Magnetic Shielding in Some Diatomic Molecules

Magnetic shielding constants calculated for all nuclei in LiH, BH, NH, BF, HF, LiF, CO, H2, Li2, N2, and F2 have yielded good results for lighter nuclei bonded to heavier nuclei. The difficult paramagnetic contribution of Ramsey's theory is reduced to tractable terms involving only the ground-state wave function by a choice of the gauge of the vector potential, and by an approximation involving cancellation of average excitation energies of matrix elements depending upon angular momentum and linear momentum operators. The limitations of this approximation are explored.