Embedded‐Atom Method for Surface Lattice Dynamics in Copper

Abstract

AbstractThe embedded‐atom method (EAM) based on results from density functional theory is applied to surface lattice dynamics. From the model within the framework of the EAM, the formula of surface interplanar force constant and surface lattice dynamical matrix are derived. It is found that the EAM can distinguish well the difference between atomic interactions in the bulk and near the surface without any additional parameter by its description of many‐body interaction. It is also found that the changes of surface force fields in the EAM are caused not only by the changes of interatomic distances but also by the changes of electron density background, which is quite different from ordinary empirical potential models. As an example, in the quasiharmonic approximation, the surface interplanar force consants and the surface‐phonon dispersions on unrelaxed Cu(100), (110), and (111) surfaces are calculated and analyzed without any adjustable parameter. The calculated results are in good agreement with experimental data by electron‐energy‐loss‐spectroscopy (EELS) and inelastic helium scattering. Although only the vibrational properties of Cu unrelaxed surfaces are calculated, it can be concluded that the EAM gives two competitive physical reasons affecting surface force fields: interatomic distances and electron density backgrounds.