Many-body calculations of hyperfine constants in diatomic molecules. II. First-row hydrides

Abstract

Magnetic hyperfine parameters (Frosch and Foley parameters) have been computed for first-row diatomic hydrides by use of many-body perturbation theory. The computations are complete to third order in the many-body expansion, which means that core polarization corrections are included through second and thrid order, and correlation effects by their leading third-order corrections. Computed results are presented for the ground states, and in addition for the three excited states A 2Δ, A Π, and A 2Σ in CH, NH, and OH, respectively. The vibrational dependencies of the hyperfine parameters were also predicted, and even a hyperfine centrifugal distortion constant observed for CH was computed, in good agreement with experiment. Good agreements between computed and experimental parameters were generally obtained, in particular for the ground states, where the errors in the computed values are at most a few percent.