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Articoli di riviste sul tema "Many-Body formalisms"

Autore: Grafiati
Pubblicato: 19 ottobre 2024

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1

Faber, C., P. Boulanger, C. Attaccalite, I. Duchemin e X. Blase. "Excited states properties of organic molecules: from density functional theory to the GW and Bethe–Salpeter Green's function formalisms". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, n. 2011 (13 marzo 2014): 20130271. http://dx.doi.org/10.1098/rsta.2013.0271.

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Many-body Green's function perturbation theories, such as the GW and Bethe–Salpeter formalisms, are starting to be routinely applied to study charged and neutral electronic excitations in molecular organic systems relevant to applications in photovoltaics, photochemistry or biology. In parallel, density functional theory and its time-dependent extensions significantly progressed along the line of range-separated hybrid functionals within the generalized Kohn–Sham formalism designed to provide correct excitation energies. We give an overview and compare these approaches with examples drawn from the study of gas phase organic systems such as fullerenes, porphyrins, bacteriochlorophylls or nucleobases molecules. The perspectives and challenges that many-body perturbation theory is facing, such as the role of self-consistency, the calculation of forces and potential energy surfaces in the excited states, or the development of embedding techniques specific to the GW and Bethe–Salpeter equation formalisms, are outlined.
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2

AL-SUGHEIR, M. K., H. B. GHASSIB e B. R. JOUDEH. "FERMI PAIRING IN DILUTE 3He-HeII MIXTURES". International Journal of Modern Physics B 20, n. 18 (20 luglio 2006): 2491–504. http://dx.doi.org/10.1142/s0217979206034844.

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In this paper the Galitskii–Migdal–Feynman (GMF) formalism is applied to dilute 3He-HeII mixtures. In particular, the effect of the hole-hole scattering on pairing in these systems is investigated. To this end, the relative phase shifts incorporating many-body effects based on both Brueckner–Bethe–Goldstone (BBG) and GMF formalisms are calculated. In the GMF formalism, the S-wave phase shift at zero relative momentum is –π and has a cusp at the Fermi momentum; while in the BBG formalism, this phase shift has zero values up to the Fermi momentum. From these results we conclude that hole-hole scattering plays a crucial role in any possible fermion-fermion pairing in these systems.
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3

Evangelista, Francesco A. "Automatic derivation of many-body theories based on general Fermi vacua". Journal of Chemical Physics 157, n. 6 (14 agosto 2022): 064111. http://dx.doi.org/10.1063/5.0097858.

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This paper describes Wick&d, an implementation of the algebra of second-quantized operators normal ordered with respect to general correlated references and the corresponding Wick theorem [D. Mukherjee, Chem. Phys. Lett. 274, 561 (1997) and W. Kutzelnigg and D. Mukherjee, J. Chem. Phys. 107, 432 (1997)]. Wick&d employs a compact representation of operators and a backtracking algorithm to efficiently evaluate Wick contractions. Since Wick&d can handle both fully and partially contracted terms, it can be applied to both projective and Fock-space many-body formalisms. To demonstrate the usefulness of Wick&d, we use it to evaluate the single-reference coupled cluster equations up to octuple excitations and report an automated derivation and implementation of the second-order driven similarity renormalization group multireference perturbation theory.
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4

HU, BEN YU-KUANG. "MANY-BODY EFFECTS IN FRICTIONAL DRAG BETWEEN COUPLED TWO-DIMENSIONAL ELECTRON SYSTEMS". International Journal of Modern Physics B 13, n. 05n06 (10 marzo 1999): 469–78. http://dx.doi.org/10.1142/s0217979299000369.

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Independently contacted coupled quantum wells separated by barriers which allow significant interlayer interactions but no tunneling have been fabricated. When current is passed through one layer, the interlayer interactions drag carriers in the second layer, resulting in a voltage response (for open circuits). The magnitude of the response gives a quantitative measure of the effective interlayer interactions and response functions of the system, and hence this is an excellent laboratory for the study of many-body phenomena in two-dimensional electron gases. We review the Boltzmann and Kubo formalisms for the theory of drag effects in coupled quantum wells and discuss three specific cases where many-body effects significantly affect the drag: (1) acoustic phonon-mediated drag, (2) large enhancements due to coupled plasmon modes, and (3) interplay of screening and Landau levels in large magnetic fields.
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5

Lindgren, I., S. Salomonson e D. Hedendahl. "Many-body-QED perturbation theory: Connection to the two-electron Bethe–Salpeter equation". Canadian Journal of Physics 83, n. 3 (1 marzo 2005): 183–218. http://dx.doi.org/10.1139/p05-027.

