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We carry out highly accurate \emph{ab initio} path integral Monte Carlo (PIMC) simulations to directly estimate the free energy of various warm dense matter systems including the uniform electron gas and hydrogen without any nodal…

Quantum Gases · Physics 2024-07-02 Tobias Dornheim , Zhandos Moldabekov , Sebastian Schwalbe , Jan Vorberger

Accurate thermodynamic simulations of correlated fermions using path integral Monte Carlo (PIMC) methods are of paramount importance for many applications such as the description of ultracold atoms, electrons in quantum dots, and warm-dense…

Computational Physics · Physics 2021-02-03 Tobias Dornheim , Michele Invernizzi , Jan Vorberger , Barak Hirshberg

We apply a diagrammatic Monte Carlo method to the problem of an impurity interacting resonantly with a homogeneous Fermi bath for a quasi-two-dimensional setup. Notwithstanding the series divergence, we can show numerically that the three…

Quantum Gases · Physics 2014-09-18 Peter Kroiss , Lode Pollet

Microscopic processes on surfaces such as adsorption, desorption, diffusion and reaction of interacting particles can be simulated using kinetic Monte Carlo (kMC) algorithms. Even though kMC methods are accurate, they are computationally…

Mathematical Physics · Physics 2013-12-24 Yannis Pantazis , Markos Katsoulakis

We present a quantum Monte Carlo method which allows calculations on many-fermion systems at finite temperatures without any sign decay. This enables simulations of the grand-canonical ensemble at large system sizes and low temperatures.…

Condensed Matter · Physics 2009-10-31 Shiwei Zhang

We propose an efficient Markov Chain Monte Carlo method for sampling equilibrium distributions for stochastic lattice models, capable of handling correctly long and short-range particle interactions. The proposed method is a Metropolis-type…

Numerical Analysis · Mathematics 2010-06-21 Evangelia Kalligiannaki , Markos A. Katsoulakis , Petr Plechac

The study of matter at extreme densities and temperatures as they occur in astrophysical objects and state-of-the art experiments with high-intensity lasers is of high current interest for many applications. While no overarching theory for…

An improved real-time quantum Monte Carlo procedure is presented and applied to describe the electronic transfer dynamics along molecular chains. The model consists of discrete electronic sites coupled to a thermal environment which is…

Chemical Physics · Physics 2009-11-10 L. Muehlbacher , J. Ankerhold , C. Escher

We construct a quantum Monte Carlo algorithm for interacting fermions using the two-body density as the fundamental quantity. The central idea is mapping the interacting fermionic system onto an auxiliary system of interacting bosons. The…

Statistical Mechanics · Physics 2008-07-30 Balazs Hetenyi , L. Brualla , S. Fantoni

We introduce regular series expansion for weakly- and moderately-correlated fermionic systems, based on Fluctuating Local Field approach. The method relies on the explicit account of leading fluctuating mode(s) and is therefore suitable for…

Strongly Correlated Electrons · Physics 2024-12-25 Ya. S. Lyakhova , S. D. Semenov , A. I. Lichtenstein , A. N. Rubtsov

One-dimensional multi-component Fermi or Bose systems with strong zero-range interactions can be described in terms of local exchange coefficients and mapping the problem into a spin model is thus possible. For arbitrary external confining…

Monte Carlo simulations are a powerful tool to investigate the thermodynamic properties of atomic systems. In practice however, sampling of the complete configuration space is often hindered by high energy barriers between different regions…

Statistical Mechanics · Physics 2020-05-04 Jonas A. Finkler , Stefan Goedecker

We propose a new Monte Carlo method for efficiently sampling trajectories with fixed initial and final conditions in a system with discrete degrees of freedom. The method can be applied to any stochastic process with local interactions,…

Statistical Mechanics · Physics 2012-03-30 Thierry Mora , Aleksandra M. Walczak , Francesco Zamponi

We demonstrate the applicability of a recently proposed multiscale thermalization algorithm to two-color quantum chromodynamics (QCD) with two mass-degenerate fermion flavors. The algorithm involves refining an ensemble of gauge…

High Energy Physics - Lattice · Physics 2016-12-06 William Detmold , Michael G. Endres

Monte Carlo simulations are performed to study the in-plane transport of spin-polarized electrons in III-V semiconductor quantum wells. The density matrix description of the spin polarization is incorporated in the simulation algorithm. The…

Mesoscale and Nanoscale Physics · Physics 2010-09-22 Min Shen , Semion Saikin , Ming-C. Cheng , Vladimir Privman

Precise knowledge of the static density response function (SDRF) of the uniform electron gas (UEG) serves as key input for numerous applications, most importantly for density functional theory beyond generalized gradient approximations.…

Strongly Correlated Electrons · Physics 2017-11-06 Simon Groth , Tobias Dornheim , Michael Bonitz

We present a promising coarse-graining strategy for linking micro- and mesoscales of soft matter systems. The approach is based on effective pairwise interaction potentials obtained from detailed atomistic molecular dynamics (MD)…

Soft Condensed Matter · Physics 2007-05-23 A. P. Lyubartsev , M. Karttunen , I. Vattulainen , A. Laaksonen

The Wigner formulation of quantum mechanics is used to derive a new path integral representation of quantum density of states. A path integral Monte Carlo approach is developed for the numerical investigation of density of states, internal…

Computational Physics · Physics 2023-09-12 V. Filinov , P. Levashov , A. Larkin

We study through a computer experiment, using the restricted path integral Monte Carlo method, a one-component fermion plasma on a sphere at finite, non-zero, temperature. We extract thermodynamic properties like the kinetic and internal…

Statistical Mechanics · Physics 2019-04-08 Riccardo Fantoni

Density matrix quantum Monte Carlo (DMQMC) is used to sample exact-on-average $N$-body density matrices for uniform electron gas systems of up to 10$^{124}$ matrix elements via a stochastic solution of the Bloch equation. The results of…

Strongly Correlated Electrons · Physics 2016-09-14 Fionn D. Malone , N. S. Blunt , Ethan W. Brown , D. K. K. Lee , J. S. Spencer , W. M. C. Foulkes , James J. Shepherd