Molecular dynamic investigation of size-dependent surface energy of icosahedral copper nanoparticles at different temperature

The study of the surface free energy (SFE) of metal at nanoscale is far from perfection and the obtained results are approach dependent. Despite the extensive investigations, there is still a lack of a complete model for the surface energy of metallic nanoparticles which could be able to consider effects of the particle size and shape. Most studies emphasize the size dependence of the melting characteristics, rather than considering the lattice deformation and the surface energy of nanoclusters. This research aimed at computation of SFE of copper nanoclusters depending on temperature over a wide range of sizes, containing 147 to 10179 atoms. We employed molecular dynamics simulation by using the embedded atom model and tight-binding Cleri-Rosato potential. Calculations were carried out on icosahedral Cu nanocluster with full-closed surface. This is the most stable shape in our range of sizes. Results of two series of computer experiments, made using the two interatomic potentials in LAMMPS program and our own software, were found to be in good accordance between themselfs. It was established that surface free energy decreases with increasing of cluster size, but grows with elevating of the temperature. Distribution of potential energy upon the inner and surface atoms of particles of various sizes has been performed. It was also revealed that for larger nanoclusters SFE is more sensitive to variation of temperature than one in case of small nanoparticles. The obtained result are very relevant for understanding and manipulating the desired properties of copper nanoparticles in industrial applications.