  Nucleation in supersaturated vapor is investigated with two series of
molecular dynamics simulations in the canonical ensemble. The applied methods
are: (a) analysis of critical nuclei at moderate supersaturations by simulating
equilibria of single droplets with surrounding vapors in small systems; (b)
simulation of homogeneous nucleation during condensation with large systems
containing 10^5 to 10^6 particles for calculating the nucleation rate of vapors
at high supersaturations.
  For the Lennard-Jones fluid, truncated and shifted at 2.5 times the size
parameter, it is shown that the classical nucleation theory underestimates both
the nucleation rate and the size of the critical nucleus. A surface property
corrected modification of this theory is proposed to consistently cover data on
the surface tension of the curved interface, the critical nucleus size, and the
nucleation rate.
