  A new structural model of Au induced Si(553) surface is proposed. The model
accounts for recently experimentally found value of the Au coverage, i.e. 0.48
monolayer, which suggests formation of two gold chains on each Si(553) terrace.
The resulting structural model, like the models of other vicinal Si surfaces,
features the honey-comb chain, but there is no buckling at step edge, which is
observed on Si(335)-Au and Si(557)-Au surfaces. The present model is more
stable than the models with single Au chain only, and agrees very well with
existing experimental data. In particular, calculated band structure, featuring
two metallic bands coming from hybridization of the gold in both chains with
neighboring Si atoms, perfectly matches the photoemission data. Moreover,
theoretical scanning tunneling microscopy topography remains in excellent
agreement with the experiment.
