Diabatic molecular states and the shielded diatomic orbital method. Evolution of two-interacting state systems for molecular hydrogen

Within Lichten's method, shielded diatomic orbitals (SDO's) are proposed as a basis set for building-up diabatic molecular states in the single configuration approximation. The determination of SDO's i.e. eigenfunctions in prolate spheroidal coordinates of the two-center problem with a parametric shielding potential is extended to mono-excited states of many-electron diatomic systems, the shielding potential being obtained from simple electrostatic considerations. Four diabatic molecular states of H2 are investigated i.e. 1Σsub(g)+ (2psub(sigma)2, 1Σsub(g)+ (1ssub(sigma), 2ssub(sigma), 1Σsub(u)+ (1ssub(sigma), 4psub(sigma)), 1Σsub(u)+ (1ssub(sigma), 4fsub(sigma)) using a minimal basis of SDO's. The dynamical evolution of the nuclei for the two sets 1Σsub(g)+ and 1Σsub(u)+ of two interacting states is described in both the diabatic and the corresponding adiabatic representation. (Auth.)