Empirical-potential global minima and DFT local minima of trimetallic Ag<inf>l</inf>Au<inf>m</inf>Pt<inf>n</inf>(l + m + n = 13, 19, 33, 38) clusters

Rafael Pacheco-Contreras, J. Octavio Juárez-Sánchez, Maribel Dessens-Félix, Faustino Aguilera-Granja, Alessandro Fortunelli, Alvaro Posada-Amarillas

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Abstract

© 2017 Elsevier B.V. Using a basin-hopping global optimization method, an exhaustive global search of the potential energy surface (PES) of trimetallic Ag-Au-Pt clusters is performed at the empirical potential (Gupta) level. The clusters contain a total of N = 13, 19, 33, 38 atoms while the Ag, Au, Pt content range from 0% to 100%. A broad region of the PES of these systems is sampled, finding a menagerie of geometries, which are catalogued into structural families according to geometrical considerations. The structural families so defined contain a fixed number of Pt atoms while the loading of Ag and Au atoms varies, and indicate that selective Pt doping can stabilize Ag-Au subnanometer clusters. Structural stability trends are identified thus obtaining the optimal composition for each cluster size. Segregation is analyzed through a chemical order parameter, and found to exhibit a size-dependent behavior, with a transition from mixed to segregated structures clearly evidenced at 38-atom cluster size. Optimal composition structures of the Gupta global minima and a few isomers are subjected to DFT reoptimization, which is found to predict qualitatively similar atomic arrangements with a certain degree of deformation, especially for 38-atom clusters, and to introduce changes in the energy ordering among structures with respect to the Gupta potential predictions, although the stabilizing effect of Pt and a cross-over character of 38-atom size seem confirmed.
Original languageAmerican English
Pages (from-to)30-40
Number of pages11
JournalComputational Materials Science
DOIs
StatePublished - 1 Jan 2018

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