ABINITIO (HEH2)+ ENERGY SURFACES AND NONADIABATIC COUPLINGS BETWEEN THEM

The energy surfaces of the three lowest adiabatic states of the (HeH 2)+ triatomic molecular system have been calculated ab initio as functions of all three variables describing the triatomic geometry, using the BRLJHU set of quantum chemistry programs. The procedure is described by the acronym SA-MCSCF/CI, for state-averaged multiconfiguration self-consistent-field calculation, followed by a full configuration interaction calculation. In addition the nonadiabatic matrix elements which couple these adiabatic states have been calculated. Results have been obtained on a sufficiently fine mesh for interpolation by a spline-fit program to produce energy differences and nonadiabatic coupling matrix elements over the full mesh required for collisional excitation problems of He+ on H2 and H2+ on He involving these states. © 1990 American Institute of Physics.