全国催化量子化学学术报告会在苏州举行

1986年5月7日至10日,中国科学院在苏州召开了“全国催化量子化学学术报告会”。来自北京、天津、上海、吉林、辽宁、福建、四川、江苏等地的科研、高等院校等37个单位的70多名学者、专家、研究生云集于苏州大学。会上,交流了60多篇学术论文和研究报告。与会者从催化量子化学的角度阐明催化剂表面的化学吸附,探讨催化反应机理,研究催化反应动力学,讨论电子结构和化学键,计算小分子与金属晶面相     

量子化学现状和展望(上)

量子化学是应用量子力学的原理和方法解决化学问题的一门科学,它包括基础研究和应用研究两个方面。在基础量子化学方面,主要是建立了三种化学键理论,也就是分子轨道理论、价键理论和配位场理论,以及创建了多种计算方法,包括从头算方法和各种半经验方法,例如HMO、EHMO、CNDO与X_α方法等。在应用量子化学方面,过去主要是稳定态分子及其有关性质的研究,近年来激发态分子,催化与表面化学,微观反应动力学,生物大分子与药物大分子的计算正在逐渐增多。量子化学的发展过程是与合成化学、结构化学的发展密切结合的,并且相互促进。本文对上述内容作一简要介绍。     

电化学表面增强拉曼光谱的量子化学研究

对于在分子水平上研究电化学表面吸附和反应过程,表面增强拉曼光谱(SERS)显示出了其独到的优势,提供了有力的技术方法,但对于其表面增强机理仍有待深入研究.本文总结了将量子化学计算应用于电化学表面增强拉曼光谱(EC-SERS)分析的研究,以电化学界面分子吸附、电化学反应以及光电化学反应的研究体系为模型,提取EC-SERS光谱所蕴藏的物理化学信息.通过对吡啶在电化学表面的吸附、水的吸附及其电化学反应、以及对巯基苯胺的电化学表面催化偶联反应等体系的研究,揭示了电化学表面吸附、反应和光电化学过程的本质.     

电化学界面SERS光谱的密度泛函理论研究

运用量子化学密度泛函DFT理论和拉曼光谱研究了吡啶在过渡金属(Ⅷ族)和币族金属(IB族)表面吸附的成键机理及其拉曼光谱的变化规律.总结了作者研究组有关吡啶-金属SERS体系的研究,并从化学成键机理和光驱电荷转移机理两个方面探讨了电化学界面SERS谱峰的频率位移和增强效应,解释了实验观测到的SERS光谱随金属电极材料、激发光波长以及电极电位变化的现象.     

计算化学在认识吸附现象中的应用*

吸附是重要的表面物理化学现象,其在工业实践及生活中有较多的应用。随着量子化学理论的发展及计算机技术的不断突破,采用计算化学的方法研究物质结构及化学反应已经变为现实,本文着重讲述如何采用计算化学方法研究吸附现象,在分子原子层次对吸附现象的本质进行模拟研究。     

物理化学学报

<正>投稿范围热力学、动力学和结构化学化学平衡与热力学参数、量热学、非平衡态热力学与耗散结构、统计热力学、宏观动力学、分子动态学、超快动力学、激发态、溶液化学、复杂流体、溶液结构、大气化学、动态结构、分子结构、体相结构、簇、谱学理论与计算化学量子化学、统计力学、模拟方法与应用、计算化学、化学信息学胶体与界面化学表面活性剂、分散体系与流变性能、分子组装与聚集体、大分子、界面结构催化和表面科学多相催化、均相催比、仿生催化、光催化、环境化学、绿色化学、膜、表面结构、表面吸附     

催化表面化学

催化表面化学是表面科学和催化科学的交叉研究领域,主要是通过固体表面化学研究在原子分子层次理解固体表面催化作用机制和建立催化剂结构-性能关系.由于固体表面结构的复杂性和不均一性,催化表面化学研究具有极大的挑战性.本文介绍了基于"从单晶到纳米晶模型催化体系"开展催化表面化学研究的创新研究思路,并综述了基于该研究思路取得的催化表面化学系列研究进展,包括建立了氧缺陷控制氧化物表面羟基反应性能的概念,揭示了氧化物催化作用的晶面效应,阐述了金催化作用的结构敏感性."从单晶到纳米晶模型催化体系"催化表面化学研究有望实现"从原子分子水平的基础理解到高效催化剂的设计合成"这一多相催化基础研究目标.     

