NORMAL COORDINATES-FINITE ELEMENTS CALCULATION OF 3D VIBRATIONAL-ENERGY LEVELS - HENON-HEILES AND ECKART POTENTIALS, H-3(+) MOLECULE

Theoretical and numerical results related to the calculation of multidimensional vibrational levels are presented. A description of the methodological details of a very general method (normal coordinates-finite elements, NC-FEM) is provided. Several representative three-dimensional (3D) systems (Henon-Heiles and Eckart potentials, and the H-3+ molecule) are studied, and NC-FEM results are compared with those published by other authors. For the H-3+, a vibrational Hamiltonian expressed in terms of the three internuclear distances is integrated, and the results obtained are compared with the experimental ones. (C) 1994 by John Wiley & Sons, Inc.