The electronic structure of the lattice vacancy in Si in the negative charge state V– were calculated by using the self-consistent charge density-functional theory based tight-binding scheme for the computation of large super-cells containing up to 512 atoms in combination with the linear muffin-tin orbitals method in the atomic-spheres approximation. Many-body effects were treated in the local spin density approximation of the density functional theory. It was found that the ground state of V– was the low-spin 2B1 state of the group C2v, which was lower in energy by 0.09eV than the 4A2 high-spin state of the group Td. Calculations were also made of the hyperfine interactions with 18

shells containing 46 29Si ligand atoms. The largest HF interactions were found in the (1¯10) plane; in agreement with experimental data. The HF interactions with nuclei in the (110) plane, which were about two orders of magnitude smaller than those with nuclei in the (1¯10) plane, also agree with the experimental data. It was concluded that the local spin density approximation of the density functional theory well-described the magnetization density of the V–. It was therefore not necessary to include configuration interactions.

Understanding the Negative Vacancy in Silicon without Configuration Interaction Theory. U.Gerstmann, E.Rauls, H.Overhof, T.Frauenheim: Physical Review B, 2002, 65[19], 195201 (7pp)