Poisoning of magnetism in silicon doped with Re, caused by a charge   transfer from interstitials to substitutionals, by means of the   self-interaction corrected density-functional approach
  The self-interaction corrected density-functional calculations are performed for Re impurities and their pairs in silicon. Rhenium ions form in the host crystal not very tight pairs, with impurities separated by one Si atom or by a distance close to two silicon bonds. Comparison of formation energies for various pairs of substitutionals, interstitials, and mixed-site impurities favours the last type. Electron transfer from the interstitial into the substitutional impurity makes the both Re sites nonmagnetic, but the p-type and the n-type co-doping revives magnetism again, the latter more efficiently. 
Malgorzata Wierzbowska
cond-mat.mtrl-sci cond-mat.str-el