The Boundary Condition in the Gibbs Ensemble Simulation of a Stockmayer Fluid under an Applied Field

Abstract

We calculate the vapour-liquid coexistence properties of the Stockmayer fluid with reduced permanent dipole μ∗ = 2.0 under an applied electrostatic field E ₀∗ = 1.0 for various boundary conditions by the Gibbs ensemble simulation. In contrast to the system under no field, the phase behaviour of the Stockmayer fluid under the applied field calculated in simulation strongly depends on the dielectric constant of the surroundings used in the Hamiltonian. We propose that the value of the dielectric constant of the surroundings for the vapour and the liquid phase used in the simulation should be adjusted to that of the system in the corresponding phase, in order to best represent the thermodynamics of the bulk system under applied field.

Key Words:

• Vapour-liquid coexistence
• polar fluids
• applied field