Structure and thermal stability of gold nanoclusters: The Au-38 case

Cold nanoclusters with disordered and ordered structures are obtained as th e lowest-energy configurations of the cluster potential energy surface (PES ) by unconstrained dynamical and genetic/symbiotic optimization methods usi ng an n-body Gupta potential and first-principle calculations [Phys. Rev. L ett. 81., 1600 (1998)]. In this paper, we report the distribution of lowest -energy minima which characterize the PES of the Au-38 cluster, and a compa rison of structural and thermal stability properties among several represen tative isomers is presented. Coexistence among different cluster isomeric s tructures is observed at temperatures around 250 K. The structure factor ca lculated from the most stable (lowest-energy) amorphous-like cluster config uration is in better agreement with the X-ray powder-diffraction experiment al measurements than those calculated from ordered structures.