Spin-dependent localized Hartree-Fock density functional theoretical approach for excited-state potential energies of diatomic molecules

A density-functional theoretical (DFT) approach based on spin-dependent localized Hartree-Fock (SLHF) potential is proposed for excited-state potential energies of diatomic molecules. This approach is applied to the calculation of excited-state potential energies of H₂⁺ and H₂. The exchange-only results are in very good agreement with those of the exact and Hartree-Fock (HF) methods, demonstrating the proposed DFT approach using the SLHF potential as exchange potential is a good approach. The traditional correlation potential and energy functionals are also explored and they underestimate the correction energy at large internuclear distance. (author)