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Theoretical Studies on the Reaction Mechanism of AsCl_3 with H_2 in the Vapor Phase Epitaxy of GaAs

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Chinese Journal of Structural Chemistry 2007年第3期26卷 267-272页

作者： MA Lin GUAN Wen-Jia XU Chang-Zhi SUN Ren-An School of Chemistry and Chemical Engineering Liaoning Normal University Dalian 116029 China School of Pharmaceutical Science Sun Yat-sen University Guangzhou 510080 China

The reaction mechanism of AsCl3 with H2 has been studied by using the method of BHandHLYP in Density Functional Theory （DFT） at the 6-31 1G^＊＊ basis set. The transition state of each reaction is verified via the analysis of vibration mode and Intrinsic Reaction Coordinate （IRC）. Meanwhile, single-point energy has been calculated at the QCISD（T）/6-311^G＊＊ level, and the zero-point energy correction has been made to the total energy and reaction energy barrier. It shows that AsCl3 reacts with H2 to first result in AsHCl2 which may incline to self-decompose and finally afford the product As2, or continue to react with H2 to provide the product ASH3. The computing result demonstrates that the former is the main reaction channel.

关键词： AsCl3/H2 transition state DFT

Surface for methane combustion:O(^3P)+CH4→OH+CH3

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Chinese Physics B 2020年第7期29卷 286-294页

作者： Ya Peng Zhong-An Jiang Ju-Shi Chen School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China

Kinetic investigations including quasi-classical trajectory and canonical unified statistical theory method calculations are carried out on a potential energy surface for the hydrogen-abstraction reaction from methane by atom O(^3P).The surface is constructed using a modified Shepard interpolation *** ab initio calculations are performed at the CCSD(T)*** account of the contribution of inner core electrons to electronic correlation interaction in ab initio electronic structure calculations,modified optimized aug-cc-pCVQZ basis sets are applied to the all-electrons *** this potential energy surface,the triplet oxygen atom attacks methane in a near-collinear H-CH3 direction to form a saddle point with barrier height of 13.55 kcal/mol,which plays a key role in the kinetics of the title *** the temperature range of 298-2500 K,our calculated thermal rate constants for the O(^3P)+CH4→OH+CH3 reaction show good agreement with relevant experimental *** work provides detailed mechanism of this gas-phase reaction and a theoretical guidance for methane combustion.

关键词： methane combustion potential energy surface transition state kinetic ab initio electronic structure calculation

Theoretical study of the degradation mechanism on the reactions 2,3,7,8-tetrachlorinated dibenzo-p-dioxins with hydrogen and chlorine atoms

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Science China(Technological Sciences) 2015年第1期58卷 181-190页

作者： ZHANG Hui ZHANG Kun SUN ShengMin College of Chemical and Environmental Engineering Harbin University of Science and Technology

The mechanism of the multiple-pathway and multiple-step degradation reactions of 2,3,7,8-tetrachlorinated dibenzo-p-dioxins with H and Cl atoms is investigated using the density functional *** electronic structures and the minimum energy path(MEP)are calculated at the B3LYP/6-311+G(d,p)level,and energetic information(single-point)is further refined at the B3LYP/6-311++G(3df,2p)*** main possible ring opening reaction pathways of the C–O bond breakdown include indirect cleavage ring opening reaction,hydrogen addition reaction,hydrogen addition elimination reaction,and chlorine addition elimination *** reaction steps of the six reaction pathways are *** calculations indicate that hydrogen addition reaction step TS1c is of the smallest barrier height,and indirect cleavage ring opening reaction channel has the largest barrier height and is the most endothermic.

