DFT (LSDA, B3LYP and B3PW91) comparative vibrational spectroscopic analysis of alpha-acetonaphthone.

FT-IR and FT-Raman spectra of alpha-acetonaphthone have been recorded and analyzed. The geometry, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) B3PW91/6-311G method and also a comparative studies between different levels and various basis sets combination. The scaled B3PW91/6-11G results are best, even though LSDA/6-311G wavenumbers are well in agreement before scaling. The complete vibrational assignments of wavenumbers are made on the basis of potential energy distribution (PED). The effects due to the substitutions of methyl group and carbon-oxygen bond are investigated. The results of the calculations are applied to simulated spectra of the title compound, which shows excellent agreement with observed spectra.