S2ClF的构型及其异构化反应的密度泛函理论研究

采用量子化学中的密度泛函理论B3LYP方法,在6-311+G(3df)水平上,全优化得到了S2ClF线型和分叉型2种异构体的平衡结构,同时对可能发生的分子内卤素原子迁移反应的过渡态进行了考察。计算结果表明,从能量角度看,线型的ClSSF为稳定构型,热力学和动力学计算表明,无论是F原子迁移还是Cl原子迁移,分子内的原子迁移需要较高的活化能,并且速度很慢。     

H2S2的构型及其异构化反应的密度泛函理论研究

B3LYP calculations of density functional theory with the 6-311 + G（3df,2p）basis set level are used to investigate the equilibrium structures and intramolecular rearrangement reaction between the linear HSSH and branched H2SS isomers. The predicted geometrical parameters and scaled harmonic vibrational frequencies for HSSH are in good agreement with the available values experimentally. The predicted S-S and S-H bond lengths in the thiosulfoxide structure H2SS are 0.1986 and 0.1366 nm respectively and the values of 5SSH and 5HSH bond angles are 108. 3o and 89. 5o respectively. The transition-state for the unimolecular isomerization is suitably characterized by diagonalizing the matrix of energy second derivatives to determine the unique imaginary vibrational frequency and confirmed by the IRC calculation. The calculated results show that the linear structure is stable with respect to the branched form（lower 109.8 kJ/mol corrected with zero point vibrational energy）energetically. The calculated energy barrier for the direct intramolecular hydrogen atom transfer isomerization process is 190.3 kJ/mol. The kinetic results demonstrate that the isomerization is a unimolecular process,but the reaction rate is pretty slow. This agrees with the thermodynamical results. So the isomerization process should proceed via the other likely processes.     

S2O2分子稳定结构的密度泛函理论研究

采用密度泛函理论中的B3LYP方法,在6-311+G(3df)和Aug-cc-pVTZ水平上,研究了单态S2O2分子的各种可能的异构体及其相对稳定性。结果表明,具有C2v对称性的三角平面分叉异构体的热力学稳定性要高于目前实验上唯一被发现的具有C2v对称性的cis-OSSO异构体,同时trans-OSSO的稳定性与顺式异构体十分接近,这2种异构体应该可以在实验上被观察到。同时本文还讨论了3个最稳定构型的前线分子轨道和链型OSSO的内扭转势能。     

密度泛函方法研究HS2X的稳定构型

采用量子化学中的密度泛函理论(DFT),在B3LYP／6-311 G(3df,2p)水平上全优化得到了单卤代二硫烷HSSX(X-H,F,Cl,Br)链型和分叉型两种异构体的平衡结构。计算结果表明．在热力学上,所有链型的HSSX为稳定构型．其能量分别较分叉型构型低109．8、60．2、74．8和73．1kJ／mol。同时,采用统计热力学方法,研究了两种平衡结构之间相互转化的化学热力学性质,发现异构化反应的平衡常数很小。     

团簇Fe4P异构化反应的理论研究

采用B3LYP泛函以及程序内置的LANL2DZ基组并结合拓扑学原理,运用Gaussian 09程序对团簇Fe4 P的16种初始构型进行优化,得到8种优化构型.依据过渡态理论,从化学热力学和动力学方面对团簇Fe4 P的异构化反应进行研究,结果表明:二重态构型的稳定性最大且自旋多重度会影响团簇Fe4 P异构化转化的反应程度...     

C2H3和NO2反应势能面的理论研究

在CCSD(T)／6—311G(d，p)／／B3LYP／6—3llG(d，p)水平上给出了反应C2H3 NO2的详细势能面信息，并列出了中间体和过渡态的几何构型．通过深入分析反应路径及反应机理，得到5个能量可行的产物和6条反应通道，其中产物C2H3O NO的形成又有利，而产物CH2CO HNO则是次要产物，其他产物在通常条件下可以忽略．     

BrSSCl和SSBrCl相对稳定性的理论研究

采用量子化学中的密度泛函理论，在B3LYP／6-311 G(3df)水平上全优化得到了S2BrCl分子线型和分叉型2种异构体的平衡结构，同时对可能发生的分子内原子迁移过程的过渡态进行了考察。计算结果表明，从能量角度看，线型的BrSSCl为稳定构型。采用统计热力学及过渡态理论，研究了Z种平衡结构之间相互转化的热力学和动力学性质。根据计算结果，无论是Cl迁移还是Br迁移，分子内的原子迁移都需要较高的活化能，并且迁移速度较慢。     

