It was recalled that, at a given temperature, clean and adatom-covered silicon surfaces usually exhibited well-defined reconstruction patterns. Finite temperature ab initio molecular dynamics calculations showed that the tellurium-covered Si(001) surface was an exception. Soft longitudinal modes of surface phonons due to the strongly anharmonic potential of the bridged tellurium atoms prevented the reconstruction structure from attaining a permanent 2-dimensional periodic geometry. This explained why experiments which attempted to find a definite model for the reconstruction had reached conflicting conclusions.

Te Covered Si(001) - a Variable Surface Reconstruction. P.Sen, S.Ciraci, I.P.Batra, C.H.Grein: Physical Review B, 2001, 64[19], 193310 (4pp)