Structural stability and lattice defects in copper:Ab initio, tight-binding, and embedded-atom calculations

Abstract

We evaluate the ability of the embedded-atom method ͑EAM͒ potentials and the tight-binding ͑TB͒ method to predict reliably energies and stability of nonequilibrium structures by taking Cu as a model material. Two EAM potentials are used here. One is constructed in this work by using more fitting parameters than usual and including ab initio energies in the fitting database. The other potential was constructed previously using a traditional scheme. Excellent agreement is observed between ab initio, TB, and EAM results for the energies and stability of several nonequilibrium structures of Cu, as well as for energies along deformation paths between different structures. We conclude that not only TB calculations but also EAM potentials can be suitable for simulations in which correct energies and stability of different atomic configurations are essential, at least for Cu. The bcc, simple cubic, and diamond structures of Cu were identified as elastically unstable, while some other structures ͑e.g., hcp and 9R͒ are metastable. As an application of this analysis, nonequilibrium structures of epitaxial Cu films on ͑001͒-oriented fcc or bcc substrates are evaluated using a simple model and atomistic simulations with an EAM potential. In agreement with experimental data, the structure of the film can be either deformed fcc or deformed hcp. The bcc structure cannot be stabilized by epitaxial constraints.

An embedded-atom potential for the Cu–Ag system

“…Given that the potential generation procedure was similar to the one used previously for Cu [19], both potentials are expected to be nearly equally accurate. Except for experimental thermal expansion factors and Hayes [35].…”

“…Since the parametrization and fitting procedures applied for constructing the Ag potential are very similar to those used previously for Cu [19], only a brief description will be given. The potential is generated directly in the effective pair format [17].…”

Displacement field of a screw dislocation in a〈011〉Cu nanowire: An atomistic study

“…This is possible by considering again a series of additional terms in the image fields whose role is to fulfill the compatibility condition of Eq. (17). The last question we wish to elucidate in this section is the interpretation of the displacement fields u z shown in Fig.…”

Atomic-scale plasticity in the presence of Frank loops

“…a SFE lower than that of usual FCC materials, was retained. Thus, a Cu Embedded Atom Method (EAM) potential developed by Mishin et al [33] with a SFE close to that of austenitic steels at 600 K was employed. Also, since in irradiated materials dislocations glide in pile-ups [6], the leading dislocation is helped by its followers in its glide through the defect environment.…”