Calculation of paramagnetic susceptibilities using electronic atomic axial tensors (or nuclear shielding tensors) and the distributed origin gauge: ethylene oxide

A new procedure for the calculation of paramagnetic susceptibility tensors, χαβp, is presented and implemented for ethylene oxide at the ab initio SCF level of approximation. A relationship between χαβp and the electronic atomic axial tensors, Iαβλ (or, equivalently, the nuclear shielding tensors, ξαβλ(0)) is employed. Iαβλ is evaluated in the distributed origin with origins at nuclei gauge, using both analytical derivative techniques and the random phase approximation. The new procedure is substantially more accurate than the direct calculation of χαβp. Results obtained using the largest basis sets are in excellent agreement with the experimentally derived χαβp tensor.