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The connection between many-body perturbation theory (MBPT) and quantum electrodynamics (QED) is reviewed for systems of two fermions in an external field. The treatment is mainly based on the recently developed covariant-evolution-operator method for QED calculations (I. Lindgren, S. Salomonson, and B. Åsén. Phys. Rep. 389, 161 (2004)), which is quite similar in structure to MBPT. At the same time, this procedure is closely related to the S-matrix and Green's-function formalisms and can therefore serve as a bridge connecting various approaches. It is demonstrated that the MBPT–QED scheme, when carried to all orders, leads to a Schrödinger-like equation, equivalent to the Bethe–Salpeter (BS) equation. A Bloch equation in commutator form that can be used for an "extended" or quasi-degenerate model space is derived. This is a multi-state equation that has the same relation to the single-state BS equation as the standard Bloch equation has to the ordinary Schrödinger equation. It can be used to generate a perturbation expansion compatible with the BS equation even in the case of a quasi-degenerate model PACS Nos.: 01.65.+g, 02.60.Cb, 03.65.Pm, 31.10+z, 31.15Md, 31.30Jv
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6

Chaudhuri, Rajat, Dhiman Sinha e Debashis Mukherjee. "On the extensivity of the roots of effective Hamiltonians in many-body formalisms employing incomplete model spaces". Chemical Physics Letters 163, n. 2-3 (novembre 1989): 165–70. http://dx.doi.org/10.1016/0009-2614(89)80029-6.

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7

Bauman, Nicholas P., Eric J. Bylaska, Sriram Krishnamoorthy, Guang Hao Low, Nathan Wiebe, Christopher E. Granade, Martin Roetteler, Matthias Troyer e Karol Kowalski. "Downfolding of many-body Hamiltonians using active-space models: Extension of the sub-system embedding sub-algebras approach to unitary coupled cluster formalisms". Journal of Chemical Physics 151, n. 1 (7 luglio 2019): 014107. http://dx.doi.org/10.1063/1.5094643.

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8

Alastuey, A. "Statistical Mechanics of Quantum Plasmas Path Integral Formalism". International Astronomical Union Colloquium 147 (1994): 43–77. http://dx.doi.org/10.1017/s0252921100026312.

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AbstractIn this review, we consider a quantum Coulomb fluid made of charged point particles (typically electrons and nuclei). We describe various formalisms which start from the first principles of statistical mechanics. These methods allow systematic calculations of the equilibrium quantities in some particular limits. The effective-potential method is evocated first, as well as its application to the derivation of low-density expansions. We also sketch the basic outlines of the standard many-body perturbation theory. This approach is well suited for calculating expansions at high density (for Fermions) or at high temperature. Eventually, we present the Feynman-Kac path integral representation which leads to the introduction of an auxiliary classical system made of extended objects, i.e., filaments (also called “polymers”). The familiar Abe-Meeron diagrammatic series are then generalized in the framework of this representation. The truncations of the corresponding virial-like expansions provide equations of state which are asymptotically exact in the low-density limit at fixed temperature. The usefulness of such equations for describing the inner regions of the sun is briefly illustrated.
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9

Villani, Matteo, e Xavier Oriols. "Can Wigner distribution functions with collisions satisfy complete positivity and energy conservation?" Journal of Computational Electronics 20, n. 6 (23 novembre 2021): 2232–44. http://dx.doi.org/10.1007/s10825-021-01798-1.

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AbstractTo avoid the computational burden of many-body quantum simulation, the interaction of an electron with a photon (phonon) is typically accounted for by disregarding the explicit simulation of the photon (phonon) degree of freedom and just modeling its effect on the electron dynamics. For quantum models developed from the (reduced) density matrix or its Wigner–Weyl transformation, the modeling of collisions may violate complete positivity (precluding the typical probabilistic interpretation). In this paper, we show that such quantum transport models can also strongly violate the energy conservation in the electron–photon (electron–phonon) interactions. After comparing collisions models to exact results for an electron interacting with a photon, we conclude that there is no fundamental restriction that prevents a collision model developed within the (reduced) density matrix or Wigner formalisms to satisfy simultaneously complete positivity and energy conservation. However, at the practical level, the development of such satisfactory collision model seems very complicated. Collision models with an explicit knowledge of the microscopic state ascribed to each electron seems recommendable (Bohmian conditional wavefunction), since they allow to model collisions of each electron individually in a controlled way satisfying both complete positivity and energy conservation.
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10

Baer, Roi, e Daniel Neuhauser. "Many-body scattering formalism of quantum molecular conductance". Chemical Physics Letters 374, n. 5-6 (giugno 2003): 459–63. http://dx.doi.org/10.1016/s0009-2614(03)00709-7.

