Crystal nucleation is numerically simulated in the Lennard-Jones model. By isobaric cooling and isothermal compression of a liquid, we succeeded in fully crystallizing a large number of systems containing up to 10 000 atoms. We assessed thermodynamic data (density, enthalpy, and chemical potential) of the crystalline as well as the (metastable) liquid phase for considerably larger ranges of pressure and temperature than published so far. Using these data, we were able to confront our simulation results with classical nucleation theories without the need to recognize a critical cluster during the simulations. One of the findings is that in our experiments the steady-state nucleation regime was almost never reached. Careful analysis resulted in an estimate of the time-dependent effects in the nucleation rate, during which the nucleation rate grows from zero to its steady-state value. This way we were able to determine the values of the steady-state nucleation rate, which are consistent with independent estimates for both the preexponential factor and the nucleation barrier. In most previous experimental and simulation studies by other research groups, preexponential factors have been found that are orders of magnitude too large or too small. Our investigations show that an important factor in this discrepancy could be due to an underestimation of time-dependent nucleation effects.

• Received 3 March 2000

DOI:https://doi.org/10.1103/PhysRevB.62.14690