  We performed molecular dynamics simulations to study relaxation phenomena
during vapor-liquid transitions in a single component Lennard-Jones system.
Results from two different overall densities are presented; one in the
neighborhood of the vapor branch of the coexistence curve and the other being
close to the critical density. The nonequilibrium morphologies, growth
mechanisms and growth laws in the two cases are vastly different. In the low
density case growth occurs via diffusive coalescence of droplets in a
disconnected morphology. On the other hand, the elongated structure in the
higher density case grows via advective transport of particles inside the
tube-like liquid domains. The objective in this work has been to identify how
the decay of the order-parameter autocorrelation, an important quantity to
understand aging dynamics, differs in the two cases. In the case of the
disconnected morphology, we observe a very robust power-law decay, as a
function of the ratio of the characteristic lengths at the observation time and
at the age of the system, whereas the results for the percolating structure
appear rather complex. To quantify the decay in the latter case, unlike
standard method followed in a previous study, here we have performed a
finite-size scaling analysis. Outcome of this analysis shows the presence of a
strong preasymptotic correction, while revealing that in this case also, albeit
in the asymptotic limit, the decay follows a power-law. Even though the
corresponding exponents in the two cases differ drastically, this study,
combined with a few recent ones, suggests that power-law behavior of this
correlation function is rather universal in coarsening dynamics.
