surface-hopping coupled coherent states
NASA Astrophysics Data System (ADS)
Humeniuk, Alexander; Mitrić, Roland
2016-06-01
A surface-hopping extension of the coupled coherent states-method [D. Shalashilin and M. Child, Chem. Phys. 304, 103-120 (2004)] for simulating non-adiabatic dynamics with quantum effects of the nuclei is put forward. The time-dependent Schrödinger equation for the motion of the nuclei is solved in a moving basis set. The basis set is guided by classical trajectories, which can hop stochastically between different electronic potential energy surfaces. The non-adiabatic transitions are modelled by a modified version of Tully's fewest switches algorithm. The trajectories consist of Gaussians in the phase space of the nuclei (coherent states) combined with amplitudes for an electronic wave function. The time-dependent matrix elements between different coherent states determine the amplitude of each trajectory in the total multistate wave function; the diagonal matrix elements determine the hopping probabilities and gradients. In this way, both interference effects and non-adiabatic transitions can be described in a very compact fashion, leading to the exact solution if convergence with respect to the number of trajectories is achieved and the potential energy surfaces are known globally. The method is tested on a 2D model for a conical intersection [A. Ferretti, J. Chem. Phys. 104, 5517 (1996)], where a nuclear wavepacket encircles the point of degeneracy between two potential energy surfaces and interferes with itself. These interference effects are absent in classical trajectory-based molecular dynamics but can be fully incorpo rated if trajectories are replaced by surface hopping coupled coherent states.
Zero-point energy, tunneling, and vibrational adiabaticity in the Mu + H2 reaction
Mielke, Steven L.; Garrett, Bruce C.; Fleming, Donald G.; Truhlar, Donald G.
2015-01-09
Abstract: Isotopic substitution of muonium for hydrogen provides an unparalleled opportunity to deepen our understanding of quantum mass effects on chemical reactions. A recent topical review [Aldegunde et al., Mol. Phys. 111, 3169 (2013)] of the thermal and vibrationally-stateselected reaction of Mu with H2 raises a number of issues that are addressed here. We show that some earlier quantum mechanical calculations of the Mu + H2 reaction, which are highlighted in this review and which have been used to benchmark approximate methods, are in error by as much as 19% in the low-temperature limit. We demonstrate that an approximate treatment of the Born–Oppenheimer diagonal correction that was used in some recent studies is not valid for treating the vibrationally-state-selected reaction. We also discuss why vibrationally adiabatic potentials that neglect bend zero-point energy are not a useful analytical tool for understanding reaction rates and why vibrationally nonadiabatic transitions cannot be understood by considering tunneling through vibrationally adiabatic potentials. Finally, we present calculations on a hierarchical family of potential energy surfaces to assess the sensitivity of rate constants to the quality of the potential surface.
Kern, Carola C; Vogel, Rudi F; Behr, Jürgen
2014-06-01
Lactobacillus (L.) brevis is one of the most frequently encountered bacteria in beer-spoilage incidents. As the species Lactobacillus brevis comprises strains showing varying ability to grow in beer, ranging from growth in low hopped wheat to highly hopped pilsner beer, differentiation and classification of L. brevis with regard to their beer-spoiling ability is of vital interest for the brewing industry. Matrix-Assisted-Laser-Desorption-Ionization-Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) has been shown as a powerful tool for species and sub-species differentiation of bacterial isolates and is increasingly used for strain-level differentiation. Seventeen L. brevis strains, representative of different spoilage types, were characterized according to their tolerance to iso-alpha-acids and their growth in wheat-, lager- and pilsner beer. MALDI-TOF MS spectra were acquired to perform strain-level identification, cluster analysis and biomarker detection. Strain-level identification was achieved in 90% out of 204 spectra. Misidentification occurred nearly exclusively among strains belonging to the same spoilage type. Though spectra of strongly beer-spoiling strains showed remarkable similarity, no decisive single markers were detected to be present in all strains of one group. However, MALDI-TOF MS spectra can be reliably assigned to the corresponding strain and thus allow to track single strains and connect them to their physiological properties.
Kern, Carola C; Vogel, Rudi F; Behr, Jürgen
2014-06-01
Lactobacillus (L.) brevis is one of the most frequently encountered bacteria in beer-spoilage incidents. As the species Lactobacillus brevis comprises strains showing varying ability to grow in beer, ranging from growth in low hopped wheat to highly hopped pilsner beer, differentiation and classification of L. brevis with regard to their beer-spoiling ability is of vital interest for the brewing industry. Matrix-Assisted-Laser-Desorption-Ionization-Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) has been shown as a powerful tool for species and sub-species differentiation of bacterial isolates and is increasingly used for strain-level differentiation. Seventeen L. brevis strains, representative of different spoilage types, were characterized according to their tolerance to iso-alpha-acids and their growth in wheat-, lager- and pilsner beer. MALDI-TOF MS spectra were acquired to perform strain-level identification, cluster analysis and biomarker detection. Strain-level identification was achieved in 90% out of 204 spectra. Misidentification occurred nearly exclusively among strains belonging to the same spoilage type. Though spectra of strongly beer-spoiling strains showed remarkable similarity, no decisive single markers were detected to be present in all strains of one group. However, MALDI-TOF MS spectra can be reliably assigned to the corresponding strain and thus allow to track single strains and connect them to their physiological properties. PMID:24549193
On the work distribution for the adiabatic compression of a diluteclassical gas
Crooks, Gavin E.; Jarzynski, Christopher
2006-02-23
We consider the adiabatic and quasi-static compression of adilute classical gas, confined in a piston and initially equilibratedwith a heat bath. We find that the work performed during this process isdescribed statistically by a gamma distribution. We use this result toshow that the model satisfies the non-equilibrium work and fluctuationtheorems, but not the fluctation-dissipation relation. We discuss therare but dominant realizations that contribute most to the exponentialaverage of the work, and relate our results to potentially universal workdistributions.
The adiabatic phase mixing and heating of electrons in Buneman turbulence
Che, H.; Goldstein, M. L.; Drake, J. F.; Swisdak, M.
