MOLECULAR ELECTROSTATIC POTENTIALS - A TOPOGRAPHICAL STUDY

The topography of the molecular electrostatic potential (MESP) is stud ied for some small neutral molecules and OH- ion. Different kinds of c ritical points (CP's) of rank 3 are identified and their occurrences a re discussed. The correlation of these CP's with the molecular structu re is brought out. Bond ellipticities are determined in terms of curva tures of bond CP's. These ellipticities show trends similar to those r eported by Bader et al. [J. Am. Chem. Soc. 105, 5061 (1983)]. A typica l example of OH- illustrates the existence of a degenerate nonisolated ring of CP's, which is a rather unique feature of the topology of the MESP of linear molecules. Some suggestive arguments with suitable exa mples, regarding indeterminacy of the nonisolated degenerate CP's have been made.