Structural and thermodynamic properties of Au2-20 clusters

Isolated neutral gold clusters with 2-20 atoms are studied theoretically using a parametrized density-functional tight-binding method combined with genetic algorithms. The structural and energetic properties are analyzed by studying the total energy per atom, the relative stability, the overall shape, and through a common-neighbor analysis. In addition, the temperature dependence of the vibrational heat capacities of the optimized gold clusters has been studied for the first time. We find the vibrational heat capacity of the clusters to be strongly size dependent at low temperature. For instance, the cluster with 6 atoms has a high vibrational heat capacity at low temperature, a finding rationalized in terms of structure.