Atomically perfect lines of bismuth (200 nm long or more) form in the Si(00
1) surface when a bismuth covered surface is annealed around the bismuth de
sorption temperature. We describe modeling results for the structure of the
se lines based on tight binding calculations, examine evidence for their ex
traordinary perfection, and describe the procedure used to fit the tight bi
nding parametrization. The perfection of the lines is found to arise from a
combination of thermodynamic and kinetic reasons.