Connecting three zigzag graphene nanoribbons（ZGNRs） together through the sp^3 hybrid bonds forms a star-like ZGNR（S-ZGNR）. Its band structure shows that there are four edge states at k = 0.5, in which the three el...Connecting three zigzag graphene nanoribbons（ZGNRs） together through the sp^3 hybrid bonds forms a star-like ZGNR（S-ZGNR）. Its band structure shows that there are four edge states at k = 0.5, in which the three electrons distribute at three outside edge sites, and the last electron is shared equally（50%） by two sites near the central site. The lowest conductance step in the valley is 2, two times higher than that of monolayer ZGNR（M-ZGNR）. Furthermore, in one quasithree-dimensional hexagonal lattice built, both of the Dirac points and the zero-energy states appear in the band structure along the z-axis for the fixed zero k-point in the x-y plane. In addition, it is an insulator in the x-y plane due to band gap 4 eV, however, for any k-point in the x-y plane the zero-energy states always exist at kz = 0.5.展开更多
The title compound, [Zn（Pybta）Cl2]n （Pybta = 1-（2-pyridylmethyl）benzontriazole）, has a zigzag chain structure. It crystallizes in the monoclinic system, space group P21/c with a = 9.0103（11）, b = 17.0276（18）...The title compound, [Zn（Pybta）Cl2]n （Pybta = 1-（2-pyridylmethyl）benzontriazole）, has a zigzag chain structure. It crystallizes in the monoclinic system, space group P21/c with a = 9.0103（11）, b = 17.0276（18）, c = 9.2288（11）A,β = 101.309（6）°, Mr= 346.51, V= 1388.4（3）A^3, Z= 4, De= 1.658 g/cm^3, F（000） = 696,/a = 2.143 mm^-1, the final R = 0.0492 and wR = 0.1236 for 2545 observed reflections with I 〉 2σ（I）. The Zn atom is four-coordinated by two N and two Cl atoms, forming a slightly distorted tetrahedral geometry. Each zigzag chain links its adjacent symmetryrelated equivalents via multiple π-π interactions, which are not frequently observed in the previously reported architectures.展开更多
We study the adsorption of zigzag graphene nanoribbons （GNRs） on Si（001） substrates using the first-principles density functional theory, exploring the effects of the interface interaction on the structurM and ele...We study the adsorption of zigzag graphene nanoribbons （GNRs） on Si（001） substrates using the first-principles density functional theory, exploring the effects of the interface interaction on the structurM and electronic prop- erties of both GNRs and the substrate. By comparing the adsorption structures predicted by the local density approximation, the generalized gradient approximation, and the DFT-D2 approach, we confirm that both edge and inner C atoms of GNRs can form covalent bonds with the substrate. The GNR/substrate interaction destroys the antiferromagnetic coupling of the edge states in GNB.s. The charge transfer from the substrate to GNRs exhibits a complicated pattern and is mainly localized near the C-Si bonds. We also observe a strong perturbation of the surface states and a surface reconstruction transition induced by the GNR adsorption.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.10947004)the Jiangsu Government Scholarship for Overseas Studies,China
文摘Connecting three zigzag graphene nanoribbons（ZGNRs） together through the sp^3 hybrid bonds forms a star-like ZGNR（S-ZGNR）. Its band structure shows that there are four edge states at k = 0.5, in which the three electrons distribute at three outside edge sites, and the last electron is shared equally（50%） by two sites near the central site. The lowest conductance step in the valley is 2, two times higher than that of monolayer ZGNR（M-ZGNR）. Furthermore, in one quasithree-dimensional hexagonal lattice built, both of the Dirac points and the zero-energy states appear in the band structure along the z-axis for the fixed zero k-point in the x-y plane. In addition, it is an insulator in the x-y plane due to band gap 4 eV, however, for any k-point in the x-y plane the zero-energy states always exist at kz = 0.5.
基金The project was supported by the Natural Science Foundation of Fujian Province (No. 2006J0272)
文摘The title compound, [Zn（Pybta）Cl2]n （Pybta = 1-（2-pyridylmethyl）benzontriazole）, has a zigzag chain structure. It crystallizes in the monoclinic system, space group P21/c with a = 9.0103（11）, b = 17.0276（18）, c = 9.2288（11）A,β = 101.309（6）°, Mr= 346.51, V= 1388.4（3）A^3, Z= 4, De= 1.658 g/cm^3, F（000） = 696,/a = 2.143 mm^-1, the final R = 0.0492 and wR = 0.1236 for 2545 observed reflections with I 〉 2σ（I）. The Zn atom is four-coordinated by two N and two Cl atoms, forming a slightly distorted tetrahedral geometry. Each zigzag chain links its adjacent symmetryrelated equivalents via multiple π-π interactions, which are not frequently observed in the previously reported architectures.
基金Supported by the National Natural Science Foundation of China under Grant No 11204296the National Basic Research Program of China under Grant No 2013CB933304
文摘We study the adsorption of zigzag graphene nanoribbons （GNRs） on Si（001） substrates using the first-principles density functional theory, exploring the effects of the interface interaction on the structurM and electronic prop- erties of both GNRs and the substrate. By comparing the adsorption structures predicted by the local density approximation, the generalized gradient approximation, and the DFT-D2 approach, we confirm that both edge and inner C atoms of GNRs can form covalent bonds with the substrate. The GNR/substrate interaction destroys the antiferromagnetic coupling of the edge states in GNB.s. The charge transfer from the substrate to GNRs exhibits a complicated pattern and is mainly localized near the C-Si bonds. We also observe a strong perturbation of the surface states and a surface reconstruction transition induced by the GNR adsorption.
