A molecular-dynamics study of the anisotropic surface-melting properties of Al(110)

Surface melting of Al(110) was studied by molecular dynamics simulations with a well tested glue potential. We found that the surface began to disorder above 600 K via the formation of adatoms and vacancies. While bulk melting was observed at 945 K (experimental melting point is 933.5 K), the top four atomic layers were found to become liquid-like just before the bulk melts. Both the diffusion constants and the structure factors confirmed that surface melting of Al(110) was anisotropic, with random atom motion faster in the [11̄0] direction than in the [100] direction. On the other hand, in agreement with recent experimental observations [M. Polčik et al., Phys. Rev. Lett. 78 (1997) 491], our calculations showed the presence of a residual order preferentially along the [11̄0] direction via the presence of intact [11̄0] atom chain segments, even above 900 K.