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Full configuration interaction perspective on the homogeneous electron gas
Journal article   Open access   Peer reviewed

Full configuration interaction perspective on the homogeneous electron gas

James J Shepherd, George Booth, Andreas Grüneis and Ali Alavi
Physical review. B, Condensed matter and materials physics, Vol.85(8), 081103(R)
02/07/2012
DOI: 10.1103/PhysRevB.85.081103
url
https://arxiv.org/pdf/1109.2635View
Open Access

Abstract

Phys. Rev. B 85, 081103(R) (2012) 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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