Non-adiabatic effects on properties of the hydrogen molecular cation and its isotopomers

Abstract

It is shown how accurate non-adiabatic properties of H⁺ ₂, D⁺ ₂ and HD⁺ may be obtained, even for vibrational levels near dissociation. The bond lengths of rotationless levels are calculated and it is reported that, as a function of dissociation energy, non-adiabatic corrections, as well as adiabatic corrections, scale with the reduced mass for the homonuclear ions. For HD⁺, if that part of the non-adiabatic correction due to mass asymmetry is allowed for separately, then the remaining non-adiabatic corrections also scale. However, the ν = 20 level of HD⁺ proves to be anomalous in that its non-adiabatic correction is opposite in sign to those for other levels; this anomaly is discussed. The electric dipole moment of HD⁺ is also studied.