Thermal Evolution of a Platinum Cluster Encapsulated in Carbon Nanotubes

Abstract

A Monte Carlo method has been performed to simulate the thermal evolution of an icosahedral Pt55 cluster encapsulated in the (15, 15) and (20, 20) single wall carbon nanotubes (SWNTs), using the second-moment approximation of the tight-binding potentials for metal−metal interactions. The metal−carbon interactions are modeled by the Lennard-Jones potential, and the carbon atoms on the SWNTs are considered to be fixed. The melting-like structural transformation is found for the icosahedral clusters encapsulated in SWNTs. The melting-like transformation temperatures of the icosahedral clusters encapsulated in SWNTs are estimated from the fluctuations of the total potential energy, which are 280 and 320 K, respectively. The simulations indicate that the melting-like transformation temperature for the encapsulated icosahedral clusters increases with the pore size of SWNTs. At higher temperatures, a stacked structure in layers is found for the encapsulated icosahedral Pt55 clusters. Simulation results reveal that SWNTs have a significant effect on the structures of the encapsulated icosahedral Pt clusters.