NUMERICAL EVIDENCE FOR BCC ORDERING AT THE SURFACE OF A CRITICAL FCC NUCLEUS

We report a computer-simulation study of the crystal nucleation barrier and the structure of crystal nuclei in a Lennard-Jones system at moderate supercooling. The stable structure of the Lennard-Jones solid is known to be face-centered cubic. We find that the precritical nuclei are predominantly body-centered cubic ordered. But, as the nucleus grows to its critical size, the core becomes fee ordered. Surprisingly, however, the interface of the critical nucleus retains a high degree of bcc-like ordering.