Mass scaling in the molecular approach: direct correlation among vibrational H2+ and electronic He energy levels

The molecular approach to ABA Coulomb systems is successfully extended to atomic systems. Adiabatic and nonadiabatic energies of some low-lying J = 0 bound states of the helium atom are calculated. These energy levels are directly related to vibrational levels of the hydrogen molecular ion in a correlation diagram, a procedure that is equivalent to mass scaling, relative to the mass ratio λ mA/mB, of the adiabatic and nonadiabatic wavefunction, that has the same analytical form for all λ. (author)