He原子基态波函数的实验检验

以作者所在实验室最近完成的He原子基态的电子动全港学实验结果为基础，对三类He原子基态波函数进行了分析与检验．结果表明，电子动量话学是获取电子波西数信息的有用手段．且实验结果与理论计算的联系文＊已报导了本实验室最近完成的He原子基态的电子动量话学实验结果．此实验的条件满足准自由碰撞的要求问，平面波冲量近似是适用的，因而实验测定的（e，Ze）反应的符合计数N可表为问本文自始至终采用原子单位（an），除非另有说明．在（1）中，C是比例常数，只与实验条件有关；PO，PI和马分别是人射电子和两个出射电子的动量，Th是…     

匀强电场中基态惰性原子的边界轮廓

应用原子特征边界轮廓模型, 计算了在5.292×10^-5 - 5.292×10^-3 a.u. 匀强电场下, 基态惰性原子的边界轮廓. 计算结果表明, 在电场中原子的边界轮廓呈现近椭球形, 轮廓的变化随电场强度的增强而增大; 在电场强度不变的情况下, 原子边界轮廓的变化随原子序数的增加而增大. 并且计算中得到的单位强度原子平均径向变化率与原子极化率实验结果呈现很好的线性相关性.     

基态N原子与CS2反应机理的理论研究

用密度泛函理论B3LYP/6 311+G 和高级电子相关偶合簇CCSD(T)/6 311+G 方法,计算研究了四重态氮原子与二硫化碳的反应,找到了分别形成CS+NS、NCS+S和CN+S2三个反应通道,优化搜索了各反应的过渡态,并用频率分析和内禀坐标法(IRC)验证了各鞍点构型和反应路径.在三个反应通道中,反应N+CS2→CS+NS由于具有较低的活化能而容易发生,其它两个通道活化能高很难发生,计算结果与实验结果一致.同时,对反应机理进行了详细的讨论.     

二步萃取-缝式石墨管原子捕集原子吸收法测定水样中的硒(Ⅳ)和硒(Ⅵ)

本文研究了水样中的硒(Ⅳ)和硒(Ⅵ)在DDTC-MIBK体系中的选择性萃取和反萃取,并用缝式石墨管原子捕集技术结合火焰原子吸收法,通过二步萃取,测定了水样中的硒(Ⅳ)和硒(Ⅵ)。     

镍-1-(2-吡啶偶氮)-2-萘酚共沉淀分离富集碱金属盐中痕量铅及铅的原子吸收光谱测定

采用Ｎｉ（Ⅱ）－１－（２－吡啶偶氮）－２－萘酚在ｐＨ ９．７溶液中共沉淀分离富集碱金属盐试剂中的痕量铅，用火焰原子吸收光谱测定，克服了基体干扰，取得了较为满意的结果。同时对共沉淀机理进行了初步的探讨，结果表明其属于吸附共沉淀类型。     

10-30T恒定磁场下碱金属原子的边界轮廓

孤立原子是具有球对称性的.如果将孤立原子置于磁场中,原子的边界半径必然会发生变化.根据原子边界轮廓理论模型,研究和计算了在10~30 T磁场强度下碱金属原子的边界轮廓,可供有关参考.     

小镍团簇Nin(n=2～6)电子结构和拓扑分析

在UBP86/TZVP水平上计算了小镍团簇(Ni<,n>,n=2～6)的稳定基态结构并用自然键轨道(NBO)和分子中的原子量子理论(QTAIM)分析了这些团簇的电子结构.计算结果表明,Ni团簇基态结构具有较高自旋多重度.QTAIM分析表明镍团簇中Ni-Ni键均为金属键.除Ni<,2>团簇中Ni-Ni键为纯粹的σ键外,其...     