2013-06-15
The nonlinear development of the strong Buneman instability and the associated fast electron heating in thin current layers with Ω{sub e}/ω{sub pe}<1 is explored. Phase mixing of the electrons in wave potential troughs and a rapid increase in temperature are observed during the saturation of the instability. We show that the motion of trapped electrons can be described using a Hamiltonian formalism in the adiabatic approximation. The process of separatrix crossing as electrons are trapped and de-trapped is irreversible and guarantees that the resulting electron energy gain is a true heating process.
Adiabatic Field-Free Alignment of Asymmetric Top Molecules with an Optical Centrifuge
NASA Astrophysics Data System (ADS)
Korobenko, A.; Milner, V.
2016-05-01
We use an optical centrifuge to align asymmetric top SO2 molecules by adiabatically spinning their most polarizable O-O axis. The effective centrifugal potential in the rotating frame confines the sulfur atoms to the plane of the laser-induced rotation, leading to the planar molecular alignment that persists after the molecules are released from the centrifuge. The periodic appearance of the full three-dimensional alignment, typically observed only with linear and symmetric top molecules, is also detected. Together with strong in-plane centrifugal forces, which bend the molecules by up to 10 deg, permanent field-free alignment offers new ways of controlling molecules with laser light.
Adiabatic field-free alignment of asymmetric top molecules with an optical centrifuge
NASA Astrophysics Data System (ADS)
Korobenko, Aleksey; Milner, Valery
2016-05-01
We use an optical centrifuge to align asymmetric top SO2 molecules by adiabatically spinning their most polarizable O-O axis. The effective centrifugal potential in the rotating frame confines sulfur atoms to the plane of the laser-induced rotation, leading to the planar molecular alignment which persists after the molecules are released from the centrifuge. Periodic appearance of the full three-dimensional alignment, typically observed only with linear and symmetric top molecules, is also detected. Together with strong in-plane centrifugal forces, which bend the molecules by up to 10 degrees, permanent field-free alignment offers new ways of controlling molecules with laser light.
An, Ran; Li, Yamei; Li, Mu; Bai, Yan; Lu, Yanjie; Du, Zhimin
2015-05-01
Daming capsule is a traditional Chinese medicine for hyperlipidemia treatment. However, the vague understanding of the bioactive components of Daming capsule hampers its modernization and internationalization. This work first developed a high-throughput, high-resolution, and high-sensitivity ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry method for identifying the absorbed compounds and monitoring the pharmacokinetics of Daming capsule. A high-throughput strategy integrating plasma pharmacochemistry, pharmacokinetics, and pattern recognition analysis was also established for screening the bioactive components of Daming capsule in vivo. The established strategy based on ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry was successfully applied to screen the bioactive components of Daming capsule. Up to 53 absorbed compounds were identified. Six anthraquinones with fast and high absorption, namely, emodin-O-glucoside, aurantio-obtusin, aloe-emodin, rhein, emodin, and chrysophanol, were screened as potentially bioactive components of Daming capsule. The plasma pharmacochemistry and pharmacokinetics of Daming capsule were reported for the first time. Notably, the high-throughput and reliable strategy facilitated the screening and identification of bioactive components of traditional Chinese medicine, thereby providing novel insights into the research and development of new drugs.
An, Ran; Li, Yamei; Li, Mu; Bai, Yan; Lu, Yanjie; Du, Zhimin
2015-05-01
Daming capsule is a traditional Chinese medicine for hyperlipidemia treatment. However, the vague understanding of the bioactive components of Daming capsule hampers its modernization and internationalization. This work first developed a high-throughput, high-resolution, and high-sensitivity ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry method for identifying the absorbed compounds and monitoring the pharmacokinetics of Daming capsule. A high-throughput strategy integrating plasma pharmacochemistry, pharmacokinetics, and pattern recognition analysis was also established for screening the bioactive components of Daming capsule in vivo. The established strategy based on ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry was successfully applied to screen the bioactive components of Daming capsule. Up to 53 absorbed compounds were identified. Six anthraquinones with fast and high absorption, namely, emodin-O-glucoside, aurantio-obtusin, aloe-emodin, rhein, emodin, and chrysophanol, were screened as potentially bioactive components of Daming capsule. The plasma pharmacochemistry and pharmacokinetics of Daming capsule were reported for the first time. Notably, the high-throughput and reliable strategy facilitated the screening and identification of bioactive components of traditional Chinese medicine, thereby providing novel insights into the research and development of new drugs. PMID:25678430
Does temperature increase or decrease in adiabatic decompression of magma?
NASA Astrophysics Data System (ADS)
Kilinc, A. I.; Ghiorso, M. S.; Khan, T.
2011-12-01
We have modeled adiabatic decompression of an andesitic and a basaltic magma as an isentropic process using the Melts algorithm. Our modeling shows that during adiabatic decompression temperature of andesitic magma increases but temperature of basaltic magma decreases. In an isentropic process entropy is constant so change of temperature with pressure can be written as dT/dP=T (dV/dT)/Cp where T (dV/dT)/Cp is generally positive. If delta P is negative so is delta T. In general, in the absence of phase change, we expect the temperature to decrease with adiabatic decompression. The effect of crystallization is to turn a more entropic phase (liquid) into a less entropic phase (solid), which must be compensated by raising the temperature. If during adiabatic decompression there is small amount or no crystallization, T (dV/dT)/Cp effect which lowers the temperature overwhelms the small amount of crystallization, which raises the temperature, and overall system temperature decreases.
On adiabatic stabilization and geometry of Bunsen flames
Sun, C.J.; Sung, C.J.; Law, C.K.
1994-12-31
Two aspects of stretched flame dynamics are investigated via the model problem of the stabilization and geometry of Bunsen flames. Specifically, the possibility of stabilizing a Bunsen flame without heat loss to the burner rim is experimentally investigated by examining the temperature of the rim, the temperature gradient between the rim and the flame base, and the standoff distance of the flame base in relation to the flame thickness. Results show that, while heat loss is still the dominant stabilization mechanism for flames in uniform flows and for strong flames in parabolic flow, adiabatic stabilization and, subsequently, blowoff are indeed possible for weak flames in parabolic flows. The adiabatically stabilized flame is then modeled by using the scalar field formulation and by allowing for the effects of curvature and aerodynamic straining on the local flame speed. The calculated flame configuration agrees well with the experiment for the adiabatically stabilized flame but not for the nonadiabatic flame. Results further show that active modification of the flame curvature is the dominant cause for the flame to maintain adiabatic stabilization. Implications of the present results on turbulent flame modeling are discussed.
