WHAT MAKES A POLAR LIQUID A LIQUID

We report computer simulations of the phase behavior of dipolar (ferro) fluids. We consider a model in which the dispersive interactions can be varied independently from the dipolar (magnetic) interactions. The simulation results show that a minimum amount of dispersive energy is required to observe liquid-vapor coexistence. If the dispersive energy is below this threshold, as for example in the dipolar hard-sphere fluid, the system forms chains of dipoles aligning nose to tail. Our simulations did not give any evidence that these ''polymerlike'' systems phase separate into a liquid and vapor phase.