Towards efficient and accurate ab initio solutions to periodic systems via transcorrelation and coupled cluster theory

Ke Liao,Hongjun Luo,Ali Alavi,Daniel Kats,Thomas Schraivogel

doi:10.1103/physrevresearch.3.033072

Ke Liao, Hongjun Luo + Show 3 more

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https://doi.org/10.1103/physrevresearch.3.033072

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Abstract

We propose a streamlined combination scheme of the transcorrelation (TC) and coupled cluster (CC) theory, which not only increases the convergence rate with respect to the basis set, but also extends the applicability of the lowest order CC approximations to strongly correlated regimes in the three dimensional uniform electron gas (3D UEG). With the correct physical insights built into the correlator used in TC, highly accurate ground state energies with errors $\leq 0.001 $ a.u./electron relative to the state-of-the-art quantum Monte Carlo results can be obtained across a wide range of densities. The greatly improved efficiency and accuracy of our methods hold great promise for strongly correlated solids where many other methods fail.

Highlights

The coupled cluster (CC) methodologies [1,2,3] at the level of singles and doubles (CCSD) and perturbative triples (CCSD(T)) [4] have become the de facto standard of singlereference ab initio quantum chemistry and can be applied to systems consisting of hundreds of electrons [5,6,7,8]
The purpose of this paper is to report such an investigation, applied to the uniform electron gas (UEG) over a broad range of densities to assess the accuracy of our new methods at different correlation strengths
In our previous study of the exact TC method in the UEG, we proposed a form of the correlator which was found to work successfully in accelerating convergence to the basis set limit, without changing the correlation that could be captured with the basis set by a FCI level function

Summary

Introduction

The coupled cluster (CC) methodologies [1,2,3] at the level of singles and doubles (CCSD) and perturbative triples (CCSD(T)) [4] have become the de facto standard of singlereference ab initio quantum chemistry and can be applied to systems consisting of hundreds of electrons [5,6,7,8]. Because of quite steep computational scaling (O(N6) and O(N7) for CCSD and CCSD(T), respectively), it is desirable to keep the methods at the lowest possible CC level, namely, CCSD, while maintaining accuracy.

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