VARIATION OF GEOMETRY, VIBRATIONAL FREQUENCIES AND ZERO-POINT ENERGIES WITH INTERNAL-ROTATION

Corrections to calculated potential energy functions for internal rotation in methanol, acetaldehyde and propanal due to the zero-point energies of the other vibrations are calculated by a variety of ab initio methods. En route, the variations of some molecular parameters and vibrational ''constants'' with torsional angle are exhibited, and in particular the correlation between individual methyl CH bond lengths and isolated CH stretching frequencies for methanol and acetaldehyde is demonstrated.