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Journal of materials Science & Technology 2004年第2期20卷 206-208页

作者： Xuyan XUE, Chunlei WANG and Weilie ZHONGschool of physics and Microelectronics, state key laboratory of crystal materials, shandong university, jinan 250100, china shandong Univ Sch Phys & Microelect State Key Lab Crystal Mat Jinan 250100 Peoples R China

The crystal and electronic structure of antiferroelectric squaric acid is studied using density functional theory method, and the exchange correlation effects are treated by the generalized approximation. In order to understand the ferroelectricity of H2SQ in the molecular plane and the antiferroelectricity in whole crystal, the density of states, charge density distribution and band structure are calculated. The result showed that O2p and C2p play important roles in the interactions between layers. The hybridizations of 02s-Hls and 02p-Hls are responsible for the tendency to ferroelectricity within each layer.

关键词： Antiferroelectricity Electronic structure Squaric acid

A first-principles study of dihydroazulene as a possible optical molecular switch

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Science china(physics,Mechanics & Astronomy) 2011年第3期Mechanics & Astronomy) .卷 437-441页

作者： XIA CaiJuan1, LIU DeSheng2,3 & LIU HanChen1 1 school of Science, Xi’an polytechnic university, Xi’an 710048, china 2 school of physics, state key laboratory of crystal materials, shandong university, jinan 250100, china 3 Department of physics, Jining university, Qufu 273155, china school of Science Xi’an Polytechnic University Xi’an China school of physics State Key Laboratory of Crystal Materials Shandong University Jinan China Department of physics Jining University Qufu China

By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of the dihydroazulene optical molecular switch. Three kinds of adsorption sites including the hollow, bridge and top sites are studied. The two forms of this molecule, namely the open form and the closed form, can reversibly switch from each other upon photoexcitation. Their transmission spectra are remarkably distinctive. Theoretical results show that the current of the closed form is always significantly larger than that of the open form for all three adsorption sites, which promises this system as possibly one of the good candidates for optical switches due to its unique advantage, and which may have some potential applications in the future molecular circuit.

关键词： molecular switch nonequilibrium Green’s function electronic transport density functional theory

Electron transport properties of boron-doped capped-carbon-nanotube-based molecular junctions

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Science Bulletin 2010年第36期55卷 4104-4107页

作者： ZHAO peng1 & LIU DeSheng2 1 school of Science, university of jinan, jinan 250022, china 2 school of physics, state key laboratory of crystal materials, shandong university, jinan 250100, china school of Science University of Jinan Jinan China school of physics State Key Laboratory of Crystal Materials Shandong University Jinan China

Using the Landauer formalism that combines both the non-equilibrium Green’s function and first-principles density functional theory, the electron transport properties of a one-dimensional molecular junction based on capped carbon nanotubes with boron doping at various sites are investigated. The results show that the electron transport properties are strongly dependent on the boron-doping site. Negative differential resistance behavior can be observed when boron-atom dopants are present in the tip region.

关键词： carbon nanotube doping non-equilibrium Green’s function density functional theory

Lattice Effects and Irreversible Magnetoresistance in Gd Doped La-Ca-Mn-O

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Journal of materials Science & Technology 2002年第6期18卷 509-512页

作者： Baoxin HUANG, Yihua LIU, ruzhen zhang, Chengjian WANG, Gang JI and liangmo MEIDepartment of physics and state key laboratory of crystal materials, shandong university, jinan, 250100, china shandong Univ Dept Phys Jinan 250100 Peoples R China shandong Univ State Key Lab Crystal Mat Jinan 250100 Peoples R China

The Gd substituting effects for La in La0.67Ca0.33MnO3 has been studied. With increasing the substituting amount of Gd, the phase transition temperature of metal-isolator for the samples decreases, the corresponding peak resistivity increases, the Curie temperature decreases monotonically. The substitution of La-Ca-Mn-O with 11% Gd for La improved the magnetoresistance ratio by an order of magnitude. The effects of substituting Gd can be explained in terms of the lattice effects. An irreversible Mr behaviour was observed in Gd-substituting compounds. This effect became marked when the substituting amount of Gd was greater than 7%. A maximum irreversible increment of Mr ratio as large as 91% was obtained when Gd substituting amount was 11%.

关键词： Manganese perovskites Colossal magnetoresistance Lattice effect Irreversible magnetoresistance

Capped carbon nanotube-based molecular switch

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Science Bulletin 2010年第13期55卷 1227-1230页

作者： ZHAO peng1, WANG peiJi1, zhang Zhong1 & LIU DeSheng2 1 school of Science, university of jinan, jinan 250022, china 2 school of physics, state key laboratory of crystal materials, shandong university, jinan 250100, china school of Science University of Jinan Jinan China school of physics State Key Laboratory of Crystal Materials Shandong University Jinan China

Using the Landauer formalism that combines both the non-equilibrium Green's function (NEGF) and first-principles density functional theory (DFT), the electron transport characteristics of one-dimensional molecular switching device based on the capped carbon nanotubes have been investigated. The results show that the transmission can be efficiently tuned within two orders of magnitude just by changing 0.2 nm of the tube-tube separation. Moreover, the electron transport is insensitive to the topology of the facing conformations which can improve the practical stability of the chosen system as a molecular switch.

