Atomistic simulations of Cu2O bulk and Cu/Cu2O interface properties by using a new interatomic potential

In this paper, we propose a simple interatomic model for Cu2O bulk and Cu/Cu2O interface properties. The energetic scheme followed here is based on the fixed partial charge model in which the covalent contribution compensates the electrostatic forces in the total cohesive energy. The new interatomic potential is constructed by using the Lennard–Jones functional form for the non-bonded interactions (Cu–Cu and O–O) and the Morse functional form for the Cu–O bonded interaction. From literature, the existing Morse parameters for the Cu–O system overestimate the energetic cohesion between the metal and oxygen at the equilibrium interatomic distance. To address this energy excess we proceed by a new potential parameterization in order to obtain a good relative ratio between the covalent and electrostatic parts in the global energy. The new interatomic potential developed in this study successfully reproduces the bulk cohesive energy and the Cu2O(1 1 1) surface energy. The Cu2O(1 1 1) surface energy is found to be in very good agreement with the predicted ab initio value despite producing slightly different atomic relaxation effects. The behavior of the atomic relaxation on the Cu2O(1 1 1) surface shows that the relaxed surface is less reactive compared to the expected one after energy minimization. These results are consolidated by studying the bonding of the Cu(1 1 1)/Cu2O(1 1 1) oriented interface. The calculated Cu(1 1 1)/Cu2O(1 1 1) interface properties are found to be consistent with the physical concept of interface adhesion. This interface example is also studied in order to capture the interfacial elastic behavior as a function of applied stress normal to the interface plane. The results display an unexpected dependence between the interfacial excess energy and tensile stresses by defining a new interfacial transverse tensor characterizing the dimension of the perturbed interface region. This is a promising result since the misfit strain may play a major role in redefining the elastic tensors of a heterogeneous interface.