An Introduction to Equation-of-Motion and Linear-Response Coupled-Cluster Methods for Electronically Excited States of Molecules

Abstract

This chapter presents a review of equation-of-motion coupled-cluster (EOM-CC) and linear-response coupled-cluster (LR-CC) methods for excited states of molecules. These methods derive from ground-state CC theory and, just as CC has become a very effective tool for ground electronic states, EOM-CC/LR-CC methods have become increasingly useful tools for excited states. The general theory is first outlined. This is followed by a survey of the different approximate schemes that have been developed and implemented. Next, the performance of some of these different schemes is assessed by numerical comparisons with exact results and with experimental data. Finally, a few illustrative applications are described in order to show the scope and applicability of EOM-CC/LR-CC methods