[2~3]Cyclophanes电子结构的理论研究

用改造的重叠模型多重散射X~α自洽场方法计算环芳类化合物[2~3]cyclophanes的电子结构, 分析该类分子中分子轨道通过空间和通过键的相互作用,单键连接桥.双键连接桥对通过键相互作用的影响, 用过渡态理论方法计算分子前线分子轨道的电离能,理论结果与紫外光电子能谙符合较好.     

化学反应过程中分子中1个电子所受到的作用势与力常数的理论研究

通过典型的双分子亲核取代和烯烃亲电加成反应,讨论了反应过程中,化学键伸缩振动力常数和分子中1个电子所受到的作用势(D_(pb))之间的关联.研究表明分子中1个电子所受到的作用势能够很好地描述反应中键形成和断裂时的化学键强度.     

分子轨道图形理论应用于单环共轭分子中的一个教学问题

对于单环共轭分子,简单分子轨道理论只处理π电子,把平面内的σ电子系统连同核和内层电子看作刚性的分子实,单电子薛定谔方程为Hψ=Eψ(1) 其中H是哈密顿算符,ψ是π电子分子轨道,E是能级·分子轨道近似用原子轨道的线性组合来表示.     

PdCO(OH)-体系中OH-助催化性能的成键能研究

本文使用相对论赝势从头计算方法和成键能判据[1 ] 研究了模型化合物 Pd CO(OH) -的电子结构 ,讨论了 OH-的助催化作用。得出 OH-对 Pd CO的助催化作用既可以通过其与金属 Pd形成化学键 (通过金属 )来实现 ,也可以通过空间电荷静电作用 (通过空间 )来实现。由分子轨道成键能分析指出 CO分子的强成键占据分子轨道 3σ和 1π的削弱是活化 CO的关键。     

Fluorescein有机薄膜在Ag(110)面上的生长研究

利用紫外光电子能谱(UPS)对在Ag(110)表面上荧光素(fluorescein)的生长进行研究. 研究表明, 与fluorescein分子轨道有关的4个特征峰分别位于费米能级以下2.70, 3.80, 7.40和9.80 eV处. 角分辨紫外光电子能谱(ARUPS)测量结果表明, fluorescein分子的三苯环平面平行衬底平面, 分子的C=O轨道轴向接近于[1-10]晶向.     

BH_3及其等电子分子片的杂化轨道和轨道相互作用

本文在文[1—3]和MNDO分子轨道计算的基础上,分析一些等电子分子片X(BH_(?)、BF_3、CH_3~+、CF_3~+)的前线杂化轨道,讨论它们同配体L(H~-、CO、CN~-、NC~-、NH_3)的轨道相互作用,从而研究X+L→XL反应的进程和产物XL分子稳定结构。     

O3分子在CuO(110)面吸附的密度泛函理论研究

应用密度泛函理论研究了O3分子在2×1 CuO(110)面(S1)和掺杂一个Fe原子的2×1 CuO(110)面(S2)的吸附过程和电子特性. 计算结果表明, O3分子与表面S1和S2有很强的相互作用, O3分子在表面吸附反应的活化能和反应能均为负值, 反应很容易进行. 态密度和电荷密度分析结果进一步证实了O3分子在S1上吸附是桥位化学吸附, 形成表面臭氧化物, 在S2上吸附分解为1个被吸附的表面氧原子和1个自由氧分子. 电子特性分析表明, O3分子与S1和S2相互作用的本质是O3分子的价轨道2p与CuO(110)表面杂化轨道的相互作用.     

[He3H]＋分子基态势能面的从头计算研究

使用CCSD(T)/aug-cc-pVTZ从头计算方法，对[He3H]＋分子的一些特殊构型的电子基态势能进行扫描，并以此为基础对三体相互作用势在惰性气体质子簇中的影响进行了讨论.结果表明即使在这样一个简单的体系中三体相互作用的影响都是不能忽略的.另一方面，在[He3H]＋分子稳定构型附近仅将势能展开至三体相互作用项便可提供较精确的相互作用信息，但在强排斥区域更高阶作用的影响变得越来越突出.本文同时讨论了[He4H]＋的稳态结构. [He3H]＋与[He4H]＋的稳态结构表明,[HenH]＋簇中存在着一个[He2H]＋核.     

