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We investigate the viability of the phaseless finite temperature auxiliary field quantum Monte Carlo (ph-FT-AFQMC) method for ab initio systems using the uniform electron gas as a model. Through comparisons with exact results and finite…

Chemical Physics · Physics 2021-02-15 Joonho Lee , Miguel A. Morales , Fionn D. Malone

Phaseless Auxiliary-Field Quantum Monte Carlo (ph-AFQMC) has recently emerged as a promising method for the production of benchmark-level simulations of medium to large-sized molecules, due to its accuracy and favorable polynomial scaling…

Quantum Monte Carlo (QMC) is commonly used in simulations for Quantum Annealing (QA), but QMC as a heuristic approach has great difficulty in that it takes much time to find minimum energy. It mainly depends on the existence of a trotter…

Quantum Physics · Physics 2024-03-13 Kiyotaka Murashima

We calculate the equation of state of neutron matter at zero temperature by means of the auxiliary field diffusion Monte Carlo method (AFDMC) combined with a fixed-phase approximation. The calculation of the energy is carried out by…

Nuclear Theory · Physics 2009-06-30 S. Gandolfi , A. Yu. Illarionov , K. E. Schmidt , F. Pederiva , S. Fantoni

By precisely writing down the matrix element of the local Boltzmann operator, we have proposed a new path integral formulation for quantum field theory and developed a corresponding Monte Carlo algorithm. With current formula, the…

Strongly Correlated Electrons · Physics 2022-03-08 J. Wang , W. Pan , D. Y. Sun

We extend the use of coupled cluster (CC) trial states in the phaseless auxiliary-field quantum Monte Carlo (AFQMC) method beyond single and double excitations to include both triple and quadruple excitations. With this AFQMC/CC hierarchy,…

Chemical Physics · Physics 2025-10-09 Eirik F. Kjønstad , Yann Damour , Sandeep Sharma , Garnet Kin-Lic Chan

In the following article we consider approximate Bayesian computation (ABC) inference. We introduce a method for numerically approximating ABC posteriors using the multilevel Monte Carlo (MLMC). A sequential Monte Carlo version of the…

Methodology · Statistics 2017-02-14 Ajay Jasra , Seongil Jo , David Nott , Christine Shoemaker , Raul Tempone

The quantum Monte Carlo (QMC) is one of the most promising many-body electronic structure approaches. It employs stochastic techniques for solving the stationary Schr\" odinger equation and for evaluation of expectation values. The key…

Other Condensed Matter · Physics 2007-12-20 Michal Bajdich

We formulate a quantum Monte Carlo (QMC) method for calculating the ground state of many-boson systems. The method is based on a field-theoretical approach, and is closely related to existing fermion auxiliary-field QMC methods which are…

Computational Physics · Physics 2009-11-10 Wirawan Purwanto , Shiwei Zhang

In this thesis, the properties of mixtures of Bose-Einstein condensates at $T = 0$ have been investigated using quantum Monte Carlo (QMC) methods and Density Functional Theory (DFT) with the aim of understanding physics beyond the…

Quantum Gases · Physics 2021-05-05 Viktor Cikojević

We build on auto-encoding sequential Monte Carlo (AESMC): a method for model and proposal learning based on maximizing the lower bound to the log marginal likelihood in a broad family of structured probabilistic models. Our approach relies…

Machine Learning · Statistics 2018-04-06 Tuan Anh Le , Maximilian Igl , Tom Rainforth , Tom Jin , Frank Wood

A central problem in quantum mechanics involves solving the Electronic Schrodinger Equation for a molecule or material. The Variational Monte Carlo approach to this problem approximates a particular variational objective via sampling, and…

Chemical Physics · Physics 2025-01-22 Daniel Freedman , Eyal Rozenberg , Alex Bronstein

We describe an approach for many-body calculations with a finite-temperature, grand canonical ensemble formalism using auxiliary-field quantum Monte Carlo (AFQMC) with a self-consistent constraint to control the sign problem. The usual…

Strongly Correlated Electrons · Physics 2019-06-18 Yuan-Yao He , Mingpu Qin , Hao Shi , Zhong-Yi Lu , Shiwei Zhang

This is a book chapter soon to appear (2002) in the "Handbook for Numerical Analysis" volume dedicated to "Computational Chemistry" edited by Claude Le Bris. The series editors are P.G. Ciarlet and J. L. Lions. [North Holland/Elservier].…

Strongly Correlated Electrons · Physics 2007-05-23 Alán Aspuru-Guzik , William A. Lester

We present a simple approach to the fixed phase method in Quantum Monte Carlo. This applies to electrons in molecules and electron gas and is straightforwardly extended to the Schr\"odinger equation with magnetic field.

Computational Physics · Physics 2018-02-01 F. Delyon , B. Bernu

In this paper we propose an ab initio method to solve quantum many-body problems of molecular dynamics where both the electronic and the nuclear degrees are represented by ensembles of trajectories and guiding waves in physical space. Both…

Atomic Physics · Physics 2025-01-28 Ivan P. Christov

The dependence of the nuclear level density on intrinsic deformation is an important input to dynamical nuclear processes such as fission. Auxiliary-field Monte Carlo (AFMC) method is a powerful method for computing nuclear level densities.…

Nuclear Theory · Physics 2018-09-26 M. T. Mustonen , C. N. Gilbreth , Y. Alhassid , G. F. Bertsch

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

Calculations of the binding energy of the transition metal oxide molecules TiO and MnO are presented, using a recently developed phaseless auxiliary field quantum Monte Carlo approach. This method maps the interacting many-body problem onto…

Strongly Correlated Electrons · Physics 2007-05-23 W. A. Al-Saidi , Henry Krakauer , Shiwei Zhang

Quantum Monte Carlo methods have recently been employed to study properties of nuclei and infinite matter using local chiral effective field theory interactions. In this work, we present a detailed description of the auxiliary field…

Nuclear Theory · Physics 2018-05-02 D. Lonardoni , S. Gandolfi , J. E. Lynn , C. Petrie , J. Carlson , K. E. Schmidt , A. Schwenk
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