Non-crystalline structures in the growth of silver nanoclusters

The growth of nanometer-size free Ag clusters is studied by Molecular Dynamics simulations. The morphology transition from the icosahedron at the magic size of N = 55 atoms to the Marks truncated decahedron at N = 75 is analyzed in details, in order to single out kinetic trapping and entropic effects. At very low T, the cluster is kinetically trapped in an icosahedral structure, At intermediate T the transition takes place sharply at N similar or equal to 65. At higher T, the transition is smeared out and finally, around 550 K no transition is found because the 75 decahedron is melted.