纳米碳管电子结构和键合特性的第一原理研究

First-principles Study on Electronic Structure and Bonding Characteristics of Carbon Nanotubes

利用第一原理方法对一系列尺寸变化的单层纳米碳管电子结构进行了研究.得到的总态密度和态密度随碳管半径R的变化情况与实验结果完全一致,Fermi能级处态密度值随着管径R的增大而减小,说明纳米碳管的化学活性随着管径的增大而增强.碳管中C-C之间的键合为2s和2p价电子混合而成的弯曲的σ,π键.随着管径R的增大,化学键的弯曲度逐渐减小,C-C之间的键合作用和结合能逐渐增强,电荷密度和对应的势场也逐渐减弱.这些结果表明管径较小的纳米碳管在复合材料的合成中具有一定的优势.

In this paper, electronic structures of a series of dimension-variational single-walled carbon nanotubes are investigated by use of the first- principles calculations. The density of states and the variation of density of states with the tubular radius R obtained are in good agreement with the experimental results. The value of density of states at the Fermi level is reduced with increasing tubular radius R, which shows the chemical reactivity of carbon nanotubes is strengthened. The bonding between C-C in nanotubes is distorted a and Tr bonds consisting of 2s, 2p valence electrons. As the tubular radius R increases, the curvature of the chemical bonds is reduced, the bonding between C-C and binding energy are increased, electronic density and the corresponding potential field are reduced. The above results show the nanotubes with small size have advantage in the syntheses of nanometer-scale composites.