On the melting phase transition of aluminum clusters around 55 atoms

Melting phase transition of atomic clusters has attracted a lot of interest in the last several decades due to their peculiar behaviors different from their bulk counterpart. Investigation of this kind of phase transition leads to the understanding of thermodynamics of finite systems. Recent progress in the experiments measuring thermodynamic properties of sized-selected atomic clusters has motivated the theoretical research interest in this area. In this report, heat capacities of aluminum clusters with around 55 atoms are investigated using extremely long constant energy molecular dynamics simulation with empirical many-body interaction potential. Some features of the heat capacity can be interpreted by the energy spectra obtained from quenches along the trajectories. Dips that emerged in the heat capacities in the previous experiment are not found. Different isomers are taken as the initial structures and found to anneal into the lowest energy structure before melting during the temperature increasing process.