[C(AuPH3)m]n+ (m=4-6; n=0-2)成键性质和稳定性研究

用MP2/LanL2DZ方法优化C(AuPH3)4[1a(C4v); 1b(Td)], [C(AuPH3)5]+[2a(C3h); 2b(Cs)]以及[C(AuPH3)6}]2+[3a(C2h); 3b(C2v)]的结构, 得到的几何参数与实验值相符. MP2水平下的自然键轨道(Natural bond orbitals, NBO)分析表明, Au具有d(sp)杂化性质, 其中(sp)具有s-p混合的轨道性质; 沿C-Au辐射方向形成的σ键和切向Au-Au之间的弱吸引相互作用使得整个分子稳定. 化合物1a, 2和3具有2或3个二电子三中心键, 表明该类化合物具有与传统C化学不同的电子结构和立体化学构型.     

含杂原子富勒烯C_(58)X_2(X=B、N、P)电子结构的量子化学研究

用CNDO／2方法在586微机上计算了C60，C59X1和C58X2（X=B、N、P）的23种位置异构体共73个分子的电子结构。在C58X2的23种位置异构体中C58B2（1，9），C58N2（1，9）和C58P2（1，2）分别是最稳定的。C59X1和的稳定性都比C60差，氧化或还原都比C60容易。在C59X1和分子中与杂原子相距1个、2个或3个键的C原子的电荷密度比C60分子的增加或减少较多，其亲电或亲核反应能力增强；与杂原子直接相连的键或挪巨1个、2个、3个键的2个C原子间WibergOrder比C60分子增加或减少较多，其键的强度增强或减弱。     

径向基神经网络奥斯特杨方波伏安法同时测定铬和锌

径向基函数神经网络(RBFN)和核心偏最小二乘法(KPLS)用于分析重叠的Cr（Ⅲ）和Zn(Ⅱ）的奥斯特杨(Osteryoung)方波伏安图，程序SPRBFN和SPKPLS被设计用于全部计算。在RBFN方法中，普通高斯函数可用作隐藏层非线性转移函数。由于其局部性质，RBFN能被快速训练，避免陷入局部最小。对两个方法预测能力的研究结果显示其所有组分的相对预测标准偏差(RSEP)分别为0．677％和13．0％。因此，RBFN方法较之K眦方法可提供更为精确的结果，而且在解决局部最小，改进收敛速率方面也不失为一个重要的工具。     

Die Reaktion des [(Me3Si)2CH]2Al?CH2?Al [CH(SiMe3)2]2 mit Neopentyllithium: Bildung des {[(Me3Si)2CH]2Al?CH2?Al [CH(SiMe3)2]2CH2CMe3}⊖ [Li(TMEDA)2]⊕

Reaction of [(Me₃Si)₂CH]₂Al? CH₂? Al [CH(SiMe₃)₂]₂ with Neopentyllithium: Formation of {[(Me₃Si)₂CH]₂Al? CH₂? Al [CH(SiMe₃)₂]₂CH₂CMe₃} ? [Li(TMEDA)₂]⊕ The recently synthesized methylene bridged dialuminium compound [(Me₃Si)₂CH]₂Al? CH₂? Al [CH(SiMe₃)₂]₂ reacts with neopentyl lithium in the presence of TMEDA to give the stable {[(Me₃Si)₂CH]₂Al? CH₂? Al [CH(SiMe₃)₂]₂CH₂ · CMe₃}? [Li(TMEDA)₂]⊕ decomposing at 115°C. The aluminium atoms therein are not additionally bridged, but the new substituent is occupying a terminal position as detected by crystal structure determination. A compound is formed containing a saturated, fourfold coordinated neighbouring a formally unsaturated, threefold coordinated aluminium atom. Due to high sterical restrictions the Al? C bonds are lengthened up to 209.0(3) pm at the alanate site and the Al? C? Al angle in the methylene bridge is extraordinarily enlarged to 144.4(2)°.     

