SPECTROSCOPIC SIGNATURES OF BOND BREAKING INTERNAL ROTATION IN HCP

Abstract

Changes in the eigenvalue structure in the vicinty of a saddle-point on the potential energy suface are illustrated by semi-classical and quantum mechanical studies on model potential energy surfaces for HCP. The following points are addressed: (a) The connection between classical periodic orbits and Fermi resonace polyads, and the breakdown of the polyad model as the bending frequency tunes out of 2:1 resonance with the CP stretch250 (2001)}. (b) The observation of 'quantum mondromy' in the underlying spherical pendulum model, and its influence of the values of the spectroscopic vibration-rotation parameters, as the H atom approaches the P end of the molecule, 262 (2001).}. (c) A possible formulation of the spectroscopic theory at the saddle point in terms of spherical pendulum eigenstates, and the nature of the relevant matrix elements, 8446 (2001).}.