Analytic evaluation of the nonadiabatic coupling vector between excitedstates using equation-of-motion coupled-cluster theory

摘要

Theory and implementation for evaluation of the nonadiabatic coupling vector between excitedelectronic states described by equation-of-motion excitation energy coupled-cluster singles anddoubles (EOMEE-CCSD) method is presented. Problems arising from the non-Hermitian nature ofthe theory are discussed in detail. The performance of the new approach is demonstrated by the niceagreement of the nonadiabatic coupling curves for LiH obtained at the EOMEE-CCSD andMR-CISD levels. Using the tools developed we also present a computational procedure to evaluatethe interstate coupling constants used in vibronic coupling theories. As an application of this part ofthe implementation we present simulation of the electronic absorption spectrum of the pyrazinemolecule within the linear vibronic coupling model.