  We present results from direct, large-scale molecular dynamics (MD)
simulations of homogeneous bubble (liquid-to-vapor) nucleation. The simulations
contain half a billion Lennard-Jones (LJ) atoms and cover up to 56 million
time-steps. The unprecedented size of the simulated volumes allows us to
resolve the nucleation and growth of many bubbles per run in simple direct
micro-canonical (NVE) simulations while the ambient pressure and temperature
remain almost perfectly constant. We find bubble nucleation rates which are
lower than in most of the previous, smaller simulations. It is widely believed
that classical nucleation theory (CNT) generally underestimates bubble
nucleation rates by very large factors. However, our measured rates are within
two orders of magnitude of CNT predictions - only at very low temperatures does
CNT underestimate the nucleation rate significantly. Introducing a small,
positive Tolman length leads to very good agreement at all temperatures, as
found in our recent vapor-to-liquid nucleation simulations. The critical
bubbles sizes derived with the nucleation theorem agree well with the CNT
predictions at all temperatures. Local hot spots reported in the literature are
not seen: Regions where a bubble nucleation events will occur are not above the
average temperature, and no correlation of temperature fluctuations with
subsequent bubble formation is seen.