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11

Lungu, Radu Paul, e Andrei Manolescu. "Many-Body Fermion Systems in the Floquet Formalism". Physica Scripta 62, n. 6 (1 dicembre 2000): 433–45. http://dx.doi.org/10.1238/physica.regular.062a00433.

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12

Dardi, Peter S., e R. I. Cukier. "Vibrational relaxation in fluids: A many body scattering formalism". Journal of Chemical Physics 86, n. 4 (15 febbraio 1987): 2264–75. http://dx.doi.org/10.1063/1.452125.

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13

Shiau, Shiue-Yuan, Ching-Hang Chien, Yia-Chung Chang e Monique Combescot. "Coboson many-body formalism for atom–dimer scattering length". Annals of Physics 400 (gennaio 2019): 366–82. http://dx.doi.org/10.1016/j.aop.2018.11.026.

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14

Nest, Maarten Van den. "A monomial matrix formalism to describe quantum many-body states". New Journal of Physics 13, n. 12 (1 dicembre 2011): 123004. http://dx.doi.org/10.1088/1367-2630/13/12/123004.

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15

Gomes, Rosana O., Cesar A. Z. Vasconcellos, Bruno Franzon, Stefan Schramm e Veronica Dexheimer. "Highly Magnetized Neutron Stars in a Many-body Forces Formalism". International Journal of Modern Physics: Conference Series 45 (gennaio 2017): 1760033. http://dx.doi.org/10.1142/s2010194517600333.

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In this work, we study the effects of different magnetic field configurations in neutron stars described by a many-body forces formalism (MBF model). The MBF model is a relativistic mean field formalism that takes into account many-body forces by means of a meson field dependence of the nuclear interaction coupling constants. We choose the best parametrization of the model that reproduces nuclear matter properties at saturation and also describes massive neutron stars. We assume matter to be in beta-equilibrium, charge neutral and at zero temperature. Magnetic fields are taken into account both in the equation of state and in the structure of the stars by the self-consistent solution of the Einstein-Maxwell equations. We assume a poloidal magnetic field distribution and calculate its effects on neutron stars, showing its influence on the gravitational mass and deformation of the stars.
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16

Saito, Susumu, S. B. Zhang, Steven G. Louie e Marvin L. Cohen. "New formalism for determining excitation spectra of many-body systems". Physical Review B 42, n. 12 (15 ottobre 1990): 7391–97. http://dx.doi.org/10.1103/physrevb.42.7391.

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17

BENHAR, OMAR. "MANY-BODY THEORY OF THE ELECTROWEAK NUCLEAR RESPONSE". International Journal of Modern Physics E 18, n. 05n06 (giugno 2009): 1282–301. http://dx.doi.org/10.1142/s0218301309013506.

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After a brief review of the theoretical description of nuclei based on nonrelativistic many-body theory and realistic hamiltonians, these lectures focus on its application to the analysis of the electroweak response. Special emphasis is given to electron-nucleus scattering, whose experimental study has provided a wealth of information on nuclear structure and dynamics, exposing the limitations of the shell model. The extension of the formalism to the case of neutrino-nucleus interactions, whose quantitative understanding is required to reduce the systematic uncertainty of neutrino oscillation experiments, is also discussed.
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18

Chakrabarti, Barnali. "Use of supersymmetric isospectral formalism to realistic quantum many-body problems". Pramana 73, n. 2 (agosto 2009): 405–16. http://dx.doi.org/10.1007/s12043-009-0132-6.

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19

Schuck, Peter. "Many-body Dyson equation approach to the seniority model of pairing". International Journal of Modern Physics E 29, n. 04 (aprile 2020): 2050023. http://dx.doi.org/10.1142/s0218301320500238.

