Eur. Phys. J. D (2016) 70: 194
https://doi.org/10.1140/epjd/e2016-70021-1

Regular Article

Structure and electronic behavior of 26-atom Cu-Ag and Cu-Au nanoalloys

¹ Departamento de Ingenierías, Centro Universitario de Tonalá, Universidad de Guadalajara, Jal. 48525 Tonalá, México
² Departamento de Farmacia, Universidad de Guanajuato, GTO. 36050 Guanajuato, México
³ Instituto de Física “Manuel Sandoval Vallarta”, Universidad Autónoma de San Luis Potosí, 78000 San Luis Potosí, México

^a e-mail: gregoriogr@gmail.com

Received: 12 January 2016
Received in final form: 27 April 2016
Published online: 27 September 2016

Abstract

We hereby present a density functional theory (DFT) study of the structural, energetic, and electronic properties of the binary clusters Cu_nX_26-n (with X = Ag and Au). Our electronic calculations were performed with the DFT package GAUSSIAN 09, and we chose the BPW91 exchange correlation functional in combination with an effective core potential LANL2DZ basis set as our level of theory. We find that in the case of these clusters and in a completely different way – as compared to the bulk chemical order observed in both alloys CuAg (segregation) and CuAu (ordering) –, for small n both Ag and Au clusters exhibit a similar chemical order, finding the Cu atoms in the center of the cluster with the tendency to form core shell structures. On the other hand, for large n values the Ag and Au atoms tend to occupy surface positions forming separated surface islands that keep the two metal atoms separated as long as the concentration allows it. Concerning the structural properties, a clear increase in the interatomic distance of the Ag-Ag and Au-Au surface pairs is observed, particularly in the equiatomic region. In conclusion, both nanoalloys CuAg and CuAu behave quite similarly in contrast to their respective bulk cases.