Computer simulation of polar liquids the influence of molecular shape

Adding an electrostatic term to the three centre Lennard-Jones potential used for liquid carbon disulphide some time ago, the structure and dynamics of this polar model fluid is studied by the molecular dynamics method. Two simulations with (εR = ∞) and without (εR = 1) long range corrections were carried out. Each run covered 1500 time steps (= 15 ps). From the g-coefficient analysis it is concluded that the anisotropic steric forces over-whelm the electrostatic ones. The average cosine and the average dipole energy exhibit a detailed finite structure. The oscillating sign of the average cosine leads to a quenching of the Kirkwood g-factor so that deviations from the Onsager equation do not exceed 30 per cent. As compared with the effect on the structure, the electrostatic term has a great influence on the dynamics. Respective dynamical constants are approximately doubled.