Systematics of structural and cohesive properties, Debye temperature and melting transition of Au nanoclusters: A multimethod theretical study

ARMANDO FERNÁNDEZ GUILLERMET; DALÍA S. BERTOLDI

Congreso; Discussion Meeting on Thermodynamics of Alloys (TOFA 2016); 2016

Thedevelopment of methods to establish and systematize the properties ofnanoclusters is at present an issue of considerable theoretical and practicalinterest. In particular, the question may be stated about the possibility ofdeveloping an integrated picture of the manner by which the structural andthermodynamic properties change with the size of the clusters. This problem hasbeen studied in the present work by focusing on Au nanoclusters and applyingvarious methods, as follows. In the first place molecular dynamics (MD) simulationsusing the LAMMPS code [1] are used to establish the size dependence of thestructural properties, the energy of formation from the macroscopic solid andthe cohesive energy. In the second place, the size-dependence of thetemperature, energy and entropy of melting are determined by combining MDsimulations and thermodynamic calculations. Finally, the size dependence of theDebye temperatures for Au nanoclusters is analyzed by comparing the predictionsof two methods. The first method is based on Lindemann´s formula relatingmelting temperature and Debye temperature. The second method, a theoreticalone, relies on the predictions of a recently presented modification of theDebye formalism, which takes into account the main physical features of a nanoscalecrystal [2]. On this basis, a discussion is reported of the frequently reportedDebye temperature estimates for nanoclusters based on the Lindemann approach