Bond length dependence of the nuclear magnetic shielding of the hydrogen molecule

Abstract

Self-consistent perturbation theory has been used to obtain the components of the nuclear magnetic shielding tensor of the hydrogen molecule at several values of the internuclear distance. A basis set consisting of 1s and 2p atomic orbitals on each atom was chosen for the ground state. The perturbing magnetic field was allowed to mix in two perpendicular 2p orbitals on each atom. The origin of the vector potential of the field was taken at the bond mid-point. The results show that the nuclear shielding for the field parallel or perpendicular to the bond diminishes as the bond length increases. Furthermore, the shielding with the field along the bond is greater than when the field is perpendicular to the bond, for all the bond lengths dealt with. The shielding anisotropy reaches its maximum at 0·9 A.U.