Application of the Optimized Effective Potential Method to Quantum Chemistry

In this final year of the grant period, we have concentrated our efforts in three areas: (1) The determination of the exact exchange mixing parameter by requiring that the ionization energy theorem for atoms with Z less than or equal 20 be satisfied as closely as possible, (2) the completion of the application of Kohn-Sham Theory for Orbital Dependent (Self-Interaction-Corrected) Exchange-Correlation Energy Functionals to Diatomic Molecules, and (3) The development of a new accurate, zero parameter, correlation energy functional obtained from the homogeneous electron gas with an energy gap and its application to the calculation of the ionization potentials and electron affinities of atoms. This approach is the first one that takes explicit account of the non zero energy of excitation for bound electrons. The functional includes the important self-interaction effects employing a method that is invariant under a unitary transformation. In both (1) and (2) the KLI approximation is employed to provide an accurate solution to the integral equation for the Optimized Effective Potential.