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As is well known, the single level seniority model of pairing has been solved exactly, since long using angular momentum algebra. It is shown that it can also be solved using the Dyson equation of standard many-body theory. The formalism shows some interesting many-body aspects.
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20

Larder, B., D. O. Gericke, S. Richardson, P. Mabey, T. G. White e G. Gregori. "Fast nonadiabatic dynamics of many-body quantum systems". Science Advances 5, n. 11 (novembre 2019): eaaw1634. http://dx.doi.org/10.1126/sciadv.aaw1634.

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Modeling many-body quantum systems with strong interactions is one of the core challenges of modern physics. A range of methods has been developed to approach this task, each with its own idiosyncrasies, approximations, and realm of applicability. However, there remain many problems that are intractable for existing methods. In particular, many approaches face a huge computational barrier when modeling large numbers of coupled electrons and ions at finite temperature. Here, we address this shortfall with a new approach to modeling many-body quantum systems. On the basis of the Bohmian trajectory formalism, our new method treats the full particle dynamics with a considerable increase in computational speed. As a result, we are able to perform large-scale simulations of coupled electron-ion systems without using the adiabatic Born-Oppenheimer approximation.
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21

Wang, Huai-Yu. "Many-body theories for negative kinetic energy systems". Physics Essays 36, n. 2 (12 giugno 2023): 198–211. http://dx.doi.org/10.4006/0836-1398-36.2.198.

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In the author’s previous works, it is derived from the Dirac equation that particles can have negative kinetic energy (NKE) solutions, and they should be treated on an equal footing as the positive kinetic energy (PKE) solutions. More than one NKE particles can make up a stable system by means of interactions between them and such a system has necessarily negative temperature. Thus, many-body theories for NKE systems are desirable. In this work, the many-body theories for NKE systems are presented. They are Thomas‐Fermi method, Hohenberg‐Kohn theorem, Khon‐Sham self-consistent equations, and Hartree‐Fock self-consistent equations. They are established imitating the theories for PKE systems. In each theory, the formalism of both zero temperature and finite negative temperature is given. In order to verify that tunneling electrons are of NKE and real momentum, an experiment scenario is suggested that lets PKE electrons collide with tunneling electrons.
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22

Honet, Antoine, Luc Henrard e Vincent Meunier. "Semi-empirical many-body formalism of optical absorption in nanosystems and molecules". Carbon Trends 4 (luglio 2021): 100073. http://dx.doi.org/10.1016/j.cartre.2021.100073.

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23

Dardi, Peter S., e R. I. Cukier. "Vibrational relaxation in fluids: Calculations based on a many‐body scattering formalism". Journal of Chemical Physics 86, n. 12 (15 giugno 1987): 6893–907. http://dx.doi.org/10.1063/1.452389.

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24

Nakano, Masahiro, e Akira Hasegawa. "Relativistic many-body theory of finite nuclei and the Schwinger-Dyson formalism". Physical Review C 43, n. 2 (1 febbraio 1991): 618–33. http://dx.doi.org/10.1103/physrevc.43.618.

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25

Sellier, J. M., e I. Dimov. "On the simulation of indistinguishable fermions in the many-body Wigner formalism". Journal of Computational Physics 280 (gennaio 2015): 287–94. http://dx.doi.org/10.1016/j.jcp.2014.09.026.

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26

Hikami, Kazuhiro. "Dunkl Operator Formalism for Quantum Many-Body Problems Associated with Classical Root Systems". Journal of the Physical Society of Japan 65, n. 2 (15 febbraio 1996): 394–401. http://dx.doi.org/10.1143/jpsj.65.394.

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27

Moldoveanu, Manolescu e Gudmundsson. "Generalized Master Equation Approach to Time-Dependent Many-Body Transport". Entropy 21, n. 8 (25 luglio 2019): 731. http://dx.doi.org/10.3390/e21080731.

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We recall theoretical studies on transient transport through interacting mesoscopic systems.It is shown that a generalized master equation (GME) written and solved in terms of many-body statesprovides the suitable formal framework to capture both the effects of the Coulomb interaction andelectron–photon coupling due to a surrounding single-mode cavity. We outline the derivation of thisequation within the Nakajima–Zwanzig formalism and point out technical problems related to itsnumerical implementation for more realistic systems which can neither be described by non-interactingtwo-level models nor by a steady-stateMarkov–Lindblad equation. We first solve the GME for a latticemodel and discuss the dynamics of many-body states in a two-dimensional nanowire, the dynamicalonset of the current-current correlations in electrostatically coupled parallel quantum dots and transientthermoelectric properties. Secondly, we rely on a continuous model to get the Rabi oscillations ofthe photocurrent through a double-dot etched in a nanowire and embedded in a quantum cavity.A many-bodyMarkovian version of the GME for cavity-coupled systems is also presented.
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28

Ternovsky, V. B. "OPTIMIZED RELATIVISTIC MANY-BODY PERTURBATION THEORY IN CALCULATIONS OF ATOMIC SPECTRAL AND RADIATION CHARACTERISTICS: Eu ATOM". Photoelectronics, n. 30 (21 agosto 2022): 97–104. http://dx.doi.org/10.18524/0235-2435.2021.30.262864.