原子和分子水平层次的表面电化学与电催化研究

本文从金属单晶表面电化学和模型由催化，分子水平上的电催化反应机理和反应途径控制，有机小分子电催化氧化反应动力不冢电催化剂表面化学状态与性能等四个方面，综述本研究小组近年来取得的主要进展，侧重展示在原子和分子等微观层次开展表面电化学和电化学催化的科研方向和结果。     

学科代码表

B0301结构化学B030101体相静态结构BO30102表面结构B030103溶液结构B030104动态结构B030lO5谱学B030106结构化学方法和理论B0302五子化学B030201基础量子化学B030202应用量子化学B0303催化B030301多相催化B030302均相催化B030303人工酶催化B030304光催化B0304化学动力学B03004（）宏观反应动力学B0300402分子动态学B0300403反应途径和过渡态B0300404快速反应动力学B0300405结晶过程动力学B0305胶体与界面化学B0305011面活性剂B030502分散体系B030503流体性能B030504野由吸附现象B030505超细粉和颗粒B0306电化学B030601电极过程…     

金属上化学吸附的簇模型量子化学研究

簇模型方法是研究化学吸附的最重要的量子化学方法之一。本文对‘簇──表面类比法’的物理内涵、研究现状、以及发展趋势作了简要的评述。     

氧化锡表面的原子簇模型计算

Cluster models of SnO2(110) face and oxygen vacancies and oxygen adsorption on its surface have been calculated by EHMO method. The results show that a tin atom with a coordination number of four is the adsorption center, because the total energy of cluster model becomes lower when an oxygen atom adsorpts on the tin atom with a coordination number of four. The tin atom with this coordination number gains and loses electrons more easily than tin atoms with a coordination number of five. All tin atoms in the cluster of SnO2(110) face are Sn4+.     

升温烧结过程中TiO2纳米颗粒的原子分类分析(Ⅰ):表面原子识别

开发表面原子识别模型,对单个TiO₂颗粒升温烧结过程中表面原子进行分类研究。模型对颗粒空间立方体网格化,利用标准球形颗粒体积积分法确定最佳网格尺寸为0.3 nm。通过表面网格识别实现表面原子分类,采用近邻网格中外部网格数量(N_ext)作为准则数判断目标网格是否为表面网格,确定最佳N_ext=9。基于LAMMPS软件模拟了半径为0.75 nm颗粒的升温过程,发现系统能量弛豫速度明显高于结构弛豫速度;利用表面识别模型分类分析原子特性,表面原子平均位移大于内部原子,且表面O原子迁移活性高于Ti原子;表面原子配位数低于内部原子,佐证表面结构规律性较差。研究结果为深入分析纳米材料活性位等结构分布奠定基础。     

Methanol adsorption on the beta-Ga2O3 surface with oxygen vacancies: theoretical and experimental approach

Methanol adsorption on beta-Ga2O3 surface has been studied by Fourier transform infrared spectroscopy (FTIR) and by means of density functional theory (DFT) cluster model calculations. Adsorption sites of tetrahedral and octahedral gallium ions with different numbers of oxygen vacancies have been compared. The electronic properties of the adsorbed molecules have been monitored by computing adsorption energies, optimized geometry parameters, overlap populations, atomic charges, and vibrational frequencies. The gallia-methanol interaction has different behaviors according to the local surface chemical composition. The calculations show that methanol can react in three different ways with the gallia surface giving rise to a nondissociative adsorption, a dissociative adsorption, and an oxidative decomposition. The surface without oxygen vacancies is very reactive and produces the methanol molecule decomposition. The molecule is nondissociatively adsorbed by means of a hydrogen bond between the alcoholic hydrogen atom and a surface oxygen atom and a bond between the alcoholic oxygen atom and a surface gallium atom. Two neighbor oxygen vacancies on tetrahedral gallium sites produce the dissociation of the methanol molecule and the formation of a bridge bond between two surface gallium atoms and the methoxy group.     

