Ab initio and density functional calculations of the energies of the singlet and triplet valence excited states of pyrazine

An examination of the ability of a number of computational methods to forecast the vertical excitation and perhaps also symmetric relaxation energies for 14 excited electronic states of pyrazine is presented. It seems that the most reliable results are provided by B3LYP, EOM-CCSD(T) and CASPT2 methods.