A tier model calculation of the absorption spectrum of the fourth CH stretch overtone state CH(v=5) in benzene

The absorption spectrum of the fourth CH stretch overtone state CH(v=5) in benzene has been calculated quantum mechanically using a completely symmetrized vibrational basis set and a combined local mode normal mode model, including all 30 molecular vibrations in the calculations. An artificial intelligence search procedure, based on a tier model, with subsequent time and memory saving Lanczos tridiagonalization was employed in the calculation. The dependence of the spectral shape upon the number of tiers included, has been studied.