Noniterative corrections to equation-of-motion coupled-cluster excited state energies based on the reduced method of moments of coupled cluster equations

摘要

A new formalism closely related to the Method of Moments of Coupled-Cluster equations (MMCC) is obtained by embedding approximate coupled cluster (CC) or equation-of-motion CC (EOMCC) formalism into a formalism which uses cluster or excitation operators defined by excitation operators of higher rank with respect to a given approximation. Noniterative corrections akin to completely renormalized EOM-CCSD(T) corrections reveal structural similarities to the CCSD(T) corrections for the ground state. Several benchmark calculations on the O-3 and Cl2O molecules are discussed to illustrate the performance of this approach. (c) 2008 Wiley Periodicals, Inc.