Similarity transformed equation of motion coupled-cluster study of excited states of selected azabenzenes

摘要

The recently developed similarity transformed equation-of-motion coupled-cluster method (STEOM-CC) is applied to calculate the vertical excitation spectra and various 0-0 transitions of selected azabenzenes. The primary pupose of these studies is to gain further experience with the STEOM-CCSD approach, and to gauge its accuracy. It is shown that the accuracy of the method exceeds the accuracy of EOM-CCSD, and that results for valence excited states are often close to EOM-CCSD(T-tilde). A number of low lying 0-0 transitions are determined in pyridine and the diazines. The geometries and vibrational frequencies of excited states are determined at the CI singles level, while final electronic energies are calculated through single point STEOM-CCSD. The manifold of excited states, ionized and electron attached states are analyzed as the geometries are distorted from the ground state equilibrium structures.