Stone-Wales transformation is a key mechanism responsible for growth, transformation, and fusion in fullerene, carbon nanotube and other carbon nanostructures. These topological defects also substantially alter the physical and chemical properties of the carbon nanostructures. However, this transformation is thermodynamically limited by very high activation energy (\sim 7 eV in fullerene), which can get reduced due to the presence of hydrogen, extra carbon atom, or due to endohedral metal doping. Using first-principles density functional calculations, we show that the substitutional boron doping substantially reduces the Stone-Wales activation barrier (from \sim 7 eV to 2.54 eV). This reduction is the largest in magnitude among all the mechanisms of barrier reduction reported till date. Analysis of bonding charge density and phonon frequencies suggests that the bond weakening at and around the active Stone-Wales site in B-heterofullerene is responsible for such reduction. The formation of Stone-Wales defect is, therefore, promoted in such heterofullerenes, and is expected to affect their proposed H2 storage properties. Such substitutional doping can also modify the Stone-Wales activation barrier in carbon nanotube and graphene naonostructures, and catalyze isomerization, fusion, and nanowelding processes.
Performance Analysis of Boron Nitride Embedded Armchair Graphene Nanoribbon MOSFET with Stone Wales Defects
研究了石墨烯-氮化硼（GNR-BN）扶手椅型纳米晶（a-GNR-BN）MOSFET在其弹道输运极限下的性能。我们考虑了BN原子嵌在GNR两侧{每侧2，4，6个BN}的a-GNR-BN的三种几何构型3 p，3 p +1和3 p +2。利用密度泛函理论{DFT}对这些H钝化结构的带隙、有效质量和态密度等材料性质进行了计算。利用这些材料参数，在非平衡格林函数（NEGF）形式下进行了自洽Poisson-Schrodinger模拟，计算了弹道MOSFET器件的特性。对于宽度约为5 nm的混合纳米管，发现模拟的导通电流在276 uA - 291 uA的范围内，对于VDD = 0.68 V，导通/关断比为7.1 x 10^6 - 7.4 x 10^6，对应于10 nm技术节点。我们进一步研究了随机分布的Stone Wales {SW}缺陷在这些混合结构中的影响，并且对于6.35%的SW缺陷密度，仅观察到2.52%的导通电流退化。
Interaction of chlorine with Stone-Wales de- fects in graphene and carbon nanotubes, and thermodynamical prospects of chlorine-induced nanotube unzipping
