Molecular dynamics simulations of simple monatomic amorphous nanoparticles

Abstract

Monatomic amorphous nanoparticles were studied in a spherical model containing different numbers of atoms ranging from 1189 to 9093 by using molecular dynamics method under nonperiodic boundary conditions. We use the double-well interaction pair potential developed by Engel and Trebin, and amorphous nanoparticles were obtained by cooling from the melts. The structural properties of nanoparticles were studied via radial distribution function, mean atomic distances, coordination number, and bond-angle distributions. In addition, we also analyzed local order in nanoparticles by using the technique proposed by Honeycutt and Andersen, and we found the existence of icosahedral order in the system. We found strong size effects on the static properties of nanoparticles. Aging effects on the structure of nanoparticles were also observed and discussed. The radial atomic density profile of nanoparticles was found and discussed. On the other hand, the surface and core structures of nanoparticles were studied in detail. Moreover, we found the size dependence of several quantities such as the glass transition temperature (Tg), the potential energy, and surface energies of nanoparticles. The mean-squared displacement of atoms was discussed. © 2008 The American Physical Society.