Charge-density-wave formation by Van Hove nesting in the α-phase of Sn/Ge(111)

4 págs.; 4 figs.We study the role of electron correlations in the formation of the surface charge-density-wave state in the Sn/Ge(111) interface. The Fermi energy of the overlayer is treated as a dynamical variable, which undergoes a substantial renormalization by the interaction. We show that the Fermi level turns out to be pinned to a Van Hove singularity in the density of states, which explains the formation of the charge density wave, the observation of a very flat band in photoemission experiments, and the reduction of the spectral weight in the low-temperature phase. ©2000 American Physical SocietyPeer Reviewe