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The new formalism of the relativistic gauge-invariant perturbation theory (RMBPT-ODF) with the optimized Dirac-Fock approximation and a generalized energy approach is applied to the study of energy, radiation, and spectroscopic characteristics of a group of heavy atomic systems, in particular, energy levels and transition probabilities and oscillator strengths of the transitions 4f7(8S)6s2 8S7/2 4f7(8S)6s6p 8P5/2,7.2,9.2, 4f7(8S)6s7p 8P5/2,7\2, 4f7(8S)6s8p 8P9/2,7\2 in spectrum of the europium atom Eu I. It is shown that the required formalism, in comparison with the standard non-optimized relativistic Hartree-Fock and Dirac-Fock methods, allows obtaining more accurate data both on energies and amplitudes and probabilities of radiative transitions, which is due to the use of the optimized zero ODF approximation, a fairly complete and effective account of complex many-body exchange-correlation effects. The contribution due to the polarization of the core reaches 30% of the value of the oscillator strength; the value of the calibration-invariant contribution to the radiation width is fractions of a percent, in contrast to all existing methods of modern atomic spectroscopy, for which the contribution reaches 5-50%.
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29

RATH, ASWINI KUMAR, P. M. WALKER e C. R. PRAHARAJ. "SPECTROSCOPY OF HIGH-K BANDS IN THE A=180 REGION USING A QUANTUM MANY-BODY METHOD". International Journal of Modern Physics B 17, n. 28 (10 novembre 2003): 5215–19. http://dx.doi.org/10.1142/s0217979203020351.

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Using deformed Hartree–Fock and the angular momentum projection formalism, the nature of the first band crossings in the high spin structure of 182,184,186 Os , 181,183 Re and 181 Ta are studied. The degree of high-K mixing obtained in the calculation provides a microscopic understanding of the K-forbidden transitions from the high-K bandheads to the yrast states with low-K intrinsic structure.
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30

Nevzorov, Alexander A., e Jack H. Freed. "Direct-product formalism for calculating magnetic resonance signals in many-body systems of interacting spins". Journal of Chemical Physics 115, n. 6 (8 agosto 2001): 2401–15. http://dx.doi.org/10.1063/1.1382816.

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Takada, Yasutami, e Takafumi Kita. "Effective-potential expansion method for the many-body problem at finite temperatures. I. Basic formalism". Physical Review A 42, n. 6 (1 settembre 1990): 3242–50. http://dx.doi.org/10.1103/physreva.42.3242.

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32

Makushkina, M., O. Antoshkina e O. Khetselius. "HYPERFINE STRUCTURE PARAMETERS FOR COMPLEX ATOMS WITHIN RELATIVISTIC MANY-BODY PERTURBATION THEORY". Photoelectronics, n. 29 (28 dicembre 2021): 52–59. http://dx.doi.org/10.18524/0235-2435.2020.29.225493.

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The calculational results for the hyperfine structure (HFS) parameters for the Mn atom (levels of the configuration 3d64s) and the results of advanced calculating the HFS constants and nuclear quadrupole moment for the radium isotope are obtained on the basis of computing within the relativistic many-body perturbation theory formalism with a correct and effective taking into account the exchange-correlation, relativistic, nuclear and radiative corrections. Analysis of the data shows that an account of the interelectron correlation effects is crucial in the calculation of the hyperfine structure parameters. The fundamental reason of physically reasonable agreement between theory and experiment is connected with the correct taking into account the inter-electron correlation effects, nuclear (due to the finite size of a nucleus), relativistic and radiative corrections. The key difference between the results of the relativistic Hartree-Fock Dirac-Fock and many-body perturbation theory methods calculations is explained by using the different schemes of taking into account the inter-electron correlations as well as nuclear and radiative ones.
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Tanaka, Toshiaki. "Parasupersymmetry and N-fold supersymmetry in quantum many-body systems. I: General formalism and second order". Annals of Physics 322, n. 10 (ottobre 2007): 2350–73. http://dx.doi.org/10.1016/j.aop.2006.11.009.

