Excited states of the benzyl radical

The CI method is used in the -electron approximation with orbitals for closed and open shells to calculate the properties of excited doublet states with allowance for all singly excited configurations and some doubly excited ones, and also for the first quartet and sextet states, which are calculated in the one-configuration approximation via the open-shell theory. The energies and transition moments agree satisfactorily with the available experimental evidence. A classification and assignment is given for the excited terms. Truncation of the complete set of singly excited configurations greatly distorts the calculated spectrum. Inclusion of doubly excited configurations in the CI also produces a substantial change in the spectrum; in some cases it alters the order of adjacent terms. Conversion in CI from basis closed-shell orbitals to open-shell ones produces a considerable lowering of all terms in the spectrum. As in the case of triplet terms for molecules, weakening of electron interaction brings the lowest excited term of the radical closer to the ground-state term. The electron-density and spin-density distributions are calculated for the excited states.