The linear, quadratic, and cubic response of a multiconfigurational Hartree-Fock state to a time independent one-electron perturbation has been derived. A comparison between the exact response functions as obtained from Rayleigh-Schrodinger perturbation theory and the multiconfigurational Hartree-Fock response functions allows a identification of matrix elements of the perturbation operator between the ground and excited states and between excited states. We discuss some ambiguities which result from such an identification.
We show how an optimization constraint algorithm of Fletcher that guarantees convergence to the lowest state of a given symmetry may be practically implemented in a multiconfigurational self-consistent field (MCSCF) calculation. Other MCSCF procedures in current use have not been proven mathematically to guarantee convergence. Calculations on the ground states of N2 and CO show that rapid and efficient convergence is obtained with the Fletcher restricted step size algorithm.
Various second-order properties for H20 have been computed using a near Hartree-Fock gaussian wave function and a coupled Hartree-Fock scheme. Satisfactory agreement with experimental data is obtained for vibrational frequencies and for magnetic properties. The calculated electric polarizability only accounts for 64 per cent of the experimental value.
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