检索结果-南通市图书馆

Chemical Research in Chinese Universities 1999年第2期15卷 60-65页

作者： tGONG Xuedong xiao heming DONG Haishan Department of Chemistry Nanjing University of Science and TechnologyNanjing210094 Institute of Chemical Materials China Academy of Engineering PhysicsMianyang610003

The molecular geometries,heats of formation and electronic structures of three trinitrobenzenes(1,2,3TNB,1,2,4TNB and 1,3,5TNB)and their chloro derivatives were studied by using the quantum chemical MO AM1 method at the RHF level and ab initio method at the HF/321G *** decompositions of the title compounds were investigated by using the AM1 method at the UHF *** decomposition activation energies were obtained and the order of the relative stabilities of the title compounds is *** substituent effects on the structures and properties and on the decompositions of the title compounds are discussed in the present paper.

关键词： Trinitrobenzene Molecular orbital method Molecular structure Stability Decomposition method, Molecular structure, Stability, Decomposition

Density Functional Theory Study on （Cl2GaN3）n （n=1 4） Clusters

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2011年第9期29卷 1817-1823页

作者： Xia, Qiying Ma, Dengxue Zhao, Wenwei xiao, heming School of Chemistry and Resources Environment Linyi University Linyi Shandong 276005 China School of Engineering Nanjing University of Science and Technology Nanjing Jiangsu 210094 China

The molecular geometries, vibrational properties, and thermodynamic properties of the clusters （Cl2GaN3）n （n= 1--4） have been predicted at the B3LYP/6-311 ＋G＊ level. The optimized clusters （Cl2GaN3）n （n=2--4） all possess cyclic structures containing Ga--N,--Ga linkages. The relationships between geometrical parameters and oli- gomerization degree n are discussed. The gas-phase structures of the trimers prefer to exist in boat-twisting confor- mation. As for the tetramer, the $4 symmetry structure is the most stable. The infrared spectra are obtained and as- signed by vibrational analysis. Thermodynamic properties derived from the infrared spectra on the basis of statistical thermodynamic principles are linearly correlated with the oligomerization degree n as well as the temperature. Meanwhile, thermodynamic analysis of the gas-phase reaction suggests that the oligomerization is exothermic and favorable under high temperature.

关键词： (Cl2GaN3). (n =1--4) clusters azide density functional theory (DFT) structural feature IR spectra,thermodynamics

Theoretical studies on new potential high energy density compounds (HEDCs) adamantyl nitrates from gas to solid

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2008年第5期51卷 427-439页

作者： XU xiaoJuan ZHU WeiHua GONG XueDong xiao heming Department of Chemistry Nanjing University of Science and TechnologyNanjing 210094China Department of Chemistry Yancheng Teacher’s CollegeYancheng 224002China

A series of adamantyl nitrates have been theoretically studied from gas to solid to search for new po-tential high energy density compounds (HEDCs). The heats of formation (HOFs) for the 26 title com-pounds were calculated by designing isodesmic reactions at the B3LYP/6-31G level. It was found that the HOFs of the 26 isomers with the same number of —ONO2 groups (n) are not correlated well with the corresponding substituted positions. According to the obtained heats of detonation (Q),detonation velocities (D),and detonation pressures (P) using the Kamlet-Jacobs equations,it was found that when n=7～8,the adamantyl nitrates meet the criterion as an HEDC. The calculations on bond dissociation energies of O—N (EO—N) showed that the adamantyl nitrates with gemi —ONO2 always have the worst stability among the isomers,and all the adamantyl nitrates with gemi —ONO2 have similar stability. Due to the complexity of their structures,values of EO—N do not decrease with the increase of the substituent number n obviously,and the stability of adamantyl nitrates is not determined by only one structural parameter. Considering the stability requirement,only 1,2,4,6,8,9,10-adamantyl heptanitrate is recom-mended as a feasible HEDC. Molecular packing searching for 1,2,4,6,8,9,10-adamantyl heptanitrate among 7 most possible space groups (P21/c,P-1,P212121,P21,Pbca,C2/c,and Pna21) using Compass and Dreiding force fields showed that this compound tends to crystallize in P21/c. Ab initio periodic calculations on the electronic structure of the predicted packing showed that the O—NO2 bond is the trigger bond during thermolysis,which agrees with the result derived from the study of dissociation energies of O—N bonds.

