A relation between the rotational g-factor and the electric dipole moment of a diatomic molecule

The relation between the rotational g-factor and the electric dipole moment of a diatomic molecule is investigated. An explicit expression for the irreducible nonadiabatic contribution in terms of excited electronic states is derived. The importance of this expression for the analysis of vibration–rotational spectra of diatomic molecules is discussed and explicit expressions are presented for the first two fitting parameters in an expansion of the nonadiabatic rotational term in an effective vibration-rotational Hamiltonian. Results of ab initio self-consistent field, multiconfigurational self-consistent field and second-order polarization propagator approximation calculations of nonadiabatic contributions to rotational g-factors of hydrides and fluorides of Li, B, Al, Ga and monoxides of C, Si and Ge are presented. Problems connected with usage of finite basis sets of one-electron functions in these calculations are discussed.