Impact of PES on MD Results of the Coalescence of M2 + M with M = Ir, Pt, Au, Ag.

The accuracy of the Sutton-Chen potential energy surface (PES) for describing atomic interactions in small metal clusters was investigated by comparison with density functional theory (DFT) calculation results. The binding energies calculated using the Sutton-Chen PES for the dimers, trimers, and 8- and 13-atom clusters of four transition metals, Ir, Pt, Au, and Ag, differ from those obtained with DFT calculations. As the DFT results agree well with the available experimental data, the above disagreement indicates that the original Sutton-Chen PES cannot accurately describe the interactions among atoms in the cluster for these metals. The parameters of the Sutton-Chen potential were therefore optimized to the DFT results for each of the metals. Molecular dynamics (MD) simulations were carried out on the coalescence of a dimer with a single atom for these metals. Both the original bulk and the cluster optimized Sutton-Chen PESs were tested with various incident angles and initial kinetic energies. The MD results show that the coalescence is highly dependent on the PES. This demonstrates that use of an accurate PES is critical, particularly at low-energy regime. The kinetic energy, incident angle, and choice of metal were examined for their role in the outcome of the coalescence process.