Theoretical study of the He I photoelectron spectra of HBS and FBS

MP2 and CCSD(T) geometry optimization and harmonic vibrational frequency ca lculations were performed on the X(1)Sigma(+) states of HBS and FBS and the X(2)Pi and A(2)Sigma(+) states of their cations with basis sets as large a s 6-311G(2df,2p). Franck-Condon analyses and spectral simulation were carri ed out on the first two He I photoelectron bands of these species. The theo retical spectra obtained by employing the ab initio geometries, vibrational frequencies and force constants agree well with the observed ones. (C) 199 8 Elsevier Science B.V. All rights reserved.