An estimation of the contribution of Πg electronic states to magnetic shielding asymmetry in HD

To rationalize the recently found (Garbacz et al., 2012) [1] difference in magnetic shielding for H and D nuclei in HD, the contribution of excited Πg states has been considered in combination with a symmetry breaking term in Hamiltonian as perturbation (Moss and Sadler, 1987) [2]. The first order perturbed wavefunctions for the ground and four lowest excited 1 Π g states were estimated. The resulted difference, σD − σH = 0.009 ppm, is close to the experimental value, 0.012 ppm. In this approach, the effect is originated from nuclear mass dependence of matrix elements of the operator, describing the magnetic coupling of the ground and excited states.