Digitized adiabatic quantum computing with a superconducting circuit
NASA Astrophysics Data System (ADS)
Barends, R.; Shabani, A.; Lamata, L.; Kelly, J.; Mezzacapo, A.; Heras, U. Las; Babbush, R.; Fowler, A. G.; Campbell, B.; Chen, Yu; Chen, Z.; Chiaro, B.; Dunsworth, A.; Jeffrey, E.; Lucero, E.; Megrant, A.; Mutus, J. Y.; Neeley, M.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Solano, E.; Neven, H.; Martinis, John M.
2016-06-01
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable.
Digitized adiabatic quantum computing with a superconducting circuit.
Barends, R; Shabani, A; Lamata, L; Kelly, J; Mezzacapo, A; Las Heras, U; Babbush, R; Fowler, A G; Campbell, B; Chen, Yu; Chen, Z; Chiaro, B; Dunsworth, A; Jeffrey, E; Lucero, E; Megrant, A; Mutus, J Y; Neeley, M; Neill, C; O'Malley, P J J; Quintana, C; Roushan, P; Sank, D; Vainsencher, A; Wenner, J; White, T C; Solano, E; Neven, H; Martinis, John M
2016-06-01
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable. PMID:27279216
Digitized adiabatic quantum computing with a superconducting circuit.
Barends, R; Shabani, A; Lamata, L; Kelly, J; Mezzacapo, A; Las Heras, U; Babbush, R; Fowler, A G; Campbell, B; Chen, Yu; Chen, Z; Chiaro, B; Dunsworth, A; Jeffrey, E; Lucero, E; Megrant, A; Mutus, J Y; Neeley, M; Neill, C; O'Malley, P J J; Quintana, C; Roushan, P; Sank, D; Vainsencher, A; Wenner, J; White, T C; Solano, E; Neven, H; Martinis, John M
2016-06-08
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable.
Fast Quasi-Adiabatic Gas Cooling: An Experiment Revisited
ERIC Educational Resources Information Center
Oss, S.; Gratton, L. M.; Calza, G.; Lopez-Arias, T.
2012-01-01
The well-known experiment of the rapid expansion and cooling of the air contained in a bottle is performed with a rapidly responsive, yet very cheap thermometer. The adiabatic, low temperature limit is approached quite closely and measured with our apparatus. A straightforward theoretical model for this process is also presented and discussed.…
Quantum back-reaction from non-adiabatic changes
NASA Astrophysics Data System (ADS)
Asplund, Curtis; Berenstein, David
2011-04-01
Motivated by the problem of thermalization in QFTs and the dual non-equilibrium BH dynamics, we examine a generic and non-trivial aspect of these phenomena, non-adiabatic changes, in a highly simplified setting. We consider a harmonic oscillator whose frequency depends on a second quantum variable x. Beginning with a classical analysis, we show how the system can be described by an improved adiabatic expansion with a velocity dependent force for x. We find an instability at a critical velocity beyond which the adiabatic (Born-Oppenheimer) approximation breaks down. We extend this calculation to the fully quantum system and to field theory and describe how to study fermions with similar techniques. Finally, we set up a model with an abrupt change in the oscillator whose quantum mechanics can be solved exactly so that one can study the effects of back-reaction of a fully non-adiabatic change in a controlled setting. We comment on applications of these general results to the physics of D-branes, inflation, and BHs in AdS/CFT.
Adiabatic quantum computing with phase modulated laser pulses
Goswami, Debabrata
2005-01-01
Implementation of quantum logical gates for multilevel systems is demonstrated through decoherence control under the quantum adiabatic method using simple phase modulated laser pulses. We make use of selective population inversion and Hamiltonian evolution with time to achieve such goals robustly instead of the standard unitary transformation language. PMID:17195865
Adiabatic frequency conversion with a sign flip in the coupling
NASA Astrophysics Data System (ADS)
Hristova, H. S.; Rangelov, A. A.; Montemezzani, G.; Vitanov, N. V.
2016-09-01
Adiabatic frequency conversion is a method recently developed in nonlinear optics [H. Suchowski, D. Oron, A. Arie, and Y. Silberberg, Phys. Rev. A 78, 063821 (2008), 10.1103/PhysRevA.78.063821], using ideas from the technique of rapid adiabatic passage (RAP) via a level crossing in quantum physics. In this method, the coupling coefficients are constant and the phase mismatch is chirped adiabatically. In this work, we propose another method for adiabatic frequency conversion, in which the phase mismatch is constant and the coupling is a pulse-shaped function with a sign flip (i.e., a phase step of π ) at its maximum. Compared to the RAP method, our technique has comparable efficiency but it is simpler to implement for it only needs two bulk crystals with opposite χ(2 ) nonlinearity. Moreover, because our technique requires constant nonzero frequency mismatch and has zero conversion efficiency on exact frequency matching, it can be used as a frequency filter.
The flat Grothendieck-Riemann-Roch theorem without adiabatic techniques
NASA Astrophysics Data System (ADS)
Ho, Man-Ho
2016-09-01
In this paper we give a simplified proof of the flat Grothendieck-Riemann-Roch theorem. The proof makes use of the local family index theorem and basic computations of the Chern-Simons form. In particular, it does not involve any adiabatic limit computation of the reduced eta-invariant.
When an Adiabatic Irreversible Expansion or Compression Becomes Reversible
ERIC Educational Resources Information Center
Anacleto, Joaquim; Ferreira, J. M.; Soares, A. A.
2009-01-01
This paper aims to contribute to a better understanding of the concepts of a "reversible process" and "entropy". For this purpose, an adiabatic irreversible expansion or compression is analysed, by considering that an ideal gas is expanded (compressed), from an initial pressure P[subscript i] to a final pressure P[subscript f], by being placed in…
A Kinetic Study of the Adiabatic Polymerization of Acrylamide.
ERIC Educational Resources Information Center
Thomson, R. A. M.
