Interpretation and accurate prediction of vibrational spectra—a modified ab initio scaled quantum mechanical approach

Abstract

A novel method is described to obtain a scale factor for each force constant in the force constant matrix as a quantitative measure of the systematic error in ab initio methods. These scale factors offer a simple solution to the problem of interpretation and prediction of vibrational spectra using the scaled quantum mechanical (SQM) approach. The advantages of the method are illustrated using benzene, acrolein, pyridine and benzaldehyde as examples. This method also simplifies the traditional, tedious way of performing normal coordinate analysis.