Tentatively Standardized Symmetry Coordinates for Vibrations of Polyatomic Molecules Part III. Symmetrical X2Y4 Models, with some Related WX2Y4 and W2X2Y4

Abstract

Abstract A theoretic treatment is given for the planar ethylene-like (D2h) model, the corresponding twisted (right-angled) model (D2d), and the general case of D2 symmetry. The correlations between the various symmetry species which pertain to the molecular vibrations of the considered models are explained. Complete sets of symmetry coordinates are proposed. The G matrix is given for the general D2 model. Also the various types of Coriolis couplings are discussed, including the relationships between Cα elements involving the degenerate a and b species in the twisted (D0) model. Some of the most im portant Cα elements are listed. Sets of symmetry coordinates are also given for the allene (D2d) and butatriene (D2h) type models.