The Molecular Symmetry Group; A Personal View of the History of Its Development

This article gives the author's perspective on the history of the development of the molecular symmetry (MS) group. It explains how the initial work of Hougen, which was developed for nonlinear rigid molecules, inspired Longuet-Higgins to introduce nuclear permutations and the inversion as the fundamental elements of molecular symmetry. The symmetry group that is obtained applies to all molecules, rigid or nonrigid. The criticism of Altmann, and the rebuttal of that work by Watson, is described. Altmann's work had the unfortunate effect of delaying the appreciation of Longuet-Higgins' ideas.