Equilibrium Crystal Shape of Ni from First Principles

Abstract

We have determined the equilibrium crystal shape of Ni at 0 K using Wulff construction based on 36 orientation-dependent surface energies, which are calculated from first principles. The (111), (100), (110), (210), (221), (311), and (322) surfaces are found in the predicted equilibrium shape based on DFT data, whereas the commonly used broken-bond model predicts that only (111) and (100) surfaces are present. This significant difference of equilibrium shape can be ascribed to the fact that the calculated surface energies show an orientation-dependent deviation from that predicted by the broken-bond model. Moreover, the (111), (100), (110), and (210) surfaces observed in available experiments have also been identified in the present calculations. This indicates that the broken-bond model is insufficient for obtaining the accurate surface energies and their anisotropy of real systems, and the high Miller index surfaces have to be considered to predict the reliable equilibrium shape of the metal.