A simple qualitative theory of instability and reconstruction of surfaces of solids exhibiting a certain covalent component of bonding was applied to (2 x 1) Si (001) and (111) surfaces with a possible extension to analogous surfaces of germanium and GaAs (001). Shockley surface states from the vicinity of the Fermi energy were supposed to play a crucial role in the electron-phonon coupling. For the Si (001) surface the interaction between bridge and dangling bonds causes the dimerization (primary effect) and the buckling distortions to couple. If the latter effect was pronounced, the asymmetric dimer might exist as a stable or metastable surface phase. For the Si (111) surface the Pandey π-bonded chain model seems to be a natural candidate for reconstruction from the present simple point of view.

On a Rudimentary Model of Instability and (2 x 1) Reconstruction of Si (001) and (111) Surfaces. M.Tomášek, S.Pick: Czechoslovak Journal of Physics, 1988, 38[1], 97-103