Theoretical Quantum Chemical Study of Benzoic Acid: Geometrical Parameters and Vibrational Wavenumbers

摘要

The structure of benzoic acid as monomer was studied by semiempirical, ab initio, and density functional methods using several basis sets. The performance of these methods in calculating and describing the vibrational frequencies of benzoic acid and several derivatives was determined. The cyclic dimer form of benzoic acid was also reproduced. Two new procedures of scaling the from benzene molecule. For the carboxylic group, scaling equations and specific scale factors at different levels were also determined to be used in benzoic acid derivatives. A reassignment of several bands was done. A comparison of the error in the predicted frequencies was obtained over the one-factor standard scaling procedure.