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采用第一性原理和非平衡格林函数方法,系统研究了含氮空位缺陷锯齿状石墨烯纳米条带的自旋极化输运特性.理论计算结果表明边界非对称的这类石墨纳米条带的基态具有铁磁性,由其构建的分子结中负微分电阻效应具有鲁棒性,是电极局域的态密度及依赖偏压的散射区-电极耦合作用结果.此外,在特定偏压区域还观察到几乎完美的自旋过滤效应. 相似文献
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Density Functional Calculation of the 0.5ML-Terminated Allyl Mercaptan/Si(100)-(2 × 1) Surface
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The structural and electronic properties of the 0.5 ML-terminated allyl mercaptan (ALM)/Si(IO0)-(2 x 1) surface are studied using the density functional method. The calculated absorption energy of the ALM molecule on the 0.5 ML-terminated ALM/Si(IO0)-(2 x 1) surface is 3.36eV, implying that adsorption is strongly favorable. The electronic structure calculations show that the ALM/Si(IO0)-(2 x 1), the clean Si(100)-(2 x 1), and the fully-terminated H/Si(IO0)-(2 ~ 1) surfaces have the nature of an indirect band gap semiconductor. The highest occupied molecular orbital is dominated by the ALM, confirming the mechanism proposed by Hossain for its chain reaction. 相似文献
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采用第一性原理研究了SnPc分子在Ag(111)表面的吸附构型和电子结构. Sn-up和Sn-down两种优化的吸附构型与实验测量结果非常吻合,SnPc以Sn-down构型吸附在Ag(111)表面显得更稳定. Sn原子在两种吸附构型之间转换所需要能量与转换方向有关,由Sn-up向Sn-down构型转换时需翻越一个1.68 eV的能垒,反之需要2.17 eV. 扫描隧道显微镜理论模拟图像给出实验观测结果的主要特征,Sn-up分子的中心处为一个亮斑,而Sn-down分子中心为一个空洞. 计算结果验证了实验提出的Sn原子吸附位置的转换机理. 相似文献
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Using density-functional calculations within the generalized gradient approximation (GGA)+U framework,we investigate the structural,electronic,and magnetic properties of the ground states of SrFeOn (n = 2 and 2.5).The magnetism calculations show that the ground states of both SrFeO2 and SrFeO2.5 have G type antiferromagnetic ordering,with indirect band gaps of 0.89 and 0.79 eV,respectively.The electronic structure calculations demonstrate that Fe cations are in the high-spin state of (dz2 )2(dxz,dyz)2(dxy)1(dx2 y2 )1(S = 2),unlike the previous prediction of (dxz,dyz)3(dxy)1(dz2 )1(dx2 y2 )1(S = 2) for SrFeO2,and in the high-spin state of (dxy,dxz,dyz,dx2 y2 ,dz2 )5(S = 5/2) for SrFeO2.5. 相似文献
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