Transformation of ab initio force fields on going to a set of redundant vibrational coordinates in tetrahedral molecular fragments

Abstract

The valence force fields of methane and methanol molecules computed using the quantum-chemical GAMESS package with a set of independent vibrational coordinates in the approximations B3LYP/acc-pVQZ and B3LYP/6-311G**, respectively, have been transformed to a set of redundant vibrational coordinates. It has been shown that the use of the transformed fields enables one to represent in full the initial frequencies of normal molecular vibrations, establishing the field symmetry and making the forms of normal vibrations more adequate and clear.