Stability of crystal structures of metallic nanoparticles and their cohesive energy

A model was developed to account for the size, shape and structure dependent cohesive energy of metallic nanoparticles. The cohesive energies of V, Cr, Nb, Mo, Ta, W and Fe were calculated. The results show that the cohesive energy of nanoparticles of bcc structure is the same as that of fcc structure at the critical size and specific shape. When the nanoparticle size is larger than the critical size, the nanoparticles in bcc structure are more stable, but when the nanoparticle size is less than the critical value those in fcc structure are more stable. Furthermore, as the nanoparticles is close to the polyhedral shape, the critical size of polyhedral shape lies in the middle of spherical and tetrahedral shape, which is consistent with the experimental and other theoretical predictions.