Theoretical study of the atomic and electronic structure of the (111) surface in ZnSe and CdSe crystals

Abstract

For the first time ab initio calculations of the atomic and electronic structure of four variants of the polar surfaces ZnSe and CdSe (111)–(2 x 2) cation–terminated: ideal, relaxed, reconstructed and reconstructed with the subsequent relaxation have been performed. In the approximation of a layered superlattice the surfaces were simulated by a film with a thickness of 12 atomic layers and a vacuum gap of ~1,6 nm. To close the Se dangling bonds on the opposite side of the film 4 fictitious hydrogen atoms with a charge of 0,5 electron each were added. Ab initio calculations have been performed using the program QUANTUM ESPRESSO based on the density functional theory. It is shown that the relaxation leads to the splitting of the layers. Band structures as well as full and layered electronic densities of states have been calculated and analyzed for 4 surface variants.