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Search Results: 1 - 10 of 83647 matches for " Gao Hong-Jun "
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Anchoring of a Single Molecular Rotor and Its Array on Metal Surfaces using Molecular Design and Self-Assembly
Li Gao,Shi-Xuan Du,Hong-Jun Gao
International Journal of Molecular Sciences , 2010, DOI: 10.3390/ijms11020656
Abstract: Functionalizing of single molecules on surfaces has manifested great potential for bottom-up construction of complex devices on a molecular scale. We discuss the growth mechanism for the initial layers of polycyclic aromatic hydrocarbons on metal surfaces and we review our recent progress on molecular machines, and present a molecular rotor with a fixed off-center axis formed by chemical bonding. These results represent important advances in molecular-based nanotechnology.

Quan Hong-jun,Gong Xin-gao,

中国物理 B , 2000,
Abstract: The electronic structures of the cluster-assembled solid Al12C(Si) are studied by the ab initio method. We find that Al12C(Si) can solidify into a van der Waals solid. The electronic band structures show very weak dispersion. The main features in the electronic structure of cluster are retained in the solid, and an energy gap up to about 1.5 eV is observed for Al12C and Al12Si solids.
Structural transformation of Ge dimmers on Ge(001) surfaces induced by bias voltage

Qin Zhi-Hui,Shi Dong-Xia,Gao Hong-Jun,

中国物理 B , 2008,
Abstract: Scanning tunneling microscopy is utilized to investigate the local-bias- voltage-dependent transformation between (2x1) and c(4x2) structures on Ge(001) surfaces, which is reversibly observed at room temperature and a critical bias voltage of -0.80V. Similar transformation is also found on an epitaxial Ge islands but at a slightly different critical bias voltage of -1.00V. It is found that the interaction between the topmost atoms on the STM tip and the atoms of the dimers, and the pinning effect induced by Sb atoms, the vacancies or the epitaxial clusters, can drive the structural transformation at the critical bias voltage.
Electronic structures and vibrational properties of coronene on Ru(0001): first-principles study

