Quadratic response functions for a multiconfigurational self-consistent field wave function

We describe an efficient implementation of the quadratic response function for a multiconfiguration self-consistent field reference wave function. The quadratic response function determines the hyperpolarizability and its residues determine the two-photon transition matrix elements and the transition matrix elements between excited states. We report sample calculations for the hyperpolarizability of Ne and for the two-photon transition matrix elements of Ne and H2.