An efficient and accurate perturbative correction to initiator full configuration interaction quantum Monte Carlo

Nick S. Blunt

doi:10.1063/1.5037923

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arXiv · 1804.09528

An efficient and accurate perturbative correction to initiator full configuration interaction quantum Monte Carlo

Nick S. Blunt

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Abstract

We present a perturbative correction within initiator full configuration interaction quantum Monte Carlo (i-FCIQMC). In the existing i-FCIQMC algorithm, a significant number of spawned walkers are discarded due to the initiator criteria. Here we show that these discarded walkers have a form that allows calculation of a second-order Epstein-Nesbet correction, that may be accumulated in a trivial and inexpensive manner, yet substantially improves i-FCIQMC results. The correction is applied to the Hubbard model, the uniform electron gas and molecular systems.

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Nick S. Blunt. 2018-06-12. An efficient and accurate perturbative correction to initiator full configuration interaction quantum Monte Carlo. https://doi.org/10.1063/1.5037923

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