How to renormalize coupled cluster theory

TL;DR

This paper introduces a renormalization approach within coupled cluster theory to effectively include three-body correlations, improving accuracy for various nuclei without the high computational cost of triples calculations.

Contribution

It proposes a novel renormalization method for three-body interactions in coupled cluster theory, enhancing accuracy while maintaining computational efficiency.

Findings

Accurate CCSD results for multiple nuclei achieved

Renormalization captures dominant three-body effects

Method reduces computational cost compared to triples inclusion

Abstract

Coupled cluster theory is an attractive tool to solve the quantum many-body problem because its singles and doubles (CCSD) approximation is computationally affordable and yields about 90% of the correlation energy. Capturing the remaining 10%, e.g. via including triples, is numerically expensive. Here we assume that short-range three-body correlations dominate and - following Lepage [How to renormalize the Schr\"odinger equation, arXiv:nucl-th/9706029] - that their effects can be included within CCSD by renormalizing the three-body contact interaction. We renormalize this contact in $^{16}$O and obtain accurate CCSD results for $^{24}$O, $^{20-34}$Ne, $^{40,48}$Ca, $^{78}$Ni, $^{90}$Zr, and $^{100}$Sn.