December 05 2002

Bond coloring of 1409 atoms

GAccording to the curvature between two surface atoms, the bonds are colored as red (c<0.7) or dark gray (c>0.7). The xyz files can be downloaded.

Conclusions from papers

G. Bilalbegovic, F. Ercolessi, E. Tosatti Europhys. Lett. 18 (2), 163 (1992).

1. On gold it was found that (at T=1273K) a sharp edge seperates the smooth, flat (111) facet and the rough, rounded region around it.
2. Sharp edges on crystal shape correspond to first-order phase transitions, while smooth edges correspond to second-order phase transitions.
3. Reconstruction of Au(111) is still present at T=1250K (0.94T_m).
4. For Au(111), at T~0.8T_m flat regions with the (111) orientation coexist with additional regions which correspond to a vicinal surface with 22-23 atom wide terrace, clearly stabilized by reconstruction.
5. When the temperature goes closer to the melting point, some Au(111) vicinals undergo a faceting induced by surface melting anisotropy.

D. Passerone, F. Ercolessi, F. Celestini, E. Tossatti Surf. Rev. Lett. Vol. 6, No. 5, 663 (1999).

1. Au(100) surface shows a quasihexagonal reconstruction characterized by an approximate unit cell, arising from the interplay of a slightly contracted and distorted triangular surface layer with the (square) second layer.

2. At a temperature of 0.81T_m, a deconstruction transition occurs, and the long-range haxagonal order paramter vanishes.

T. S. Rahman, Z. Tian, J. E. Black Surf. Sci. 374, 9 (1997).

1. Ag(110): disorder -- 750K, roughen -- 930K, premelt -- 1000K (EAM method).
2. Surface roughening transition is not of the first order but infinite-order (Kosterlitz-Thouless type).
3. Premelting is defined as the ability to diffuse freely between layers. Pair correlation function, 3-D layer-by-layer structure factor, the orientational order parameters are used to check surface premelting.
4. Roughening is examined by height-height correlation function g(R).