title: Relativistic two-component geometric approximation of the electron-positron contribution to magnetic properties in terms of Breit-Pauli spinors.
abstract: An alternative approach for the calculation of the electron-positron (e-p) contribution to magnetic properties based on two-component Breit-Pauli spinors is presented. In it, the elimination of the small component scheme is applied to the inverse propagator matrix of e-p pairs. The effect of the positronic manifold is expressed as an operator acting on Breit-Pauli spinors. The operator form thus obtained sums up the relativistic correction as a geometric series and as a result a totally different behavior in the vicinity of a nucleus is obtained as compared to the one of the linear response approximation. This feature has deep influence in numerical values of the e-p contribution to the nuclear magnetic shielding of heavy atoms. Numerical calculations carried out for Kr, Xe, and I show that with this approach, the e-p contributions to this property are in good agreement with those of four-component methods.
authors.affiliation: Departamento de Fisica, Facultad de Ciencias Exactas, Fisicoquimicas y Naturales, Universidad Nacional de Rio Cuarto, Ruta 36, km 601, 5800 Rio Cuarto, Cordoba, Argentina.
authors.forename: Daniel
authors.initials: D
authors.lastname: Zaccari
authors.forename: Juan I
authors.initials: JI
authors.lastname: Melo
authors.forename: Martín C
authors.initials: MC
authors.lastname: Ruiz de Azúa
authors.forename: Claudia G
authors.initials: CG
authors.lastname: Giribet