Atomistic simulation of copper-vacancy clusters in bcc-Fe

We have investigated how the lattice vibrations affect the thermodynamics of nanosized coherent clusters in bcc-Fe consisting of vacancies and/or copper. The study is carried out within the harmonic approximation. We have applied a combination of on-lattice simulated annealing based on Metropolis Monte Carlo simulations and off-lattice relaxation by molecular dynamics in order to find the most stable cluster configurations at 0 K. We have used the most recent interatomic potential built within the framework of the embedded-atom method for the Fe–Cu system. For finite temperatures, we determined the total free energy of pure bcc-Fe and fcc- Cu as well as the total formation free energy and the total binding free energy of the vacancy–copper clusters. Our results are compared with the available data from previous investigations performed using many-body interatomic potentials and first-principles methods.