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A diffusion Monte Carlo algorithm is introduced that can determine the correct nodal structure of the wave function of a few-fermion system and its ground-state energy without an uncontrolled bias. This is achieved by confining signed…

Computational Physics · Physics 2020-02-05 Alexander A. Kunitsa , So Hirata

Neural Network-based Quantum Monte Carlo (NNQMC), an emerging method for solving many-body quantum systems with high accuracy, has been limitedly applied to small systems due to demanding computation requirements. In this work, we introduce…

Molecular dynamics simulations using semi-empirical potentials are examined for three liquids to check the reliability of reverse Monte Carlo (RMC) simulations to reproduce atomic configurations when only total pair correlation functions…

Materials Science · Physics 2018-10-22 R. Ashcraft , K. F. Kelton

We have used diffusion Monte Carlo (DMC) simulations to calculate the energy barrier for H$_2$ dissociation on the Mg(0001) surface. The calculations employ pseudopotentials and systematically improvable B-spline basis sets to expand the…

Materials Science · Physics 2009-11-13 M. Pozzo , D. Alfe`

In many applications, such as plasma edge simulation of a nuclear fusion reactor, a coupled PDE/kinetic description is required, which is usually solved with a coupled finite-volume/Monte-Carlo method. Different procedures have been…

Numerical Analysis · Mathematics 2020-12-17 Bert Mortier , Martine Baelmans , Giovanni Samaey

In this paper we develop a direct simulation Monte Carlo (DSMC) method for simulating highly nonequilibrium dynamics of nearly degenerate ultra-cold gases. We show that our method can simulate the high-energy collision of two thermal clouds…

Quantum Gases · Physics 2012-10-16 A. C. J. Wade , D. Baillie , P. B. Blakie

In Molecular Dynamics (MD), the forces applied to atoms derive from potentials which describe the energy of bonds, valence angles, torsion angles, and Lennard-Jones interactions of which molecules are made. These de finitions are classic;…

Statistical Mechanics · Physics 2014-01-07 Bernard Monasse , Frédéric Boussinot

Diagrammatic expansions are a central tool for treating correlated electron systems. At thermal equilibrium, they are most naturally defined within the Matsubara formalism. However, extracting any dynamic response function from a Matsubara…

Strongly Correlated Electrons · Physics 2020-02-19 Jaksa Vucicevic , Michel Ferrero

Variational methods are used to calculate structural and thermodynamical properties of a titrating polyelectrolyte in a discrete representation. The Coulomb interactions are emulated by harmonic repulsive forces, the force constants being…

chem-ph · Physics 2008-02-03 B. Jönsson , M. Ullner , C. Peterson , O. Sommelius , B. Söderberg

Ground state energies and chemical potentials of parahydrogen clusters are calculated from 3 to 40 molecules using the diffusion Monte Carlo technique with two different pH2-pH2 interactions. This calculation improves a previous one by the…

Atomic and Molecular Clusters · Physics 2009-11-13 R. Guardiola , J. Navarro

Using a diffusion Monte Carlo algorithm, we calculated the spectra of all possible $S$-wave fully heavy pentaquarks within the framework of the quark model. Our aim was to compare the masses of different spin-color configurations…

High Energy Physics - Phenomenology · Physics 2024-09-09 M. C. Gordillo , J. Segovia , J. M. Alcaraz-Pelegrina

Density functional theory (DFT) is widely used to study defects in monolayer graphene with a view to applications ranging from water filtration to electronics to investigation of radiation damage in graphite moderators. To assess the…

Materials Science · Physics 2022-06-16 D. M. Thomas , Y. Asiri , N. D. Drummond

Neutral molecules with sufficiently large dipole moments can bind electrons in diffuse nonvalence orbitals with most of their charge density far from the nuclei, forming so-called dipole-bound anions. Because long-range correlation effects…

Chemical Physics · Physics 2018-10-30 Hongxia Hao , James Shee , Shiv Upadhyay , Can Ataca , Kenneth D. Jordan , Brenda M. Rubenstein

We calculate the linear and non-linear susceptibilities of periodic longitudinal chains of hydrogen dimers with different bond-length alternations using a diffusion quantum Monte Carlo approach. These quantities are derived from the changes…

Chemical Physics · Physics 2015-05-14 Paolo Umari , Nicola Marzari

A rich literature has been produced on the quantum states of atoms and molecules confined into infinite potential wells with a specified symmetry. Apart from their interest as basic quantum systems, confined atoms and molecules are useful…

Chemical Physics · Physics 2019-04-03 Savino Longo , Gaia Micca Longo , Domenico Giordano

We present results from a fully relativistic Monte Carlo simulation of diffusive shock acceleration (DSA) in unmodified (i.e., test-particle) shocks. The computer code uses a single algorithmic sequence to smoothly span the range from…

Astrophysics · Physics 2007-05-23 Donald C. Ellison

We introduce a constrained energy functional to describe dielectric response. We demonstrate that the local functional is a generalization of the long ranged Marcus energy. Our re-formulation is used to implement a cluster Monte Carlo…

Soft Condensed Matter · Physics 2009-11-11 A. C. Maggs , R. Everaers

The Diffusion Monte Carlo (DMC) method is applied to the water monomer, dimer, and hexamer, using q-TIP4P/F, one of the most simple, empirical water models with flexible monomers. The bias in the time step ($\Delta\tau$) and population size…

Chemical Physics · Physics 2016-09-28 Joel D. Mallory , Sandra E. Brown , Vladimir A. Mandelshtam

Wavefunction correction scheme, which was developed as a variance reduction tool for the pure and fixed-node diffusion Monte Carlo (DMC) computations by Anderson and Freihaut, is applied to the DMC computations of fermions without using the…

Computational Physics · Physics 2010-03-29 Nazim Dugan , Inanc Kanik , Sakir Erkoc

We present unbiased, finite--variance estimators of energy derivatives for real--space diffusion Monte Carlo calculations within the fixed--node approximation. The derivative $d_\lambda E$ is fully consistent with the dependence…

Materials Science · Physics 2021-05-20 Jesse van Rhijn , Claudia Filippi , Stefania De Palo , Saverio Moroni