Molecular dynamics simulation of plastic adamantane

Abstract

The rotational diffusion in the plastic phase of adamantane is studied by molecular dynamics simulation. The investigated system contains 108 molecules and is studied at two temperatures T = 309 K and T = 403 K corresponding to the high temperature rotator phase. The rotational motion consists of rotational jumps between two different molecular orientations. The jumps are identified by using suitable criteria, the most probable correspond to C 4 and C 3 rotations. The jump frequencies corresponding to the different types of rotation are calculated together with the average jump and residence times. The results obtained for the two investigated temperatures show that the rotational motion is a thermally activated process and the activation energies for the different rotations are also calculated.