Relativistic effects on the nuclear magnetic shielding tensor

JUAN I. MELO, MARTIN C. RUIZ DE AZUA, CLAUDIA G. GIRIBET, GUSTAVO A. AUCAR, AND RODOLFO H. ROMERO

JOURNAL OF CHEMICAL PHYSICS

Año: 2003 vol. 1181 p. 471 - 487

0021-9606

A new approach for calculating relativistic corrections to the nuclear magnetic shieldings ispresented. Starting from a full relativistic second order perturbation theory expression atwo-component formalism is constructed by transforming matrix elements using the elimination ofsmall component scheme and separating out the contributions from the no-virtual pair and thevirtual pair part of the second order corrections to the energy. In this way we avoid a strongsimplification used previously in the literature. We arrive at final expressions for the relativisticcorrections which are equivalent to those of Fukui et al. @J. Chem Phys. 105, 3175 ~1996!# and at some other additional terms correcting both the paramagnetic and the diamagnetic part of the nuclear magnetic shielding. Results for some relativistic corrections to the shieldings of the heavy and light nuclei in HX and CH3X (X5Br,I) at both random phase and second order polarization propagator approach levels are given.