Theoretical comparison of conformational properties of molecules: Conformational probability maps and similarity index

The conformational analysis for a molecule is often performed by assuming that the total conformational energy is a function of two dihedral angles. The resulting conformational energy map is sometimes not easy to interpret because what counts is not energy differences but rather the probability distribution map at a given temperature. In the present article, an algorithm to calculate such a map is given. An example concerning N ‐substituted amino sugars shows how the conformational probability map may be interpreted. In addition, a similarity index is proposed to get a measure of similarity of the conformational properties of two molecules. The index is based upon the analysis of the conformational probability maps for both molecules. © 1993 John Wiley & Sons, Inc.