
TY  - JOUR
A1  - Kansal, MK 
A1  - Trikha, SK 
T1  - Effect of Short-range Repulsive Interactions on the Dynamics of the Methane Molecule
JF  - Australian Journal of Physics
JO  - Aust. J.  Phys.
Y1  - 1993
VL  - 46
IS  - 2
SP  - 305
EP  - 316
KW  - 
UR  - https://doi.org/10.1071/PH930305 
N2  - 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. 
ER  -

