rnWe report a fully self-consistent investigation of the electronic structure, relation between charge transfer and electronegativity, bonding characteristics, and alloying of Al, P, S, and C1 with silicon. The present study indicates that the charge transfer from the host Si atoms to the central impurity atom increases with electronegativity of the impurity element. The bonding between host Si atoms and the impurity atoms is ionic in nature. 0 1996 John Wiley & Sons, Inc. scattering x a (MSX a) method within the framework of the standard muffin tin potential approximation is used. This method, developed by Johnson and Smith E5, 61, has been successfully employed for defects in