Close packing of clusters: Application to Al100

The lowest-energy configurations of close-packed clusters up to N=110 atoms with stacking faults are studied using the Monte Carlo method with a Metropolis algorithm. Two types of contact interactions, a pair-potential and a many-atom interaction, are used. Enhanced stability is shown for N=12, 26, 38, 50, 59, 61, 68, 75, 79, 86, 100, and 102, of which only the sizes 38, 75, 79, 86, and 102 are pure fcc clusters, the others having stacking faults. A connection between the model potential and density functional calculations is studied in the case of Al-100. The density functional calculations are consistent with the experimental fact that there exist epitaxially grown fcc clusters starting from relatively small cluster sizes. Calculations also show that several other close-packed motifs exist with comparable total energies