Density functional calculations on low-lying singly excited states of open-shell atoms

By employing a simple density-functional approach, low-lying singly excited states of several open-shell atoms, viz. B, C, O, F, Na, Mg, Al, Si, P and Cl, have been calculated and compared with experimental results. The work-function-based exchange potential has been used in a nonrelativistic, single-determinantal framework. The effects of two different correlation energy functionals (local Wigner and nonlocal Lee–Yang–Parr) on excitation energies and excited-state energies have been studied. While the exchange-only results show good agreement with numerical Hartree–Fock results, the correlation energy functionals do not show any significant improvements in excitation energies over the exchange-only results, although the excited-state energies are improved significantly.