Structures and vibrational frequencies of pyruvic acid: density functional theory study

Abstract

Density functional theory BLYP (using Becke's exchange and Lee–Yang–Parr's correlation functionals ), ab initio Hartree–Fock (HF) and hybrid DFT/HF B3LYP calculations were carried out to study the structure and vibrational spectra of pyruvic acid. Molecular conformation calculations were made for two possible conformers (eclipsed and staggered of C4O8 bond with respect to the methyl group) of the compound. Calculated results show that the stable conformer of pyruvic acid is the eclipsed one. The raw BLYP and B3LYP frequencies approximate the experimental results much better than the Hartree–Fock results, the scaled B3LYP results are more reliable than that of the BLYP and HF methods with the mean absolute deviation about 12.3 cm −1. On the basis of the comparison between calculated and experimental results, assignments of fundamental vibrational modes are examined.