Relativistic effects on nuclear magnetic shielding constants in HX and CH3X (X=Br,I) based on the linear response within the elimination of small component approach

J I Melo; M C Ruiz de Azua; C G Giribet; G A Aucar; P F Provasi

doi:10.1063/1.1787495

Relativistic effects on nuclear magnetic shielding constants in HX and CH3X (X=Br,I) based on the linear response within the elimination of small component approach

J Chem Phys. 2004 Oct 8;121(14):6798-808. doi: 10.1063/1.1787495.

Authors

J I Melo¹, M C Ruiz de Azua, C G Giribet, G A Aucar, P F Provasi

Affiliation

¹ Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Cdad. Universitaria, Pab. 1, 1428 Buenos Aires, Argentina.

PMID: 15473737
DOI: 10.1063/1.1787495

Abstract

Numerical calculations of relativistic effects on nuclear magnetic shielding constants sigma corresponding to all one-body operators obtained within a formalism developed in previous work were carried out. In this formalism, the elimination of small component scheme is applied to evaluate all quantities entering a four-component RSPT(2) expression of magnetic molecular properties. HX and CH3X (X=Br,I) were taken as model compounds. Calculations were carried out at the Hartree-Fock level for first-order quantities, and at the random-phase approximation (RPA) level for second- and third-order ones. It was found that values of sigma(X) are largely affected by several relativistic corrections not previously considered in the bibliography. sigma Values of the H nucleus are in close agreement with four-component RPA ones. Overall relativistic effects on the shift of sigma(X) from HX to CH3X are smaller than the nonrelativistic shifts.