Knowledge Bank

Extensive ab initio SCF and CI calculations have been performed on the valence and Rydberg excited states of pyrazine, as well as the low-lying cationic states. The results are used to interpret the ultraviolet and photoelectron spectra. Simple models for describing the $n\pi \ast$ and lone pair cation states are developed. The possibility of having an electric-dipole forbidden$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ $n\pi \ast$ state nearly degenerate with the lowest observed$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ $n\pi \ast$ state is considered.