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Bian, Wensheng, e Conghao Deng. "Direct solution of the many-body Schrödinger equation in the hyperspherical formalism: Formulation of theCFHH-GLFmethod". International Journal of Quantum Chemistry 51, n. 5 (15 agosto 1994): 285–91. http://dx.doi.org/10.1002/qua.560510504.

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Lubatsch, Andreas, e Regine Frank. "Quantum Many-Body Theory for Exciton-Polaritons in Semiconductor Mie Resonators in the Non-Equilibrium". Applied Sciences 10, n. 5 (6 marzo 2020): 1836. http://dx.doi.org/10.3390/app10051836.

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We implement externally excited ZnO Mie resonators in a framework of a generalized Hubbard Hamiltonian to investigate the lifetimes of excitons and exciton-polaritons out of thermodynamical equilibrium. Our results are derived by a Floquet-Keldysh-Green’s formalism with Dynamical Mean Field Theory (DMFT) and a second order iterative perturbation theory solver (IPT). We find that the Fano resonance which originates from coupling of the continuum of electronic density of states to the semiconductor Mie resonator yields polaritons with lifetimes between 0.6 ps and 1.45 ps. These results are compared to ZnO polariton lasers and to ZnO random lasers. We interpret the peaks of the exciton-polariton lifetimes in our results as a sign of gain narrowing which may lead to stable polariton lasing modes in the single excited ZnO Mie resonator. This form of gain may lead to polariton random lasing in an ensemble of ZnO Mie resonators in the non-equilibrium.
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Whitfield, Troy W., e Glenn J. Martyna. "A unified formalism for many-body polarization and dispersion: The quantum Drude model applied to fluid xenon". Chemical Physics Letters 424, n. 4-6 (giugno 2006): 409–13. http://dx.doi.org/10.1016/j.cplett.2006.04.035.

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Wang, Hainan, Yanling Lü, Jiaxin Chen, Yuzhi Song, Chengyuan Zhang e Yongqing Li. "An accurate many-body expansion potential energy surface for SiH2 (11 A′) using a switching function formalism". Physical Chemistry Chemical Physics 24, n. 13 (2022): 7759–67. http://dx.doi.org/10.1039/d1cp05432e.

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The two potential energy curves for H–H bond stretching when r1 = 25 a0 at the MRCI(Q)/AV(Q+d)Z level dissociate inconsistently. A switching function formalism has been utilized to warrant the correct behavior at the Si (1D) + H2 (X1Σ+g) dissociation channels.
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Palos, Etienne, Saswata Dasgupta, Eleftherios Lambros e Francesco Paesani. "Data-driven many-body potentials from density functional theory for aqueous phase chemistry". Chemical Physics Reviews 4, n. 1 (marzo 2023): 011301. http://dx.doi.org/10.1063/5.0129613.

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Density functional theory (DFT) has been applied to modeling molecular interactions in water for over three decades. The ubiquity of water in chemical and biological processes demands a unified understanding of its physics, from the single molecule to the thermodynamic limit and everything in between. Recent advances in the development of data-driven and machine-learning potentials have accelerated simulation of water and aqueous systems with DFT accuracy. However, anomalous properties of water in the condensed phase, where a rigorous treatment of both local and non-local many-body (MB) interactions is in order, are often unsatisfactory or partially missing in DFT models of water. In this review, we discuss the modeling of water and aqueous systems based on DFT and provide a comprehensive description of a general theoretical/computational framework for the development of data-driven many-body potentials from DFT reference data. This framework, coined MB-DFT, readily enables efficient many-body molecular dynamics (MD) simulations of small molecules, in both gas and condensed phases, while preserving the accuracy of the underlying DFT model. Theoretical considerations are emphasized, including the role that the delocalization error plays in MB-DFT potentials of water and the possibility to elevate DFT and MB-DFT to near-chemical-accuracy through a density-corrected formalism. The development of the MB-DFT framework is described in detail, along with its application in MB-MD simulations and recent extension to the modeling of reactive processes in solution within a quantum mechanics/MB molecular mechanics (QM/MB-MM) scheme, using water as a prototypical solvent. Finally, we identify open challenges and discuss future directions for MB-DFT and QM/MB-MM simulations in condensed phases.
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39

Balaž, Antun, Ivana Vidanović, Aleksandar Bogojević, Aleksandar Belić e Axel Pelster. "Fast converging path integrals for time-dependent potentials: II. Generalization to many-body systems and real-time formalism". Journal of Statistical Mechanics: Theory and Experiment 2011, n. 03 (4 marzo 2011): P03005. http://dx.doi.org/10.1088/1742-5468/2011/03/p03005.