关键词： high energy density compound (HEDC) adamantyl nitrate molecular packing periodic calculation energetic property density of states (DOS)

Substituent effect on the molecular stability,group interaction,detonation performance,and thermolysis mechanism of nitroamino-substituted cyclopentanes and cyclohexanes

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2008年第12期51卷 1231-1245页

作者： QIU Ling GONG XueDong JU XueHai xiao heming Institute for Computation in Molecular and Material Science School of Chemical EngineeringNanjing University of Science and TechnologyNanjing 210094China Key Laboratory of Nuclear Medicine Ministry of HealthJiangsu Institute of Nuclear MedicineWuxi 214063China

Density functional theory (DFT) method has been employed to study the effect of nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct the polycyclic or caged nitra-mines. Molecular structures were investigated at the B3LYP/6-31G** level, and isodesmic reactions were designed for calculating the group interactions. The results show that the group interactions ac-cord with the group additivity, increasing with the increasing number of nitroamino groups. The dis-tance between substituents influences the interactions. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the predicted densities and heats of formation, while thermal stability and pyrolysis mechanism were studied by the computations of bond dissociation energy (BDE). It is found that the contributions of nitroamino groups to the detonation heat, detonation velocity, detonation pressure, and stability all deviate from the group additivity. Only 3a, 3b, and 9a-9c may be novel potential candidates of high energy density materials (HEDMs) according to the quantitative cri-teria of HEDM (ρ≈ 1.9 g/cm3, D ≈ 9.0 km/s, P ≈ 40.0 GPa). Stability decreases with the increasing number of N-NO2 groups, and homolysis of N-NO2 bond is the initial step in the thermolysis of the title com-pounds. Coupled with the demand of thermal stability (BDE > 20 kcal/mol), only 1,2,4-trinitrotriazacy-clohexane and 1,2,4,5-tetranitrotetraazacyclohexane are suggested as feasible energetic materials. These results may provide basic information for the molecular design of HEDMs.

关键词： density functional theory (DFT) substituent effect monocyclic nitramine high energy density material (HEDM) group interaction detonation performance thermal stability bond dissociation energy (BDE)

Periodic DFT approaches to crystalline alkali metal azides

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2002年第14期47卷 1180-1183页

作者： Xuehai Ju heming xiao Guangfu Ji Nanjing Univ Sci & Technol Dept Chem Nanjing 210094 Peoples R China

The energy bands, electronic structures and relationship between structures and properties of the crystalline alkali metal azides, LiN3, α-NaN3 and KN3, are investigated at the DFT-B3LYP level. The crystalline bulks are predicted to be insulator, speculated from their band gaps of ca. 0.23-0.25 a.u. and from their level frontier bands. The atomic overlaps and electron densities show that the metals and the azides are combined by ionic bonds. The crystal lattice energies, being corrected for the basis set superposition errors, are -852.30, -771.45 and - 614.78 kJ·mol-1 for LiN3, a-NaN3 and KN3 respectively. These values are similar to those by Gray’s approximate method. The frontier crystal orbital mainly consists of the atomic orbital of the terminal nitrogen of azides. The contribution of the metallic orbital to the LUMO is very small. The electron transition from the HOMO to the LUMO is difficult to occur. Hence all the alkali metal azides are expected to be insensitive explosives, according to the '

关键词： crystalline alkali metal azides DFT band structure electronic structure.

Molecular dynamics simulation of mechanical properties of TATB/fluorine-polymer PBXs along different surfaces

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2005年第6期48卷 504-510页

作者： xiao Jijun1, HUANG Yucheng1, HU Yingjie1,2 & xiao heming1 1. Department of Chemistry, Nanjing University of Science and Technology, Nanjing 210094, China 2. Department of Chemistry, Nanjing xiaozhuang College, Nanjing 210017, China Correspondence should be addressed to xiao heming (email: xiao@***) 1. Department of Chemistry Nanjing University of Science and Technology 210094 Nanjing China 2. Department of Chemistry Nanjing Xiaozhuang College 210017 Nanjing China

The mechanical properties of PBXs composed of the well-known insensitive explo-sive TATB (1,3,5-Triamino-2,4,6-trinitrobenzene) crystal and four kinds of typical fluo-rine-polymers, i.e. poly (vinylidene difluoride) (PVDF), polychlorotrifluoroethylene (PCTFE), fluo-rine rubber (F2311) and fluorine resin (F2314) individually, have been simulated by molecular dy-namics (MD) method. The results show that the mechanical properties of TATB can be effectively improved by blending with a small amount of fluorine-polymers. Different mechanical properties of PBXs are obtained by putting fluorine-polymer binders parallel to different crystalline surfaces. The whole effect of improving mechanical properties is found to be (010)?(100)>(001).

关键词： TATB, polymer bonded explosives, mechanical properties, molecular dynamics.

