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Ground state and polaron and bipolaron excited states in polydiacetylene

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Science china({1.,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 {1. and Microelectronics, shandong University, jinan 2501.0, china 2. National key laboratory of crystal materials, shandong University, jinan 2501.0, china 1. school of {1. and Microelectronics Shandong University Jinan 250100 China 2. National key {1. of crystal materials 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.

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

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Science china({1.,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 71.048,{1. 2 school of physics, state key laboratory of crystal materials, shandong University, jinan 2501.0,{1. 3 Department of physics, Jining University, Qufu 2731.5,{1. 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

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 {1., {1. 250022, china 2 school of physics, state key laboratory of crystal materials, shandong University, jinan 2501.0, china school of Science University of Jinan Jinan 250022 China school of {1. 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

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

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Science china({1.,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 {1., state key laboratory of crystal materials, shandong University, jinan 2501.0, china 2 school of Science, University of jinan, jinan 250022, china 3 Department of {1. and Information Engineering, Jining University, Qufu 2731.0, china 1. school of {1. 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

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, jinan 2501.0, china 2. school of Information Science and Engineering, shandong University, jinan 2501.0, china 3. Department of Chemical Engineering, Light Industry College of shandong, jinan 2501.0, 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 {1. 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 1.64 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 P21.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.

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 {1. 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

Multi-carbazole derivatives for two-photon absorption data storage:Synthesis,optical properties and theoretical calculation

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Science china Chemistry 2010年第4期53卷 884-890页

作者： LI Lin1, YANG JiaXiang1,2, WANG CaiXia1, HU ZhangJun1, TIAN YuPeng1,2, LI Jing3, WANG ChuanKui3, LI Ming4, CHENG GuangHua4, TANG HuoHong5, HUANG WenHao5, TAO XuTang2 & JIANG MinHua2 1Department of Chemistry, Anhui University, Hefei 230039, china 2state key laboratory of crystal materials, Institute of crystal materials of shandong University, jinan 2501.0, china 3Department of physics, shandong Normal University, jinan 250014, china 4state key laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119, china 5Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of china, Hefei 230026, china 1. Department of Chemistry Anhui University Hefei 230039 China2. State Key Laboratory of Crystal Materials Institute of Crystal Materials of Shandong University Jinan 250100 China3. Department of Physics Shandong Normal University Jinan 250014 China4. State Key Laboratory of Transient Optics and Photonics Xi’an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi’an 710119 China5. Department of Precision Machinery and Precision Instrumentation University of Science and Technology of China Hefei 230026 China

Two novel quadrupolar organic compounds, 3-(4-((E)-2-(9-butyl-9H-carbazol-6-yl) vinyl)styryl)-9-propyl-9H-carbazole (BCSPC) and 3-(3-(3-((1.)-2-(4-((E)-2-(3-(3,5-bis(9-butyl-9H-carbazol-6-yl)phenyl)-9-butyl-9H-carbazol-6-yl)vinyl)phenyl) vinyl)-9-butyl-9H-carbazol-6-yl)-5-(9-butyl-9H-carbazol-6-yl)phenyl)-9-butyl-9H-carbazole (BCPBC), with different conjugated arms, have been designed and synthesized. Their one-and two-photon absorption (TPA) and excited fluorescence properties have been experimentally investigated. The two-photon absorption cross-sections of two compounds were estimated by two-photon excited fluorescence technique using 200 fs, 76 MHz, Ti:sapphire laser, which are 22 and 1.4 GM for BCSPC and BCPBC, respectively. The optimal excitation wavelengths are 780 nm for both BCSPC and BCPBC. A data recording experiment proved the potential application of the materials.

关键词： initiator optical data storage fluorescence two-photon absorption theoretical calculation

Photocatalytic performance of TiO_2 thin films connected with Cu micro-grid

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Science china(Technological Sciences) 2009年第8期52卷 2175-2179页

作者： ZHU HaiLing1. ZHANG JunYing1. WANG TianMin1. WANG LiuGang1. LAN Xiang1.& HUANG BaiBiao2 1.school of Science, Beihang University, Beijing 1.01.1.{1. 2 state key laboratory of crystal materials, shandong University, Ji’nan 2501.0,{1. school of Science Beihang University Beijing 100191 China state {1. laboratory of crystal materials Shandong University Ji’nan 250100 China

Aiming at reducing the recombination of photo-induced carriers in semiconductor photocatalytic process, we prepared TiO2 thin film with its surface modified by a connected Cu micro-grid via a microsphere lithography strategy, which showed higher photocatalytic activity than the pure TiO2 film. The improvement of photocatalytic activity of Cu micro-grid to the TiO2 film is due to the charge carrier separation and electron transfer by the conducting metal grid. The photocatalytic activity was improved as metal loading increased, which obtained the best performance at a certain loading amount, and then decreased at higher loading amount. This phenomenon was attributed to the metal’s bulk effect which could be explained by the relationship between the energetic positions and the metal cluster size.

关键词： surface modification photocatalysis PS microspheres micro-grid

Study progresses of lead-free piezoelectric ceramic

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Study progresses of lead-free piezoelectric ceramic