查询词典 ab initio

Ab initio and density functional theory (B3LYP) in G98 were employed to study the following four direct aldol reactions between acetone and isobutyraldehyde or 3,3-dimethylbutyric aldehyde or benzaldehyde or 4-bromo-phenyl aldehyde catalyzed by-proline .

中文摘要：本文采用G98程序包中的从头计算方法和密度泛函方法计算研究了-脯氨酸催化丙酮与异丁醛、3，3-二甲基丁醛、苯甲醛及对溴苯甲醛的不对称直接羟醛缩合反应，共计四个反应体系。

Using ab initio methods, three molecular reactions about Isocyanic acid were investigated in this thesis, that is :(1) HNCO+HCO→TS→NCO+CH2O (2) A:HNCO+CN→TS→NCO+HCN B:HNCO+CN→TS1→INT→TS2→HNCN+CO (3) HNCO+NO2→TS1→INT1→TS2→INT2→TS3→HNNO+CO2 The theoretical studies show that the reaction (2) may occur by two different reaction channels, A and B.

本论文采用量子化学从头算方法，研究了异氰酸下列三个反应的反应机理和速率常数。

Using ab initio methods, three molecular reactions about Isocyanic acid were investigated inthis thesis, that is :(1) HNCO+HCO→TS→NCO+CH2O (2) A:HNCO+CN→TS→NCO+HCN B:HNCO+CN→TS1→INT→TS2→HNCN+CO (3) HNCO+NO2→TS1→INT1→TS2→INT2→TS3→HNNO+CO2 The theoretical studies show that the reaction (2) may occur by two different reaction channels,A and B.

本论文采用量子化学从头算方法，研究了异氰酸下列三个反应的反应机理和速率常数。

The relative stabilities and probable proton transfer in isolated and monohydrated 2-hydroxyimidazole molecules have been studied in gas phase using ab initio (MP2/6-31＋G *) method.

采用从头算方法在MP2/6-31＋G*水平上研究了2-羟基咪唑分子在孤立分子和一水合物的异构体的相对稳定性和可能的质子迁移反应，分析了一个水分子的参与对2-羟基咪唑分子异构体的相对稳定性和质子迁移速率的影响，采用Monte Carlo模拟方法研究了反应体系在水溶液中反应的溶剂化效应。

State Key Laboratory of Coal Conversion, Institute of Coal Chemistry,Chinese Academy of Sciences, Taiyuan 030001The siting of B, Al or Ga and the bridging hydroxyl group in mordenite framework were studied by using ab initio HartreeFock methods. The influence of the presence of B or Ga in the framework on the Bronsted acidity of mordenite was investigated.

用从头计算HartreeFock方法研究了B、Al、Ga等同晶取代进入丝光沸石骨架后可能存在的位置，确定了与电荷平衡质子结合的氧位置，考察了B、Ga等杂原子进入骨架对丝光沸石Brnsted酸性的影响。

The fully optimized geometries and electronic structures of seven nitramino derivatives of tetrazole are calculated by ab initio method at HF/6 - 31G* level.

运用从头计算法，在HF/6-31G水平下，全优化计算了7种硝氨四唑衍生物的分子几何和电子结构。

In this paper, the electrostatic potentials at the midpoint of C-NO2 bond and the net electric charge on every element in nitrobenzene derivatives, nitrotoluene derivatives, nitrophenol derivatives and nitroaniline derivatives were calculated using ab initio.

根据分子结构、静电势最大值、实验撞击感度及分子中各元素所带的净电荷，对影响炸药感度的因素及DATB和TATB的特殊稳定性进行了分析。通过分析，我们发现，影响上述炸药撞击感度的因素主要有硝基、甲基、羟基和胺基。

The molecular structure and the electrostatic potentials at the midpoints of C-NO2 bonds and C-CH 3 bonds for seven nitrotoluene explosives were calculated by ab initio method.

利用HONDO程序包，采用从头计算法对硝基甲苯类炸药的分子结构及其C-NO2键中点的静电势进行了计算，讨论了硝基甲苯类炸药C-NO2键中点的静电势最大值Vmidmax与其实验撞击感度之间的关系。

A new method for ab initio energy partition is being developed in order to gain new insight into the nature of electron delocalization, and it is able to provide any molecule with a fragment MO basis set in which the π and σ systems have been separated out no matter whether molecule is planar or nonplanar as well as whether the π system is conjugated or cumulated.

我们的方法可以为任何一个共轭分子(无论是平面的还是非平面的，是含共轭双键的还是含累积双键的)，提供一个π与σ体系彻底分离的片断分子轨道基组。这个轨道基组不仅满足分子特殊的对称性，而且还具有确切的电子占据数。

Spectroscopy ; ion attachment mass spectrometry ; ab initio molecular orbital theory ; density functional theory ; fluoromethyl peroxyl

光谱学；离子附着质谱；分子轨道理论；密度泛涵理论；氟甲基过氧自由基

It's rather showy.I'd like something plainer.

赶花了，我想要素净些的。

The Kremlins Spassky Tower and passers-by are reflected in the wet cobblestones of Moscows Red Square on Feb.

克里姆林宫的斯巴斯克塔和旅客的身影倒映在潮湿的鹅卵石墙上。