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We present a method which extends Monte Carlo studies to situations that require a large dynamic range in particle number. The underlying idea is that, in order to calculate the collisional evolution of a system, some particle interactions…

Astrophysics · Physics 2009-11-13 C. W. Ormel , M. Spaans

We present computer simulations of a dynamic Monte Carlo algorithm for polymer chains on the FCC lattice which takes explicitly into account the possibility to overcome topological constraints by controlling the rate at which nearby polymer…

Soft Condensed Matter · Physics 2021-12-01 Mattia Alberto Ubertini , Angelo Rosa

The quantum theory of the Friedmann cosmological model with dust and cosmological constant ($\Lambda$) is not exactly solvable analytically. We apply Path Integral Monte Carlo (PIMC) techniques to study its quantum dynamics using the…

General Relativity and Quantum Cosmology · Physics 2020-09-10 Masooma Ali , Syed Moeez Hassan , Viqar Husain

We introduce modifications to Monte Carlo simulations of the Feynman path integral that improve sampling of localised interactions. The new algorithms generate trajectories in simple background potentials designed to concentrate them about…

Quantum Physics · Physics 2025-08-06 Ivan Ahumada , James P. Edwards

We employ constrained path Auxiliary Field Quantum Monte Carlo (AFQMC) in the pursuit of studying physical nuclear systems using a lattice formalism. Since AFQMC has been widely used in the study of condensed-matter systems such as the…

Nuclear Theory · Physics 2024-07-16 Ryan Curry , Jayani Dissanayake , Stefano Gandolfi , Alexandros Gezerlis

The dynamical properties of nuclei, carried by the concept of phonon quasiparticles (QP), are central to the field of condensed matter. While the harmonic approximation can reproduce a number of properties observed in real crystals, the…

Materials Science · Physics 2023-12-19 Aloïs Castellano , J. P. Alvarinhas Batista , Matthieu J. Verstraete

A rigourous Monte Carlo method for protein folding simulation on lattice model is introduced. We show that a parameter which can be seen as the rigidity of the conformations has to be introduced in order to satisfy the detailed balance…

Soft Condensed Matter · Physics 2007-05-23 Olivier Collet

We apply Quantum Monte Carlo technique to analyze the non equlibrium state of a trapped 1d Bose gas just after the quenching of the confining potential. As a matter of fact we solve the time dependent Schroedinger equation for the system of…

Quantum Gases · Physics 2017-05-23 Sumita Datta , Maxim Olshanii

Among lattice configurations of densely packed hard ellipses, Monte Carlo simulations are used to identify the so-called parallel and diagonal lattices as the two favourable states. The free energies of these two states are computed for…

Soft Condensed Matter · Physics 2024-03-27 Susanne Wagner , Gerhard Kahl , Roman Melnyk , Andrij Baumketner

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

In these lectures we provide a short introduction to the Monte Carlo integration method and its applications. We show how the origin of ultraviolet divergences if Field Theories is in the undefined formal product of distributions and how…

High Energy Physics - Lattice · Physics 2007-05-23 Massimo Di Pierro

The recently developed density matrix quantum Monte Carlo (DMQMC) algorithm stochastically samples the N -body thermal density matrix and hence provides access to exact properties of many-particle quantum systems at arbitrary temperatures.…

Strongly Correlated Electrons · Physics 2015-10-15 Fionn D. Malone , N. S. Blunt , James J. Shepherd , D. K. K. Lee , J. S. Spencer , W. M. C. Foulkes

Neutrinos have an unique quantum feature as flavor conversions. Recent studies suggested that collective neutrino oscillations play important roles in high-energy astrophysical phenomena. Quantum kinetic equation (QKE) is capable of…

High Energy Astrophysical Phenomena · Physics 2021-12-15 Chinami Kato , Hiroki Nagakura , Taiki Morinaga

An approach to approximate evaluation of the continuum Feynman path integrals is developed for the study of quantum fluctuations of particles and fields in Euclidean time-space. The paths are described by sum of Gauss functions and are…

Quantum Physics · Physics 2012-06-20 Takayasu Sekihara

We introduce and discuss Monte Carlo methods in quantum field theories. Methods of independent Monte Carlo, such as random sampling and importance sampling, and methods of dependent Monte Carlo, such as Metropolis sampling and Hamiltonian…

High Energy Physics - Theory · Physics 2020-12-01 Anosh Joseph

In this paper we present a Path Integral Monte Carlo (PIMC) simulation of the orthorhombic phase of crystalline polyethylene, using an explicit atom force field with unconstrained bond lengths and angles. This work represents a quantum…

Materials Science · Physics 2009-10-30 R. Martonak , W. Paul , K. Binder

Certain models with purely repulsive pair interactions can form cluster crystals with multiply-occupied lattice sites. Simulating these models' equilibrium properties is, however, quite challenging. Here, we develop an expanded…

Soft Condensed Matter · Physics 2015-03-20 Kai Zhang , Patrick Charbonneau

An efficient Quantum Monte Carlo algorithm for the simulation of bosonic systems on a lattice in a grand canonical ensemble is proposed. It is based on the mapping of bosonic models to the spin models in the limit of the infinite total spin…

Statistical Mechanics · Physics 2007-05-23 Jurij Smakov , Kenji Harada , Naoki Kawashima

Unbiased stochastic sampling of the one- and two-body reduced density matrices is achieved in full configuration interaction quantum Monte Carlo with the introduction of a second, "replica" ensemble of walkers, whose population evolves in…

Computational Physics · Physics 2015-09-02 Robert E. Thomas , Daniel Opalka , Catherine Overy , Peter J. Knowles , Ali Alavi , George H. Booth

Quantum Monte Carlo (QMC) methods can very accurately compute ground state properties of quantum systems. We applied these methods to a system of boson hard spheres to get exact, infinite system size results for the ground state at several…

Computational Physics · Physics 2016-09-08 Mark Dewing