On surface phonons and reconstruction: Comparison of the W and the Fe (001) surface

A phenomenological surface phonon model of the (001) surface of W and Fe is used to clarify some questions related to the problem of which high-symmetry surface phonon mode is the most perspective candidate for the tungsten (001) surface reconstruction observed experimentally. Conditions are derived for the appearance and softening of the relevant modes. The ¯M ₁,¯M ₅ and ¯X ₃ modes seem to be the most promising. A few points from the current literature on the reconstruction problem are discussed. The results seem to support the idea about the general instability of the tungsten (001) surface.