Magnetic screening of nuclei by electrons as manifestation of geometric vector potential

Summary The usual Born-Oppenheimer approach to a molecule in a magnetic field leads to an effective nuclear hamiltonian in which bare nuclei interact with the field. We show that the geometric phase, which has been the object of much interest in recent years, is capable of correcting this defect, accounting for corrections to the molecular charge and magnetic moment due to the electron cloud accompanying the nuclei.