Periodic Local Coupled-Cluster Theory for Insulators and Metals

TL;DR

This paper presents an efficient implementation of periodic local coupled-cluster theory with singles, doubles, and perturbative triples for insulators and metals, achieving significant speedups and accurate predictions.

Contribution

It introduces a versatile periodic LNO-CCSD(T) method applicable to both insulators and metals with substantial computational speedups.

Findings

Achieves 100-1000x speedup over traditional methods.

Accurately predicts cohesive energy, lattice constant, and bulk modulus.

Applicable to both insulators and metals with good agreement to experiments.

Abstract

We describe the implementation details of periodic local coupled-cluster theory with single and double excitations (CCSD) and perturbative triple excitations [CCSD(T)] using local natural orbitals (LNOs) and $k$-point symmetry. We discuss and compare several choices for orbital localization, fragmentation, and LNO construction. By studying diamond and lithium, we demonstrate that periodic LNO-CC theory can be applied with equal success to both insulators and metals, achieving speedups of two to three orders of magnitude even for moderately sized $k$-point meshes. Our final predictions of the equilibrium cohesive energy, lattice constant, and bulk modulus for diamond and lithium are in good agreement with previous theoretical predictions and experimental results.