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We construct a new mean-field theory for quantum (spin-1/2) Heisenberg antiferromagnet in one (1D) and two (2D) dimensions using a Hartree-Fock decoupling of the four-point correlation functions. We show that the solution to the…

Mesoscale and Nanoscale Physics · Physics 2018-06-13 A. Werth , P. Kopietz , O. Tsyplyatyev

In this work, we propose a path integral-inspired formalism for computing the quantum thermal expectation values of spin systems, when subject to magnetic fields that can be time-dependent and can accommodate the presence of Heisenberg…

Quantum Physics · Physics 2025-06-18 Thomas Nussle , Stam Nicolis , Iason Sofos , Joseph Barker

How a system initially at infinite temperature responds when suddenly placed at finite temperatures is a way to check the existence of phase transitions. It has been shown in [R. da Silva, IJMPC 2023] that phase transitions are imprinted in…

Equilibrium properties of long-range interacting systems on lattices are investigated. There was a conjecture by Cannas et. al. that the mean-field theory is exact for spin systems with non-additive long-range interactions. This is called…

Statistical Mechanics · Physics 2011-10-31 Takashi Mori

We present an inhomogeneous dynamical mean field theory (I-DMFT) that is suitable to investigate electron-lattice interactions in non-translationally invariant and/or inhomogeneous systems. The presented approach, whose only assumption is…

Materials Science · Physics 2018-10-26 Kevin-Davis Richler , Simone Fratini , Sergio Ciuchi , Didier Mayou

The competition between Hamiltonian and Lindblad dynamics in quantum systems give rise to non-equillibrium phenomena with no counter part in conventional condensed matter physics. In this paper, we investigate this interplay of dynamics in…

Quantum Physics · Physics 2024-01-31 Irfan A Dar , Faisal Farooq , Junaid Majeed , Mehboob Rashid , Sheikh Irfan , Muzaffar Qadir Lone

Universality is a crucial concept in modern physics, allowing us to capture the essential features of a system's behavior using a small set of parameters. In this work, we unveil universal spin relaxation dynamics in anisotropic random…

Strongly Correlated Electrons · Physics 2025-04-09 Tian-Gang Zhou , Wei Zheng , Pengfei Zhang

A mean-field theory of differential rotation in a density stratified turbulent convection has been developed. This theory is based on a combined effect of the turbulent heat flux and anisotropy of turbulent convection on the Reynolds…

Fluid Dynamics · Physics 2020-04-17 I. Rogachevskii , N. Kleeorin

We establish a way to handle main collective fluctuations in correlated quantum systems based on a Fluctuation Local Field concept. This technique goes beyond standard mean-field approaches, such as Hartree-Fock and dynamical mean-field…

Strongly Correlated Electrons · Physics 2021-01-04 Alexey N. Rubtsov , Evgeny A. Stepanov , Alexander I. Lichtenstein

The dynamical mean field theory (DMFT), which is successful in the study of strongly correlated fermions, was recently extended to boson systems [Phys. Rev. B {\textbf 77}, 235106 (2008)]. In this paper, we employ the bosonic DMFT to study…

Quantum Gases · Physics 2015-05-13 Wen-Jun Hu , Ning-Hua Tong

Using an adaptation of Schwinger boson mean field theory (SBMFT) for nonuniform systems, we study the nature of low-energy spin excitations on the square and Bethe lattice at their percolation threshold. The optimal SBMFT parameters are…

Strongly Correlated Electrons · Physics 2015-08-04 Shivam Ghosh , Hitesh J. Changlani , Christopher L. Henley

A stochastic differential equation that describes the dynamics of single-domain magnetic particles at any temperature is derived using a classical formalism. The deterministic terms recover existing theory and the stochastic process takes…

Mesoscale and Nanoscale Physics · Physics 2015-10-28 Michail Tzoufras , Gregory J. Parker , Michael K. Grobis

Nonlocal correlations play an essential role in correlated electron systems, especially in the vicinity of phase transitions and crossovers, where two-particle correlation functions display a distinct momentum dependence. In nonequilibrium…

Strongly Correlated Electrons · Physics 2023-06-29 Olivier Simard , Philipp Werner

We show that an high temperature expansion at fixed order parameter can be derived for the quantum Ising model. The basic point is to consider a statistical generating functional associated to the local spin state. The probability at…

Statistical Mechanics · Physics 2007-05-23 F. De Pasquale , S. M. Giampaolo

We develop a nanoscale dynamical mean-field theory (nano-DMFT) to deal with strong Coulomb interaction effects in physical systems that are intermediate in size between atoms and bulk materials, taking into account the tunneling into nearby…

Strongly Correlated Electrons · Physics 2009-11-13 Serge Florens

A dynamic mean field theory is developed for finite state and action Bayesian reinforcement learning in the large state space limit. In an analogy with statistical physics, the Bellman equation is studied as a disordered dynamical system;…

Machine Learning · Statistics 2023-07-13 George Stamatescu

A rigorous derivation of macroscopic spin-wave equations is demonstrated. We introduce a macroscopic mean-field limit and derive the so-called Landau-Lifshitz equations for spin waves. We first discuss the ferromagnetic Heisenberg model at…

Statistical Mechanics · Physics 2009-10-31 M Moser , A Prets , W L Spitzer

Simple elastic models of spin-crossover compounds are known empirically to exhibit classical critical behavior. We demonstrate how the long-ranged interactions responsible for this behavior arise naturally upon integrating out mechanical…

Statistical Mechanics · Physics 2020-07-15 Layne B. Frechette , Christoph Dellago , Phillip L. Geissler

The concept of electronic correlations plays an important role in modern condensed matter physics. It refers to interaction effects which cannot be explained within a static mean-field picture as provided by Hartree-Fock theory. Electronic…

Strongly Correlated Electrons · Physics 2015-03-17 Dieter Vollhardt

We use a recently developed bosonic mean-field theory (MFT) to study the ordered ground states of frustrated Heisenberg antiferromagnets (FHAFM) in two dimensions. We emphasize the role of condensates in satisfying the MF variational…

Condensed Matter · Physics 2007-05-23 R. Chitra , Sumathi Rao , Diptiman Sen