不饱和类碳烯H2C=CLiCI的构型及异构化的理论研

采用量子化学中的DFT理论方法，在B3LYP/6-311G*水平上全优化得到了不饱和类碳烯H2C=CLiCl的平衡结构。结果表明，不饱和类碳烯H2C=CLiCl只有2种平衡结构。对这2种平衡结构之间相互转化的过渡态进行计算，同时，采用统计热力学及过渡态理论，研究了2种平衡结构之间相互转化的热力学及动力学性质，进而讨论了2种平衡结构在不同温度下的稳定性问题，结果表明在所研究的100-600K温度范围内，只有一种平衡结构能够存在，在计算得到振动频率及吸收强度的基础上，模拟了稳定平衡结构的红外光谱图。     

ClONO2异构化反应和分解反应的理论研究

The potential energy surface for the decomposition and isomerization of Chlorine Nitrate（ClONO2）is calculated using the G3 theory. Geometries of related species are optimized at the MP2（ full）/6-31+G（d）and B3LYP/6-31+G（d）level. Vibrational frequencies and IR intensities of ClONO2 have been calculated at the same level. Obtained geometries and vibrational frequencies as well as IR intensities for ClONO2 are in good agreement with experimental values. A new stable stereoisomer is verified by CCSD（T）and QCISD（T）methods at 6-311G （d）basis set. Calculated geometries using above methods for this stereoisomer are in accord with each other. The calculated reaction heat of ClONO2 are also in good agreement with the available data in the literature. Among these reactions of ClONO2,the stereoisomer reaction is the hardest one. The barrier height for this reaction is 481.52 kJ/mol relative to ClONO2 and the reaction is endothermic by 299.85 kJ/mol. On the other hand,among these unimolecular reactions of ClONO2,the decomposition reaction of NO2+ClO is the easiest one. These results indicate that ClONO2 is very stable.     

O(3P)+O2H→OH+O2反应机理的密度泛函理论研究

用密度泛函理论方法研究了O(3P)与O2H反应生成羟基和氧分子的反应机理. 在PW91/6-31+G水平上用梯度解析技术全自由度优化上述反应物、产物和反应路径上的中间体及过渡态几何构型, 并通过频率振动分析加以确认, 计算IRC反应路径及中间体异构化过程, 确定了此反应的可能反应通道. 结果表明: 该反应是多通道多步骤的强放热反应. 首先形成顺式或反式O3H富能中间体, 此过程无能垒; 然后跨过一个能垒分解成产物OH和O2. 通道IM1→TS1比IM2→TS2克服的能垒要大, 反应放热372.822 kJ*mol-1. IM1TS3IM2 可相互转化.     

A Theoretical Study on the Equilibrium Structures and Relative Stabilities of H_2SO

1INTRODUCTIONTheconformationandvariousphysicalprope-rtiesofdichalcogencompoundsR-X-Y-R?(X,Y=O,S,Se,andTe)havebeenatopicofseveralexperi-mentalandtheoreticalinvestigations[1].CompoundscontainingS=SandS=Obondshavelongbeenpro-posedasintermediatesinorganicsynthesisand,onoccasion,asstableentities[2～18].Despitethecom-monlyusedrepresentationofS–Obondinsulfoxi-desandothersulfinylderivativesasS=O,sulfoxidesareinmanywaysbestdescribedasylideswithhighlypolarizedS–Oσ-bondbecauseofelectro-sta…     

配体保护下的Au_(20)团簇吸附和活化CO的理论研究

用密度泛函理论方法计算了CO分子吸附在有机配体聚乙烯吡咯烷酮poly(N-vinyl-2-pyrrolidone)(PVP)保护下的Au20团簇上的稳定构型的结构和性质。配体PVP通过物理吸附主要作用于Au20团簇的顶点位置。与Au20比较,配体的存在有利于CO的吸附和活化,其根本原因是PVP和CO在Au20表面分别作为供电子和吸电子基团产生的协同效应。中性及阴离子Au20团簇对配体和CO的吸附强度不同,前者对PVP吸附作用较强,后者对CO的吸附和活化作用较强。     

Mechanism and Kinetics for the Reaction of NCS and OH Radicals

The mechanism and dynamical properties for the reaction of NCS and OH radicals have been investigated theoretically. The minimum energy paths (MEP) of the reaction were calculated using the density functional theory(DFT) at the B3LYP/6-311 G^** level, and the energies along the MEP were further refined at the QCISD(T)/6-311 G^** level. As a result, the reaction mechanism of the title reaction involves three channels, producing HCS NO and HNC SO products, respectively. Path Ⅰ and path Ⅱ are competitive, with some advantages for path Ⅰ in kinetics. As for path Ⅲ, it looks difficult to react for its high energy barrier. Moreover, the rate constant have been calculated over the temperature range of 8190-2500K using canonical variational transition-state theory (CVT). It was found that the rate constants for both path Ⅰ and path Ⅱ are negatively dependent on temperature, which is similarwith the experimental results for reactions of NCS with NO and NO2, and the variational effect for the rate constant calculation olavs an important role in whole temperature range.     

