First-principles study on the relaxed structures and electronic properties of Fe nanowires

Under GGA, the relaxed structures and electronic properties have been investigated for Fe nanowires with cross-sections of 3×3, 5×5, 7×7, 9×9 and 11×11 atom layers by using the first-principles PAW potential within DFT. For all five-size nanowires, the inward relaxed structures still have the C4 symmetry and show a “round corner” phenomenon. An increase in the distance of the atoms away from the central axis of the nanowires and thus a decrease in the number of the neighbor atoms lead to not only a driving down the DOS in lower energy region and a driving up the DOS in higher energy region below the Fermi level but also a decrease in the atomic total charge. The enhanced interactions appear between the surface atoms as well as between the surface atoms and their near neighbor atoms, but such a “skin effect” decreases with increase in the nanowire size. And it may lead to the mechanical and electronic transport properties of the nanowire being different from the bulk. In fact, the conclusions drawn here are applicable to not only the nanowires but also the other structures, such as nanobelts, nanotubes, nanocables, clusters, thin films, etc.