Theoretical study of CO adsorption on gold/alumina substrates

Aiming to understand the role of the substrate in the adsorption of carbon monoxide on gold clusters supported on metal-oxides, we have started a study of that process on two different alumina substrates: an amorphous-like fully relaxed stoichiometric (Al2O3)20 cluster and the Al terminated (0001) surface of alpha-(Al2O3) crystal. In this paper, we present first principles calculations for the adsorption of one Au atom on both alumina substrate and the adsorption of Au8 on (Al2O3)20. Then, we study the CO adsorption on the minimum energy structure of these three different gold/alumina systems. A single Au adsorbs preferably on top of an Al atom with low coordination, the binding energy being higher in the case of Au/(Al2O3)20. CO absorbs preferably on top of the Au atom, but in the case of Au/(Al2O3)20, Au forms a bridge with the Al and O substrate atoms after CO adsorption. We find other stable sites for CO adsorption on the cluster but not on the surface. This result suggests that the Au activity toward CO may be larger for the amorphous cluster than for the crystal surface substrate. For the most stable Au8/(Al2O3)20 configuration, two Au atoms bind to Al and a O atoms respectively and CO adsorbs on top of the Au which binds to the Al atom. We find other CO adsorption sites on supported Au8 which are not stable for the free Au8 cluster.     

Electronic structure of a uranium impurity center in zircon

The electronic structure of a large fragment of the crystal lattice of zircon ZrSiO₄ with a uranium impurity atom replacing the zirconium atom was investigated using the completely relativistic discrete variation (DV) cluster method. The results are compared with the data of a similar calculation of the ideal ZrSiO₄ crystal. An analysis of the overlap populations and effective charges on the atoms of the matrix and impurity showed that chemical binding of uranium with the environment is covalent, and the electron density redistribution caused by this substitution changes not only the impurity and the nearest environment, but also the atoms of the next coordination spheres.     

钼的原子簇化合物研究——一些两核和三核钼原子簇化合物的合成与晶体结构分析

本文总结了作者们研究一系列两核和三核钼原子簇化合物的结果。这些化合物是三核原子簇: (C_5H_7S_2)_3[Mo_3(μ_3-S)_2(μ_2-Cl)_3Cl_6] (Ⅰ); (C_5H_7S_2)_3[Mo_3(μ_3-S)(μ_2-S_2)_3Cl_7] (Ⅱ); Mo_3(μ_3-S)(μ_2-S_2)_3[S_2P(OEt)_2)_3Cl (Ⅲ); (Et_4N)_2[Mo_3(μ_3-O)(μ_2-Cl)_3(Oac)_2Cl_5] (Ⅳ); (C_5H_7S_2)[Mo_3(μ_3-O)(μ_2-Cl)_3(Oac)_3Cl_3] (Ⅴ); 和两核原子簇: (C_5H_7S_2)_3[Mo_2Cl_9] (Ⅵ); M0_2S_4[S_2P(OEt)_2]_2 (Ⅶ)。 本文的第一部分简要地介绍了这些化合物的合成方法。第二部分扼要地给出了这些化合物的晶体与分子结构。簇合物Ⅰ是离子型结构,簇阴离子是双(S)帽三核原子簇,每个Mo原子周围为八面体六配位,Mo—Mo间距为2.617。簇阴离子Ⅱ和簇分子Ⅲ均是单(S)帽三核簇,Mo原子周围为畸变五角双锥构型,Mo—Mo键长分别为2.751和2.725。簇阴离子Ⅳ和Ⅴ均是单(O)帽三核簇,Mo原子周围的配位为畸变八面体,Mo—Mo键长分别为2.597和2.577。化合物Ⅵ是三(μ_2—Cl)桥两核原子簇,其构型为两个共面八面体,Mo—Mo间距为2.707。化合物Ⅶ为双(S)桥两核原子簇,Mo原子周围为四角锥配位,Mo—Mo键长为2.828。 本文的第三部分用简化分子轨道方法分析了三种主要类型的三核钼原子簇中Mo_3体系的M—M键?     