Zhang Yu-Yang,Du Shi-Xuan,Gao Hong-Jun,

中国物理 B , 2012,
Abstract: We calculate the configurations, electronic structures, vibrational properties at the coronene/Ru(0001) interface, and adsorption of a single Pt atom on coronene/Ru(0001) based on density functional theory calculations. The geometric structures and electronic structures of the coronene on Ru(0001) are compared with those of the graphene/Ru(0001). The results show that the coronene/Ru(0001) can be a simplified model system used to describe the interaction between graphene and ruthenium. Further calculations of the vibrational properties of coronene molecule adsorbed on Ru(0001) suggest that the phonon properties of differently corrugated regions of graphene on Ru(0001) are different. This model system is also used to investigate the selective adsorption of Pt atoms on graphene/Ru(0001). The configurations of Pt on coronene/Ru(0001) with the lowest binding energy give clues to explain the experimental observation that a Pt cluster selectively adsorbs on the second highest regions of graphene/Ru(0001). This work provides a simple model for understanding the adsorption properties and vibrational properties of graphene on Ru(0001) substrate.
The Origin of Half-Metallicity in Conjugated Electron System -- a Study on Transition Metal Doped Graphyne
Lida Pan,Boqun Song,Jiatao Sun,Lizhi Zhang,Werner Hofer,Shixuan Du,Hong-jun Gao
Physics , 2013, DOI: 10.1088/0953-8984/25/50/505502
Abstract: We studied the mechanism of half-metallicity (HM) formation in transition metal doped (TM) conjugated carbon based structures by first-principles electronic structure simulations. It is found that the HM is a rather complex phenomenon, determined by the ligand field splitting of d-orbitals of the transition metal (TM) atoms, the exchange splitting and the number of valence electrons. Since most of the conjugated carbon based structures possess ligands with intermediate strength, the ordering of the d-orbital splitting is similar in all structures, and the HM properties evolve according to the number of valence electrons. Based on this insight we predict that Cr-, Fe-, Co-doped graphyne will show HM, while Mn- and Ni-doped graphyne will not. By tuning the number of valence electron, we are thus able to control the emergence of HM and control the energy gaps evolving in majority or minority spin channels.
Molecular Adsorption on Metal Surfaces with a van der Waals Density Functional
Guo Li,Isaac Tamblyn,Valentino R. Cooper,Hong-Jun Gao,Jeffrey B. Neaton
Physics , 2012, DOI: 10.1103/PhysRevB.85.121409
Abstract: The adsorption of 1,4-benzenediamine (BDA) on the Au(111) surface and azobenzene on the Ag(111) surface is investigated using density functional theory (DFT) with a non-local density functional (vdW-DF) and a semi-local Perdew-Burke-Ernzerhof (PBE) functional. For BDA on Au(111), the inclusion of London dispersion interactions not only dramatically enhances the molecule-substrate binding, resulting in adsorption energies consistent with experimental results, but also significantly alters the BDA binding geometry. For azobenzene on Ag(111), the vdW-DF produces superior adsorption energies compared to those obtained with other dispersion corrected DFT approaches. These results provide evidence for the applicability of the vdW-DF method and serves as a practical benchmark for the investigation of molecules adsorbed on noble metal surfaces.
Unveiling the Origin of the Basal-plane Antiferromagnetism in the Jeff=1/2 Mott Insulator Ba2IrO4: A Density Functional and Model Hamiltonian Study
Yu-Sheng Hou,Hong-Jun Xiang,Xin-Gao Gong
Physics , 2015,
Abstract: Based on the density functional theory and our new model Hamiltonian, we have studied the basal-plane antiferromagnetism in the novel Jeff=1/2 Mott insulator Ba2IrO4. By comparing the magnetic properties of the bulk Ba2IrO4 with those of the single-layer Ba2IrO4, we demonstrate unambiguously that the basal-plane antiferromagnetism is caused by the intralyer magnetic interactions rather than by the previously proposed interlayer ones. In order to reveal the origin of the basal-plane antiferromagnetism, we propose a new model Hamiltonian by adding the single ion anisotropy and pseudo-quadrupole interactions into the general bilinear pseudo-spin Hamiltonian. The obtained magnetic interaction parameters indicate that the single ion anisotropy and pseudo-quadrupole interactions are unexpectedly strong. Systematical Monte Carlo simulations demonstrate that the basal-plane antiferromagnetism is caused by the isotropic Heisenberg, bond-dependent Kitaev and pseudo-quadrupole interactions. Our results show for the first time that the single ion anisotropy and pseudo-quadrupole interaction can play significant roles in establishing the exotic magnetism in the Jeff=1/2 Mott insulator.
Toward a Detailed Understanding of Si(111)- Surface and Adsorbed Ge Nanostructures: Fabrications, Structures, and Calculations
Ye-Liang Wang,Hai-Ming Guo,Zhi-Hui Qin,Hai-Feng Ma,Hong-Jun Gao
Journal of Nanomaterials , 2008, DOI: 10.1155/2008/874213
Abstract: Firstly, both the rest atoms and the adatoms of Si(111)-7×7 surface are observed simultaneously by scanning tunneling microscopy (STM) when the sample bias voltages are kept less than − 0.7 V. The visibility of the rest atoms is rationalized by first-principle calculations and a very sharper tip can resolve them. Secondly, the behaviors of various Ge nanostructures fabricated on Si(111)-7×7, ranging from the initial adsorption sites of individual Ge atoms to the aggregation patterns of Ge nanoclusters, and then to 2D extended Ge islands, are comprehensively investigated by STM. The individual Ge atoms tend to substitute for Si adatoms at Si(111)-7×7 with the preference of corner adatoms in the faulted half unit when keeping substrate at 150°C. With increasing Ge coverage, individual Ge atoms and Ge nanoclusters coexist on the substrate. Subsequently, the density of Ge nanoclusters increase and cluster-distribution becomes gradually regular with the formation of final 2D extended hexagonal configuration. When keeping the substrate at 300°C, Ge islands consisting of more complicated reconstructions with intermixing Ge/Si components are present on the substrate. The detail structural characterizations and the bonding nature of the observed Ge nanostructures are enunciated by the first-principle calculations.
Research on Relations between Sexual Propagation of Salix psammophila and Key Environmental Factors

MI Zhi-ying,ZHANG Hong-jun,GAO Yong,
,张宏俊,高 永

中国沙漠 , 2011,
Abstract: 沙柳种子的萌发受到多个因素的综合作用。在沙土含水量较低时沙柳种子可以萌发,但沙土含水量低于2%时不能萌发;干旱胁迫使沙柳实生苗发芽率降低;盐分可明显抑制沙柳种子萌发,同时抑制沙柳实生苗的茎生长;沙柳种子适宜的覆沙厚度是1.0~4.0 mm,当覆沙达到7 mm时种子出苗受到抑制;沙柳最适宜的发芽温度是25 ℃,当温度升到40 ℃时发芽率明显下降,而当降到10 ℃时种子发芽率也明显下降,达到5 ℃时沙柳种子尽管能发芽,但无茎生长。
Transport properties of boron nanotubes investigated by ab initio calculation

Guo Wei,Hu Yi-Bin,Zhang Yu-Yang,Du Shi-Xuan,Gao Hong-Jun,

中国物理 B , 2009,
Abstract: We investigate atomic and electronic structures of boron nanotubes (BNTs) by using the density functional theory (DFT). The transport properties of BNTs with different diameters and chiralities are studied by the Keldysh nonequilibrium Green function (NEGF) method. It is found that the cohesive energies and conductances of BNTs decrease as their diameters decrease. It is more difficult to form (N, 0) tubes than (M, M) tubes when the diameters of the two kinds of tubes are comparable. However, the (N, 0) tubes have a higher conductance than the (M, M) tubes. When the BNTs are connected to gold electrodes, the coupling between the BNTs and the electrodes will affect the transport properties of tubes significantly.
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