Size, shape and structure dependent cohesive energy of gold nanoparticles: empirical many-body potential energy function calculations

A thermodynamic model based on an empirical many-body potential energy function is used, to investigate the stability and energetic features of gold nanoparticles as a function of both size and shape. The concept of a localized atomic bond for surface atoms, and a non-relaxed atomic bond for the interior atoms is used. Among the five different investigated shapes, the qualitative behaviour for the cohesive energy per atom of gold nanoparticles with size range 200 < n < 250 atoms is; sphere < cubic < truncated octahedron <cuboctahedron < octahedron. For the size range 250 < n < 400 atoms is; sphere < cubic < cuboctahedron < truncated octahedron < octahedron. For the size range 400 < n < 700 atoms, a phase transition between truncated trend is; sphere < cuboctahedron < cubic < Octahedron < truncated octahedron; whereas, for n > 1000 atoms, the general behaviour prefers; sphere < cubic <cuboctahedron < truncated octahedron < octahedron. On the other hand, the surface energy for gold nanoparticles is observed to be prominent in the nano-scale and it differs from shape to another, and falls down fast in the size range 200 < n < 1000 atoms having general trend; sphere < cubic <octahedron < truncated octahedron < cuboctahedron.