Using first-principles calculations, we have examined structural stability and electronic states of an atomic wire that consists of a row of dangling bonds formed by extraction of hydrogen atoms from a H-terminated Si(111) surface. This atomic wire is found to be stable. Within the local-density-functional approach, it is electrically conductive due to the appearance of a half-filled state in the energy-gap region of the surface. This wire becomes semiconducting if the Peierls distortion is taken into account, but the total energy gain due to this distortion is estimated to be only 6.5 meV. Silicon atoms with dangling bonds are found not to dimerize as is expected in the usual Peierls distortion condition, but to relax in the direction perpendicular to the wire.
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