Electronic and structural properties of ultrathin germanium nanowires by density functional theory calculations

Employing the basin-hopping method with the Stillinger-Weber potential and penalty function, four germanium nanowires with the most stable energies were obtained at cross-section radii of 1.8 angstrom, 2.0 angstrom, 2.4 angstrom, and 2.9 angstrom, respectively. Because the coordination numbers and orbital hybridizations of Ge atoms in these nanostructures are different from bulk Ge, their density of states (DOS) profiles are distinctly different from that of bulk. Besides, the discrepancies of DOS among these nanowires arising from different electron density overlaps induce the different Coulomb interactions. Furthermore, the enhanced Coulomb interaction and the quantum confinement in germanium nanowires cause the original p-orbitals below Fermi-level shift up to cross the Fermi-level, which leads Ge nanowires to be conductors. Published by AIP Publishing.