Disordered flat phase separation of the Lennard-Jones fcc(111) surface

SURFACE SCIENCE

卷:460

Letter

Jayanthi, CS ; Celestini, F ; Ercolessi, F ; Tosatti, E

关键词: computer simulations;    equilibrium thermodynamics and statistical mechanics;    low index single crystal surfaces;    molecular dynamics;    noble gases;    surface melting;    surface roughening;    surface thermodynamics (including phase transitions);   

DOI  :  10.1016/S0039-6028(00)00550-1

来源: Elsevier

【 摘 要 】

Recent lattice model calculations have suggested that a full-layered crystal surface may undergo, under canonical (particle-conserving) conditions, a preroughening-driven two-dimensional phase separation into two disordered flat regions, of opposite order parameter. We have carried out extensive classical molecular dynamics (MD) simulations of the Lennard-Jones fcc(lll) surface, to check whether these predictions are relevant or not for a realistic continuous system. Very long simulation times, a grid of temperatures from 2/3 T-m to T-m, and unusually large system sizes are employed to ensure full equilibrium and good statistics. By examining layer-by-layer occupancies, height fluctuations, sublattice order parameter and X-ray structure factors, we find a clear anomaly at similar to 0.83T(m). The anomaly is distinct from roughening (whose incipiency is also detected at similar to 0.94T(m)), and is seen to be consistent with the preroughening plus phase separation scenario. (C) 2000 Elsevier Science B.V. All rights reserved.

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