THE ROTATIONAL-VIBRATIONAL SPECTRUM OF SYMMETRICAL NONRIGID TRIATOMICS IN HYPERSPHERICAL COORDINATES - THE H-3+ MOLECULE

Theoretical methods are described for the calculation of rovibrational levels of symmetric non-rigid triatomics using the symmetric hyperspherical coordinates of Smith and Whitten. An adiabatic separation of radial and angular motion is shown to be valid for H3+. The adiabatic angular functions are chosen as a linear combination of products of angular-momentum eigenfunctions and specially developed hyperspherical basis functions. Corrections to the adiabatic approximation are included by Brillouin-Wigner perturbation theory. Results are given for the H3+system. The present approach has the advantage that all symmetric arrangements are treated equivalently. © 1990 Taylor & Francis Ltd.