First Principles Study of Muon and Muonium in Heme Systems, Nucleic Acids, and Condensed Matter Systems

We have continued our investigations in Transition Metal Impurities in Silicon. We have been concentrating on single TM ions in silicon, specifically Mn0, V2+, Cr+ and Mn2+ in larger clusters, testing for convergence with respect to cluster size. The probable locations of the isolated ions were determined by first-principles investigations of their binding energies at different sites using Hartree-Fock theory1 combined with many-body perturbation theory. From this procedure it was found that the binding energies for V2+ and Mn2+ ions were largest for the Sv site, followed by the Ti site and then the Hi. For Cr+ ion, the binding energies were found to be positive for the Hi and Ti sites but an order of magnitude smaller than for Mn2+ and V2+ ions, with the binding energy for the Sv site very close to zero. For Mn0 atom, both Hi and Ti sites are unstable with negative binding energy, only the Sv site being stable with positive binding energy. For Mn2+ ion, channeling data in Silicon have shown that while the Ti site is the most abundant site for the Mn2+ ion, the Sv site also can be present. The observed greater abundance of the Ti site for Mn2+ in silicon over the Sv site can perhaps be explained by the fact that while the Ti site available in pure silicon, the Sv site requires the presence of substitutional vacancies with low formation probability when the vacancy concentration is low. There was noticeable convergence for these results with respect to cluster size.