DISTRIBUTION OF CONFORMATIONAL ENERGY MINIMA IN MOLECULES WITH MULTIPLE TORSIONAL DEGREES OF FREEDOM

In this work, the results of a simple model aimed at explaining the overall distribution of conformational minima for a chain molecule are presented. The model assumes that the conformations can be described in terms of rotational isomers associated with each torsion, as done in polymer statistics. Under the model assumptions, the distribution of potential energy minima can be given a closed, though approximate, form. When compared to a thorough conformational search for aliphatic acids, carried out using molecular mechanics, the present approach is found to account for some of the essential, qualitative features of the distribution. The results can be viewed as a first step toward the development of rules to assess the completeness of conformational searches, as well as in locating ranges that may require further exploration.