LEED intensity analysis of the clean W(100) c(2×2) surface reconstruction

A LEED structure analysis is performed for the W(100) c(2*2) surface reconstruction. Models with pure vertical displacements of the surface atoms can be clearly ruled out while others with predominant lateral displacements in the (11) and (01) directions result in a very good agreement with the experimental curves. However, a clear discrimination between these models is prevented by the insensitivity of normal incidence spectra to the direction of atomic displacements parallel to the surface. A minimum Pendry r-factor of r=0.26 is achieved for a refined model suggested by Debe and King (1979) with a multilayer relaxation (first inter-layer spacing d₁₂=witht1.47 AA second inter-layer spacing d₂₃=1.60 AA, and a reconstruction in the first and second layer with lateral displacements in the (11) direction (first layer: 0.24 AA; second layer: 0.02 AA).