N,N-二(N-亚甲基-2-吡咯烷酮)甘氨酸(C12H19N3O4)的结构及配位性能的研究

用量子化学 Ｐ Ｍ３ 方法优化了 Ｎ, Ｎ二（ Ｎ亚甲基２吡咯烷酮） 甘氨酸（ Ｃ１２ Ｈ１９ Ｎ３ Ｏ４） 分子的顺式和反式两种构型;计算了分子的电离能、电子亲合能、电荷密度和前线轨道,并研究了该分子的配位性能。结果表明标题化合物稳定,顺式构型分子内有氢键,反式则没有。 Ｐ Ｍ３ 计算的标题化合物顺式构型几何参数与实验测定结果一致,顺式构型能与希土金属离子形成稳定的配合物。     

共轭烯烃的分子几何构型、电子结构和生成热的DMM和AM1、PM3的比较研究

运用Ｄｅｌｆｔ分子力学（ＤＭＭ）力场和程序以及半经验分子轨道ＡＭ１和ＰＭ３方法计算研究了丁二烯、苯、甲苯、联苯、苯乙烯、富烯、、环辛四烯、［２，２］对环烷和菲等１０个共轭烯烃分子的几何构型、电子结构和生成热．ＤＭＭ计算的几何构型和生成热与实验结果相吻合，电荷分布结果与从头计算结果较接近．ＡＭ１和ＰＭ３计算的几何构型较好，但计算的生成热与实验结果偏差较大．ＰＭ３计算值比ＡＭ１的稍好．     

对位环芳烃及其衍生物分子轨道的通过空间和通过键相互…

应用改进的重叠模型多重散射Ｘａ自洽场方法对对位环芳烃及其衍生物分子的分子轨道通过空间和通过键的相互作用进行了研究，讨论分子轨道相互作用对分子轨道能级顺序的影响以及不同的连接桥对分子轨道相互作用的影响，进一步应用过渡态理论方法计算对位环芳烃及其衍生物分子的分子轨道电离能，计算结果与实验结果符合较好。     

NFCl自由基的理论研究

采用分子轨道从头计算方法,研究了ＮＦＣｌ自由基的基态（Ｘ＾２Ａ）和激发态（１＾２Ａ,２＾２Ａ’）,得到了它们的平衡构型和谐振频率,计算确认了第一激发态（１＾２Ａ）,研究表明第一激发态的平衡构型是弯曲构型,而非前人建议的线性构型,实验观察到的位于３００－４００ｎｍ的吸收谱带归属于１＾２Ａ←Ｘ＾２Ａ”跃迁。     

电子转移的外电场效应——苯分子与苯正离子自由基间电子 …

基于半经典电子转移理论，结合量子化学计算，城ＨＦ／ＤＺＰ水平上，研究外电场作用下平行的苯分子－苯正离子自由基体系（Ｃ６Ｈ４）２＾＋的分子内电子转移问题。在给体和受体几何构型优化的基础上，用线性反应坐标确定电子转移过渡态，分别用两态变分方法和基于Ｋｏｏｐｍａｎｓ定理的分子轨道跃迁能方法计算电子转移矩阵元ＶＡＢ，讨论了ＶＡＢ对给体和受体中心距ｄ的指数衰减关系，取中心距为０．６ｎｍ，研究了外电场对反应热     

BrCl紫外光电子能谱实验及理论研究

采用紫外光电子能谱研究了影响大气臭氧浓度的重要卤素互化物一氯化溴的精细电离能谱．实验得到BrCl的第一绝热电离能和垂直电离能分别为10．95eV和11．00eV．BrCl的最高占据轨道6π电离产生了明显的旋轨分裂谱带．这对旋轨分裂谱带分别清晰地显示出4个振动精细结构峰．频率分析显示BrCl分子最高占据轨道为弱反键性质．比较了HF方法和外壳层格林函数方法(OVGF)对电离能的计算结果，并对实验值进行了分析比较及指认．采用实验构型OVGF方法给出的电离能结果无论在低电离能区还是在高电离能区都和实验值一致，特别是第一垂直电离能10．988eV与实验值11．00eV非常好地吻合．     

配合物CoF^n—6（n=2,3,4）光谱的理论研究

本文建议了一种将多重散射Ｘａ方法与不可约张量法相结合过解过渡金属配合物价电子体系多电子Ｓｃｈｒｏｄｉｎｇｅｒ方程的新方法，并将其应用到系列分子ＣｏＦ＾ｎ－６（ｎ＝２，３，４）ｄ－ｄ跃迁能的计算，计算结果与实验结果的均方根偏差仅为２ｋｃｍ＾－１，同时分析了Ｘａ方法中重叠修正项对单电子结构及光谱计算结果的影响。     