1986-01-01
Discusses theory, procedures, and results for an experiment which demonstrates the application of basic physics to chemical problems. The experiment involves the adiabatic process, in which polymerization carried out in a vacuum flask is compared to the theoretical prediction of the model with the temperature-time curve obtained in practice. (JN)
Christensen, Doran M; Livingston, Gordon K; Sugarman, Stephen L; Parillo, Steven J; Glassman, Erik S
2014-07-01
Ionizing radiation exposure can induce profound changes in intracellular components, potentially leading to diverse health effects in exposed individuals. Any cellular component can be damaged by radiation, but some components affect cellular viability more profoundly than others. The ionization caused by radiation lasts longer than the initial inciting incident, continuing as 1 ionization incident causes another. In some cases, damage to DNA can lead to cellular death at mitosis. In other cases, activation of the genetic machinery can lead to a genetic cascade potentially leading to mutations or cell death by apoptosis. In the third of 5 articles on the management of injuries and illnesses caused by ionizing radiation, the authors provide a clinically relevant overview of the pathophysiologic process associated with potential exposure to ionizing radiation.
NASA Astrophysics Data System (ADS)
Chhabra, P. S.; Lambe, A. T.; Canagaratna, M. R.; Stark, H.; Jayne, J. T.; Onasch, T. B.; Davidovits, P.; Kimmel, J. R.; Worsnop, D. R.
2014-07-01
Recent developments in high resolution, time-of-flight chemical ionization mass spectrometry (HR-ToF-CIMS) have made possible the direct detection of atmospheric organic compounds in real-time with high sensitivity and with little or no fragmentation, including low volatility, highly oxygenated organic vapors that are precursors to secondary organic aerosol formation. Here, for the first time, we examine gas-phase O3 and OH oxidation products of α-pinene and naphthalene formed in the PAM flow reactor with an HR-ToF-CIMS using acetate reagent ion chemistry. Integrated OH exposures ranged from 1.2 × 1011 to 9.7 × 1011 molec cm-3 s, corresponding to approximately 1.0 to 7.5 days of equivalent atmospheric oxidation. Measured gas-phase organic acids are similar to those previously observed in environmental chamber studies. For both precursors, we find that acetate-CIMS spectra capture both functionalization (oxygen addition) and fragmentation (carbon loss) as a function of OH exposure. The level of fragmentation is observed to increase with increased oxidation. We present a method that estimates vapor pressures of organic molecules using the measured O/C ratio, H/C ratio, and carbon number for each compound detected by the CIMS. The predicted condensed-phase SOA average acid yields and O/C and H/C ratios agree within uncertainties with previous AMS measurements and ambient CIMS results. While acetate reagent ion chemistry is used to selectively measure organic acids, in principle this method can be applied to additional reagent ion chemistries depending on the application.
Chhabra, P. S.; Lambe, A. T.; Canagaratna, M. R.; Stark, H.; Jayne, J. T.; Onasch, T. B.; Davidovits, P.; Kimmel, J. R.; Worsnop, D. R.
2014-07-01
Recent developments in high resolution, time-of-flight chemical ionization mass spectrometry (HR-ToF-CIMS) have made possible the direct detection of atmospheric organic compounds in real-time with high sensitivity and with little or no fragmentation, including low volatility, highly oxygenated organic vapors that are precursors to secondary organic aerosol formation. Here, for the first time, we examine gas-phase O3 and OH oxidation products of α-pinene and naphthalene formed in the PAM flow reactor with an HR-ToF-CIMS using acetate reagent ion chemistry. Integrated OH exposures ranged from 1.2 × 1011 to 9.7 × 1011 molec cm−3 s, corresponding to approximately 1.0 to 7.5 daysmore » of equivalent atmospheric oxidation. Measured gas-phase organic acids are similar to those previously observed in environmental chamber studies. For both precursors, we find that acetate-CIMS spectra capture both functionalization (oxygen addition) and fragmentation (carbon loss) as a function of OH exposure. The level of fragmentation is observed to increase with increased oxidation. We present a method that estimates vapor pressures of organic molecules using the measured O/C ratio, H/C ratio, and carbon number for each compound detected by the CIMS. The predicted condensed-phase SOA average acid yields and O/C and H/C ratios agree within uncertainties with previous AMS measurements and ambient CIMS results. While acetate reagent ion chemistry is used to selectively measure organic acids, in principle this method can be applied to additional reagent ion chemistries depending on the application.« less
The exact forces on classical nuclei in non-adiabatic charge transfer.
Agostini, Federica; Abedi, Ali; Suzuki, Yasumitsu; Min, Seung Kyu; Maitra, Neepa T; Gross, E K U
2015-02-28
The decomposition of electronic and nuclear motion presented in Abedi et al. [Phys. Rev. Lett. 105, 123002 (2010)] yields a time-dependent potential that drives the nuclear motion and fully accounts for the coupling to the electronic subsystem. Here, we show that propagation of an ensemble of independent classical nuclear trajectories on this exact potential yields dynamics that are essentially indistinguishable from the exact quantum dynamics for a model non-adiabatic charge transfer problem. We point out the importance of step and bump features in the exact potential that are critical in obtaining the correct splitting of the quasiclassical nuclear wave packet in space after it passes through an avoided crossing between two Born-Oppenheimer surfaces and analyze their structure. Finally, an analysis of the exact potentials in the context of trajectory surface hopping is presented, including preliminary investigations of velocity-adjustment and the force-induced decoherence effect.
The exact forces on classical nuclei in non-adiabatic charge transfer.
Agostini, Federica; Abedi, Ali; Suzuki, Yasumitsu; Min, Seung Kyu; Maitra, Neepa T; Gross, E K U
2015-02-28
The decomposition of electronic and nuclear motion presented in Abedi et al. [Phys. Rev. Lett. 105, 123002 (2010)] yields a time-dependent potential that drives the nuclear motion and fully accounts for the coupling to the electronic subsystem. Here, we show that propagation of an ensemble of independent classical nuclear trajectories on this exact potential yields dynamics that are essentially indistinguishable from the exact quantum dynamics for a model non-adiabatic charge transfer problem. We point out the importance of step and bump features in the exact potential that are critical in obtaining the correct splitting of the quasiclassical nuclear wave packet in space after it passes through an avoided crossing between two Born-Oppenheimer surfaces and analyze their structure. Finally, an analysis of the exact potentials in the context of trajectory surface hopping is presented, including preliminary investigations of velocity-adjustment and the force-induced decoherence effect. PMID:25725727
The exact forces on classical nuclei in non-adiabatic charge transfer
Agostini, Federica; Abedi, Ali; Suzuki, Yasumitsu; Min, Seung Kyu; Gross, E. K. U.; Maitra, Neepa T.