固氮酶催化活性中心及其化学模拟

固氮酶是固氮微生物在常温常压下固氮成氨的催化剂,其催化机理和化学模拟一直是国际上长期致力研究的对象.钼铁蛋白高分辨1.0单晶X射线衍射分析表明,固氮酶催化活性中心铁钼辅基的结构为Mo Fe7S9C(R-homocit),其中,Mo原子和3个u2-硫配体、1个组氨酸和1个高柠檬酸配位,形成八面体构型.高柠檬酸以α-烷氧基氧和α-羧基氧与钼螯合形成双齿配位,氨基酸残基上的组氨酸咪唑氮和半胱氨酸巯基与钼和铁单齿配位.在固氮酶铁钼辅基的生物合成过程中,高柠檬酸和咪唑侧基是在最后的合成步骤插入铁硫碳簇前驱体中,其中高柠檬酸和咪唑侧基有可能对质子传递以及稳定Mo Fe7S9C簇起到重要作用.本文从固氮酶铁钼辅基结构出发,结合最近本课题组从化学模拟出发,将固氮酶催化活性中心铁钼辅基结构修订为加氢新结构Mo Fe7S9C(R-Hhomocit)的研究,着重介绍了近年来国内外固氮酶活性中心、生物合成和催化作用机理的研究进展,并展望了固氮酶的研究前景.     

Two-dimensional to three-dimensional structural transition of gold cluster Au10 during soft landing on TiO2 surface and its effect on CO oxidation

We investigate the possible structural transition of a planar Au(10) cluster during its soft landing on a TiO(2) (110) surface with or with no oxygen defects. The collision between the gold cluster and the oxide surface is simulated using the Car-Parrinello quantum molecular dynamics method. Both high-speed and low-speed conditions typically implemented in soft-landing experiments are simulated. It is found that under a high-speed condition, the gold cluster Au(10) can undergo a sequence of structural transitions after colliding with a defect-free TiO(2) (110) surface. When the TiO(2) (110) surface possesses oxygen vacancies, however, chemical bonds can form between gold and Ti atoms if gold atoms contact directly with the vacancies. As a consequence, one oxygen vacancy is capable of trapping one Au atom, and thus can split the Au(10) into two parts while bouncing back from the surface. In addition, we study reaction pathways for the CO oxidation based on three isomer structures of Au(10) observed in the soft-landing simulation: (1) the precollision two-dimensional structure, (2) a postcollision three-dimensional (3D) structure, and (3) an intermediate (transient) 3D structure that appeared in the midst of the collision. This study allows us to examine the structure-activity relationship using the Au(10) as a prototype model catalyst.     

Density functional theory calculations of lithium alloying with Ge_(10)H_(16) atomic cluster

We exploited a hydrogen-passivated germanium atomic cluster(Ge_(10)H_(16) as a model to study the mechanism of lithium alloying with germanium. Based on the density functional theory, the electronic and crystal structures of lithium-alloyed Ge_(10)H_(16 were investigated. The theoretical results indicate that the alloying of lithium with Ge_(10)H_(16 will weaken the germanium-hydrogen bond and repel the closest germanium atom away from the alloyed lithium atom. Based on the maps of the electron density distribution, the nature of the lithium-germanium chemical bond was analyzed. Moreover, the diffusion process of the lithium on the Ge_(10)H_(16 cluster was detected, which suggested that there is a close relationship between the diffusion barriers and the coordination number around the lithium atom.     

Density functional embedding approach to the Mn impurities in NaBr crystals

We have performed density functional calculations for three 19‐atom clusters, two 25‐atom clusters, and one 18‐atom cluster, each embedded in a Madelung potential that takes into account the long‐range electrostatic interactions of the ion lattice of a NaBr crystal. One of the three 19‐atom and one of the two 25‐atom clusters model bulk crystalline NaBr; the others model a Mn²⁺ impurity trapped in a cubically symmetric crystalline electric field (CEF) site of the NaBr host. One of the latter has the NaBr bulk interatomic distance, while in the others relaxation of the Br atoms around the metallic impurity has been considered. The 18‐atom cluster models a relaxed Mn impurity Na vacancy system. All of our calculated clusters have a Na site at the center, and they all include at least first and second nearest‐neighbor host atoms. In the center of the doped clusters the Mn impurity replaces the missing Na ion. The electronic structure of the embedded impurity ion in its local environment was computed self‐consistently by means of all‐electron density functional theory (DFT) techniques. We have examined the lattice relaxation around the impurity and calculated the hyperfine coupling constants (HFCC). The results for the Mn electronic structure and for the HFCC are in agreement with experimental results using electron paramagnetic resonance measurements. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 79: 34–46, 2000