Stability of molecular hydrogen inside C720 fullerene: A path integral Monte Carlo study

Abstract

The stability of H2 molecules trapped inside a 720 carbon atoms fullerene (C720) was studied using the path integral Monte Carlo formalism. The change in free energy with respect to the free molecules as a function of H2 molecules inside the fullerene was computed using alchemy methods coupled to replica exchange algorithms. The most stable number of molecules and the maximum number of molecules that could be trapped inside C720 were obtained at T=300 K and 200 K. Modifications in the interparticle potential were considered to increase the trapping capacity of C720. Four clearly defined concentric layers of H2 in the molecular fluid phase were observed inside the C720 at loading that are acceptable for efficient storages.