| Abstract
| - We report on the atomic structure and energetics of H-passivated silicon nanowires that are oriented alongthe [112] crystallographic direction and have effective diameters of approximately 1 nm and below. Using agenetic algorithm structural optimization followed by ab initio density functional theory calculations, we findthat at certain values of the hydrogen chemical potential the nanowires can take relatively stable (magic)structures with rectangular cross sections bounded by monohydride {110} and {111} facets with dihydridewire edges. Variations in the chemical potential of hydrogen alter the wire structures retrieved by theoptimization, the most prominent example of this being that the {111} nanofacets acquire trihydride terminationsinstead of monohydride ones when the H chemical potential is raised. While the trihydride-passivated wireshave already been experimentally observed, the magic-number monohydride-facetted wires found here mayserve as useful predictions to be tested in the future.
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