Thermo-Stimuli Response of Doped MAu_n^– Clusters (n = 4–8; M = Si, Ge) at Discrete Temperatures: A BOMD Undertaking

Abstract

Gold clusters are emblematic members of the family of nanofunctional materials with unique properties that can be customized through the incorporation of impurities. One such controllable property is catalytic activity. Experimental investigations have demonstrated that, upon the addition of group-14-based atomic impurities such as Si, Ge, and Sn atoms, Au clusters demonstrate augmented catalytic behavior. The present work explores the structural response of such experimentally derived and catalytically active Si- and Ge-doped gold clusters [Au n M– (n = 4–8; M = Si, Ge)] at finite temperatures. The study is carried out using Born–Oppenheimer molecular dynamics (BOMD) within the framework of density functional theory (DFT). Dynamical simulations reveal that the presence of Si impurity imparts a notably higher thermal stability in some cases as compared to Ge impurity or even the parent Au cluster. In some other cases, both of the dopant atoms reduce the thermal stability by 200–300 K with respect to that of the parent Au cluster. The enhanced or reduced dynamical stabilities of the dopant clusters can be explained on the basis of the underlying structural arrangement of atoms and the ensuing electronic properties. The amount of charge retained on the impurity atom and the contributions of the impurity atom to the frontier molecular orbitals (FMOs) play a role in controlling the stability of a given cluster.

Structural exploration of AuxM− (M = Si, Ge, Sn; x = 9–12) clusters with a revised genetic algorithm

“…[39][40][41][42] Few studies have been undertaken on the gold clusters doped with group-14 atoms. 26,[43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] Small Si-doped gold clusters, such as Au 4 Si À1/0 , Au 4 Si 2 À1/0 , Au 2 Si 2 À1/0 , and Au 3 Si 3 À1/0/+1 , have been investigated by Wang et al 26,43,44 The Au/H analogy has been found in the tetrahedral Au 4 Si À1/0 cluster. For Ge or Sn dopant, they also affect the structure of gold clusters by different ways relative to the Si dopant.…”