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40

Li, Jing, Gabriele D’Avino, Ivan Duchemin, David Beljonne e Xavier Blase. "Combining the Many-Body GW Formalism with Classical Polarizable Models: Insights on the Electronic Structure of Molecular Solids". Journal of Physical Chemistry Letters 7, n. 14 (12 luglio 2016): 2814–20. http://dx.doi.org/10.1021/acs.jpclett.6b01302.

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41

Campana, L. S., A. Cavallo, L. De Cesare, U. Esposito e A. Naddeo. "Thermodynamics of the Classical Planar Ferromagnet Close to the Zero-Temperature Critical Point: A Many-Body Approach". Advances in Condensed Matter Physics 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/619513.

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We explore the low-temperature thermodynamic properties and crossovers of ad-dimensional classical planar Heisenberg ferromagnet in a longitudinal magnetic field close to its field-induced zero-temperature critical point by employing the two-time Green’s function formalism in classical statistical mechanics. By means of a classical Callen-like method for the magnetization and the Tyablikov-like decoupling procedure, we obtain, for anyd, a low-temperature critical scenario which is quite similar to the one found for the quantum counterpart. Remarkably, ford>2the discrimination between the two cases is found to be related to the different values of the shift exponent which governs the behavior of the critical line in the vicinity of the zero-temperature critical point. The observation of different values of the shift-exponent and of the related critical exponents along thermodynamic paths within the typical V-shaped region in the phase diagram may be interpreted as a signature of emerging quantum critical fluctuations.
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42

Hertl, Nils, Alexander Kandratsenka e Alec M. Wodtke. "Effective medium theory for bcc metals: electronically non-adiabatic H atom scattering in full dimensions". Physical Chemistry Chemical Physics 24, n. 15 (2022): 8738–48. http://dx.doi.org/10.1039/d2cp00087c.

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43

Soler-Polo, Diego, José Ortega e Fernando Flores. "A local-orbital density functional formalism for a many-body atomic Hamiltonian: Hubbard–Hund’s coupling and DFT + U functional". Journal of Physics: Condensed Matter 33, n. 42 (12 agosto 2021): 425604. http://dx.doi.org/10.1088/1361-648x/ac1155.

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44

Mullins, Nicki, Mauricio Hippert, Lorenzo Gavassino e Jorge Noronha. "A new approach to stochastic relativistic fluid dynamics from information flow". EPJ Web of Conferences 296 (2024): 13001. http://dx.doi.org/10.1051/epjconf/202429613001.

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We present a new general formalism for introducing thermal fluctuations in relativistic hydrodynamics, which incorporates recent developments on the causality and stability of relativistic hydrodynamic theories. Our approach is based on the information current, which measures the net amount of information carried by perturbations around equilibrium in a relativistic many-body system. The resulting noise correlators are guaranteed to be observer-independent for thermodynamically stable models. We obtain an effective action within our formalism and discuss its properties.
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45

OSTERLOH, ANDREAS. "ENTANGLEMENT AND ITS MULTIPARTITE EXTENSIONS". International Journal of Modern Physics B 27, n. 01n03 (26 novembre 2012): 1345018. http://dx.doi.org/10.1142/s0217979213450185.

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The aspects of many particle systems, as far as their entanglement is concerned, is highlighted. To this end we briefly review the bipartite measures of entanglement and the entanglement of pairs both for systems of distinguishable and indistinguishable particles. The analysis of these quantities in macroscopic systems shows that close to quantum phase transitions, the entanglement of many particles typically dominates that of pairs. This leads to an analysis of a method to construct many-body entanglement measures. SL-invariant measures are a generalization to quantities as the concurrence, and can be obtained with a formalism containing two (actually three) orthogonal antilinear operators. The main drawback of this antilinear framework, namely to measure these quantities in the experiment, is resolved by a formula linking the antilinear formalism to an equivalent linear framework.
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46

Pang, Jin-Yi. "Three-particle system in a finite volume: formalism, quantization condition, spectrum and energy shift". EPJ Web of Conferences 241 (2020): 02005. http://dx.doi.org/10.1051/epjconf/202024102005.

