Application of the Optimized Effective Potential Method to Quantum Chemistry

摘要

The difficulties in conventional density functional theory (DFT) are discussed. An alternative exact procedure, the Optimized Effective Potential (OEP) method, is discussed and its analytic properties that are significant in DFT are presented. The difficulties in solving the integral equation for the OEP are eliminated by the introduction of the Krieger-Li-Iafrate (KLI) approximation which leads to important analytic properties that are identical to those of the OEP. Detailed self-consistent calculations on atoms and negative ions demonstrate that the KLI yields results that are nearly identical to those of the OEP and are a significant improvement over those given by the local spin density approximation and its gradient corrected versions. Calculations have been extended to molecules in the exchange-only approximation and are close to Hartree-Fock results. An accurate self-interaction-free correlation energy functional has been constructed from considerations of a homogeneous electron gas with an energy gap. Calculations on atoms, molecules and surfaces demonstrate that this functional is at least as accurate as any alternative generalized gradient approximation. The contributions from low lying virtual states is being studied.