PSEUDOPOTENTIAL TOTAL-ENERGY CALCULATIONS OF COLUMN-V ACCEPTORS IN ZNSE

We demonstrate the applicability of a recently developed ultra-soft pseudopotential scheme to the study of point defects in II-VI semiconductors. While conventional pseudopotentials typically treat all but the most loosely bound atomic levels as core states, the present scheme allows us to treat the Zn 3d states with a modest plane-wave cutoff, and thus to include the Zn d-shell as a valence shell. Moreover, the nitrogen p-states can be treated as easily as those of the heavier column-V dopants within this scheme. As a preliminary application, we study the total energy of column-V acceptors (N, P and As) as a function of structural degrees of freedom in ZnSe, with particular attention to the bond-breaking instability which has been proposed by Chadi as a mechanism for dopant self-compensation.