Equation-of-motion coupled cluster method with full inclusion of the connected triple excitations for ionized states: IP-EOM-CCSDT

摘要

The equation-of-motion (EOM) coupled cluster (CC) method with full inclusion of the connected triple excitations forionization energies has been formulated and implemented. Using proper factorization of the three- and four-body parts of the effective Hamiltonian, an efficient computational procedure has been proposed for IP-EOM-CCSDT which at the EOM level requires no-higher-than n_occ~3n_vir~4 scaling. The method is calibrated by the evaluation of the valence vertical ionization potentials for CO, N_2, and F_2 molecules for several basis sets up to 160 bais functions. At the basis set limit, errors vary from 0.0 to 0.2 eV, compared to "experimental" vertical ionization potentials.