QUANTUM REACTIVE SCATTERING IN 3 DIMENSIONS USING HYPERSPHERICAL (APH) COORDINATES .6. ANALYTIC BASIS METHOD FOR SURFACE FUNCTIONS

We continue development of the theory of reactive (rearrangement) scattering using adiabatically adjusting principal axes hyperspherical (APH) coordinates. The surface functions, functions of the APH hyperangles covering the surface of the internal coordinate sphere, are expanded in analytic basis functions centered in each of the arrangement channels. The rotational functions are associated Legendre polynomials, and the vibrational functions are harmonic functions of an ''anharmonic'' variable which covers an infinite range, allows accurate Gauss-Hermite quadrature, and includes effects of anharmonicity. Example calculations show that these functions provide an efficient basis which can markedly decrease the computational effort required to generate accurate surface functions.