PRELIMINARY-STUDY ON THE CHARGE-TRANSFER AND BOND IONICITY OF BINARY CRYSTALS

Charge transfer and bond ionicity of some monovalent, divalent, and tr ivalent binary crystals of A(N)B(8-N) type have been investigated usin g the self-consistent method. The method divides the binary crystal sy stems into two subsystems which contain only one kind of element each in physical space. The charge transfer values are obtained by adjustin g the charge in a self-consistent way. Based on the obtained charge tr ansfer values, an empirical formula for bond ionicity has been propose d. It has been shown that the present results for bond ionicity are in good agreement with the previous theoretical study delivered by Levin e and Pauling. The results also indicate that a large magnitude of cha rge transfer (or less excess charge in the bonding region) gives rise to high bond ionicity (or low bond covalency); this agrees well with t he viewpoint that the excess charge in the bonding region is the origi n of the formation of bond covalency. (C) 1998 American Institute of P hysics. [S0021-9606(98)00837-X].