Migration of interstitials in silicon.

We calculate total configurational energies for interstitial aluminum and silicon in silicon. The calculations, based on the self-consistent Green's function technique, are done for a selective migration path along the "empty" channel in crystalline silicon. Short and long range structural distortions are found to be sizable and strongly varying along the migration path. Carrier capture is possible along the migration path resulting in a drastic dependence of the migration barrier on the nominal charge state of the defect.