Group 12 Carbonates and their Binary Complexes with Nitrogen Bases and FH2Z Molecules (Z=P,As, Sb): Synergism in Forming Ternary Complexes

MCO₃ (M=Zn, Cd, Hg) forms a spodium bond with nitrogen-containing bases (HCN, NHCH₂, NH₃) and a pnicogen bond with FH₂Z (Z=P, As, Sb). The spodium bond is very strong with the interaction energy ranging from −31 kcal/mol to −56 kcal/mol. Both NHCH₂ and NH₃ have an equal electrostatic potential on the N atom, but the corresponding interaction energy is differentiated by 1.5–4 kcal/mol due to the existence of spodium and hydrogen bonds in the complex with NHCH₂ as the electron donor. The spodium bond is weakest in the HCN complex, which is not consistent with the change of the binding distance. The spodium bond becomes stronger in the CdCO₃<ZnCO₃<HgCO₃ sequence although the positive electrostatic potential on the Hg atom is smallest. This is because the electrostatic interaction is dominant in the spodium-bonded complexes of CdCO₃ and ZnCO₃ but the polarization interaction in that of HgCO₃. The pnicogen bond is much weaker than the spodium bond and the former has a larger enhancement than the latter in the FH₂Z⋅⋅⋅OCO₂M⋅⋅⋅N-base ternary complexes.     

Stereoselective Synthesis of (Z)-2-Acylamido-4-phenylcrotonates

Stereospecificsynthesisof(Z)-a,o-dehydroaminoacidsisofgreatimportanceinthepreparationofuncommonornatUralopticallypureaminoacids,because,ingeneral,(Z)-isomersaffordmuchhigherenantioselectivitieswithfasterratesthan(E)-isomersinthecatalyticasymmetrichydrogenation'.(Z)-isomersofethyl2-acylamido-4-phenylcrotonate2areimpoFtantprecursorsinthecourseofoursynthesisofL-homopheny1alaninel,akeysynthonformostcommerciallyimportantantihypertensiveACEinhibitorssuchasEnalapril,Benazepril,Lisinopril.Hereinwe…     

The Effect of cis-trans Isomerism on the Electronic-vibrational Structure of the Ground and Excited States and Reactivity of 2-(2-Furyl)- and 2-(2-Thienyl)oxazole

The fluorescent properties, structure, and electronic structure of the ground and excited singlet and triplet electronic states of the cis and trans forms of 4,5-dihydro-2-(2-furyl)oxazole, 4,4-dihydro-2-(2-thienyl)oxazole, 2-(2-furyl)oxazole (FO), and 2-(2-thienyl)oxazole (TO) have been studied. The orbital nature of the lower excited singlet and triplet states has been studied by the semiempirical INDO/S (valence approximation) and PPP/S ( approximation) methods. It was shown that for FO and TO molecules the lower triplet state is of the * type, for which delocalization of the electronic excitation on atoms is characteristic. In the singlet excitation state inversion was observed of the energy levels of the delocalized * states and n* states localized over several bonds (for the free TO and FO molecules the lower excited singlet states S₁* were assigned to * and n* types respectively). Owing to the low position of the T * and T _n* levels relative to the singlet level of * type, the rate constant for intercombination conversion is greater than the rate constant for radiative decay. Consequently an efficient population of the triplet states of the molecules occurs under conditions of electronic-vibrational excitation. The direction of reactions during synthesis was compared with the localization indices in the ground state for electrophilic, nucleophilic, and radical substitution, and also with the excitation localization numbers L for a wide selection of electronically excited states. It was concluded that the change in the structure of the azole molecule on replacing an O atom by an S atom, or on changing from a partially hydrogenated to a heteroaromatic system, was the main reason for the change of all the spectral parameters characterizing the electronic-vibrational or the spin-orbital interaction of the most reactive groups of atoms in the molecular structure.     

二元合金团簇CoGe-n(n=1~12)的结构和稳定性

用密度泛函(DFT)方法与反射式飞行时间质谱及光电子能谱的实验结果相结合, 研究了二元合金团簇负离子CoGe-n(n=1~12)的结合能、几何结构与电子结构. 理论计算得到的电子亲和势(EA)光电子能谱测量的结果符合得较好. 通过分态密度(PDOS)分析了s, p和d轨道电子的相互作用规律. 讨论了团簇的稳定性, 认为CoGe-10具有幻数团簇的性质.