  Kinetics of phase separation in a three dimensional single-component
Lennard-Jones fluid, that exhibits vapor-liquid transition, is studied via
molecular dynamics simulations after quenching homogeneous systems, of
different overall densities, inside the coexistence region. For densities close
to the vapor branch of the coexistence curve, phase separation progresses via
nucleation of liquid droplets and collisions among them. This is different from
the evaporation-condensation mechanism proposed by Lifshitz and Slyozov, even
though both lead to power-law growth of average domain size, as a function of
time, with an exponent $\alpha=1/3$. Beyond a certain threshold value of the
overall density, we observe elongated, percolating domain morphology which
suddenly enhances the value of $\alpha$. These results are consistent with some
existing theoretical expectations.
