Excitation energies from the coupled cluster singles and doubles linear response function (CCSDLR). Applications to Be, CH+, CO, and H2O

Abstract

The linear response function for a coupled cluster singles and doubles wave function is used to calculate vertical electronic energies for the closed shell system Be, CH+, CO, and H2O. It is shown that excitations of single electron replacement character can be described accurately in such an approach. Improved convergence is obtained using a preconditioned form of the coupled cluster linear response matrix.