On the transferable SETB method for Si

The two types of transferable semi-empirical tight-binding (SETB) method for Si recently proposed by Goodwin et al. (1989) and by Sawada, which are intended to reproduce the binding energies and equilibrium volumes of variously coordinated structures of Si, have been examined and compared with each other. It has been found that there are some drawbacks in the method proposed by Goodwin et al, and that the method proposed by Sawada is much superior. The parameters in the Sawada method have been readjusted in order to apply this method to lattice defects or disordered systems of Si. The present results indicate the importance of incorporating the dependence on the local environment into the repulsive energy in the transferable SETB method. This can be explained by the origin of the repulsive energy.