PARITY ISSUES, STRESS RESULTS, AND OSCILLATOR-STRENGTHS OF THE ROTATIONAL TUNNELING (H,BE) AND (D,BE) COMPLEXES IN SILICON - THE RIGID ROTOR IN A TETRAHEDRAL FIELD

We apply a model of a rigid rotor in a tetrahedral field to the (H,Be) and (D,Be) complexes in silicon. The issue of [111] versus [100] mini ma is explored within this model, with the latter gaining support for these complexes. It is then shown that parity is nearly a good quantum number for the wave functions when the minima are in [100] directions , even though the Hamiltonian is invariant under operations of the gro up T-d. We then calculate the stress effects on the levels within this model, refuting the notion that [111] stress has no effect when the m inima are in six [100] directions. The stress effects for the small ba sis-set tetrahedral tunneling model are recalculated, and it is found that conclusions that had been drawn must be reevaluated. Also, we pre sent formulas for stress effects in the small basis-set octahedral tun neling model. Finally, a coupling scheme is developed by using symmetr y arguments, and oscillator strengths are calculated for transitions i n both the infrared (hole transition plus rotational sidebands) and fa r-infrared (coupled rotational transitions).