关键词： gas-phase reaction transition state dioxin degradation

Theoretical Study of Isoprene Dissociative Photoionization

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Chinese Journal of Chemical Physics 2017年第1期30卷 43-49,I0001页

作者： Qiao Maa b Ming-qiang Huangc Xian-yun Liud Yan-bo Gaia Xiao-xiao Lina Cheng-qiang Yanga e Liu-si Shengf Xiao-bin Shanf Wei-jun Zhanga a. Laboratory of Atmospheric Physico-Chemistry Anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences Hefei 230031 China b. University of Science and Technology of China Hefei 230026 China c. College of Chemistry and Environment Minnan Normal University Zhangzhou 363000 China d. School of Mathematics and Physics Changzhou University Changzhou 213164 China e. School of Environmental Science and Optoelectronic Technology University of Science and Technology of China Hefei 230026 China f. School of Nuclear Science and Technology University of Science and Technology of China Hefei 230029 China

Theoretical calculations have been carried out to investigate the possible dissociation channels of isoprene. We focus on the major fragment ions of C5H7＋, C5H5＋, C4H5＋, C3H6＋, C3H5＋, C3H4＋, C3H3＋ and C2H3＋, which were observed experimentally from the isoprene dissociative photoionization. The energy calculations were performed with the CBS-QB3 model. All the geometries and energies of the fragments, intermediates and transition states involved in the dissociations channels were determined. Finally, the mechanisms of the dissociation pathways were discussed on the comparison of theoretical and experimental results.

关键词： Appearance energy Dissociation channel transition state CBS-QB3

Studies on the Reaction Mechanism of Br_2+I_2=2IBr

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Chinese Journal of Structural Chemistry 2006年第10期25卷 1280-1286页

作者： ZHAO Hui-Ming YUAN Li-Xia YANG Guo-Ying SUN De-Sheng WANG Zun-Yao CHI Qing-Qing School of Biological and Chemical Engineering Jiaxing University Jiaxing Zhejiang 314001 China School of Science Nanjing University of Technology Jiangsu 210009 China

The reaction mechanism of Br2 ＋ I2 = 2IBr was investigated at the （U）MP2/3-21G^＊ level, and one four-centred transition state as well as two three-atom molecules （IBr2,I2Br） were thus obtained. The same result was achieved by comparing the activation energy of three reaction paths, i.e., the minimum activation energy of the bimolecular elementary reaction Br2 ＋ I2 = 2IBr is less than the dissociation energy of Br2 or I2. It is thus theoretically proved that the title reaction occurs more easily in the bimolecular form without light initiation. However, once the reaction system was initiated by light through the reaction path of Br atom reacting with I2 or I atom reacting with Br2, the title reaction was completed quickly, which was verified with absorbance measurement at 516 nm in the present study.

关键词： bromine iodine iodine bromide transition state reaction mechanism spectrophotometry

Theoretical investigation on the excited state intramolecular proton transfer in Me_(2)N substituted flavonoid by the time-dependent density functional theory method

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Chinese Physics B 2018年第5期27卷 534-538页

作者： Hang Yin Ying Shi Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China state Key Laboratory of Supramolecular Structure and Materials College of ChemistryJilin UniversityChangchun 130012China

Time-dependent density functional theory(TDDFT)method is used to investigate the details of the excited state intramolecular proton transfer(ESIPT)process and the mechanism for temperature effect on the Enol^(*)/Keto^(*)emission ratio for the Me_(2)N-substited flavonoid(MNF)*** geometric structures of the S_(0) and S_(1) states are denoted as the Enol,Enol^(*),and Keto*.In addition,the absorption and fluorescence peaks are also *** is noted that the calculated large Stokes shift is in good agreement with the experimental ***,our results confirm that the ESIPT process happens upon photoexcitation,which is distinctly monitored by the formation and disappearance of the characteristic peaks of infrared(IR)spectra involved in the proton transfer and in the potential energy ***,the calculations of highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)reveal that the electronegativity change of proton acceptor due to the intramolecular charge redistribution in the S_(1) state induces the ***,the thermodynamic calculation for the MNF shows that the Enol^(*)/Keto^(*)emission ratio decreasing with temperature increasing arises from the barrier lowering of ESIPT.

