Molecular applications of coupled-cluster-based linear response theory: inner and outer valence ionization potentials of nitrogen and water

Abstract

We report the first ab initio molecular applications of our recently formulated linear response theory in the coupled-cluster framework for calculating inner and outer valence ionization potentials (IPs). The response model utilizes the coupled-cluster representation for the ground state Ψ_gr and calculates the linear response of Ψ_gr as it is subjected to the coupling of a photon field of frequency ω which destroys an electron. The poles of the response function provide the IPs. Applications to H₂O and N₂ show encouraging results.