Variable-charge interatomic potentials for molecular-dynamics simulations of TiO2

An interatomic potential model has been developed for molecular-dynamics si mulations of TiO2 (rutile) based on the formalism of Streitz and Mintmire [ J. Adhes. Sci. Technol. 8, 853 (1994)], in which atomic charges vary dynami cally according to the generalized electronegativity equalization principle . The present model potential reproduces the vibrational density of states, the pressure-dependent static dielectric constants, the melting temperatur e, and the surface relaxation of the rutile crystal, as well as the cohesiv e energy, the lattice constants, and the elastic moduli. We find the physic al properties of rutile are significantly affected by dynamic charge transf er between Ti and O atoms. The potential allows us to perform atomistic sim ulations on nanostructured TiO2 with various kinds of interfaces (surfaces, grain boundaries, dislocations, etc.). (C) 1999 American Institute of Phys ics. [S0021-8979(99)07618-5].