杯[4]吡咯-阴离子体系相互作用的理论研究——杯[4]吡咯-卤素阴离子体系的密度泛函研究

用密度泛函B3LYP/LANL2DZ方法对自由杯[4]吡咯的最低能量构象和卤素阴离子-杯[4]吡咯复合物进行了计算研究.结果表明,杯[4]吡咯与卤素离子能通过彼此间的相互作用形成复合物,并且这种相互作用在本质上应为分子间的氢键相互作用;杯[4]吡咯与卤素阴离子形成的复合物在构型变化、电荷转移、前线轨道及其作用方式、成键布居以及能量和热力学参数等方面均按元素周期律有规律地变化,杯[4]吡咯与卤素阴离子间的相互作用沿元素周期依次减少.     

Theory on the molecular characteristic contour(Ⅰ)——A new approach to defining molecular characteristic contour

Based on the classical turning point of electron movement in a molecule, a model for defining the molecular characteristic boundary contour is advanced. By using an accurate ab initio MELD program and an auxiliary program, some electron parameters in a molecule, such as the potential felt by an electron, have been evaluated. According to our model and definition, the molecular characteristic contour of the equilibrium geometry configuration is drawn and a vivid intuitive picture for describing the forming or breaking of a chemical bond is displayed.     

Theory on the molecular characteristic contour (I)

Based on the classical turning point of electron movement in a molecule, a model for defining the molecular characteristic boundary contour is advanced. By using an accurateab initio MELD program and an auxiliary program, some electron parameters in a molecule, such as the potential felt by an electron, have been evaluated. According to our model and definition, the molecular characteristic contour of the equilibrium geometry configuration is drawn and a vivid intuitive picture for describing the forming or breaking of a chemical bond is displayed.     

Electron Transport through Single π‐Conjugated Molecules Bridging between Metal Electrodes

Understanding electron transport through a single molecule bridging between metal electrodes is a central issue in the field of molecular electronics. This review covers the fabrication and electron‐transport properties of single π‐conjugated molecule junctions, which include benzene, fullerene, and π‐stacked molecules. The metal/molecule interface plays a decisive role in determining the stability and conductivity of single‐molecule junctions. The effect of the metal–molecule contact on the conductance of the single π‐conjugated molecule junction is reviewed. The characterization of the single benzene molecule junction is also discussed using inelastic electron tunneling spectroscopy and shot noise. Finally, electron transport through the π‐stacked system using π‐stacked aromatic molecules enclosed within self‐assembled coordination cages is reviewed. The electron transport in the π‐stacked systems is found to be efficient at the single‐molecule level, thus providing insight into the design of conductive materials.     

Single‐Enzyme Biofuel Cells

Herein, we demonstrate that the intramolecular electron transfer within a single enzyme molecule is an important alternative pathway that can be harnessed to generate electricity. By decoupling the redox reactions within a single type of enzyme (for example, Trametes versicolor laccase), we harvested electricity efficiently from unconventional fuels including recalcitrant pollutants (for example, bisphenol A and hydroquinone) in a single‐laccase biofuel cell. The intramolecular electron‐harnessing concept was further demonstrated with other enzymes, including power generation during CO₂ bioconversion to formate catalyzed by formate dehydrogenase from Candida boidinii . The novel single‐enzyme biofuel cell is shown to have potential for utilizing wastewater as a fuel as well as for generating energy while driving bioconversion of chemical feedstock from CO₂.     

生物体系中电子转移机理的理论研究Ⅰ: 一种计算电子转移 的方法及在螺环化 合物中的应用

应用"相应轨道变换"和"广义"密度矩阵的方法,向MOPAC程序包中加入了新的功能,使其能处理电子转移反应中的部分参数。然后用此程序包中AM1方法对具有螺环结构的分子进行处理,计算了化合物在不同外加电场强度下的势能面、反应热ΔE,重组能λ及电子转移矩阵元V~A~B,结果表明,λ,V~A~B受外加电场的影响较小,而ΔE则与之成正比。对标题化合物1的计算结果也同abinitio法的结果进行了比较,发现其变化趋势完全一致,这说明本方法在计算电子转移方面是可靠的。与abinitio方法相比,本程序不仅适用于计算较大体系(如生物大分子),而且还具有速度快,耗时少的优点。     

