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We describe an efficient algorithm to compute forces in quantum Monte Carlo using adjoint algorithmic differentiation. This allows us to apply the space warp coordinate transformation in differential form, and compute all the 3M force…

Other Condensed Matter · Physics 2015-05-20 Sandro Sorella , Luca Capriotti

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

A theoretical study is reported of the molecular-to-atomic transition in solid hydrogen at high pressure. We use the diffusion quantum Monte Carlo method to calculate the static lattice energies of the competing phases and a…

Materials Science · Physics 2014-04-23 Sam Azadi , Bartomeu Monserrat , W. M. C. Foulkes , R. J. Needs

We present a first-principle numerical study of charge transport in a realistic two-dimensional tight-binding model of organic molecular semiconductors. We use the Hybrid Monte Carlo (HMC) algorithm to simulate the full quantum dynamics of…

Materials Science · Physics 2024-09-12 Johann Ostmeyer , Tahereh Nematiaram , Alessandro Troisi , Pavel Buividovich

In order to find the equilibrium geometries of molecules and solids and to perform ab initio molecular dynamics, it is necessary to calculate the forces on the nuclei. We present a correlated sampling method to efficiently calculate…

Condensed Matter · Physics 2009-10-31 Claudia Filippi , C. J. Umrigar

X-ray dose constantly gains interest in the interventional suite. With dose being generally difficult to monitor reliably, fast computational methods are desirable. A major drawback of the gold standard based on Monte Carlo (MC) methods is…

Reliable theoretical predictions of noncovalent interaction energies, which are important e.g. in drug-design and hydrogen-storage applications, belong to longstanding challenges of contemporary quantum chemistry. In this respect, the…

Chemical Physics · Physics 2016-06-06 Matúš Dubecký , René Derian , Petr Jurečka , Lubos Mitas , Pavel Hobza , Michal Otyepka

Quantum Monte Carlo calculations of the first-row atoms Li-Ne and their singly-positively-charged ions are reported. Multi-determinant-Jastrow-backflow trial wave functions are used which recover more than 98% of the correlation energy at…

Computational Physics · Physics 2016-08-14 P. Seth , P. López Ríos , R. J. Needs

Quantum Monte Carlo (QMC) is applied to obtain the fundamental (quasiparticle) electronic band gap, $\Delta_f$, of a semiconducting two-dimensional (2D) phosphorene whose optical and electronic properties fill the void between graphene and…

Mesoscale and Nanoscale Physics · Physics 2019-02-06 Tobias Frank , Rene Derian , Kamil Tokar , Lubos Mitas , Jaroslav Fabian , Ivan Stich

We study the properties of classical and quantum compacton chains by means of extensive numerical simulations. Such chains are strongly nonlinear and their classical dynamics remains chaotic at arbitrarily low energies. We show that the…

Statistical Mechanics · Physics 2011-01-05 O. V. Zhirov , A. S. Pikovsky , D. L. Shepelyansky

This paper studies the rate of convergence for conditional quasi-Monte Carlo (QMC), which is a counterpart of conditional Monte Carlo. We focus on discontinuous integrands defined on the whole of $R^d$, which can be unbounded. Under…

Numerical Analysis · Mathematics 2018-06-07 Zhijian He

In the past decade, quantum diffusion Monte Carlo (DMC) has been demonstrated to successfully predict the energetics and properties of a wide range of molecules and solids by numerically solving the electronic many-body Schr\"odinger…

Chemical Physics · Physics 2023-03-10 Bing Huang , O. Anatole von Lilienfeld , Jaron T. Krogel , Anouar Benali

A compression algorithm is introduced for multi-determinant wave functions which can greatly reduce the number of determinants that need to be evaluated in quantum Monte Carlo calculations. We have devised an algorithm with three levels of…

Computational Physics · Physics 2015-06-17 Gihan L. Weerasinghe , Pablo Lopez Rios , Richard J. Needs

This paper proposes a method of quantum Monte Carlo integration that retains the full quadratic quantum advantage, without requiring any arithmetic or quantum phase estimation to be performed on the quantum computer. No previous proposal…

Quantum Physics · Physics 2022-10-05 Steven Herbert

The pressure-induced structural phase transition from diamond to beta-tin in silicon is an excellent test for theoretical total energy methods. The transition pressure provides a sensitive measure of small relative energy changes between…

Materials Science · Physics 2009-12-24 Wirawan Purwanto , Henry Krakauer , Shiwei Zhang

Ab initio auxiliary-field quantum Monte Carlo (AFQMC) is a systematically improvable many-body method, but its application to extended solids has been severely limited by unfavorable computational scaling and memory requirements that…

Strongly Correlated Electrons · Physics 2026-02-25 Jinghong Zhang , Meng-Fu Chen , Adam Rettig , Tong Jiang , Paul J. Robinson , Hieu Q. Dinh , Anton Z. Ni , Joonho Lee

We present a force-biased Monte Carlo (FMC) method for structural modeling of transition metal clusters of Fe, Ni, and Cu with 5 to 60 atoms. By employing the Finnis-Sinclair potential for Fe and the Sutton-Chen potential for Ni and Cu, the…

Materials Science · Physics 2017-12-06 Dil K. Limbu , Parthapratim Biswas

Electronic structure of the manganese oxide solid is studied by the quantum Monte Carlo (QMC) methods. The trial wavefunctions are built using orbitals from unrestricted Hartree-Fock and Density Functional Theory, and the electron-electron…

Strongly Correlated Electrons · Physics 2007-05-23 Ji-Woo Lee , Lubos Mitas , Lucas K. Wagner

Motivated by recent developments in conformal field theory (CFT), we devise a Quantum Monte Carlo (QMC) method to calculate the moments of the partially transposed reduced density matrix at finite temperature. These are used to construct…

Strongly Correlated Electrons · Physics 2014-08-08 Chia-Min Chung , Vincenzo Alba , Lars Bonnes , Pochung Chen , Andreas M. Läuchli

We review an approach where the energy functional of Density-Functional Theory (DFT) can be determined without empiricism via a Quantum Monte Carlo (QMC) procedure. The idea consists of a nested iterative loop where the configurational…

Strongly Correlated Electrons · Physics 2017-11-22 Luigi Delle Site