The band-structure contribution to the force constants of an unrelaxed W(001) system was computed within a tight-binding approach. It was shown that the high density of surface states near the Fermi level gives rise to an enhanced attractive interaction between nearest neighbours on the surface. The attractive nearest-neighbour interaction drives a reconstruction in the surface plane. On the corresponding surface of Ta the surface peak was not occupied and the interaction was less attractive. This could account for the different surface structures observed for the two metals at low temperatures.

Electronic Structure and the Attractive Interaction between Atoms on the (001) Surface of W. D.P.Joubert: Journal of Physics C, 1987, 20[12] 1899-907