TRANSFERABLE NONORTHOGONAL TIGHT-BINDING SCHEME FOR SILICON

A minimal-parameter tight-binding theory incorporating explicit use of nonorthogonality of the basis is used to generate a transferable sche me for silicon. Good results are obtained for band structure, phase di agram, and bulk phonons. The diamond structure is found to be the grou nd state even when compared with the clathrate structure. The results for clusters show good agreement with ab initio predictions. The theor y differs from the conventional orthogonal schemes in three main respe cts: (1) only three adjustable parameters are employed, (2) no artific ial cutoff is used for interactions and, (3) the need for a coordinati on-dependent energy term has been obviated for clusters of any size.