X.S. Zhou

An ab initio-based Er–He interatomic potential in hcp Er

We have developed an empirical erbium–helium (Er–He) potential by fitting to the results calculated from the ab initio method. Based on the electronic hybridization between Er and He atoms, an s-band model, along with a repulsive pair potential, has been derived to describe the Er–He interaction. The atomic configurations and the formation energies of single He defects, small He interstitial clusters (Hen) and He–vacancy (HenV) clusters obtained by ab initio calculations are used as the fitting database. The binding energies and relative stabilities of the HnVm clusters are studied by the present potential and compared with the ab initio calculations. The Er–He potential is also applied to study the migration of He in hcp Er at different temperatures, and He clustering is found to occur at 600 K in hcp Er crystal, which may be due to the anisotropic migration behavior of He interstitials.

Analytical interactomic potential for a molybdenum–erbium system

Analytical interatomic potentials of a molybdenum–erbium (Mo–Er) system are developed based on a Tersoff–Brenner-type form. The potentials well describes the bulk and defect properties of bcc Mo, including lattice parameter, cohesive energy, elastic constants, formation energies of point defects, surface energies and melting point. The adsorption behavior of Er on a Mo (1 1 0) surface is studied using ab initio calculations based on the density functional theory, which is used to fit the interatomic potential of a Mo–Er interaction. The growth mechanism of the Er film on a Mo substrate is investigated using the present potentials. The simulation results show that the microstructures and morphologies of Er films are sensitive to substrate temperatures. Columnar grains of hexagonal close-packed Er parallel to a Mo (1 1 0) surface are observed and the grain sizes increase with increasing substrate temperature.