Development of first-principles calculation program for electron-conduction properties of nanostructures

近年来，通过实验和理论已经观察到通过纳米级结的弹道电子输运的独特现象，如量子化电导。未来对输运性质的研究有望带来纳米科学的新发现和电子器件的新制造。在这项研究中，我们利用类万尼尔函数开发了半无限电极之间悬浮纳米结构的电子传导第一性原理计算程序。利用新开发的程序，我们还发现了有趣的结果：悬浮在半无限电极之间的多壳螺旋金纳米线（HGNs）表现出特殊的电子传导特性。我们的研究结果表明，HGNs中的传导通道数量及其电导率比单原子行纳米线所期望的要小，这证实了最近的实验。此外，我们还得到了一个更惊人的结果，即在薄HGNs的情况下，电子电流在壳层周围螺旋流动会产生不同的磁场。这一发现表明，HGNs可以作为纳米级螺线管的良好候选者。

Recently, the unique phenomena of ballistic electron transport through nanoscale junctions such as quantized conductance have been observed experimentally and theoretically. Future research on transport properties can be expected to lead to new discoveries of nanoscience and novel fabrications of electronic devices. In this study, we have developed first-principles computational program for electron conduction through nanostructures suspended between semi-infinite electrode using Wannier like functions. We have also found interesting result using newly developed program : Multishell helical gold nanowires (HGNs) suspended between semi-infinite electrodes are found to exhibit peculiar electron-conduction properties. Our results that the numbers of conduction channels in the HGNs and their conductances are smaller than those expected from a single-atom row nanowire verify the recent experiment. In addition, we obtained a more striking result that, in the cases of thin HGNs, distinct magnetic fields are induced by the electronic current helically flowing around the shells. This finding indicates that the HGNs can be good candidates for nanometer-scale solenoids.