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By performing first-principles calculations, we study Li doping in a double-wall carbon nanotube where a (5,0) tube is confined inside a (14,0) tube. There are three possible sites for Li doping and two of them are energetically favorable. The change of energy band structure is closely related to the doping sites and the charge transfer is investigated. Bader charge analysis indicates that Li prefers to donate its electron to the inner (5,0) tube. Moreover, the Li capacity of the system can reach LIC4.75 which makes it a promising candidate for Li-ion battery materials. 相似文献
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The phonon dispersion relations of three kinds of 4 carbon nanotubes are calculated by using the density functional perturbation theory. It is found that the frequencies of some phonon modes are very sensitive to the smearing width used in the calculations, and eventually become negative at low electronic temperature. Moreover, two kinds of soft modes are identified for the (5,0) tube which are quite different from those reported previously. Our results suggest that the (5,0) tube remains metallic at very low temperature, instead of the metallic-semiconducting transition claimed before. 相似文献
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In_2Se_3是一种常见的A_2~ⅢB_3~Ⅵ型半导体,在不同温度下可表现出不同的物相,对应的晶格参数与物理性质也会有所不同.在过去几十年间,In_2Se_3的多相性引起了人们的关注,各物相的晶体结构被广泛地研究.近年来,研究发现α-In_2Se_3具有优异的光电、压电性能以及独特的铁电性能,可以预见它将在未来的半导体电子器件中发挥出重要的作用.本文综述了一系列In_2Se_3化合物的晶体结构与电子特性,我们首先简要介绍了这些In_2Se_3化合物的基本知识,接着详细讨论了它们的晶体结构与电子特性,最后对In_2Se_3化合物的研究前景进行了展望. 相似文献
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滑坡坝及形成的堰塞湖在世界各国特别是山区一带广泛分布。它能够形成天然水库 ,在发生溃坝和洪水漫坝的情况下 ,造成的灾害损失很大。历史上产生过许多天然滑坡坝 ,有些很快发生溃坝 ,有些存在时间很长。存在时间较长的滑坡坝 ,它周围风景秀丽 ,成为旅游热点地区 ,同时也可开发其水资源。滑坡坝的形成有滑坡堵江、崩塌堵江和泥石流堵江 3种形式 ,它的形成机制对于滑坡坝的存在时间起了重要的作用。在开发和利用滑坡坝时 ,它的成因机制需要分析评价。本文对某滑坡坝的形成机制进行了研究 ,在研究某滑坡坝时发现 ,它由左右两岸的滑坡共同作用形成 ,这种形成模式在国内外报道很少 ,对类似工程也有一定的借鉴意义 相似文献
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The phonon dispersion relations of three kinds of 4~?
carbon nanotubes are calculated by using the density functional
perturbation theory. It is found that the frequencies of some phonon
modes are very sensitive to the smearing width used in the
calculations, and eventually become negative at low electronic
temperature. Moreover, two kinds of soft modes are identified for
the (5,0) tube which are quite different from those reported
previously. Our results suggest that the (5,0) tube remains metallic
at very low temperature, instead of the metallic-semiconducting
transition claimed before. 相似文献
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碳纳米管独特的一维结构和强烈的卷曲效应为外来原子提供了理想的嵌入通道。本文全面总结了近年来我们对直径仅为4A的三种单壁碳纳米管嵌锂特性的密度泛函研究工作。我们具体讨论了体系嵌锂后的结构、能量、电子、电化学等特性。由于这些超小直径的碳纳米管最初合成于沸石晶体的纳米管道,我们也讨论了碳纳米管?沸石晶体复合体系的嵌锂特性。另外,我们还研究了由(5,0)和(14,0)碳纳米管组成的双壁碳纳米管体系的嵌锂特性。我们的理论计算表明,超小直径碳纳米管及相关结构作为锂离子电池负极材料具有很好的应用前景。 相似文献
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