Experimental Born-Oppenheimer Potential for the X1Σ +Ground State of HeH +: Comparison with the Ab InitioPotential
All literature on vibration-rotational and pure rotational transition energies for theX1Σ+state of4HeH+,3HeH+,4HeD+, and3HeD+have been employed in a direct least-squares fit of the radially dependent Hamiltonian. The Born-Oppenheimer potential is represented by a modified Lennard-Jones function that provides for correct behavior in the near dissociation long-range region. Only 19 adjustable parameters were required to represent the 166 measured transition energies, which are reproduced almost to within the measurement accuracies. The fitted potential and Born-Oppenheimer breakdown functions are shown to be in good agreement with the results ofab initiocalculations. The results are used to obtain high-order centrifugal distortion constants as well as level widths for quasi-bound levels.