Small clusters of II-VI materials:: ZniSi, i=1-9 -: art. no. 053201

The improvements in the characterization of II-VI compound-based solar cells and the recent experimental characterization of small clusters and nanoparticles make the study of small II-VI clusters very interesting. In this work, the ground states of small ZniSi clusters are studied, i = 1-9. Ringlike structures have been found to be the global minima in the case of the smaller studied clusters, i.e., i = 1-5, and three-dimensional spheroid structures for larger ones, i = 6-9. This is doe to the stability of obtuse S-Zn-S angles in the first case, and to the stability gained from higher coordination in the second case. The three-dimensional structures may be envisioned as being built from Zn2S2 and Zn3S3 rings, the last ring being the building block of the zinc-sulfide crystal structures, both zinc blende and wurtzite. As cluster size increases, the geometry of the Zn3S3 rings is closer to the one of bulk. Moreover, this structural tendency produces trends to bulklike properties in other properties such as cohesive energy and atomic charges.