[Comparative analysis of the theoretical methods currently used to study the conformational properties of molecules...

The study of a simple conformational problem, the rotation about the ester bond common to a series of R1COOR2 formula molecules, shows that CNDO/2, INDO and PCILO methods overestimate the interaction term between non bonded atoms. This leads to the prevision of very low barriers and amounts for the CNDO method to the failure in the prevision of some minima. Because of the exaggerated overestimation of this term, the EHT method seems not to be useful except when the steric interaction constitutes the dominant term in the conformation energy.