By using first-principles calculations, a theoretical investigation was made of the surface reconstruction caused by the adsorption of Sr on the Si (001) surface. For Sr coverages below ½ML, the system behaviour was dominated by charge transfer between Sr and silicon that resulted in the so-called unbuckling of Si dimers. At a higher coverage, the surface began to so-say undimerize. At 1ML coverage, a geometrical size constraint induced a series of reconstructions such as 3x, 5x, 7x, etc.; characterized by 1 x 1 reconstructed patches, separated by a dimer row. Calculations of the surface energy as a function of coverage suggested that, for 1ML of Sr, 3x, 5x and 7x reconstructions of the surface were preferred under Sr-rich conditions; in good agreement with experiment.

Theory of the Sr-Induced Reconstruction of the Si (001) Surface. A.A.Demkov, X.Zhang: Journal of Applied Physics, 2008, 103[10], 103710