SELF-INTERACTION-CORRECTED BAND-STRUCTURE OF BLACK-PHASE SMS

We extend a local density (LDA) calculation with self-interaction corr ections (SIG) applied to black-phase SmS with six 4f-states assumed lo calized to the case where the valency of the Sm ion becomes a non-inte ger. We propose the construction of localized molecular orbital (MO) s tates of correct symmetry by superposition of 4fs(5/2) states with a l inear combination of 5d(3/2) states at the adjacent atoms. These orbit als are more extended than pure 4f-states and, therefore, yield a smal ler SIC in dependence of the 5d weight. Simultaneously, this parameter determines the 4f occupancy. Our self-consistent SIC-LDA calculation shows that the correlation between the MO level position and the 4f oc cupancy is consistent with experiment if only one of the six 4f states is treated in this way. If the MO level reaches the bottom of the con duction band a reconstruction of the electronic structure should take place.