2015-02-28
The decomposition of electronic and nuclear motion presented in Abedi et al. [Phys. Rev. Lett. 105, 123002 (2010)] yields a time-dependent potential that drives the nuclear motion and fully accounts for the coupling to the electronic subsystem. Here, we show that propagation of an ensemble of independent classical nuclear trajectories on this exact potential yields dynamics that are essentially indistinguishable from the exact quantum dynamics for a model non-adiabatic charge transfer problem. We point out the importance of step and bump features in the exact potential that are critical in obtaining the correct splitting of the quasiclassical nuclear wave packet in space after it passes through an avoided crossing between two Born-Oppenheimer surfaces and analyze their structure. Finally, an analysis of the exact potentials in the context of trajectory surface hopping is presented, including preliminary investigations of velocity-adjustment and the force-induced decoherence effect.
Miniature Oxidizer Ionizer for a Fuel Cell
NASA Technical Reports Server (NTRS)
Hartley, Frank
2006-01-01
A proposed miniature device for ionizing the oxygen (or other oxidizing gas) in a fuel cell would consist mostly of a membrane ionizer using the same principles as those of the device described in the earlier article, Miniature Bipolar Electrostatic Ion Thruster (NPO-21057). The oxidizing gas would be completely ionized upon passage through the holes in the membrane ionizer. The resulting positively charged atoms or molecules of oxidizing gas could then, under the influence of the fringe fields of the ionizer, move toward the fuel-cell cathode that would be part of a membrane/electrode assembly comprising the cathode, a solid-electrolyte membrane, and an anode. The electro-oxidized state of the oxidizer atoms and molecules would enhance transfer of them through the cathode, thereby reducing the partial pressure of the oxidizer gas between the ionizer and the fuel-cell cathode, thereby, in turn, causing further inflow of oxidizer gas through the holes in the membrane ionizer. Optionally the ionizer could be maintained at a positive electric potential with respect to the cathode, in which case the resulting electric field would accelerate the ions toward the cathode.
Higher-Order Equation-of-Motion Coupled-Cluster Methods for Ionization Processes
Kamiya, Muneaki; Hirata, So
2006-08-21
Compact algebraic equations defining the equation-of-motion coupled-cluster (EOM-CC) methods for ionization potentials (IP-EOM-CC) have been derived and computer implemented by virtue of a symbolic algebra system largely automating these processes. Models with connected cluster excitation operators truncated after double, triple, or quadruple level and with linear ionization operators truncated after two-hole-one-particle (2h1p), three-hole-two-particle (3h2p), or four-hole-three-particle (4h3p) level (abbreviated as IP-EOM-CCSD, CCSDT, and CCSDTQ, respectively) have been realized into parallel algorithms taking advantage of spin, spatial, and permutation symmetries with optimal size dependence of the computational costs. They are based on spin-orbital formalisms and can describe both {alpha} and {beta} and ionizations from open-shell (doublet, triplet, etc.) reference states into ionized states with various spin magnetic quantum numbers. The application of these methods to Koopmans and satellite ionizations of N{sub 2} and CO (with the ambiguity due to finite basis sets eliminated by extrapolation) has shown that IP-EOM-CCSD frequently accounts for orbital relaxation inadequately and displays errors exceeding a couple of eV. However, these errors can be systematically reduced to tenths or even hundredths of an eV by IP-EOM-CCSDT or CCSDTQ. Comparison of spectroscopic parameters of the FH{sup +} and NH{sup +} radicals between IP-EOM-CC and experiments has also underscored the importance of higher-order IP-EOM-CC treatments. For instance, the harmonic frequencies of the {tilde A} {sup 2}{Sigma}{sup -} state of NH{sup +}+ are predicted to be 1285, 1723, and 1705 cm{sup -1} by IP-EOM-CCSD, CCSDT, and CCSDTQ, respectively, as compared to the observed value of 1707 cm{sup -1}. The small adiabatic energy separation (observed 0.04 eV) between the {tilde X} {sup 2}II and {tilde a} {sup 4}{sigma}{sup -} states of NH{sup +} also requires IP-EOM-CCSDTQ for a quantitative
Guo, Shuai; Qiu, Ling; Wang, Yanming; Qin, Xuzhen; Liu, Hui; He, Manwen; Zhang, Yaping; Li, Zhili; Chen, Xiaohong
2014-07-01
Changes in serum lipidome and in tissue lipidome are associated with cancer. In this study, tissue mass spectrometry imaging (MSI) and serum lipid profiling by matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS) were performed to investigate significantly changed lipids in both tumor (malignant thyroid cancer (MTC) and benign thyroid tumor (BTT)) tissues and sera. Y-scatterplots of variable importance in the projection (VIP) values vs. fold change values indicate that change trends in the levels of ten lipids (i.e., phosphatidylcholine (PC)(34:1), PC(36:1), PC(38:6), phosphatidic acid (PA) (36:2), PA(36:3), PA(38:3), PA(38:4), PA(38:5), PA(40:5), and sphingomyelin (SM)(34:1)) in both tissues and sera from MTC patients, BTT patients, and normal individuals are significantly associated with these three types of pathophysiological status. In order to examine their diagnostic ability, 289 serum samples from 124 MTC patients, 43 BTT patients, and 122 normal controls were randomly divided into the training set and validation set. A biomarker of PC(34:1) exhibited excellent diagnostic ability to differentiate both MTC and BTT patients from normal individuals, with an area under the receiver operating characteristic (ROC) curve value of 0.984, a sensitivity of 96.4 %, and a specificity of 92.7 %. A panel which included PA(36:3) and SM(34:1) could distinguish between MTC and BTT, with an area under receiver operating characteristic curve (AUC) of 0.961, a sensitivity of 87.8 %, and a specificity of 92.9 %. It is worth noting that a panel consisting of PC(34:1), PA(36:3), and SM(34:1) could differentiate MTC patients from both BTT patients and normal individuals, with an AUC of 0.841, a sensitivity of 86.6 %, and a specificity of 75.5 %.
NASA Astrophysics Data System (ADS)
Vaidya, B.; Mignone, A.; Bodo, G.; Massaglia, S.
