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Highly size-asymmetrical fluid mixtures arise in a variety of physical contexts, notably in suspensions of colloidal particles to which much smaller particles have been added in the form of polymers or nanoparticles. Conventional schemes…

Soft Condensed Matter · Physics 2011-01-14 Douglas J. Ashton , Jiwen Liu , Erik Luijten , Nigel B. Wilding

By the Wolff's cluster Monte Carlo simulations and numerical minimization within a mean field approach, we study the low temperature phase diagram of water, adopting a cell model that reproduces the known properties of water in its fluid…

Soft Condensed Matter · Physics 2009-11-13 Marco G. Mazza , Kevin Stokely , Elena Strekalova , H. Eugene Stanley , Giancarlo Franzese

Piecewise deterministic Markov process samplers are attractive alternatives to Metropolis--Hastings algorithms. A central design question is how to incorporate partial velocity refreshment to ensure ergodicity without injecting excessive…

Probability · Mathematics 2026-02-20 Hirofumi Shiba , Kengo Kamatani

Fixed-node diffusion Monte Carlo (FNDMC) is a stochastic quantum many-body method that has a great potential in electronic structure theory. We examine how FNDMC satisfies exact constraints, linearity and derivative discontinuity of total…

Chemical Physics · Physics 2019-10-16 Matej Ditte , Matus Dubecky

Many experimentally-accessible, finite-sized interacting quantum systems are most appropriately described by the canonical ensemble of statistical mechanics. Conventional numerical simulation methods either approximate them as being coupled…

Strongly Correlated Electrons · Physics 2023-05-23 Tong Shen , Hatem Barghathi , Jiangyong Yu , Adrian Del Maestro , Brenda Rubenstein

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

The convergence of full configuration interaction quantum Monte Carlo (FCIQMC) is accelerated using a quasi-Newton propagation (QN) which can also be applied to coupled cluster Monte Carlo (CCMC). The computational scaling of this optimised…

Chemical Physics · Physics 2020-06-11 Verena A. Neufeld , Alex J. W. Thom

We calculate the ground-state energy of 4He, 8He, 16O, and 40Ca using the auxiliary field diffusion Monte Carlo method in the fixed phase approximation and the Argonne v6' interaction which includes a tensor force. Comparison of our light…

Nuclear Theory · Physics 2008-11-26 S. Gandolfi , F. Pederiva , S. Fantoni , K. E. Schmidt

We extend the scope of full configuration interaction quantum Monte Carlo (FCIQMC) to be applied to coupled fermion-boson hamiltonians, alleviating the a priori truncation in boson occupation which is necessary for many other wave function…

Strongly Correlated Electrons · Physics 2022-11-09 Robert J. Anderson , Charles C. J. Scott , George H. Booth

High-quality excitation generators are crucial to the effectiveness of Coupled cluster Monte Carlo (CCMC) and full configuration interaction Quantum Monte Carlo (FCIQMC) calculations. The heat bath sampling of Holmes et al. [A. A. Holmes,…

Chemical Physics · Physics 2020-06-11 Verena A. Neufeld , Alex J. W. Thom

We present a detailed study of the energetics of water clusters (H$_2$O)$_n$ with $n \le 6$, comparing diffusion Monte Carlo (DMC) and approximate density functional theory (DFT) with well converged coupled-cluster benchmarks. We use the…

Materials Science · Physics 2015-06-04 M. J. Gillan , F. R. Manby , M. D. Towler , D. Alfè

Monte Carlo simulation provides a powerful tool for understanding and exploring thermodynamic phase equilibria in many-particle interacting systems. Among the most physically intuitive simulation methods is Gibbs ensemble Monte Carlo…

Statistical Mechanics · Physics 2015-06-12 Alan R. Denton , Michael P. Schmidt

We apply diffusion quantum Monte Carlo (DMC) to a broad set of solids, benchmarking the method by comparing bulk structural properties (equilibrium volume and bulk modulus) to experiment and DFT based theories. The test set includes…

Materials Science · Physics 2015-06-17 Luke Shulenburger , Thomas R. Mattsson

We have investigated decorrelation of samples in Quantum Monte Carlo (QMC) ground-state energy calculations for large Li and H$_{2}$O nanoclusters. Binning data as a way of eliminating statistical correlations, as is the common practice, is…

Materials Science · Physics 2007-10-11 D. Nissenbaum , B. Barbiellini , A. Bansil

The use of an approximate reference state wave function |Phi_r> in electronic many-body methods can break the spin symmetry of Born-Oppenheimer spin-independent Hamiltonians. This can result in significant errors, especially when bonds are…

Computational Physics · Physics 2008-03-19 Wirawan Purwanto , W. A. Al-Saidi , Henry Krakauer , Shiwei Zhang

We describe CPMC-Lab, a Matlab program for the constrained-path and phaseless auxiliary-field Monte Carlo methods. These methods have allowed applications ranging from the study of strongly correlated models, such as the Hubbard model, to…

Strongly Correlated Electrons · Physics 2014-10-14 Huy Nguyen , Hao Shi , Jie Xu , Shiwei Zhang

We marry tensor network states (TNS) and projector quantum Monte Carlo (PMC) to overcome the high computational scaling of TNS and the sign problem of PMC. Using TNS as trial wavefunctions provides a route to systematically improve the sign…

Strongly Correlated Electrons · Physics 2014-07-04 Sebastian Wouters , Brecht Verstichel , Dimitri Van Neck , Garnet Kin-Lic Chan

We incorporate explicit, non-perturbative treatment of spin-orbit coupling into ab initio auxiliary-field quantum Monte Carlo (AFQMC) calculations. The approach allows a general computational framework for molecular and bulk systems in…

Strongly Correlated Electrons · Physics 2023-02-16 Brandon Eskridge , Henry Krakauer , Hao Shi , Shiwei Zhang

Quantum chemistry is one of the most promising applications of quantum computers in the near future. For noisy intermediate-scale quantum devices, the quantum-classical hybrid framework based on the variational quantum eigensolver (VQE) has…

Efficient continuous time quantum Monte Carlo (CT-QMC) algorithms that do not suffer from time discretization errors have become the state-of-the-art for most discrete quantum models. They have not been widely used yet for fermionic quantum…

Strongly Correlated Electrons · Physics 2015-07-08 Mauro Iazzi , Matthias Troyer