采用Tersoff-Brenner势与L-J势的分子动力学方法,研究了双石墨层作用下(13,0)(、22,0)锯齿形碳管以及它们组合的(13,0)/(22,0)双壁碳管的径向压缩力学特性.根据计算结果,讨论了三种碳管压缩过程中的构型、能量、压缩载荷等的变化及其差...采用Tersoff-Brenner势与L-J势的分子动力学方法,研究了双石墨层作用下(13,0)(、22,0)锯齿形碳管以及它们组合的(13,0)/(22,0)双壁碳管的径向压缩力学特性.根据计算结果,讨论了三种碳管压缩过程中的构型、能量、压缩载荷等的变化及其差异.研究表明,压缩过程中,(22,0)碳管出现了明显的“塌陷”现象,“塌陷”时,能量及外载一度下降;(13,0)/(22,0)碳管的能量吸收能力及承受压缩载荷能力最大;(22,0)碳管的能量吸收能力与承受压缩载荷能力最差,且体积最容易压缩;当压缩应变小于12%时,(13,0)/(22,0)碳管的内管的构型、体积及其能量变化量均很小;内壁与外壁之间的Van der Waals能在整个压缩(13,0)/(22,0)碳管能量变化中仅占很小的份额.展开更多
Using the first-principles calculations, we studied the geometric structures, electronic structures and optical properties of the single-walled (n, 0) ZnO nanotubes (NTs). The calculated results show that all the bind...Using the first-principles calculations, we studied the geometric structures, electronic structures and optical properties of the single-walled (n, 0) ZnO nanotubes (NTs). The calculated results show that all the bind energies of the single-walled (n,0) ZnO NTs are of negative values, which indicate that the ZnO NTs can exist stably as single-walled NTs. While the calculated results of electronic structure indicate that the single-walled (n,0) ZnO NTs are a type of direct wide band-gap semiconductor materials, the whole valence bands are spread and drift to low-energy direction with the increase of the NT diameter. The defect energy levels caused by quantum size and surface effects emerge on the top of the valence bands. Furthermore, the calculated results of optical properties reveal that the dielectric peaks have a blue shift and the edge of absorption band corresponds to ultraviolet band with the decrease of the NT diameter. The single-walled (n, 0) ZnO NTs can be applied to ultraviolet semiconductor systems.展开更多
文摘采用Tersoff-Brenner势与L-J势的分子动力学方法,研究了双石墨层作用下(13,0)(、22,0)锯齿形碳管以及它们组合的(13,0)/(22,0)双壁碳管的径向压缩力学特性.根据计算结果,讨论了三种碳管压缩过程中的构型、能量、压缩载荷等的变化及其差异.研究表明,压缩过程中,(22,0)碳管出现了明显的“塌陷”现象,“塌陷”时,能量及外载一度下降;(13,0)/(22,0)碳管的能量吸收能力及承受压缩载荷能力最大;(22,0)碳管的能量吸收能力与承受压缩载荷能力最差,且体积最容易压缩;当压缩应变小于12%时,(13,0)/(22,0)碳管的内管的构型、体积及其能量变化量均很小;内壁与外壁之间的Van der Waals能在整个压缩(13,0)/(22,0)碳管能量变化中仅占很小的份额.
基金supported by the National Natural Science Foundation of China (Grant No. 60976069)the Scientific Research Program of the Educational Committee of Shaanxi Province, China (Grant No. 11JK0846)+1 种基金the Scientific Research Foundation for Doctors of Yanan University (GrantNos. YD2009-01 and YDZD2011-03)the Scientific and Technology Research and Development Program of Yanan Municipal (Grant No.2011ks-24)
文摘Using the first-principles calculations, we studied the geometric structures, electronic structures and optical properties of the single-walled (n, 0) ZnO nanotubes (NTs). The calculated results show that all the bind energies of the single-walled (n,0) ZnO NTs are of negative values, which indicate that the ZnO NTs can exist stably as single-walled NTs. While the calculated results of electronic structure indicate that the single-walled (n,0) ZnO NTs are a type of direct wide band-gap semiconductor materials, the whole valence bands are spread and drift to low-energy direction with the increase of the NT diameter. The defect energy levels caused by quantum size and surface effects emerge on the top of the valence bands. Furthermore, the calculated results of optical properties reveal that the dielectric peaks have a blue shift and the edge of absorption band corresponds to ultraviolet band with the decrease of the NT diameter. The single-walled (n, 0) ZnO NTs can be applied to ultraviolet semiconductor systems.
