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arXiv · 1109.2635

A Full Configuration Interaction Perspective on the Homogeneous Electron Gas

James J. Shepherd·George Booth·Andreas Grüneis·Ali Alavi
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Abstract

Highly accurate results for the homogeneous electron gas (HEG) have only been achieved to date within a diffusion Monte Carlo (DMC) framework. Here, we introduce a newly developed stochastic technique, Full Configuration Interaction Quantum Monte Carlo (FCIQMC), which samples the exact wavefunction expanded in plane wave Slater determinants. Despite the introduction of a basis set incompleteness error, we obtain a finite-basis energy which is significantly, and variationally lower than any previously published work for the 54-electron HEG at $r_s$ = 0.5 a.u., in a Hilbert space of $10^{108}$ Slater determinants. At this value of $r_s$, as well as of 1.0 a.u., we remove the remaining basis set incompleteness error by extrapolation, yielding results comparable or better than state-of-the-art DMC backflow energies. In doing so, we demonstrate that it is possible to yield highly accurate results with the FCIQMC method in sizable periodic systems.

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James J. Shepherd, George Booth, Andreas Grüneis, Ali Alavi. 2011-09-12. A Full Configuration Interaction Perspective on the Homogeneous Electron Gas. https://doi.org/10.1103/physrevb.85.081103

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