LARGE-DIMENSION LIMIT YIELDS GENERIC REDUCED POTENTIAL CURVES FOR H2-2, HHE+, AND HE-2(2+)(, H)

Analytic expressions for the D --> infinity limit previously evaluated for one- and two-electron diatomic molecules are compared with the fa miliar D = 3 potentials as functions of the internuclear distance R fo r H-2(+), H-2, HHe+, and He-2(2+). We find that the D = 3 potential ca n be obtained from the large-D limit simply by E(3)(R) E(infinity)(R)/ G(R), to good approximation, where the function G(R) has the same form for the four molecules. Furthermore, 1 - G(R) has a corresponding-sta tes property; when reduced by two parameters, it becomes the same func tion for all four molecules, nearly proportional to x(2)e(-2x), with x the scaled internuclear distance. This suggests that the pseudoclassi cal D --> infinity limit may provide a useful reference for analysis o f intermolecular potentials.