Tight-binding interatomic potentials based on total-energy calculation: Application to noble metals using molecular-dynamics simulation

We present an alternate approach to parametrizing the expression for the total energy of solids within the second-moment approximation (SMA) of the tight-binding theory. In order to obtain the necessary parameters, we do not use the experimental values of the lattice constant, the elastic constants, and the cohesive energy, but we fit to the total energy obtained from first-principles augmented-plane-wave calculations as a function of volume. In addition, we shift the total-energy graphs uniformly so that at the minimum they give the experimental value of the cohesive energy. We have applied the above methodology to perform molecular-dynamics simulations of the noble metals. For Cu and Ag our results for vacancy formation energies, relaxed surface energies, phonon spectra, and various temperature-dependent quantities are of comparable accuracy to those found by the standard SMA, which is based on fitting to several measured data. However, our approach does not seem to work as well for Au.