On the relative stabilities of gold nanoparticles

We calculate and compare the relative free energies of ideal/pristine gold nanoparticles for morphologies produced previously in vapor synthesis computer simulations. The results in conjunction with previous work provide a unique and direct quantitative comparison between ideal thermodynamics and kinetics in the synthesis of gold nanoparticles for an identical system. The ideal/pristine free energies suggest that the I(h) morphology was the most stable structure up to the 147(I(h)) followed by the TO(h) for all the remaining nanoparticle sizes. A grouping of m-D(h) structures was identified in the size range N=146-318 with stabilities which were very close to the most stable I(h) and TO(h) structures. The free energy analysis was somewhat at odds with population statistics obtained from our kinetic growth simulations where the I(h) dominated and where very little presumably stable TO(h) nanoparticles were produced, implying that kinetic mechanisms are more influential than thermodynamic considerations. On the other hand other possible reasons for such discrepancies are discussed; one of these includes an interesting observation where the I(h) morphology was found to have a unique ability to incorporate exposed surface disorder such as adatoms into stable hexagonal surface structures through internal and surface structural rearrangements, leading to a possible enhancement in stabilities of I(h)-type morphologies. (c) 2007 American Institute of Physics.