AB-INITIO CALCULATION OF THE VIBRATIONAL MAGNETIC DIPOLE-MOMENT

To theoretically explain the vibrational magnetic dipole moment of a m olecule with degenerate vibrational levels, it is necessary to go beyo nd the Born-Oppenheimer approximation. To obtain a nonzero electronic contribution to the vibrational g factor, electronic excited states mu st be included. Moreover, the usual perturbation expression for the vi brational magnetic moment becomes zero for degenerate vibrational stat es, unless higher order perturbation terms are included. For ab initio computation of these magnetic moments two simplified models have been tested by calculating the molecular g factors for the C2H2, HCN, OCS, and NH3 molecules and comparing them to experimental values.