Ab Initio study of the electric-field gradient at Cd-doped SnO

L.A. ERRICO, M. RENTERÍA, AND H.M. PETRILLI

Foz de Iguazú, Brasil

Conferencia; 14th International Conference on Hyperfine Interactions & 18th International Symposium on Nuclear Quadrupole Interaction; 2007

UNLP, UNCor, CBPF, USP, UFES

We perform a first principles study of the electric-field gradient (EFG) at the nucleus of Cd impurities substituting Sn atoms in crystalline SnO. The Projector Augmented Wave and the Full-Potential Linearized-Augmented Plane Wave methods allow us to treat the electronic structure of the doped system and the atomic relaxations originated by the impurities in the host neighborhood in a fully self-consistent way using the supercell approach in a state-of-the-artway. Nevertheless, the use of a supercell approach, when dealing with a non periodic system, requires some further tests when the aim is to model the extreme dilute limit. These tests are usually limited by the available computer resources since they deal with the enlargement of the supercell, what increases very rapidly the computer cost of the calculation. Since the EFG is a very subtle quantity that strongly depends on fine details of the electronic wave function near the impurity nucleus, its determination is very useful to probe ground-state properties such as the charge density. Effects of the charge state of the impurity on the electronic and structural properties of the system are also discussed. We show that the structural effects induced by the defect play a fundamental role in the understanding of the local electronic structure of this impurity-host system. Our theoretical EFG predictions are discussed in the light of available experimental results at Cd sites in SnO coming from gamma−gamma PAC experiments and compared with other binary oxides doped with Cd. The presence of spin polarization is also discussed.