Structures and electronic properties of ultrathin titanium nanowires

The structures of free-standing titanium nanowires are studied by using a genetic algorithm with a tight-binding potential. Helical multi-walled cylindrical structures are obtained and pentagonal packing is found for these thin wires with diameters from 0.747 to 1.773 nm. The angular correlation functions and vibrational properties of nanowires are discussed. We have further calculated the electronic structures of the titanium nanowires with the plane-wave pseudopotential method. Bulk-like continuous electronic bands are found in the Ti wires thicker than 1 nm. The vibrational and electronic properties of titanium nanowire are significantly dependent on the multi-walled structure of the nanowire.