CTOCD-DZ shielding polarizabilities in a set of small molecules: N2, H2, HF, HCL, HCN and SH2

Abstract

A procedure based on formal annihilation of the diamagnetic contribution to the quantum mechanical electron current density, via a continuous transformation of its origin all over the molecular domain, CTOCD-DZ method, is applied for determining shielding polarizabilities to first-order in a perturbing electric field. Analytical expressions for the third-rank tensors have been implemented in the SYSMO suite of programs employing the coupled Hartree-Fock approach. In the limit of exact eigen functions to a model Hamiltonian, the CTOCD-DZ expressions reduce to conventional terms. In any calculation relying on the algebraic approximation, irrespective of size and quality of the (gaugeless) basis set employed, all the components of the magnetic shielding polarizabilities evaluated within these methods are origin independent. Test calculations have been carried out in N2, H2, HF, HCl, HCN and SH2 compounds. © 2000 Elsevier Science B.V.