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It is known that ab initio molecular dynamics based on the electron ground state eigenvalue can be used to approximate quantum observables in the canonical ensemble when the temperature is low compared to the first electron eigenvalue gap.…

Mathematical Physics · Physics 2019-06-20 Aku Kammonen , Petr Plechac , Mattias Sandberg , Anders Szepessy

Mean-field molecular dynamics based on path integrals is used to approximate canonical quantum observables for particle systems consisting of nuclei and electrons. A computational bottleneck is the sampling from the Gibbs density of the…

Numerical Analysis · Mathematics 2023-11-30 Xin Huang , Petr Plechac , Mattias Sandberg , Anders Szepessy

The relationship between the mean-field approximations in various interacting models of statistical physics and measures of classical and quantum correlations is explored. We present a method that allows us to bound the total amount of…

Quantum Physics · Physics 2009-11-10 Vlatko Vedral

The density operator for a quantum system in thermal equilibrium with its environment depends on Planck's constant, as well as the temperature. At high temperatures, the Weyl representation, that is, the thermal Wigner function, becomes…

Quantum Physics · Physics 2021-06-30 Alfredo M. Ozorio de Almeida , Gert-Ludwig Ingold , Olivier Brodier

The mean field approximation is used to investigate the general features of the dynamics of a two-level atom in a ferromagnetic lattice close to the Curie temperature. Various analytical and numerical results are obtained. We first…

Quantum Physics · Physics 2023-07-07 Yamen Hamdouni

We investigate a mean-field approach to a quantum brownian particle interacting with a quantum thermal bath at temperature $T$, and subjected to a non-linear potential. An exact, partially classical description of quantum brownian motion is…

Statistical Mechanics · Physics 2009-11-07 A. E. Allahverdyan , R. Balian , Th. M. Nieuwenhuizen

The electromagnetic field is canonically quantized in the presence of a linear, dispersive and dissipative medium that is in uniform motion. Specifically we calculate the change in the normal modes of the coupled matter-field system and…

Quantum Physics · Physics 2012-08-21 S. A. R. Horsley

The effective independent-particle (mean-field) approximation of the Hubbard Hamiltonian is described in a many-body basis to develop a formal comparison with the exact diagonalization of the full Hubbard model, using small atomic chain as…

Strongly Correlated Electrons · Physics 2023-08-09 Antoine Honet , Luc Henrard , Vincent Meunier

The Weyl-Wigner representations for canonical thermal equilibrium quantum states are obtained for the whole class of quadratic Hamiltonians through a Wick rotation of the Weyl-Wigner symbols of Heisenberg and metaplectic operators. The…

Quantum Physics · Physics 2021-01-13 F. Nicacio

In this letter, by an approach that employs Weyl symbols for operators, a semiclassical theory is developed for the offdiagonal function in the eigenstate thermalization hypothesis, which is for offdiagonal elements…

Quantum Physics · Physics 2025-09-30 Xiao Wang , Wen-ge Wang

A mean-field model to describe electron transfer processes in ion-molecule collisions at the $\hbar =0$ level is presented and applied to collisions involving water and ammonia molecules. Multicenter model potentials account for the…

Atomic Physics · Physics 2023-11-21 Alba Jorge , Marko Horbatsch , Tom Kirchner

We assess the accuracy of finite-temperature mean-field theory using as a standard the Hamiltonian and model space of the shell model Monte Carlo calculations. Two examples are considered: the nucleus $^{162}$Dy, representing a heavy…

Nuclear Theory · Physics 2016-05-04 Y. Alhassid , G. F. Bertsch , C. N. Gilbreth , H. Nakada

In the second part of this paper in micro canonical ensemble the new numerical approach for consideration of quantum dynamics and calculations of the average values of quantum operators and time correlation functions in the Wigner…

Quantum Physics · Physics 2009-10-31 V. Filinov , Yu. Lozovik , A. Filinov , I. Zacharov , A. Oparin

The present study regards the zeroth order mean field approximation of a dipole-type interaction model, which is analytically solved in the canonical and microcanonical ensembles. After writing the canonical partition function, the free and…

Statistical Mechanics · Physics 2018-03-16 Atenas Boris , Curilef Sergio

The knowledge of quantum phase flow induced under the Weyl's association rule by the evolution of Heisenberg operators of canonical coordinates and momenta allows to find the evolution of symbols of generic Heisenberg operators. The quantum…

Quantum Physics · Physics 2016-09-08 M. I. Krivoruchenko , Amand Faessler

We present a non-perturbative, mean-field theory for the Fermi-Pasta-Ulam-Tsingou model with quartic interaction, capturing the quasiperiodic features shown by the system at all energies in the thermodynamic limit. Starting from the true…

Statistical Mechanics · Physics 2025-12-02 Antonio Ponno , Giacomo Gradenigo , Marco Baldovin , Angelo Vulpiani

The relativistic mean-field model, augmented with three types of center-of-mass corrections and two types of rotational corrections, is employed to investigate the ground-state properties of helium, beryllium, and carbon isotopes. The…

Nuclear Theory · Physics 2024-01-08 Yu-Ting Rong

The Moyal--Weyl description of quantum mechanics provides a comprehensive phase space representation of dynamics. The Weyl symbol image of the Heisenberg picture evolution operator is regular in $\hbar$. Its semiclassical expansion…

High Energy Physics - Theory · Physics 2015-06-26 T. A. Osborn , F. H. Molzahn

The dynamical mean-field concept of approximating an unsolvable many-body problem in terms of the solution of an auxiliary quantum impurity problem, introduced to study bulk materials with a continuous energy spectrum, is here extended to…

Strongly Correlated Electrons · Physics 2011-03-04 Nan Lin , C. A. Marianetti , Andrew J. Millis , David R. Reichman

We consider a one-dimensional optical lattice of three-dimensional Harmonic Oscillators which are loaded with neutral fermionic atoms trapped into two hyperfine states. By means of a standard variational coherent-state procedure, we derive…

Other Condensed Matter · Physics 2009-11-11 F. P. Massel , V. Penna
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