Excitation energies in density functional theory: comparison of several methods for the H2O, N2, CO and C2H4 molecules

Several density functional methods were applied to calculate the first and higher vertical excitation energies of the H2O molecule and the first vertical excitation energies of N2, CO and C2H4 using ground-state local and non-local potentials. From the results we can state that none of these methods leads to better values than Slaterʹs transition state method provided that ground-state exchange-correlation potentials are applied.