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Lattice QCD calculations provide an ab initio access to hadronic process. These calculations are usu ally performed in a small cubic volume with periodic boundary conditions. The infinite volume extrapolations for three-body systems are indispensable to understand many systems of high current interest. We derive the three-body quantization condition in a finite volume using an effective field theory in the particle-dimer picture. Our work shows a powerful and transparent method to read off three-body physical observables from lattice simulations. In this paper, we review the formalism, quantization condition, spectrum analysis and energy shifts calculation both for 3-body bound states and scattering states.
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47

Yue, Shuwen, Marc Riera, Raja Ghosh, Athanassios Z. Panagiotopoulos e Francesco Paesani. "Transferability of data-driven, many-body models for CO2 simulations in the vapor and liquid phases". Journal of Chemical Physics 156, n. 10 (14 marzo 2022): 104503. http://dx.doi.org/10.1063/5.0080061.

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Extending on the previous work by Riera et al. [J. Chem. Theory Comput. 16, 2246–2257 (2020)], we introduce a second generation family of data-driven many-body MB-nrg models for CO2 and systematically assess how the strength and anisotropy of the CO2–CO2 interactions affect the models’ ability to predict vapor, liquid, and vapor–liquid equilibrium properties. Building upon the many-body expansion formalism, we construct a series of MB-nrg models by fitting one-body and two-body reference energies calculated at the coupled cluster level of theory for large monomer and dimer training sets. Advancing from the first generation models, we employ the charge model 5 scheme to determine the atomic charges and systematically scale the two-body energies to obtain more accurate descriptions of vapor, liquid, and vapor–liquid equilibrium properties. Challenges in model construction arise due to the anisotropic nature and small magnitude of the interaction energies in CO2, calling for the necessity of highly accurate descriptions of the multidimensional energy landscape of liquid CO2. These findings emphasize the key role played by the training set quality in the development of transferable, data-driven models, which, accurately representing high-dimensional many-body effects, can enable predictive computer simulations of molecular fluids across the entire phase diagram.
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48

Al-Maaitah, Ibtisam F. "Total and Viscosity Cross Sections for Krypton Gas at Boiling Point". Applied Physics Research 11, n. 2 (30 marzo 2019): 88. http://dx.doi.org/10.5539/apr.v11n2p88.

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Abstract (sommario):
We have calculated total and viscosity cross sections for krypton gas at boiling point by using a Galitskii-Migdal-Feynman (GMF) formalism which is essentially an independent-pair model ‘dressed’ by a many-body medium. The interaction potential in our work is theHartree-Fock dispersion (HFD-B) potential.
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49

BERAKDAR, J. "SCATTERING PATH FORMALISM FOR THE PROPAGATION OF INTERACTING COMPOUNDS IN ORDERED AND DISORDERED MATERIALS". Surface Review and Letters 07, n. 03 (giugno 2000): 205–10. http://dx.doi.org/10.1142/s0218625x00000257.

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Abstract (sommario):
This study presents a theoretical framework for the propagation of a compound consisting of N interacting particles in a multicenter potential. A novel Green operator approach is proposed that disentangles the geometrical and dynamical properties of the scatterers from the internal evolution of the projectile compound. Furthermore, the transition operator for the scattering from the multicenter potential is expanded in terms of many-body scattering path operators, which in turn are expressed in terms of single site transition operators that are amenable to computations. To deduce the correlated many-body Green operator of the scattering compound, a cumulative method is designed that reduces the problem to the evaluation of Green operators of systems with a reduced number of interacting particles. This is particularly useful for efficient calculations and encompasses the usual perturbative approaches.
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50

Surján, Péter R., Dóra Kőhalmi e Ágnes Szabados. "A note on perturbation-adapted perturbation theory". Journal of Chemical Physics 156, n. 11 (21 marzo 2022): 116102. http://dx.doi.org/10.1063/5.0085350.

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Abstract (sommario):
The partitioning introduced recently by Knowles [J. Chem. Phys. 156, 011101 (2022)] is analyzed and its connections with the Adams partitioning and the Davidson–Kapuy partitioning are discussed. Davidson’s partitioning is reformulated using the second quantized formalism. A relation is pointed out between the Knowles condition for the many-body perturbation theory zero order Hamiltonian and the CEPA0 equations.
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