One-Body Properties and Their Perturbative Accuracy with Aufbau Suppressed Coupled Cluster Theory

We derived and implemented the calculation of the one-body
reduced
density matrix for Aufbau suppressed coupled cluster theory, from
which excited state natural orbitals and one-body properties, like
atomic populations and dipole moments, are obtained. We utilized the
natural orbitals to refine the ASCC solution for simple valence and
Rydberg systems, exploring the process of repeatedly solving the ASCC
equations in successive natural orbital bases to achieve independence
from the starting molecular orbitals. For dipole moments in small
molecules where high-level comparison data is available, we find that
the accuracy of ASCC essentially matches that of linear response and
equation-of-motion coupled cluster as long as care is taken to preserve
the response’s perturbative completeness.