A multi-reference ab initio CI study of benzene as parent molecule of the azines is presented. The results for both Rydberg and valence states are correlated with experimental VUV and electron scattering data, and with some exceptions (1B1u and 1E1u) good correlations are obtained. The difficulty in computing reasonable values for the second and third pp* singlet states by CI arise from the paucity of virtual orbitals for the upper state MO (e2u); this is largely overcome by quadruple and penta zeta pc basis sets, which have the effect of lowering the 1B1u excitation energy below the Rydberg 3s state. © 1989.
|Number of pages||9|
|Publication status||Published - 1 May 1989|