配合物CoF_6~（n－）（n＝2，3，4）光谱的理论研究

本文建议了一种将多重散射Ｘａ方法与不可约张量法相结合求解过渡金属配合物价电子体系多电子Ｓｃｈｒｄｉｎｇｅｒ方程的新方法，并将其应用到系列分子ＣｏＦ（ｎ＝２，３，４）ｄ－ｄ跃迁能的计算，计算结果与实验结果的均方根偏差仅为２ｋｃｍ（－１），同时分析了Ｘａ方法中重叠修正项对单电子结构及光谱计算结果的影响。     

N，N-二(N-亚甲基-2-吡咯烷酮)甘氨酸(C12H19N3O4)的结构及配位性能的研究

用量子化学PM3方法优化了N,N-二(N-亚甲基-2-吡咯烷酮)甘氨酸(C₁₂H₁₉N₃O₄)分子的顺式和反式两种构型;计算了分子的电离能、电子亲合能、电荷密度和前线轨道,并研究了该分子的配位性能。结果表明标题化合物稳定,顺式构型分子内有氢键,反式则没有。PM3计算的标题化合物顺式构型几何参数与实验测定结果一致,顺式构型能与希土金属离子形成稳定的配合物。     

3-苯基-6-芳基-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑的电子结构和光谱性质的含时密度泛函理论研究

对3-苯基-6-芳基-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑(PATT)用量子化学密度泛函方法(DFT)在B3LYP/6-31G(d)水平上进行了几何构型的全优化, 探讨了分子电荷转移、前线轨道能量和电子光谱等性质的变化规律, 在此基础上采用含时密度泛函方法(TDDFT)计算了分子激发态的电子跃迁能. 将其与实验所得激发态的电子跃迁能结果相比, 理论计算最大相对偏差为0.071, 最小相对偏差为0.041.     

Cun、Agn和Aun(n≤9)团簇的静电极化率

The static polarizabilities and polarizability anisotropies of Cun,Agn and Aun (n≤9)clusters have been calculated by the B3LYP density functional method,which is a three parameter mixture of density functional and"exact" Hartree Fock exchange. The calculated results are compared with experimental polarizabilities of sodium clusters. It is shown that the size dependency of the static polarizabilities per atom of Cun,and Agn clusters possesses the same trend as that observed in sodium clusters exception of the Aunclusters while the polarizability of Au atom is much smaller than these of Cu and Ag.The(α-)of Au atom is the smallest and the(α-)per atom of Au approach to the values of Cu from the dimmer to the hexamer. It indicates that in Au clusters the electrons are more strongly attracted by the nuclei because of the more electrons. However,the absolute polarizabilities of the noble mental clusters are considerably smaller than those of the sodium clusters and the electronic structures of the noblemental are much more compact.     

Aun(n=2-9)团簇与乙醇分子相互作用的第一性原理研究

利用密度泛函理论研究了Au_n(n=2-9)团簇吸附一个乙醇分子的结构和电子性质. 研究结果表明: Au_n(n=2-9)团簇的最稳定构型为二维平面结构, Au6团簇最稳定; 吸附过程是通过金团簇上一个特定的金原子与乙醇分子中氧原子相互作用完成, 形成了20种稳定构型; 金原子的配位数对吸附作用影响明显; 作为吸附主体的金团簇和被吸附的乙醇分子在吸附前后构型无明显变化, 它们之间为弱相互作用.     

Relativistic effective core potential calculations of Hg and eka-Hg (E112) interactions with gold: spin-orbit density functional theory modeling of Hg-Aun and E112-Aun systems

Interactions of eka-Hg (E112) and Hg atoms with small gold clusters were studied in the frame of the relativistic effective core potential model using the density functional theory (DFT) approach incorporating spin-dependent (magnetic) interactions. The choice of the exchange-correlation functional was based on a comparison of the results of DFT and large-scale coupled cluster calculations for E112Au and HgAu at the scalar relativistic level. A close similarity between the E112Aun and HgAun equilibrium structures was observed. The E112 binding energies on Aun are typically smaller than those for Hg by ca. 25%-32% and the equilibrium E112-Au separations are always slightly larger than their Hg-Au counterparts.     

Gas phase synthesis and reactivity of Agn+ and Ag(n-1)H+ cluster cations

Multi-stage mass spectrometry (MSn) on [(M + Ag - H)x + Ag]+ precursor ions (where M = an amino acid such as glycine or N,N-dimethylglycine) results in the formation of stable silver (Ag3+, Ag5+ and Ag7+) and silver hydride (Ag2H+, Ag4H+ and Ag6H+) cluster cations in the gas phase. Deuterium labelling studies reveal that the source of the hydride can be either from the alpha carbon or from one of the heteroatoms. When M = glycine, the silver cyanide clusters Ag4CN+ and Ag5(H,C,N)+ are also observed. Collision induced dissociation (CID) and DFT calculations were carried out on each of these clusters to shed some light on their possible structures. CID of the Agn+ and Ag(n-1)H+ clusters generally results in the formation of the same Ag(n-2)+ product ions via the loss of Ag2 and AgH respectively. DFT calculations also reveal that the Agn+ and Ag(n-1)H+ clusters have similar structural features and that the Ag(n-1)H+ clusters are only slightly less stable than their all silver counterparts. In addition, Agn+ and Ag(n-1)H+ clusters react with 2-propanol and 2-butylamine via similar pathways, with multiple ligand addition occurring and a coupled deamination-dehydration reaction occurring upon condensation of a third (for Ag2H+) or a fourth (for all other silver clusters) 2-butylamine molecule onto the clusters. Taken together, these results suggest that the Agn+ and Ag(n-1)H+ clusters are structurally related via the replacement of a silver atom with a hydrogen atom. This replacement does not dramatically alter the cluster stability or its unimolecular or bimolecular chemistry with the 2-propanol and 2-butylamine reagents.     

