On the allowed symmetries of all distorted forms of conformers, molecules, and transition structures

Abstract

Based on the catchment region point symmetry theorem, a general framework and some new results are presented on symmetry constraints of deformations preserving chemical identity. The point symmetries of the unique critical point (equilibrium) nuclear arrangement corresponding to a conformer, molecule, or a transition structure and those of a family of nuclear arrangements with an arbitrarily small limit on the allowed distortions provide a complete symmetry characterization of the entire potential surface catchment region of the chemical species. Consequently, the point symmetries of all distorted molecular forms that preserve chemical identity can be deduced by testing symmetry conditions only within an arbitrarily small domain of the potential surface, in the vicinity of the equilibrium arrangement. Additional constraints are deduced on the point symmetries of transition structures obtained directly from the given conformer. Keywords: molecular distortions, symmetry, catchment regions, new symmetry theorems, framework groups, point groups.