Molecular dynamics simulation of ethene adsorption,polarization and diffusion in three kinds of zeolites

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1999年第7期44卷 598-601页

作者： Jianfen Fan heming xiao B. van de Graaf S. L. Njo Nanjing Univ Sci & Technol Dept Chem Nanjing 210094 Peoples R China Delft Univ Technol Organ Chem & Catalysis Lab NL-2600 AA Delft Netherlands Suzhou Univ Dept Chem Suzhou 215006 Peoples R China

Molecular dynamics （MD） simulation was performed to study ethene adsorption, polarization and diffusion in orthorhombic and monoclinic MFI and H[Al] ZSM-5 at 300 K. The resuits show that the interaction between ethene molecule and orthorhombic MFI is the *** molecules possess relatively low energy in the lattice of orthorhombic MFI. The existence of Al and Brnsted H atoms in the framework of H[AI]ZSM-5 can lower the energy of adsorbed ethene molecules. At the edges of intersections of channels, especially those near Al sites,ethene molecules are polarized most. Ethene molecules prefer the locations at the centers of channel intersections. The diffusion coefficients of ethene in the lattices of orthorhombic, monoclinic MFI and H[AI]ZSM-5 are 2.7 x 10-9, 2.1 x l0-9, 1.6 x 10-9 m2·s-1, respectively. The infrared spectrum of ethene in the framework of H[Al] ZSM-5 shows five vibration peaks (v10,v7, v12, v11 and V9), which is consistent with the experimental result.

关键词： molecular dynamics simulation orthorhombic MFI monoclinic MFI H[Al]ZSM-5 ethene polarization diffusion.

硝酸甲酯与硝酸乙酯的结构、振动频率和热力学性质的密度函数理论(DFT)研究

在线全文

学校读者我要写书评

暂无评论

化学学报 1999年第7期57卷 696-705页

作者：贡雪东肖鹤鸣南京理工大学化工学院南京210094

用密度函数理论(DFT)的BLYP和B3LYP方法,取 6-31G,6-31G~*,6-31G^(**),6-311G,6-311G~*和6-311G^(**)六种基组,对硝酸甲酯和硝酸乙酯的几何构型和红外振动频率进行了计算研究.结果表明,B3LYP方法在采用极化基组(6-31G~*,6-31G^(**),6-311G~*和6-311G^(**)时计算得到的结果均较好,适用于硝酸酯类化合物的研究.而BLYP方法无论采用何种基组均不适用;运用校正后的B3LYP/6-31G~*频率(校正因子0.975)计算得到的热力学性质(C_P°,H°和S°)与实验结果较吻合.

关键词：结构 DFT 硝酸甲酯硝酸乙酯振动频率热力学

Theoretical Studies on Geometry, Stability and Electronic Spectra of DATB and TATB

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 1990年第3期6卷 218-224页

作者： xiao heming(Department of East China Institute of Technology, Nanjing)Yu Hengtai (Institute of Theoretical Chemistry, Jilin University, Changchun)

The geometries of DATB( 1,3-diamino-2,4 ,6-trinitrobenzene) and TATB( 1,3,5-tri-amino-2,4,6-trinitrobenzene) have been optimized by M1NDO/3 method. It is found that the total energy of the molecule is rather low at the plane configuration. It is also found that the orbitals between the amino-N and its adjacent nitro-N as well as the amino-N and its adjacent nitro-N on the ring are rather close and matched in symmetry and have high orbital interaction through space, which are evidently seen from the computed results of the atomic bond index. The electronic spectra of DATB have been computed by using INDO/2-CI method, and the results are well conformed with the experimental facts. For instance, the transition from 'A' (ground state' ) to 'A' (the 7th exciled state) corresponds to the computed spectrum line(2. 48×104 cm-1) which is close to the experimental value (2. 43×104 cm-1). From a similar computation, we may predict that the major spectrum line of TATB will be 2. 75, 2. 77, 3. 28 and 3. 32×104 cm-1.

关键词： Electronic spectrum Geometry Stability

四唑及其衍生物的理论研究 (8) 硝氨四唑衍生物的从头算

在线全文

学校读者我要写书评

暂无评论

化学学报 1998年第12期56卷 1198-1206页

作者：陈兆旭肖鹤鸣南京理工大学化学系南京210094

运用从头计算法,在HF/6-31G水平下,全优化计算了7种硝氨四唑衍生物的分子几何和电子结构.结果表明,标题物的四唑环近似为平面构型;2H式中性分子的芳香性大于相应的1H式异构体.5-硝氨-1H四唑分子内氢键使硝氨基与环共面;其余标题物中硝... 详细信息

运用从头计算法,在HF/6-31G水平下,全优化计算了7种硝氨四唑衍生物的分子几何和电子结构.结果表明,标题物的四唑环近似为平面构型;2H式中性分子的芳香性大于相应的1H式异构体.5-硝氨-1H四唑分子内氢键使硝氨基与环共面;其余标题物中硝氨基与环垂直.不同水平下的总能量计算表明,标题物中电子相关效应显著;1H式中性分子较2H式的能量高,5-硝氨四唑负离子在三个负离子中最稳定.根据电荷分布阐明了四唑环质子化位置和标题物与金属的配位方式.此外还计算了各标题物的红外光谱及热力学性质.

关键词：硝氨四唑分子几何红外光谱四唑衍生物从头算