2015-08-01
Context. An equation of state (EoS) is a relation between thermodynamic state variables and it is essential for closing the set of equations describing a fluid system. Although an ideal EoS with a constant adiabatic index Γ is the preferred choice owing to its simplistic implementation, many astrophysical fluid simulations may benefit from a more sophisticated treatment that can account for diverse chemical processes. Aims: In the present work we first review the basic thermodynamic principles of a gas mixture in terms of its thermal and caloric EoS by including effects like ionization, dissociation, and temperature dependent degrees of freedom such as molecular vibrations and rotations. The formulation is revisited in the context of plasmas that are either in equilibrium conditions (local thermodynamic- or collisional excitation-equilibria) or described by non-equilibrium chemistry coupled to optically thin radiative cooling. We then present a numerical implementation of thermally ideal gases obeying a more general caloric EoS with non-constant adiabatic index in Godunov-type numerical schemes. Methods: We discuss the necessary modifications to the Riemann solver and to the conversion between total energy and pressure (or vice versa) routinely invoked in Godunov-type schemes. We then present two different approaches for computing the EoS. The first employs root-finder methods and it is best suited for EoS in analytical form. The second is based on lookup tables and interpolation and results in a more computationally efficient approach, although care must be taken to ensure thermodynamic consistency. Results: A number of selected benchmarks demonstrate that the employment of a non-ideal EoS can lead to important differences in the solution when the temperature range is 500-104 K where dissociation and ionization occur. The implementation of selected EoS introduces additional computational costs although the employment of lookup table methods (when possible) can
Pulsed spheromak reactor with adiabatic compression
Fowler, T K
1999-03-29
Extrapolating from the Pulsed Spheromak reactor and the LINUS concept, we consider ignition achieved by injecting a conducting liquid into the flux conserver to compress a low temperature spheromak created by gun injection and ohmic heating. The required energy to achieve ignition and high gain by compression is comparable to that required for ohmic ignition and the timescale is similar so that the mechanical power to ignite by compression is comparable to the electrical power to ignite ohmically. Potential advantages and problems are discussed. Like the High Beta scenario achieved by rapid fueling of an ohmically ignited plasma, compression must occur on timescales faster than Taylor relaxation.
Ionization of highly excited helium atoms in an electric field
van de Water, W.; Mariani, D.R.; Koch, P.M.
1984-11-01
We present detailed measurements of ionization of highly excited triplet helium atoms in a static electric field. The atoms were prepared in states with energy E close to the saddle-point threshold E = -2(F(a.u.))/sup 1/2/. The electric field F was sufficiently strong for the states to be characterized by total spin S and absolute value of the magnetic quantum number M/sub L/. For M/sub L/ = 0 states the experiments measured ionization properties of adiabatic states. In another case, Vertical BarM/sub L/Vertical Bar = 2, they predominantly measured those of diabatic states. In both cases the ionization rate was found to be a highly nonmonotonic function of the field strength. The observations are analyzed in terms of a theory of the helium density of states in an electric field. A companion paper (D. A. Harmin, Phys. Rev. A 30, 2413 (1984)) develops in detail the general theory, which uses quantum defects to parametrize the effect of the core interaction. The agreement between measured and calculated ionization curves is good, indicating that the field ionization of a nonhydrogenic atom can now be understood in a detailed, quantitative, and predictive sense.
Hiserodt, R D; Swijter, D F; Mussinan, C J
2000-08-01
This paper describes the first high-performance liquid chromatographic-tandem mass spectrometric method for the identification of atranorin and related potential allergens in oakmoss absolute. Oakmoss absolute is ubiquitous in the fragrance industry and is a key component in many fine perfumes. However, oakmoss absolute causes an allergic response in some individuals. Research is focused toward establishing the identity of the compounds causing the allergic response so a quality controlled oakmoss with reduced allergenic potential can be prepared. Consequently a highly selective and specific analytical method is necessary to support this effort. This is not available with the existing HPLC methods using UV detection. PMID:10949477
Three-Body Coulomb Functions in the Hyperspherical Adiabatic Expansion Method
NASA Astrophysics Data System (ADS)
Garrido, E.; Kievsky, A.; Viviani, M.
2016-10-01
In this work we describe a numerical method devised to compute continuum three-body wave functions. The method is implemented using the hyperspherical adiabatic expansion for the three-body wave function imposing a box boundary condition. The continuum energy spectrum results discretized and, for specific quantum number values, all the possible incoming and outgoing channels are simultaneously computed. For a given energy, the hyperradial continuum functions form a matrix whose ij-term refers to specific incoming and outgoing channels. When applied to three-body systems interacting only through the Coulomb potential, this method provides the adiabatic representation of the regular three-body Coulomb wave function. The computation of the irregular Coulomb wave function representation is also discussed. These regular and irregular Coulomb functions can be used to extract the {S} -matrix for those reactions where, together with some short-range potential, the Coulomb interaction is also present. The method is illustrated in the case of the 3→ 3 process of three alpha particles.
Controlling vibrational cooling with zero-width resonances: An adiabatic Floquet approach
NASA Astrophysics Data System (ADS)
Leclerc, Arnaud; Viennot, David; Jolicard, Georges; Lefebvre, Roland; Atabek, Osman
2016-10-01
In molecular photodissociation, some specific combinations of laser parameters (wavelength and intensity) lead to unexpected zero-width resonances (ZWRs) with, in principle, infinite lifetimes. Their potential to induce basic quenching mechanisms has recently been devised in the laser control of vibrational cooling through filtration strategies [O. Atabek et al., Phys. Rev. A 87, 031403(R) (2013), 10.1103/PhysRevA.87.031403]. A full quantum adiabatic control theory based on the adiabatic Floquet Hamiltonian is developed to show how a laser pulse could be envelope-shaped and frequency-chirped so as to protect a given initial vibrational state against dissociation, taking advantage of its continuous transport on the corresponding ZWR all along the pulse duration. As compared with previous control scenarios that actually suffered from nonadiabatic contamination, drastically different and much more efficient filtration goals are achieved. A semiclassical analysis helps us to find and interpret a complete map of ZWRs in the laser parameter plane. In addition, the choice of a given ZWR path, among the complete series identified by the semiclassical approach, turns out to be crucial for the cooling scheme, targeting a single vibrational state population left at the end of the pulse, while all others have almost completely decayed. The illustrative example, which has the potential to be transposed to other diatomics, is Na2 prepared by photoassociation in vibrationally hot but translationally and rotationally cold states.