Density functional study of small neutral and charged silver cluster hydrides

Small neutral, anionic, and cationic silver cluster hydrides AgnH and anionic HAgnH (n=1-7) have been studied using the PW91PW91 density functional method. It was found that the most stable structure of the AgnH complex (neutral or charged) does not always come from that of the lowest energy bare silver cluster plus an attached H atom. Among various possible adsorption sites, the bridge site is energetically preferred for the cationic and most cases of neutral Agn. For anionic Agn, the top site is preferred for smaller Agn within n相似文献   

Competition among fcc-like, double-layered flat, tubular cage, and close-packed structural motifs for medium-sized Au n (n = 21-28) clusters

Using density functional theory calculations, we compared four kinds of possible structural motifs of the medium-sized Aun (n = 21-28) clusters, i.e., fcc-like, double-layered flat, tubular cage, and close-packed. Our results show strong competition between those structural motifs in the medium-sized gold clusters. Aun (n = 21-23) adopt fcc-like structure owing to the high stability of tetrahedral Au20. A structural transition from fcc-like to tubular occurs at Au24, and the tubular motif continues at Au27 and Au28. Meanwhile, a double-layered flat structure was found at Au25, and a pyramid-based structure at Au26. The relationship between electronic properties and cluster geometry was also discussed.     

High-resolution infrared spectroscopy of HCN-Agn (n = 1-4) complexes solvated in superfluid helium droplets

High-resolution infrared spectroscopy has been used to determine the structures, C-H stretching frequencies, and dipole moments of the HCN-Agn (n = 1-3) complexes formed in superfluid helium droplets. The HCN-Ag4 cluster was tentatively assigned based upon pick-up cell pressure dependencies and harmonic vibrational shift calculations. Ab initio and density functional theory calculations were used in conjunction with the high-resolution spectra to analyze the bonding nature of each cluster. All monoligated species reported here are bound through the nitrogen end of the HCN molecule. The HCN-Agn complexes are structurally similar to the previously reported HCN-Cun clusters, with the exception of the HCN-Ag binary complex. Although the interaction between the HCN and the Agn clusters follows the same trends as the HCN-Cun clusters, the more diffuse nature of the electrons surrounding the silver atoms results in a much weaker interaction.     

Intact size-selected Au(n) clusters on a TiO2(110)-(1 x 1) surface at room temperature

Experiments in which mass-selected gold clusters were deposited on a surface have found that the catalytic properties depend strongly on cluster size. However, these experiments have not established definitively that the clusters maintain their size after deposition. We report here work in which we deposit low kinetic energy, mass-selected Aun+ (n = 1-8) clusters on a rutile TiO2(1 x 1) surface and use ultrahigh vacuum scanning tunneling microscopy (UHV-STM) to determine their size and shape.     

溴化银晶体(110)表面上银原子簇的理论研究

本文采用量子化学半经验分子轨道法(CNDO方案),选取了三个晶面层数不同的AgBr晶体模型,对在这些晶体模型(110)表面上的银原子簇Ag_n(n=1,2,3,4)的电子结构及性质以及潜影机理作了量子化学研究。计算结果表明,晶体对银原子簇的性质有很大的影响,Ag₃和Ag₄优先取竖立晶面的结构。并且从Ag₃起,银原子簇的电荷分布成为上正下负的极性体。本文认为,这种极性是潜影的一个重要性质。Ag₃的热稳定性最强,又是银原子簇产生极性的转折点,故Ag₃是形成潜影的最小银原子簇。计算表明,银原子簇的增长是离子步骤先于电子步骤。     

CO oxidation on Aun/TiO2 catalysts produced by size-selected cluster deposition

Planar model catalysts were prepared by deposition of size-selected gold clusters containing up to seven atoms on rutile TiO2 (110). Molecular oxygen is observed to bind inefficiently to the surface, probably at oxygen vacancies, and some oxygen also appears to bind to the gold clusters. Stable CO binding is observed atop gold for catalysts prepared by Au and Au2 deposition, but not for larger Aun. CO oxidation activity is strongly dependent on cluster size, with Au7-prepared samples >50 times more reactive than samples prepared by Au or Au2 deposition