A GLOBAL APPROACH TO MOLECULAR SYMMETRY - THEOREMS ON SYMMETRY-RELATIONS BETWEEN GROUND-STATE AND EXCITED-STATE CONFIGURATIONS

Several simple rules have been derived, providing new insight into the role of point symmetry in controlling the energetic stability of molecules and excited-state species. General symmetry conditions have been found that interrelate the ground-state and electronic excited-state energy minima, transition structures and other stationary nuclear arrangements of neutral molecules and ions, and excimers and exciplexes. By testing the point symmetry of a family of nuclear arrangements, one can predict the existence of stationary nuclear configurations within domains of a whole series of ground- and excited-state potential energy surfaces. The catchment region point symmetry theorem and various vertical symmetry theorems provide new tools for the analysis of potential surfaces and a rational strategy for the search for stationary points. The applications of the theorems are illustrated by examples. © 1990, American Chemical Society. All rights reserved.