ELECTRONIC STRUCTURE AND ELECTRON CHARGE DENSITY IN THE INTERATOMIC BONDS OF <font>BiSBr</font> and <font>BiSeBr</font> CRYSTALS

Electronic structure and electronic charge density in the interatomic bonds are investigated with ab initio calculations based on the density-functional theory. The full potential linearized augmented plane-wave method was used with the generalized gradient approximation. Considering the partial density of states the electron charge density distribution in the Bi , S , Se and Br atomic bonds is caused by Bi-6p , S-3p , Se-4p , Br-4p orbital hybridization. Electronic charge distribution of one BiSBr and BiSeBr molecule range suggest that the Bi – S , Bi – Se and Bi – Br bonds are covalent–ionic type. Bi – S and Bi – Se bonds are strong covalent with a not great ionicity factor ([Formula: see text], Bi – S ; [Formula: see text], Bi – Se ). Bi – Br bonds are covalent type with a larger ionicity factor ([Formula: see text], Bi – Br ). </jats:p