Atomic structure and cohesion energy of ZnSe and CdSe clusters

The first-principle calculations of the atomic and electronic structures of fullerene-like Zn$_{n}$Se$_{n}$ and Cd$_{n}$Se$_{n}$ have been carried out for $n$ = 12, 36, 48, and 60. A model of two-layer fullerene-like (ZnSe)$_{60}$ and (CdSe)$_{60}$ clusters with mixed $sp^{2}/sp^{3}$ bonds has been built for the first time. Ab initio calculations are performed in terms of the electron density functional and the hybrid B3LYP functional theory. The stability and the energy gap width of the clusters are estimated in the dependence on the number of atoms in a cluster and its geometry. It is shown that the relaxation of 1.7–1.8-nm two-layer (ZnSe)$_{60}$ and (CdSe)$_{60}$ clusters with mixed $sp^{2}/sp^{3}$ bonds is accompanied by splitting out of the external layer.