关键词： carbon nanotube molecular switch non-equilibrium Green function density functional theory

Negative differential resistance in molecular devices: the role of molecule-electrode coupling

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Science china(physics,Mechanics & Astronomy) 2011年第8期Mechanics & Astronomy) .卷 1455-1460页

作者： ZHAI YaXin1, JI GuoMin1, FANG ChangFeng1, CUI Bin1, ZHAO peng2 & LIU DeSheng1,3, 1 school of physics, state key laboratory of crystal materials, shandong university, jinan 250100, china 2 school of Science, university of jinan, jinan 250022, china 3 Department of physics and Information Engineering, Jining university, Qufu 273100, china school of physics State Key Laboratory of Crystal Materials Shandong University Jinan China school of Science University of Jinan Jinan China Department of physics and Information Engineering Jining University Qufu China

By applying nonequilibrium Green's function formalism combined with the first-principles density functional theory, we investigate the electronic transport in two molecular junctions constituted by a substituted oligo (phenylene ehtynylene) sand-wiched between two Au electrodes. Our calculations show that the weak molecule-electrode coupling is responsible for the observation of the negative differential resistance (NDr) effect in experiments. When the coupling is weak, the projected density of states (pDOS) of the molecule and the electrodes undergoes a mismatch-match-mismatch procedure, which increases and then decreases the transmission peak intensities, leading to a NDr effect. We also find that the localization/delocalization of the molecular orbitals and the change of charge state of the molecule have no direct relation with the NDr effect, because they change little as the voltage increases.

关键词： negative differential resistance substituted oligo (phenylene ehtynylene) molecular junction density functional theory nonequilibrium Green’s function formalism

Ground state and polaron and bipolaron excited states in polydiacetylene

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Science china(physics,Mechanics & Astronomy) 2006年第4期49卷 430-439页

作者： LI Yuan1, HU Guichao1, XIA Caijuan1, LIU Desheng1,2 & XIE Shijie1,2 1. school of physics and Microelectronics, shandong university, jinan 250100, china 2. National key laboratory of crystal materials, shandong university, jinan 250100, china school of physics and Microelectronics Shandong University Jinan China National key laboratory of crystal materials Shandong University Jinan China

The electronic properties of ground state and charged excited states of nondegenerate polydiacetylene were investigated by means of a tight-binding model. The parameters of the model were obtained by comparison of the experimental and other theoretical results. It was found that there is a stable dimerized structure of polydiacetylene in ground state and the doping induces the nonlinear excitations, such as polarons and bipolarons. In order to compare the stability of polaron and bipolaron, the creation energy and binding energy were separately defined. By neglecting the electron-electron Coulomb interaction, a bipolaron is more stable than two independent polarons.

关键词： dimerization, polaron, bipolaron, binding energy.

Irreversible Colossal Magnetoresistance in La_(0.58)Dy_(0.09)Ca_(0.33)MnO_3

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Journal of materials Science & Technology 2003年第6期19卷 622-624页

作者： Baoxin HUANG, Yihua LIU, ruzhen zhang, Youyong DAI, Chengjian WANG, Xiaobo YUAN and liangmo MEIDepartment of physics and state key laboratory of crystal materials, shandong university, Ji’nan 250100, china Lab. of crystal Mat. Dept. of Phys. Shandong Univ. Ji'nan 250100 China

The representative sample La0.58Dy0.09Ca0.33MnO3 of Dy doped La0.67Ca0.33MnO3 rare-earth manganites was investigated. The most important effect of Dy doping is to introduce the magnetoimpurity and form the spin clusters which induce dramatically large CMr in La0.58Dy0.09Ca0.33MnO3. The fitting results of field-induced resistivity decrease to the Brillouin function indicate that the CMr is caused by the spin dependent hopping between spin clusters. It is the magnetic field that reduces the size of spin clusters and induces a field-induced irreversible CMr behaviour.

关键词： Spin cluster Magnetoimpurity Colossal magnetoresistance

Size Determination of Ultramicropores and Small Mesopores Using a Calculation procedure Based on the Tangents of Comparison plot

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Journal of Wuhan university of Technology(materials Science) 2010年第3期25卷 391-394页

作者：邱芹刘世权 school of materials Science and Engineering University of Jinan

pore size distribution（pSD） curves of synthesized hollow silica spheres with ultrmicropores and small mesopores were obtained from calculations based on the BJH,KJS,SF,Mp,NLDFT models and ***＇s *** indicate that Zhu＇s method not only gives reasonable small mesopore size but also could be further extended to the ultramicropores region for the pSD evaluation.

关键词： pore size distribution comparison plot ultramicropores mesopores