November 17, 2020
Journal Article

Real-time coupled-cluster approach for the cumulant Green's function

Fernando Vila
John Rehr
Joshua Kas
Karol Kowalski
Bo Peng

Abstract

Green’s function methods within many-body perturbation theory provide a general framework for treating electronic correlations in excited states. Here we investigate the cumulant form of the one-electron Green’s function based on the coupled-cluster equation of motion approach in an extension of our previous study. The approach yields a non-perturbative expression for the cumulant in terms of the solution to a set of coupled first order, non-linear differential equations. The method thereby adds non-linear corrections to traditional cumulant methods linear in the self energy. The approach is applied to the core-hole Green’s function and illustrated for a number of small molecular systems. For these systems we find that the non-linear contributions lead to significant improvements both for quasiparticle properties such as core-level binding energies, as well as the satellites corresponding to inelastic losses observed in photoemission spectra.

Revised: November 17, 2020 | Published: November 10, 2020

Citation

Vila F.D., J.J. Rehr, J.J. Kas, K. Kowalski, and B. Peng. 2020. "Real-time coupled-cluster approach for the cumulant Green's function." Journal of Chemical Theory and Computation 16, no. 11:6983–6992. PNNL-SA-153807. doi:10.1021/acs.jctc.0c00639