JAHN-TELLER COUPLING AT THE SILICON VACANCY

The one-electron linear Jahn-Teller coupling model for the silicon vac ancy fails to explain three key features of the negative charge state: the symmetry and hyperfine interaction for the ground state, the exis tence of six equivalent distortions, and the difference in the activat ion energies for the trigonal and tetragonal distortion reorientations . The inclusion of higher-order Jahn-Teller coupling can remedy these failures by splitting the degeneracy between the (Q(theta),Q(zeta)) ty pe distortions involving an elongation along the tetragonal axis and t hose involving a compression along the tetragonal axis. One such highe r-order coupling scheme is detailed.