Molecular dynamics simulation of liquid chloroform

Abstract

A molecular dynamics simulation of CHCl₃ is reported using a 5 × 5 Lennard-Jones atom-atom potential with partial charges at each atomic site. Thermodynamic and spectral properties have been computed for direct comparison with a range of experimental measurements. In general the agreement is good, given the semi-empirical nature of the pair potential used. Having checked the efficiency of the simulation in this way it is possible to use the algorithm to investigate molecular properties of liquid CHCl₃ which are not easily detectible with experimental or purely (non-numerical) theoretical methods. A range of mixed autocorrelation functions of the type 〈A(o)B(t)〉 has been used in this way to investigate: a) non Gaussian effects in the liquid state of CHCl₃; b) non-linear effects; c) rotation/translation effects too subtle for detection with present-day spectroscopic methods. It is clear that the classical theory of the Brownian motion [12] is in need of development because the simulation shows that it is not possible to factorise conditional probability density functions of rotation and translation into purely constituent parts. The pair-potential could be improved if measurements on the second dielectric virial coefficient of CHCl₃ vapour were to become available over a sufficient range of density.