Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

The structural evolution and dynamics of silver nanodrops Ag${}_{2896}$ (4.4 nm in diameter) during rapid cooling conditions has been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modeled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique is applied to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of $1.5625\times10^{13} Ks^{-1}$ the nanoparticles preserve an amorphous like structure containing a large amount of 1551 and 1541 pairs which correspond to the icosahedral symmetry. For a lower cooling rate ($1.5625\times10^{12} Ks^{-1}$), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the fcc and hcp structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small but in correspondence with the structural changes.