We examine two phase coexistence for soft sphere dipolar fluids in an applied field, H. Besides being a fundamental test system for theory, dipolar fluids are used as models for ferrofluids. Gibbs ensemble simulations were performed to determine the coexistence curve and an estimate of the critical temperature, ${\mathit{T}}_{\mathit{c}}$, and density, ${\mathrm{\rho }}_{\mathit{c}}$, as a function of applied magnetic field. In zero field we show that coexistence most likely does not occur and if it does can only do so in a narrow range of densities much lower than predicted theoretically. We discuss the structure of soft sphere dipolar systems, which turns out to be much more complex than previously thought.

• Received 4 February 1994

DOI:https://doi.org/10.1103/PhysRevLett.72.3686