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Accurate, efficient and simple forces with Quantum Monte Carlo methods

Simone Chiesa, David Ceperley, Shiwei Zhang

physics.comp-pharXiv:physics/0409087

Abstract

Computation of ionic forces using quantum Monte Carlo methods has long been a challenge. We introduce a simple procedure, based on known properties of physical electronic densities, to make the variance of the Hellmann-Feynman estimator finite. We obtain very accurate geometries for the molecules H2, LiH, CH4, NH3, H2O and HF, with a Slater-Jastrow trial wave function. Harmonic frequencies for diatomics are also in good agreement with experiment. An antithetical sampling method is also discussed for additional reduction of the variance.

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