Eur. Phys. J. D (2015) 69: 167
https://doi.org/10.1140/epjd/e2015-60058-y

Regular Article

Theoretical study of the thermally induced structural fluctuations in sub-nanometre size gold clusters

¹ Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, 78000 San Luis Potosí, Mexico
² Instituto de Física, Universidad Autónoma de San Luis Potosí, 78000 San Luis Potosí, Mexico
³ Departamento de Investigación en Física, Universidad de Sonora, 83000 Hermosillo, Sonora, Mexico

^a e-mail: cabrera@fc.uaslp.mx
^b e-mail: jmmc@dec1.ifisica.uaslp.mx

Received: 29 January 2015
Received in final form: 12 May 2015
Published online: 2 July 2015

Abstract

A reactive potential model and the classical molecular dynamics method (RMD) have been used to study the structure and energetics of sub-nanometre size gold clusters through well-known structural models reported in the literature for Au_N, with N = 19, 20 and 21 atoms. After several simulated-annealing simulations for temperatures up to 1500 K, the Au_N clusters clearly evolve to well-defined structures at room temperature. For the studied gold clusters, the low-lying structures are single- and double-icosahedra with mobile atoms on the surface, in agreement with experimental results on sub-nanometre size gold clusters exhibiting shape oscillations at room temperature and also with those involved in the design of molecules based on gold superatoms [J.-I. Nishigaki, K. Koyasu, T. Tsukuda, Chem. Rec. 14, 897 (2014)]. The evolution of the structural stability of the Au_N clusters under exceptional thermal conditions is analysed by comparing the size and temperature variations of the centrosymmetry parameter and the potential energy. A key understanding of the various possible structural changes undergone by these tiny particles is thus developed. The usefulness of the RMD to study nanometre or sub-nanometre size gold clusters is shown.