Glass transition in disordered clusters

Using molecular dynamics simulations, the melting behavior of disordered aluminum clusters with 30∼100 atoms has been systematically studied. We find that, all the disordered clusters undergo a glass transition before completely melting. We identify two characteristic temperatures, i.e. T_s and T_g (the glass transition temperature). When the temperature is higher than T_s, the cluster shape starts to change, accordingly the configurational entropy emerges. For temperatures between T_s and T_g, the disordered clusters show a remarkable cooperative diffusion, more importantly, the activation energy of cooperative diffusions below T_g is always lower than that of the liquid state. We have tried to understand such behavior from potential landscape and configurational entropies.