HF分子与惰性气体二聚体的分子形貌的理论研究

采用Gaussian-03程序中的MP2/6-311++G(2d,2p)方法,优化了FH- Rg(Rg=He,Ne,Ar)二聚体的结构.使用MELD精密从头计算中的CISD方法,结合我们自编的程序,计算了这些二聚体的单电子作用势(PAEM),并绘出了它们的分子形貌图象.分子形貌所提供的形貌特征、前沿电子密度的特征等,可以直观地揭示He,Ne和Ar等原子与HF分子相互作用时2种相互作用的差别,即共价相互作用与非共价相互作用区分的直观形象的表征.从二聚体的内禀特征信息可以看出,F,H和Rg原子都发生了不同程度的变形,HF分子对惰性气体原子有一定影响,而惰性气体原子对HF分子的影响较小.     

Polarization and bonding of the intrinsic characteristic contours of hydrogen and fluorine atoms of forming a hydrogen fluoride molecule based on an ab initio study

The spatial changing feature of the shapes and sizes of the system consisted of one hydrogen atom and one fluorine atom of forming a hydrogen fluoride molecule is investigated. We give formalism of the potential acting on an electron in a molecule and derive its concrete expression in Hartree-Fock self-consistent molecular orbital theory including configuration interaction. The program of calculating the potential acting on an electron in a molecule is programmed and compiled in the framework of the MELD program package. We formulate briefly the approach of the molecular intrinsic characteristic contour (MICC) which is defined in terms of the classical turning points of electronic motion. The MICC for a molecular system is intrinsic and can be calculated by means of an ab initio CI method. Then, the polarization and bonding features of the intrinsic characteristic contours of hydrogen and fluorine atoms forming a hydrogen fluoride molecule are presented and discussed from ab initio calculations. Furthermore, electron density distribution as an added dimension has been demonstrated on the changing MICC and thus the vivid polarization and bonding features for a chemical process have been shown. It seems that at the early stage (internuclear distance Ind=5.0-20.0 a.u.) the fluorine atom gives more enthusiastic with the sensitive and expanded polarization to welcome coupling with the hydrogen atom while the latter has little response even "shy" with shrinking a bit its size at the beginning of putting the two atoms into a system and it is only around the critical point, the contact point (Ind=4.73 a.u.), that both of them stretch their hands and arms to meet and then fuse together.     

Single electron densities: a new tool to analyze molecular wavefunctions

A new partitioning scheme for the electron density of a many-electron wavefunction into single electron densities is proposed. These densities are based on the most probable arrangement of the electrons in an atom or molecule. Therefore, they contain information about the electron-electron interaction and, most notably, the Fermi hole due to the antisymmetry of the many-electron wavefunction. The single electron densities overlap and can be combined to electron pair distributions close to the qualitative electron pairs that represent, for instance, the basis of the valence shell electron pair repulsion model. Single electron analyses are presented for the water, ethane, and ethene molecules. The effect of electron correlation on the single electron and pair densities is investigated for the water molecule.     

The relations of bond length and force constant with the potential acting on an electron in a molecule

Within a molecule, the potential acting on an electron (PAEM) is defined as the interaction energy of a local electron with the rest of the particles, i.e., all nuclei and remaining electrons. The formalism of the PAEM is first derived, and the calculated PAEMs are then obtained by using the ab initio program based on the MELD program package for a series of diatomic halides, namely, HX, LiX, NaX, and X(2) molecules (X= F, Cl, Br, and I), as well as H(2)O and NH(3), and some organic molecules. By comparing the 3D topological graphs of the PAEMs, we found that there is a saddle point along every chemical bond axis. Further, the good linear correlations of the force constant and bond length with the PAEMs are explored through a definition of D(pb), which is the absolute value (i.e., the negative) of the PAEM at the saddle point along the chemical bond axis. In addition, the difference between the PAEM and molecular electrostatic potential (MEP) is pointed out by analyzing both their definitions and numerical results.