Analytic Environment-Dependent Tight-Binding Bond Integrals: Application to MoSi2

We present the first derivation of explicit analytic expressions for the environmental dependence of the σ, π, and δ bond integrals within the orthogonal two-center tight-binding approximation by using the recently developed bond-order potential theory to invert the nonorthogonality matrix. We illustrate the power of this new formalism by showing that it not only captures the transferability of the bond integrals between elemental bcc Mo and Si and binary C11b MoSi2 but also predicts the absence of any discontinuity between first and second nearest neighbors for the ddσ bond integral even though large discontinuities exist for ppσ, ppπ, and ddπ.