https://doi.org/10.1140/epjb/e2018-90020-2
Regular Article
Theoretical investigation of the structures of unsupported 38-atom CuPt clusters★
1
Programa de Maestría en Ciencias (Física), División de Ciencias Exactas y Naturales, Universidad de Sonora,
Blvd. Luis Encinas & Rosales, Col. Centro,
83000
Hermosillo,
Sonora, Mexico
2
Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora,
Blvd. Luis Encinas & Rosales, Col. Centro,
83000
Hermosillo,
Sonora, Mexico
3
School of Chemistry, University of Birmingham,
Edgbaston,
B15 2TT
Birmingham, UK
4
Departamento de Investigación en Física, Universidad de Sonora,
Blvd. Luis Encinas & Rosales, Col. Centro,
83000
Hermosillo,
Sonora, Mexico
a e-mail: posada@cifus.uson.mx
Received:
12
January
2018
Received in final form:
18
April
2018
Published online: 18
June
2018
A genetic algorithm has been used to perform a global sampling of the potential energy surface in the search for the lowest-energy structures of unsupported 38-atom Cu–Pt clusters. Structural details of bimetallic Cu–Pt nanoparticles are analyzed as a function of their chemical composition and the parameters of the Gupta potential, which is used to mimic the interatomic interactions. The symmetrical weighting of all parameters used in this work strongly influences the chemical ordering patterns and, consequently, cluster morphologies. The most stable structures are those corresponding to potentials weighted toward Pt characteristics, leading to Cu–Pt mixing for a weighting factor of 0.7. This reproduces density functional theory (DFT) results for Cu–Pt clusters of this size. For several weighting factor values, the Cu30Pt8 cluster exhibits slightly higher relative stability. The copper-rich Cu32Pt6 cluster was reoptimized at the DFT level to validate the reliability of the empirical approach, which predicts a Pt@Cu core-shell segregated cluster. A general increase of interatomic distances is observed in the DFT calculations, which is greater in the Pt core. After cluster relaxation, structural changes are identified through the pair distribution function. For the majority of weighting factors and compositions, the truncated octahedron geometry is energetically preferred at the Gupta potential level of theory.
© EDP Sciences / Società Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2018