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Free keywords:
Ab initio calculations; Characteristic peaks; Competing models; Electronic systems; First principles; Ground state geometry; Infrared reflections; Quasi-one-dimensional
Abstract:
The anisotropic optical response of Si(111)-(4x1)/(8x2)-In in the mid-infrared, where significant changes in the band structure between competing models of this important quasi-1D system are expected, has been calculated from first principles. Two characteristic peaks are calculated for the hexagon model of the (8x2) structure, but not for the trimer model. The comparison with recent infrared reflection anisotropy spectroscopy (RAS) data-showing the replacement of the anisotropic Drude tail of the (4x1) phase by two peaks at 0.50 eV and 0.72 eV-gives strong evidence for the hexagon model. Our calculations thus settle decades of intense debate about the ground-state geometry of this important prototype for quasi one-dimensional electronic systems.
