
%0 Journal Article
%A Kansal, MK 
%A Trikha, SK 
%T Effect of Short-range Repulsive Interactions on the Dynamics of the Methane Molecule
%J Australian Journal of Physics
%D 1993/04/01
%V 46
%N 2
%P 305-316
%K 
%R https://doi.org/10.1071/PH930305
%U https://www.publish.csiro.au/paper/PH930305 
%X Using a computer simulation technique, an attempt has been made to explain the A-type transition in the specific heat of solid methane at around 20 K in terms of the changes in the dynamical behaviour of the methane molecule under the influence of its nearest neighbours. Different exponents of the short-range repulsive interaction occurring in the expression for the potential energy have been tried in order to select the appropriate value. The well known Lennard-Jones (6-12) and (6-15) potentials are found to reveal a phase transition in a well defined region. From an analysis of the direction cosine data, the three-dimensional motion of the central methane molecule has been visualised before and after the transition. Pertaining to the Lennard-Jones potential, the period of the torsional oscillation (libration) of the methane molecule comes out to be of the order of 0·3xlO-12 s. From the computed critical rotational kinetic. energy, the transition temperature is found to be 20·2 K which agrees well with experimental observations. 
