Numerical stability of time-dependent coupled-cluster methods for many-electron dynamics in intense laser pulses
Abstract
We investigate the numerical stability of time-dependent coupled-cluster theory for many-electron dynamics in intense laser pulses, comparing two coupled-cluster formulations with full configuration interaction theory. Our numerical experiments show that orbital-adaptive time-dependent coupled-cluster doubles (OATDCCD) theory offers significantly improved stability compared with the conventional Hartree-Fock-based time-dependent coupled-cluster singles-and-doubles (TDCCSD) formulation. The improved stability stems from greatly reduced oscillations in the doubles amplitudes, which, in turn, can be traced to the dynamic biorthonormal reference determinants of OATDCCD theory. As long as these are good approximations to the Brueckner determinant, OATDCCD theory is numerically stable. We propose the reference weight as a diagnostic quantity to identify situations where the TDCCSD and OATDCCD theories become unstable.
Keywords
Cite
@article{arxiv.1912.09217,
title = {Numerical stability of time-dependent coupled-cluster methods for many-electron dynamics in intense laser pulses},
author = {Håkon Emil Kristiansen and Øyvind Sigmundson Schøyen and Simen Kvaal and Thomas Bondo Pedersen},
journal= {arXiv preprint arXiv:1912.09217},
year = {2020}
}
Comments
5 pages, 6 figures (supplemental material, 7 pages, 11 figures)