Molecular Dynamics Studies of the Dielectric Constant of Dipolar Fluids: Dependence on Molecular Shape

Abstract

We report simulation calculations of the static dielectric constant and other distribution functions for a fluid sample of 125 two-centre Lennard-Jones molecules. The molecular dipole moment was due to equal and opposite partial point charges on the Lennard-Jones centres. The system was varied by keeping density, temperature, molecular dipole moments, centre—centre distance and molecule volume fixed and varying the ratio R of the two Lennard-Jones cr-parameters, while keeping the thermodynamic state roughly constant by suitable adjustment of the Lennard-Jones [sgrave]-parameters. The dielectric constant showed a pronounced minimum at R ≈ 2/3. The dependence of the dielectric constant on R is discussed in terms of the changes observed in the short-range structure of the fluid as R changed.

Key Words:

• Molecular dynamics
• dielectric constants
• dipolar fluids