Vibronic Energy and Dipole Moment of HD

The HD molecule has been treated by perturbation theory using the complete nonrelativistic four-particle Hamiltonian. In the zeroth order the calculations have been carried out with a 147-term variational wavefunction. The resulting energies and expectation values of several operators for the ground state and for the first vibrationally excited state are reported. The computed ground-state dissociation energy, D0, is by 1.9 cm−1 larger than the experimental value. By treating the mass difference of the nuclei as the perturbation parameter, a 103-term correction function was computed which yields the second-order correction to the energy E(2)=−0.04664 cm−1, and the dipole moment of the molecule μ=1.54 10−3 D.