The Rotational Zeeman Effect of Molecules with Low Barrier Internal Rotation. II. Derivation of the Effective Rotorsional Hamiltonian

Abstract

Abstract Theoretical expressions for the molecular parameters in the effective rotorsional Hamiltonian in a strong magnetic field are derived from a second order perturbation treatment within the electronic states which was adapted to the presence of a large am plitude internal motion. The technique developed m ay be o f use also in other applications where it should be necessary to go beyond the Born-Oppenheimer approximation. By use o f the theoretical expressions it is now possible to use experimentally determined Zeeman data to derive “experimental values” for the molecular electric quadrupole moments, the paramagnetic susceptibilities, the second m om ents o f the electron charge distribution, and the sign of the molecular electric dipole moment also for low barrier molecules.