Atomistic simulation of titanium I. A bond-order potential

The bond-order potential for hcp Ti has been constructed in the framework of a tight-binding description of the binding energy. In this scheme the energy consists of two parts: the bond part that comprises the d-electron contribution to bonding, and a pairwise part. Both parts contain fitting parameters but are treated independently. The bond part reproduces the most important characteristics of the d-band and Cauchy pressures, and the pairwise part complements the bond part so as to reproduce exactly the equilibrium lattice parameters and to a good approximation the elastic moduli. The potential is tested by examining the mechanical stability of the hcp lattice with respect to a variety of large deformations. It is applied to a study of dislocation behaviour in Ti in the accompanying paper, part II.