大基组在价键计算中的处理

编写了普适性的多键表自洽场程序，该程序能对单电子轨道展开系数和键表系数同时优化，其中单电子轨道的展开空间可任意定义，实际计算建议采用“杂化”轨道形式，即每个单电子轨道只对一个原子的基函数展开。对Ｈ２、Ｌｉ２及ＨＬｉ采用不同基组进行计算，结果表明用３个键表自洽计算所得能量与ＭＰ２结果相近，且我们的计算对键的共价性和离子性分析非常直观。     

π-Bindungsbeitrag in Boranen, 2. Mitt.:Ab initio- und Kraftfeld-Rechnungen von Vinyldifluorboran

Ab initio calculations on vinyldifluoroborane yield a -contribution of 23 kJ/mol (5.5 kcal/mol) mainly due to the C=C bond and not to the lone pairs of the fluorine atoms. The rotational barrier was also determined. The force field calculations favour the interpretation of the bond structure derived from the theab initio results.

     

纳米TiO2的光生电荷迁移特性研究

利用场诱导光电压谱(简称FISPS)和瞬态光伏(简称TPV)技术研究了TiO₂的光生电荷的产生和传输机制.发现光生电荷在体块TiO₂上的迁移机制不同于在纳米TiO₂上的迁移机制，也不同于在结界面空间电荷区的迁移机制. 400 ℃处理的TiO₂颗粒表面具有大量的表面态，光生电荷被表面态捕获-释放机制控制着光伏行为的过程是慢过程. 800 ℃处理的TiO₂已经形成了完整的能带结构，光伏响应除了表现带-带跃迁外,还有一个在带边的自由激子带，光生电荷被表面自建场驱动进行传递的过程是快过程. 600 ℃处理的TiO₂混晶由锐钛矿型和金红石型两种构型组成，在两相之间存在着较低势垒的结界面．它的光伏响应受控于两种机制 ：光生电荷在两相间结界面空间电荷区的传输和在表面自建场驱动下的传输.当激发光强较小时，界面空间电荷区的光生电子由于积累的浓度较小而不能隧穿过结界面，这种场助隧穿只有在外场作用下才能发生.     

Isoperichoric focusing field-flow fractionation and thin layer isoperichoric focusing based on coupling of gradient generated by primary field with secondary field action: general principles and performances

The primary field forces can generate spatially oriented gradient of the effective property of a continuum or pseudo-continuum fluid (carrier liquid). When this gradient is coupled with the action of a secondary field of identical or different nature the isoperichoric focused zones of the dispersed species can appear. Consequently, they can be separated according to differences responding to the property gradient of the carrier liquid. This concept can be applied under static (non-flow) conditions in thin layer focusing as well as under dynamic conditions with the elution due to the carrier liquid flow in focusing field-flow fractionation. The gradient established by the action of the primary field and the concentration distribution of the isoperichoric focused zone formed by the coupled effect of the gradient and of the primary or secondary field are described theoretically. The rigorous relationship describing the shape of the focused zone is compared with the approximate solutions. The performances of the proposed principle were evaluated by model calculations. Potential experimental configurations considering the implementation of the static and dynamic conditions are discussed. The generalized isoperichoric focusing theory can be applied to describe the particular processes operating in analytical and preparative focusing separations of the particles of various, but especially of biological origin.     

A force field study of diacetylene molecule by kinetic constant method

The potential constants of diacetylene molecule has been evaluated using kinetic constants. The other molecular constants such as the generalised vibrational mean amplitudes, shrinkage constants, Coriolis coupling constants and centrifugal distortion constants are also calculated using the vibrational frequencies and the results discussed.     

Pulsed field gradient NMR on polybutylcyanoacrylate nanocapsules

The applicability of pulsed field gradient nuclear magnetic resonance spectroscopy to nanocapsule systems is demonstrated on dispersed poly-n-butylcyanoacrylate nanocapsules as a model system. Spectroscopic data are presented that allow for the structural characterization of the inner cavities, the observation of Brownian motion of the capsules and the detection of rapid molecular exchange through the capsule walls. An analytical formula is proposed that yields equilibrium populations and average residence times of a given tracer molecule, thus leading to crucial information regarding the permeability of the capsule walls. Based on these analytical methods, two varieties of nanocapsules are compared that derive from two different preparation procedures. It is found that thinner capsule walls obtained under acidic conditions of the organic phase during interfacial polymerization lead to correspondingly higher exchange rates of benzene as a tracer molecule.     

Computation of equilibrium oxidation and reduction potentials for reversible and dissociative electron-transfer reactions in solution

Equilibrium free-energy cycles relating oxidation and reduction potentials in solution to ionization potentials and electron affinities in the gas phase are constructed and the utilities of various levels of theory for computing particular free-energy changes within these cycles are discussed within the context of several examples. Emphasis is placed on the use of quantum-mechanical continuum solvation models to compute free energies of solvation. Key systems discussed include quinones, substituted anilines, substituted phenols, and reductive dechlorination reactions.Dedicated to Prof. Jean-Louis Rivail, whose pioneering efforts in developing and exploiting continuum solvent models were critical in making quantum chemistry more applicable to solution phenomenaProceedings of the 11th International Congress of Quantum Chemistry satellite meeting in honor of Jean-Louis Rivail     

Laser field induced charge transfer: Para-nitroaniline coupled to a quantum mechanical radiation field

Summary We present a preliminary model for describing a solvated intramolecular charge transfer reaction coupled to a quantum mechanical radiation field. Actual calculations of energies and couplings were performed with a recently developed self-consistent reaction field response method. The representation of dressed molecular states is used for calculating state populations for various laser fields. The state populations are sensitive to the properties of the laser field.     

The electrostatic field of B-DNA

The electrostatic field associated with one complete turn of B-DNA is presented. Two base sequences poly (dG) · poly (dC) and poly (dA) · poly (dT) are studied and the effects of sodium counterions bound to the nucleic acid are investigated. The contrasts between the electrostatic potential and the electrostatic field of the macromolecules are discussed and the possible applications of the field are considered.     

环氧合酶－2抑制剂的三维定量构效关系研究

建立三环系COX－1和COX－2抑制剂结构与活性的三维定量构效关系模型，为设 计新型的具有选择性的COX－2抑制剂提供线索。通过与酶的对接并优化，确定化合 物在受体结合腔中的构象，利用比较分子力场分析方法建立三维定量构效关系模型 。模型1R_(cv)~2=0.685，最佳主成分数为6，传统相关系数为R~2=0.988, F-726. 2，标准偏差S = 0.080；模型2 R_(cv)~2 = 0.573，最佳主成分数为6，传统相关 系数为R~2=0.996, F = 1147.6，标准偏差S = 0.034。所得的模型不仅解释了化合 物的构效关系，而且对预测集中的化合物有很好的预测能力；比较不同模型的系数 相关图，分析了结构与活性、结构与选择性的关系，得到的结果可以指导新化合物 的设计与合成。