From periodic DFT calculations to classical molecular dynamics simulations

Molecular dynamics simulations of bulk TiN have been undertaken using pair wise interaction potentials. The interaction between Ti–N, Ti–Ti and N–N pairs is estimated following a procedure in which the interaction energy between two sets of atoms is estimated from density functional calculations performed with periodic boundary conditions using plane waves as basis set. The pair potentials are expressed as the sum of two contributions: a long range in a Coulomb form, and a short-range term, which includes the rest of the energy contributions. After solving an independent system of equations the potentials are obtained and directly used without further fitting to any analytical expression. Preliminary test simulations of the rock-salt structure of TiN are reported.