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Quantum Monte Carlo (QMC) techniques are used to calculate the one-body density matrix and excitation energies for the valence electrons of bulk silicon. The one-body density matrix and energies are obtained from a Slater-Jastrow wave…

Condensed Matter · Physics 2009-10-31 P. R. C. Kent , Randolph Q. Hood , M. D. Towler , R. J. Needs , G. Rajagopal

The diffusion Monte Carlo (DMC), auxiliary field quantum Monte Carlo (AFQMC), and equation-of-motion coupled cluster (EOM-CC) methods are used to calculate the electron binding energy (EBE) of the non-valence anion state of a model…

Chemical Physics · Physics 2021-02-03 Shiv Upadhyay , Amanda Dumi , James Shee , Kenneth D. Jordan

Deep learning has deeply changed the paradigms of many research fields. At the heart of chemical and physical sciences is the accurate ab initio calculation of many-body wavefunction, which has become one of the most notable examples to…

Chemical Physics · Physics 2025-04-01 Yubing Qian , Xiang Li , Zhe Li , Weiluo Ren , Ji Chen

In the last few years we have been developing a Monte Carlo simulation method to cope with systems of many electrons and ions in the Born-Oppenheimer (BO) approximation, the Coupled Electron-Ion Monte Carlo Method (CEIMC). Electronic…

Computational Physics · Physics 2007-05-23 Carlo Pierleoni , David M. Ceperley

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

Fixed node diffusion Monte Carlo (DMC) has been performed on a test set of forward and reverse barrier heights for 19 non-hydrogen-transfer reactions, and the nodal error has been assessed. The DMC results are robust to changes in the nodal…

Chemical Physics · Physics 2017-04-26 Kittithat Krongchon , Brian Busemeyer , Lucas K. Wagner

The sampling of the configuration space in diffusion Monte Carlo (DMC) is done using walkers moving randomly. In a previous work on the Hubbard model [\href{https://doi.org/10.1103/PhysRevB.60.2299}{Assaraf et al.~Phys.~Rev.~B \textbf{60},…

Strongly Correlated Electrons · Physics 2023-01-19 Roland Assaraf , Emmanuel Giner , Vijay Gopal Chilkuri , Pierre-François Loos , Anthony Scemama , Michel Caffarel

Dynamical mean-field theory (DMFT) is one of the most widely-used methods to treat accurately electron correlation effects in ab-initio real material calculations. Many modern large-scale implementations of DMFT in electronic structure…

Strongly Correlated Electrons · Physics 2019-06-05 Evan Sheridan , Cedric Weber , Evgeny Plekhanov , Christopher Rhodes

We present a novel way of performing kinetic Monte Carlo simulations which does not require an {\it a priori} list of diffusion processes and their associated energetics and reaction rates. Rather, at any time during the simulation,…

Materials Science · Physics 2009-11-11 Oleg Trushin , Altaf Karim , Abdelkader Kara , Talat S. Rahman

Recently Schautz and Flad concluded that the Hellmann-Feynman theorem holds within the fixed-node diffusion quantum Monte Carlo (DMC) method. We show that the Hellmann-Feynman expression is not in general equal to the derivative of the DMC…

Condensed Matter · Physics 2009-10-31 K. C. Huang , R. J. Needs , G. Rajagopal

A massively parallel kinetic Monte Carlo (kMC) approach is proposed for simulating ionic migration in a crystal system by introducing the atomic fragmentation scheme (fragment kMC). The fragment kMC method achieved a reasonable parallel…

Chemical Physics · Physics 2020-05-28 Hiroya Nakata

The transport of charged particles in various astrophysical environments permeated by magnetic fields is described in terms of a diffusion process, which relies on diffusion-tensor parameters generally inferred from Monte-Carlo simulations.…

High Energy Astrophysical Phenomena · Physics 2021-10-20 Olivier Deligny

This work generalizes the discrete implicit Monte-Carlo (DIMC) method for modeling the radiative transfer equation from a gray treatment to an frequency-dependent one. The classic implicit Monte-Carlo (IMC) algorithm, that has been used for…

Computational Physics · Physics 2023-05-16 Elad Steinberg , Shay I. Heizler

This paper introduces a Monte Carlo method for maximum likelihood inference in the context of discretely observed diffusion processes. The method gives unbiased and a.s.\@ continuous estimators of the likelihood function for a family of…

Statistics Theory · Mathematics 2009-03-03 Alexandros Beskos , Omiros Papaspiliopoulos , Gareth Roberts

We explore Implicit Monte Carlo (IMC) and Discrete Diffusion Monte Carlo (DDMC) for radiation transport in high-velocity outflows with structured opacity. The IMC method is a stochastic computational technique for nonlinear radiation…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Ryan T. Wollaeger , Daniel R. van Rossum , Carlo Graziani , Sean M. Couch , George C. Jordan , Donald Q. Lamb , Gregory A. Moses

We study beryllium dihydride (BeH$_2$) and acetylene (C$_2$H$_2$) molecules using real-space diffusion Monte Carlo (DMC) method. The molecules serve as perhaps the simplest prototypes that illustrate the difficulties with biases in the…

Context. The diffusive shock acceleration mechanism has been widely accepted as the acceleration mechanism for galactic cosmic rays. While self-consistent hybrid simulations have shown how power-law spectra are produced, detailed…

High Energy Astrophysical Phenomena · Physics 2015-06-04 M. Wolff , R. C. Tautz

We provide a mathematical study of the modified Diffusion Monte Carlo (DMC) algorithm introduced in the companion article \cite{DMC}. DMC is a simulation technique that uses branching particle systems to represent expectations associated…

Probability · Mathematics 2014-04-11 Martin Hairer , Jonathan Weare

We consider conditional tests for non-negative discrete exponential families. We develop two Markov Chain Monte Carlo (MCMC) algorithms which allow us to sample from the conditional space and to perform approximated tests. The first…

Computation · Statistics 2017-07-27 Roberto Fontana , Francesca Romana Crucinio

Quantitative theory of interbilayer interactions is essential to interpret x-ray scattering data and to elucidate these interactions for biologically relevant systems. For this purpose Monte Carlo simulations have been performed to obtain…

Biological Physics · Physics 2009-10-31 Nikolai Gouliaev , John F. Nagle