Second-moment interatomic potential for Al, Ni and Ni-Al alloys, and molecular dynamics application

We present an interatomic potential for Al, Ni and Ni-Al ordered alloys within the second-moment approximation of the tight-binding theory. The potential was obtained by fitting to the total energy of these materials computed by first-principles augmented-plane-wave calculations as a function of the volume. The scheme was validated by calculating the bulk modulus and the elastic constants of the pure metals and alloys that were found to be in fair agreement with the experimental measurements. In addition, we performed molecular-dynamics simulations and we obtained the thermal expansion coefficient, the temperature dependence of the atomic mean-square displacements and the phonon density of states of the compounds. Despite the simplicity of the model, we found satisfactory agreement with the available experimental data.