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We study the potential energy surface of the ozone molecule by means of Quantum Monte Carlo simulations based on the resonating valence bond concept. The trial wave function consists of an antisymmetrized geminal power arranged in a…

Computational Physics · Physics 2016-08-23 Sam Azadi , Ranber Singh , Thomas D. Kühne

The implementation and reliability of a quadratic diffusion Monte Carlo method for the study of ground-state properties of atoms are discussed. We show in the simple yet non-trivial calculation of the binding energy of the Li atom that the…

Condensed Matter · Physics 2009-11-07 A. Sarsa , J. Boronat , J. Casulleras

A quantum Monte Carlo method is introduced to optimize excited state trial wavefunctions. The method is applied in a correlation function Monte Carlo calculation to compute ground and excited state energies of bosonic van der Waals clusters…

Computational Physics · Physics 2009-11-06 M. P. Nightingale , Vilen Melik-Alaverdian

We have used the variational and diffusion quantum Monte Carlo methods to calculate the energy, pair correlation function, static structure factor, and momentum density of the ground state of the two-dimensional homogeneous electron gas. We…

Mesoscale and Nanoscale Physics · Physics 2010-03-02 N. D. Drummond , R. J. Needs

We present a simple and general formalism to compute efficiently the derivatives of a multi-determinant Jastrow-Slater wave function, the local energy, the interatomic forces, and similar quantities needed in quantum Monte Carlo. Through a…

Materials Science · Physics 2016-06-22 Claudia Filippi , Roland Assaraf , Saverio Moroni

The energy per particle of zero-temperature neutron matter is investigated, with particular emphasis on the role of the $\vec L\cdot\vec S$ interaction. An analysis of the importance of explicit spin--orbit correlations in the description…

Nuclear Theory · Physics 2009-11-10 L. Brualla , S. Fantoni , A. Sarsa , K. E Schmidt , S. A. Vitiello

We introduce a novel many body method which combines two powerful many body techniques, viz., quantum Monte Carlo and coupled cluster theory. Coupled cluster wave functions are introduced as importance functions in a Monte Carlo method…

Nuclear Theory · Physics 2013-12-04 Alessandro Roggero , Abhishek Mukherjee , Francesco Pederiva

This topical review describes the methodology of continuum variational and diffusion quantum Monte Carlo calculations. These stochastic methods are based on many-body wave functions and are capable of achieving very high accuracy. The…

Materials Science · Physics 2010-02-11 R. J. Needs , M. D. Towler , N. D. Drummond , P. Lopez Rios

Diffusion Monte Carlo is one of the most accurate scalable many-body methods for solid state systems. However, to date, spin-orbit interactions have not been incorporated into these calcualtions at a first-principles level; only having been…

Materials Science · Physics 2020-03-04 Yueqing Chang , Lucas K. Wagner

We present a method based on the Path Integral Monte Carlo formalism for the calculation of ground-state time correlation functions in quantum systems. The key point of the method is the consideration of time as a complex variable whose…

Statistical Mechanics · Physics 2015-06-24 Riccardo Rota , Joaquim Casulleras , Ferran Mazzanti , Jordi Boronat

A self-contained and tutorial presentation of the diffusion Monte Carlo method for determining the ground state energy and wave function of quantum systems is provided. First, the theoretical basis of the method is derived and then a…

Computational Physics · Physics 2009-10-30 Ioan Kosztin , Byron Faber , Klaus Schulten

Quantum Monte Carlo methods are accurate and promising many body techniques for electronic structure calculations which, in the last years, are encountering a growing interest thanks to their favorable scaling with the system size and their…

Chemical Physics · Physics 2014-02-17 Andrea Zen , Ye Luo , Sandro Sorella , Leonardo Guidoni

Diffusion quantum Monte Carlo calculations with partial and full optimization of the guide function are carried out for the dissociation of the FeS molecule. For the first time, quantum Monte Carlo orbital optimization for transition metal…

Chemical Physics · Physics 2017-07-31 Kaveh Haghighi Mood , Arne Lüchow

We describe the implementation of the frozen-orbital and downfolding approximations in the auxiliary-field quantum Monte Carlo (AFQMC) method. These approaches can provide significant computational savings compared to fully correlating all…

Computational Physics · Physics 2013-11-18 Wirawan Purwanto , Shiwei Zhang , Henry Krakauer

An algorithm is proposed to optimize quantum Monte Carlo (QMC) wave functions based on New ton's method and analytical computation of the first and second derivatives of the variati onal energy. This direct application of the variational…

Chemical Physics · Physics 2016-09-08 Xi Lin , Hongkai Zhang , Andrew M. Rappe

A quantum Monte Carlo method is presented for determining multi-determinantal Jastrow-Slater wave functions for which the energy is stationary with respect to the simultaneous optimization of orbitals and configuration interaction…

Other Condensed Matter · Physics 2009-11-10 Friedemann Schautz , Claudia Filippi

A method is developed that allows analysis of quantum Monte Carlo simulations to identify errors in trial wave functions. The purpose of this method is to allow for the systematic improvement of variational wave functions by identifying…

Strongly Correlated Electrons · Physics 2016-08-03 Kiel T. Williams , Lucas K. Wagner

The quantum Monte Carlo algorithm is arguably one of the most powerful computational many-body methods, enabling accurate calculation of many properties in interacting quantum systems. In the presence of the so-called sign problem, the…

Strongly Correlated Electrons · Physics 2018-02-23 Chia-Chen Chang , Miguel A. Morales

We investigate pfaffian trial wave functions with singlet and triplet pair orbitals by quantum Monte Carlo methods. We present mathematical identities and the key algebraic properties necessary for efficient evaluation of pfaffians.…

Other Condensed Matter · Physics 2013-05-29 M. Bajdich , L. Mitas , L. K. Wagner , K. E. Schmidt

Many quantum many-body wavefunctions, such as Jastrow-Slater, tensor network, and neural quantum states, are studied with the variational Monte Carlo technique, where stochastic optimization is usually performed to obtain a faithful…

Strongly Correlated Electrons · Physics 2025-08-21 Ruojing Peng , Garnet Kin-Lic Chan