NASA Astrophysics Data System (ADS)
Wu, Pei-Ying; Tzeng, Wen-Bih
2016-06-01
We applied the two-color resonant two-photon mass analyzed threshold ionization technique to record the cation spectra of 4-chloro-2-fluoroanisole by ionizing via five intermediate vibronic levels. The excitation and adiabatic ionization energies were determined to be 35 227, and 67 218 wn, respectively. Spectral analysis and theoretical calculation suggest that the geometry of the aromatic ring of the neutral species in the S1 state is non-planar, but that of the cation in the D0 state is planar.
Hudgens, J.W.; Dearden, D.V.; Johnson, R.D. III
1993-12-31
The authors report detection and characterization of AlF and AlCl using 1+2, 2=1, 2+2, 3+1, and 3+2 resonance-enhanced multiphoton ionization (REMPI) spectroscopy. REMPI Spectra of AlF reveal 13 new Rydberg states that lie between 70,000 and 77,000 cm{sup {minus}1}. These new states, in combination with previously known states, form six Rydberg series. Least-squares fitting of the Rydberg series to the Rydberg equation yields the precise adiabatic ionization potential, IP{sub a}(AlF) = 9.729 {+-} 0.001 eV. Vibrational intervals of the new Rydberg states are about 25% greater than those of AlF (X {sup 1}{Sigma}{sup +}), with most lying between 930-980 cm{sup {minus}1}. REMPI spectra of AlCl reveal new Rydberg states that lie between 54000 and 60000 cm{sup {minus}1}. Vibrational intervals of these new Rydberg states are about 25% greater than those of AlCl (X {sup 1}{Sigma}{sup +}), with most lying between 570-600 cm{sup {minus}1}.
Theory of laser-induced adiabat shaping in inertial fusion implosions: The relaxation method
Betti, R.; Anderson, K.; Knauer, J.; Collins, T.J.B.; McCrory, R.L.; McKenty, P.W.; Skupsky, S.
2005-04-15
The theory of the adiabat shaping induced by a strong shock propagating through a relaxed density profile is carried out for inertial confinement fusion (ICF) capsules. The relaxed profile is produced through a laser prepulse, while the adiabat-shaping shock is driven by the foot of the main laser pulse. The theoretical adiabat profiles accurately reproduce the simulation results. ICF capsules with a shaped adiabat are expected to benefit from improved hydrodynamic stability while maintaining the same one-dimensional performances as flat-adiabat shells.
Robust quantum logic in neutral atoms via adiabatic Rydberg dressing
NASA Astrophysics Data System (ADS)
Keating, Tyler; Cook, Robert L.; Hankin, Aaron M.; Jau, Yuan-Yu; Biedermann, Grant W.; Deutsch, Ivan H.
2015-01-01
We study a scheme for implementing a controlled-Z (cz) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a σ+/σ- orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces acting on doubly excited Rydberg atoms when the blockade is imperfect. For reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a cz gate in <10 μ s with error probability on the order of 10-3.
Adiabatic far-field sub-diffraction imaging
Cang, Hu; Salandrino, Alessandro; Wang, Yuan; Zhang, Xiang
2015-01-01
The limited resolution of a conventional optical imaging system stems from the fact that the fine feature information of an object is carried by evanescent waves, which exponentially decays in space and thus cannot reach the imaging plane. We introduce here an adiabatic lens, which utilizes a geometrically conformal surface to mediate the interference of slowly decompressed electromagnetic waves at far field to form images. The decompression is satisfying an adiabatic condition, and by bridging the gap between far field and near field, it allows far-field optical systems to project an image of the near-field features directly. Using these designs, we demonstrated the magnification can be up to 20 times and it is possible to achieve sub-50 nm imaging resolution in visible. Our approach provides a means to extend the domain of geometrical optics to a deep sub-wavelength scale. PMID:26258769
Adiabatic creation of atomic squeezing in dark states versus decoherences
Gong, Z. R.; Sun, C. P.; Wang Xiaoguang
2010-07-15
We study the multipartite correlations of the multiatom dark states, which are characterized by the atomic squeezing beyond the pairwise entanglement. It is shown that, in the photon storage process with atomic ensemble via the electromagnetically induced transparency (EIT) mechanism, the atomic squeezing and the pairwise entanglement can be created by adiabatically manipulating the Rabi frequency of the classical light field on the atomic ensemble. We also consider the sudden death for the atomic squeezing and the pairwise entanglement under various decoherence channels. An optimal time for generating the greatest atomic squeezing and pairwise entanglement is obtained by studying in detail the competition between the adiabatic creation of quantum correlation in the atomic ensemble and the decoherence that we describe with three typical decoherence channels.
Adiabatic theory of solitons fed by dispersive waves
NASA Astrophysics Data System (ADS)
Pickartz, Sabrina; Bandelow, Uwe; Amiranashvili, Shalva
2016-09-01
We consider scattering of low-amplitude dispersive waves at an intense optical soliton which constitutes a nonlinear perturbation of the refractive index. Specifically, we consider a single-mode optical fiber and a group velocity matched pair: an optical soliton and a nearly perfectly reflected dispersive wave, a fiber-optical analog of the event horizon. By combining (i) an adiabatic approach that is used in soliton perturbation theory and (ii) scattering theory from quantum mechanics, we give a quantitative account of the evolution of all soliton parameters. In particular, we quantify the increase in the soliton peak power that may result in the spontaneous appearance of an extremely large, so-called champion soliton. The presented adiabatic theory agrees well with the numerical solutions of the pulse propagation equation. Moreover, we predict the full frequency band of the scattered dispersive waves and explain an emerging caustic structure in the space-time domain.
On the Effect of Strain Gradient on Adiabatic Shear Banding
NASA Astrophysics Data System (ADS)
Tsagrakis, Ioannis; Aifantis, Elias C.