关键词： time-dependent density functional theory excited state intramolecular proton transfer intramolecular charge transfer transition state

Equilibrium folding and unfolding dynamics to reveal detailed free energy landscape of src SH3 protein by magnetic tweezers

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Chinese Physics B 2021年第7期30卷 595-599页

作者： Huanhuan Su Hao Sun Haiyan Hong Zilong Guo Ping Yu Hu Chen Institute for Biomimetics and Soft Matter Fujian Provincial Key Laboratory for Soft Functional Materials ResearchDepartment of PhysicsXiamen UniversityXiamen 361005China Center of Biomedical Physics Wenzhou InstituteUniversity of Chinese Academy of SciencesWenzhou 325000China Oujiang Laboratory Wenzhou 325000China

Src SH3 protein domain is a typical two-state protein which has been confirmed by research of denaturant-induced unfolding *** spectroscopy experiments by optical tweezers and atomic force microscopy have measured the force-dependent unfolding rates with different kinds of pulling ***,the equilibrium folding and unfolding dynamics at constant forces has not been ***,using stable magnetic tweezers,we performed equilibrium folding and unfolding dynamic measurement and force-jump measurement of src SH3 domain with tethering points at its N-and *** the obtained force-dependent transition rates,a detailed two-state free energy landscape of src SH3 protein is constructed with quantitative information of folding free energy,transition state barrier height and position,which exemplifies the capability of magnetic tweezers to study protein folding and unfolding dynamics.

关键词： protein folding and unfolding magnetic tweezers free energy landscape transition state

Theoretical Studies on Dielectric Breakdown Strength Increasing Mechanism of SF6 and Its Potential Alternative Gases

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Chemical Research in Chinese Universities 2015年第1期31卷 123-129页

作者： ZHANG Hui SHANG Yan CHEN Qingguo HAN Baozhong Key Laboratory of Engineering Dielectrics and Its Application of Ministry of Education College of Chemical and Environmental Engineering Harbin University of Science and Technology Harbin 150080 P. R. China

A theoretical investigation on the dielectric insulation mechanism of sulfur hexafluoride（SF6） and its potential alternative gases at the atomic and molecular levels was made. The electronic structures of the molecules of them were calculated at the B3LYP/6-31 11＋G（d,p） level. The HOMO-LUMO energy gaps, ionization potentials, electron affinities, and dipole moments of the studied molecules at the ground state were obtained. The 11 isomerization reactions, with the harmonic vibration frequencies of the equilibrium geometries and the minimum energy path by the intrinsic reaction coordinate theory, were also obtained at the same level. The results show that the insulation gas, with the larger HOMO-LUMO energy gap, the higher ionization potential and the stronger electron affinity, can increase the dielectric breakdown strength efficiently, which is in good agreement with the available experimental finding. We suggested that the molecule with isomerization reaction occurring can dissipate the energy of hot electrons availably, which is favorable to the dielectric breakdown strength increasing for the SF6 potential alternative gas.

关键词： Dielectric breakdown strength Sulfur hexafluoride transition state Mechanism

An Exotic Phase Change in Dynamic Electrorheological Fluids

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Communications in Theoretical Physics 2015年第1期63卷 77-85页

作者：唐强果黄俊樱李丛郑杰孟现文黄吉平周鲁卫 Department of Physics and state Key Laboratory of Surface Physics Fudan University College of Information Technology Shanghai Ocean University

It is well known that constant or time-varying electric fields can induce phase changes in electrorheological(ER) fluids, from a liquid to semi-solid state, provided the field strength is larger than some critical value. We describe here an experimental and theoretical study considering yet a different class of phase changes, specifically those for an ER fluid in the presence of both shear flow and a time-varying electric field. We note that as the frequency of the field is decreased, the ER fluid will go from a liquid to an intermediate transition state, and eventually to a shear banding state. Our theoretical analysis further indicates that this phase change originates from competing effects of viscous and electrical forces. Ultimately, we conclude that it is possible to achieve various states and corresponding(desired)macroscopic properties of dynamic colloidal suspensions by adjusting the frequency of the externally applied electric field.

关键词： electrorheological (ER) fluids electric field transition state