Influence of the potential range on the heat capacity of 13-atom Morse clusters

Heat capacity curves as a function of temperature were studied for 13-atom clusters bound by Morse potentials with different range parameters ${\rho }_0$ ε {3,4,5,6,14} using J-walking Monte Carlo. Decreasing the range of the pair potential (i.e., increasing ${\rho }_0)$ increases the peak of the heat capacity in the melting transition region and decreases the boiling temperature. For ${\rho }_0=14\mathrm{}$ the melting and boiling peaks merge. The short-range potential favors a transition from the catchment region of the icosahedral ground state to the basins of higher minima. On the other hand, clusters bound by the long-range potential $({\rho }_0=3)$ remain in the ground-state basin even for elevated temperatures, which can be explained by the destabilization of important higher minima for ${\rho }_0<4.\mathrm{}$