卤代二硫烷互变异构体相对稳定性的理论研究

由于在有机合成化学、生命科学、大气化学和环境保护中的重要性,含有S=S键的过硫化物(硫烷)XSSX(X=H,CH3,F,Cl等)得到广泛研究。过硫化物XSSX可以有如图1所示的2种异构体,一种是与过氧化氢结构类似的非平面型的线型结构(属于C2点群),另一种是硫代亚砜型的分叉型构型(SSX2,属于C     

R2C＝GeH2和R2Ge＝CH2结构与成键特征的理论研究

用密度泛函理论(DFT), 在B3LYP/6-31＋G(d, p)水平上研究了取代基对二取代锗烯R₂Ge＝CH₂和R₂C＝GeH₂ [R＝H, OH, NH₂, SH, PH₂, F, Cl, Br, (NHCH)₂, CH₃, (CH)₂]的影响. 研究发现π供电子取代基在碳上时更能引起分子结构在锗端的锥型化. 碳原子上的π电子给予取代基的给电子效应越强, R₂C的单-三态能量差越大, π电子的反极化效应就越强, 使得化合物的结构在锗端发生的弯曲越明显, 从而使得弯曲结构更稳定. 和前人的计算相比, 碳上的给电子取代基对GeH₂结构影响大于它对SiH₂的影响.     

Experimental and theoretical studying the thermolysis of nitrate

This paper presents calorimeter measurement for the thermal decomposition of n-propyl nitrate (NPN), isopropyl nitrate (IPN) and 2-ethylhexyl nitrate (EHN). Similar experimental results of triethylene glycol dinitrate (tri-EGDN) and tetraethylene glycol dinitrate (tetra-EGDN) are included for comparison. The potential energy surfaces (PESs) along O-NO₂ bond stretch are investigated using the DFT (B3P86, B3PW91 and B3LYP), ab initio Hartree-Fock and PM3 methods. The good coincidence of experimental with theoretical results indicates that initial stage in the thermal decomposition of five nitrates is only unimolecular homolytical dissociation of the O-NO₂ bonds and the activation energies of thermolysis by DSC correspond to the energies of O-NO₂ bond scission of nitrates.     

The Adsorption Behavior of Gas Molecules on Co/N Co–Doped Graphene

Herein, we have used density functional theory (DFT) to investigate the adsorption behavior of gas molecules on Co/N₃ co–doped graphene (Co/N₃–gra). We have investigated the geometric stability, electric properties, and magnetic properties comprehensively upon the interaction between Co/N₃–gra and gas molecules. The binding energy of Co is −5.13 eV, which is big enough for application in gas adsorption. For the adsorption of C₂H₄, CO, NO₂, and SO₂ on Co/N–gra, the molecules may act as donors or acceptors of electrons, which can lead to charge transfer (range from 0.38 to 0.7 e) and eventually change the conductivity of Co/N–gra. The CO adsorbed Co/N₃–gra complex exhibits a semiconductor property and the NO₂/SO₂ adsorption can regulate the magnetic properties of Co/N₃–gra. Moreover, the Co/N₃–gra system can be applied as a gas sensor of CO and SO₂ with high stability. Thus, we assume that our results can pave the way for the further study of gas sensor and spintronic devices.     

靛蓝及其取代物的密度泛函理论研究

运用量子化学中密度泛函理论(DFT)方法,在B3LYP／6-31G^ 水平上对靛蓝及其芳环4,4′-,5,5′-,6,6′-,7,7′-取代衍生物进行理论计算．探讨了F,Cl,Br,NO2,CH3O,CH3在不同位置的取代对分子的几何构型、电子结构和电子光谱的影响,获得与实验结果相一致的结论．还用含时密度泛函理论(TD-DFT)方法在相同水平计算其电子光谱．结果表明靛蓝及其芳环取代衍生物的最低激发单重态(S1)均源自HOMO-LUMO(π-π^*)跃迁．