Dimer Reconstruction of Diamond, Si, and Ge (001) Surfaces

Ab initio calculations of structural and electronic properties of the C(001)-(2 ×{} 1) diamond surface are reported and discussed in direct comparison with Si(001) and Ge(001). Our results strongly favor a symmetric dimer reconstruction of C(001)-(2 ×{} 1) as opposed to an asymmetric dimer reconstruction of Si and Ge (001). The physical origin and quantitative nature of the dimer reconstructions are investigated systematically, and it is shown by analyzing chemical trends why Si(001) is the most subtle case for an unequivocal surface structure determination.