2015-10-01
Most of the work on adiabatic shear banding is based on the effect of temperature gradients on shear band nucleation and evolution. In contrast, the present work considers the coupling between temperature and strain gradients. The competition of thermal and strain gradient terms on the onset of instability and its dependence on specimen size is illustrated. It is shown that heat conduction promotes the instability initiation in the hardening part of the homogeneous stress-strain, while the strain gradient term favors the occurrence of this initiation in the softening regime. This behavior is size dependent, i.e., small specimens can support stable homogeneous deformations even in the softening regime. The spacing of adiabatic shear bands is also evaluated by considering the dominant instability mode during the primary stages of the localization process and it is found that it is an increasing function of the strain gradient coefficient.
Steam bottoming cycle for an adiabatic diesel engine
NASA Technical Reports Server (NTRS)
Poulin, E.; Demier, R.; Krepchin, I.; Walker, D.
1984-01-01
Steam bottoming cycles using adiabatic diesel engine exhaust heat which projected substantial performance and economic benefits for long haul trucks were studied. Steam cycle and system component variables, system cost, size and performance were analyzed. An 811 K/6.90 MPa state of the art reciprocating expander steam system with a monotube boiler and radiator core condenser was selected for preliminary design. The costs of the diesel with bottoming system (TC/B) and a NASA specified turbocompound adiabatic diesel with aftercooling with the same total output were compared, the annual fuel savings less the added maintenance cost was determined to cover the increase initial cost of the TC/B system in a payback period of 2.3 years. Steam bottoming system freeze protection strategies were developed, technological advances required for improved system reliability are considered and the cost and performance of advanced systes are evaluated.
Fluctuations of work in nearly adiabatically driven open quantum systems.
Suomela, S; Salmilehto, J; Savenko, I G; Ala-Nissila, T; Möttönen, M
2015-02-01
We extend the quantum jump method to nearly adiabatically driven open quantum systems in a way that allows for an accurate account of the external driving in the system-environment interaction. Using this framework, we construct the corresponding trajectory-dependent work performed on the system and derive the integral fluctuation theorem and the Jarzynski equality for nearly adiabatic driving. We show that such identities hold as long as the stochastic dynamics and work variable are consistently defined. We numerically study the emerging work statistics for a two-level quantum system and find that the conventional diabatic approximation is unable to capture some prominent features arising from driving, such as the continuity of the probability density of work. Our results reveal the necessity of using accurate expressions for the drive-dressed heat exchange in future experiments probing jump time distributions. PMID:25768477
Coherent adiabatic transport of atoms in radio-frequency traps
Morgan, T.; O'Sullivan, B.; Busch, Th.
2011-05-15
Coherent transport by adiabatic passage has recently been suggested as a high-fidelity technique to engineer the center-of-mass state of single atoms in inhomogeneous environments. While the basic theory behind this process is well understood, several conceptual challenges for its experimental observation have still to be addressed. One of these is the difficulty that currently available optical or magnetic micro-trap systems have in adjusting the tunneling rate time dependently while keeping resonance between the asymptotic trapping states at all times. Here we suggest that both requirements can be fulfilled to a very high degree in an experimentally realistic setup based on radio-frequency traps on atom chips. We show that operations with close to 100% fidelity can be achieved and that these systems also allow significant improvements for performing adiabatic passage with interacting atomic clouds.
Two step laser desorption - laser ionization of PAHs. Experimental Setup
NASA Astrophysics Data System (ADS)
Poveda, Juan C.; Guerrero, Alfonso; Álvarez, Ignacio; Cisneros, Carmen
2012-11-01
We present an experimental setup for the photoionization of PAHs in a cooled molecular beam using laser radiation of 266 nm. Molecular beams was produced by laser desorption of samples using unfocused laser radiation of 522 nm, which was synchronously coupled with ionization laser pulses. At low energies per pulse, <1 mJ, the molecular ionization of PAHs take place in the soft conditions regimen producing a poor molecular dissociation. The R-ToF spectra are mainly characterized by the presence of the parent molecular ion. When buffer gases as Helium were used it helps to avoid the molecular clustering and contributes to the molecular cooling when the adiabatic expansion takes place.
Two-mode multiplexer and demultiplexer based on adiabatic couplers.
Xing, Jiejiang; Li, Zhiyong; Xiao, Xi; Yu, Jinzhong; Yu, Yude
2013-09-01
A two-mode (de)multiplexer based on adiabatic couplers is proposed and experimentally demonstrated. The experimental results are in good agreement with the simulations. An ultralow mode cross talk below -36 dB and a low insertion loss of about 0.3 dB over a broad bandwidth from 1500 to 1600 nm are measured. The design is also fabrication-tolerant, and the insertion loss can be further improved in the future. PMID:23988986
Adiabaticity and gravity theory independent conservation laws for cosmological perturbations
NASA Astrophysics Data System (ADS)
Romano, Antonio Enea; Mooij, Sander; Sasaki, Misao
2016-04-01
We carefully study the implications of adiabaticity for the behavior of cosmological perturbations. There are essentially three similar but different definitions of non-adiabaticity: one is appropriate for a thermodynamic fluid δPnad, another is for a general matter field δPc,nad, and the last one is valid only on superhorizon scales. The first two definitions coincide if cs2 = cw2 where cs is the propagation speed of the perturbation, while cw2 = P ˙ / ρ ˙ . Assuming the adiabaticity in the general sense, δPc,nad = 0, we derive a relation between the lapse function in the comoving slicing Ac and δPnad valid for arbitrary matter field in any theory of gravity, by using only momentum conservation. The relation implies that as long as cs ≠cw, the uniform density, comoving and the proper-time slicings coincide approximately for any gravity theory and for any matter field if δPnad = 0 approximately. In the case of general relativity this gives the equivalence between the comoving curvature perturbation Rc and the uniform density curvature perturbation ζ on superhorizon scales, and their conservation. This is realized on superhorizon scales in standard slow-roll inflation. We then consider an example in which cw =cs, where δPnad = δPc,nad = 0 exactly, but the equivalence between Rc and ζ no longer holds. Namely we consider the so-called ultra slow-roll inflation. In this case both Rc and ζ are not conserved. In particular, as for ζ, we find that it is crucial to take into account the next-to-leading order term in ζ's spatial gradient expansion to show its non-conservation, even on superhorizon scales. This is an example of the fact that adiabaticity (in the thermodynamic sense) is not always enough to ensure the conservation of Rc or ζ.