An MCSCF study of the X2B2, 2A2 and 2 2B2 states of benzyl

Abstract

A large basis set (double-zeta + polarisation and diffuse s, p on carbons) calculation is reported on the three electronic states of benzyl, X²B₂, ²A₂ and 2 ²B₂, which are of interest experimentally. Because these states cannot be represented by SCF wavefunctions, CASSCF π-space calculations are performed. Geometries are optimised. It is found that the X²B₂ state is 65 kcal mol^–1 lower than the 2 ²B₂ and ²A₂ states, which these calculations suggest have nearly the same energy (within 2 kcal mol^–1). These results agree with the most recent interpretation of emission and absorption spectra.