  The phase transition between a massive dense phase and a diluted
superparamagnetic phase has been studied by means of a direct molecular
dynamics simulation. The equilibrium structures of the ferrofluid aggregate
nucleus are obtained for different values of a temperature and an external
magnetic field magnitude. An approximate match of experiment and simulation has
been shown for the ferrofluid phase diagram coordinates "field-temperature".
The provided phase coexistence curve has an opposite trend comparing to some of
known theoretical results. This contradiction has been discussed. For given
experimental parameters, it has been concluded that the present results
describe more precisely the transition from linear chains to a dense globes
phase. The theoretical concepts which provide the opposite binodal curve
dependency trend match other experimental conditions: a diluted ferrofluid, a
high particle coating rate, a high temperature, and/or a less particles
coupling constant value.
