Band structures in coupled-cluster singles-and-doubles Green's function (GFCCSD)

TL;DR

This paper demonstrates that the GFCCSD method effectively computes electronic band structures and total energies, capturing quasiparticle and satellite peaks with high accuracy across various one-dimensional systems.

Contribution

The study applies GFCCSD to diverse 1D systems for the first time, showing its capability to accurately reproduce band structures and total energies, including correlation effects.

Findings

GFCCSD narrows band gaps compared to Hartree-Fock due to correlation.

GFCCSD captures both quasiparticle and satellite peaks.

Active space restriction maintains accuracy while reducing computational cost.

Abstract

We demonstrate that coupled-cluster singles-and-doubles Green's function (GFCCSD) method is a powerful and prominent tool drawing the electronic band structures and the total energies, which many theoretical techniques struggle to reproduce. We have calculated single-electron energy spectra via GFCCSD method for various kinds of systems, ranging from ionic to covalent and van der Waals, for the first time: one-dimensional LiH chain, one-dimensional C chain, and one-dimensional Be chain. We have found that the band gap becomes narrower than in HF due to the correlation effect. We also show that the band structures obtained from GFCCSD method include both quasiparticle and satellite peaks successfully. Besides, taking one-dimensional LiH as an example, we discuss the validity of restricting the active space to suppress the computational cost of GFCCSD method while maintaining the accuracy. We show that the calculated results without bands that do not contribute to the chemical bonds are in good agreement with full-band calculations. With GFCCSD method, we can calculate the total energy and band structures with high precision.