The hyperfine structure of H⁺₂

Refined variational calculations of the first- and second-order hyperfine interaction coefficients d₁ and d₂ have been performed for the hydrogen-molecule-ion. The electronic matrix elements were carefully stabilized for each coefficient separately and the vibration-rotation wavefunctions calculated from a nuclear potential which yields correct dissociation limits. The resulting values are in good agreement with earlier theoretical and experimental determinations for the N = 2 nuclear rotational levels, and are in impressive agreement with measurements of the N = 1 rotational levels.