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利用第一原理的离散变分方法计算了生长中纳米碳管团簇的电子结构,发现悬挂键的存在导致管口处的电子结构明显地不同于管体,对应的非键合价电子不仅直接改变管口处碳原子之间的键合模式,而且进一步增强管口处碳原子之间的结合,促使碳原子只向管芯移动,这与实验中观察到的封闭顶端的几何形态相一致;而且降低碳管的化学稳定性.与完整型纳米碳管截然不同的电子结构决定了生长中纳米碳管在合成纳米材料过程中具有不同的作用行为. 相似文献
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Spin Polarization Through Resonant unnelling in a Magnetic Double—Barrier and Double—Well Quantum Structure
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Recent studies have indicated that spin polarization of the conductance shows strong osicllation and zero average for electrons resonant tunnelling throught a magnetic double-barrier and double-well quantum structure.Our studies indicate that strong oscillation of the polarization of the conductance is not physically intrinsic but inaccurate due to problems of numeration and insufficient numerical accuracy.We also indicate that its average of the spin polarization is not zero.The reasonable explanation is presented in details. 相似文献
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