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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., state key laboratory of crystal materials, shandong university, jinan 2.0100, China 3 Department of physics, Jining university, Qufu 2.3155, China 1. school of Science Xi’an Polytechnic University Xi’an 710048 China2. School of Physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China3. Department of Physics Jining University Qufu 273155 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

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,{2., jinan 2.0100, China 2. National key laboratory of crystal materials,{2., jinan 2.0100, China 1. school of physics and Microelectronics Shandong University Jinan 250100 China 2. National key laboratory of {2. {2. Shandong University Jinan 250100 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.

Geometric and Electronic Structure of Squaric Acid from DFT Calculation

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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,{2., shandong university, jinan 2.0100, 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 H2.Q in the molecular plane and the antiferroelectricity in whole crystal, the density of {2.s, charge density distribution and band structure are calculated. The result showed that O2. and C2. play important roles in the interactions between layers. The hybridizations of 02.-Hls and 02.-Hls are responsible for the tendency to ferroelectricity within each layer.

关键词： Antiferroelectricity Electronic structure Squaric acid

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 {2., {2. 2.002., China 2.school of physics, state key laboratory of crystal materials, shandong university, jinan 2.0100, China school of Science University of Jinan Jinan 250022 China school of physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 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

Theoretical Study on the Structure and Vibrational Spectra for 4-methyl-3-penten-2.one

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Chinese Chemical Letters 1999年第10期10卷 835-838页

作者： Dong Mei DU Ai Ping FU Zheng Yu ZHOU (Department of Chemistry. Qufu Normal university, shandong, Qufu 2.3165 2.2.. shandong university, shandong, jinan 2.0100) Qufu Normal Univ Dept Chem Shandong 273165 Qufu Peoples R China shandong Univ State Key Lab Crystal Mat Jinan 250100 Peoples R China

Density functional theory BLYP (using Becke's and Lee-Yang-Parr's correlation functionals), nb initio Hartree-Fock (HF) and hybrid DFT/HF B3LYP calculations were carried out to study the structure and vibrational spectra of 4-methyl-3-penten-2.one. The BLYP/6-31G* and scaled HF/6-31G* frequencies correspond well with each other and with available experimental assignment of the functional vibrational modes.

关键词： density functional theory vibrational spectra 4-methyl-3-penten-2.one

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,{2., shandong university, jinan 2.0100, China 2.school of Science, university of jinan, jinan 2.002., China 3 Department of physics and Information Engineering, Jining university, Qufu 2.3100, China 1. school of physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China2. School of Science University of Jinan Jinan 250022 China3. Department of Physics and Information Engineering Jining University Qufu 273100 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

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

Large second-order optical nonlinearities of s-triazine derivatives: View from micro molecules to macro crystals

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Science China Chemistry 2005年第3期48卷 203-209页

作者： FANG Qi1, LEI Hong2. CUI Yuezhi3, HUANG Zhenli4, XUE Gang1 & YU Wentao1 1. state key laboratory of crystal materials, shandong university,{2., China 2. school of Information Science and Engineering, shandong university,{2., China 3. Department of Chemical Engineering, Light Industry College of shandong,{2., China 4. key laboratory of Biomedical Photonics, Ministry of Education, Huazhong university of Science and Technology, Wuhan 430074, China 1. state key laboratory of crystal materials Shandong University 250100 Jinan China 2. school of Information Science and Engineering Shandong University 250100 Jinan China 3. Department of Chemical Engineering Light Industry College of Shandong 250100 Jinan China 4. key laboratory of Biomedical Photonics Ministry of Education Huazhong University of Science and Technology 430074 Wuhan China

Three s-triazine derivatives have been synthesized and their structures been de-termined. These are Compound I: 2.4-dimethyl-6-(p-N,N-dimethylaminostyryl)-s-triazine (abbre-viated to NMe-1), Compound II: 2.4-dimethyl-6-(p-N,N-diethylaminostyryl)-s-triazine (to NEt-1), and Compound III: 2.methyl-4,6-bis(p-N,N-dimethylaminostyryl)-s-triazine (NMe-2.. NMe-1 and NEt-1 molecules belong to the D-π-A type with a one-dimensional charge-transfer character. NMe-1 crystallizes to centrosymmetric P1 space group, while NEt-1 to non-centrosymmetric polar Cc space group with all of the molecular charge-transfer axes taking the same orientation. Under the irradiation of 1064 nm fundamental laser, NEt-1 powder crystals radiate a 2.order harmonic light with an intensity 46.8 times that of urea. The Λ typed NMe-2.molecule, which has a two-dimensional charge-transfer character, crystallizes to polar P2. space group. Its powder crystals exhibit a 2.order harmonic intensity 46.2.times that of urea. The quantum chemical cal-culations and tensor analyses have been carried out to reveal the dependence of the macro 2.order nonlinear optical (NLO) efficiency on the micro 2.order NLO coefficients (β) and on the crystalline packing styles.

关键词： s-triazine derivatives, synthesis, structure, SHG intensities of crystals, βvalues of molecules.

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,{2., jinan, 2.0100, 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