Molecular electrostatic potentials: a topographical study

Abstract

The topography of the molecular electrostatic potential (MESP) is studied for some small neutral molecules and OH- ion. Different kinds of critical points (CP's) of rank 3 are identified and their occurrences are discussed. The correlation of these CP's with the molecular structure is brought out. Bond ellipticities are determined in terms of curvatures of bond CP's. These ellipticities show trends similar to those reported by Bader et al. [J. Am. Chem. Soc. 105, 5061 (1983)]. A typical 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 examples, regarding indeterminacy of the nonisolated degenerate CP's, have been made.