在这之前我们要引入价电子成键理论，和杂化轨道的概念。
And to do this we're going to introduce valence bond theory, and the idea of hybridization of orbitals.
这就是成键分子轨道的概念。
我们现在可以考虑成键了，现在我们有4个等价的轨道，每个上面有1个电子。
So we can think about now doing bonding, and now we have four equal orbitals with one electronic each.
此外，它关于键轴是圆柱对称的，这就是为什么我们知道它是sigma轨道。
Also, it is cylindrically symmetric around the bonding axis, so this is how we know that it's a sigma orbital.
但记住sigma轨道沿着，键轴方向是没有节点的。
But keep in mind sigma orbitals have no nodal planes along the bond axis.
我们会称它为2py分子轨道上的π键。
这里有p轨道是很合理的,为什么我们在这里有P轨道，为了形成一个π键，我们需要一个p轨道。
So it already should make sense why we have that p orbital there, in order to form a pi bond, we're going to need a p orbital.
如果我们考虑引入最后两个碳原子，你会看到的是对于每个碳原子，其中的两个杂化轨道，和另外的碳原子成键。
If we think about bringing in those last two carbons, what you can see is that for every carbon, two of its hybrid orbitals are being used to bond to other carbons.
所以能级较低的轨道叫做成键轨道，这就是成键分子轨道。
And so this lower level is called a bonding orbital, and it is a bonding molecular orbital.
描述一个键的办法,是描述形成键的轨道，以及键的对称性。
So the way that you describe a bond is you describe the orbitals that the bond comes from, and also the symmetry of the bond.
我们可以把它这样翻一下,这是一个π键，这是另外一个p轨道之间,相互作用的π键。
So we can kind of flip it this way this will be one pi bond, this will be another interacting between these p orbitals.
所以它是沿着键轴方向的,而且这里是一个碳sp2杂化轨道，和一个氢的1s轨道的结合,在这里我们可以合并他们。
So it's along the bond axis and it's between a carbon s p 2 hybrid, and then the hydrogen is just a 1 s orbital that we're combining here.
如果我们考虑有六个氢原子，每个都会合起来，碳杂化轨道成键，每个氢的1s轨道。
And if we think about the six hydrogens, now each of those are going to bind by combining one of the carbon hybrid orbitals to a 1 s orbital of hydrogen.
如果我们考虑,两个碳原子之间的z成键轴，我们可以画出sp杂化轨道的交叠，我们也可以画出和氢原子的成键。
So, if we think about this z bonding axis between the two carbon atoms, we can picture overlap of those s p hybrid orbitals, and then we can also picture bonding to hydrogen.
因此你能看到,反键轨道上有两组，三组成键，得到一组净成键，所以成的是单键。
so you can see that there is going to be two sets in antibonding, three sets in bonding for a net of one, giving us the single bond.
告诉我们关于，And，the，sigma，tells，us，something，about，the,分子轨道对称性的信息，特别是它关于键轴是圆柱对称的。
Sigma symmetry of this molecular orbital, specifically that it's cylindrically symmetric about the bond axis.
用前线分子轨道理论分析了反应的活性原子和活性键。
The active atoms and bonds of reaction were provided by frontier molecular orbital theory.
得到了它们的基态能量，基态自旋多重度，分子轨道组成与能级，电荷分布与键序。
The total energies, spin multiplicities, charge distribution, bond orders, the front molecular orbital compositions and orbital energies have been obtained.
由自然键轨道分析揭示了相互作用的本质。
Natural bond orbital analysis was performed to reveal the origin of the interaction.
由自然键轨道(NBO)分析揭示了相互作用的本质。
Natural bond orbital (NBO) analysis is performed to reveal the origin of the interaction.
在化学键形成时并不是电子配对的结果，而是电子从能量较高的原子轨道转移到能量较低的成键的分子轨道上使体系能量降低的结果。
It is not result of spin pairing to form chemical bonds, Instead, transfer electron from the atomic orbital of taller energy to the moleen -lar orbital of lower energy.
自然键轨道分析表明分子内与分子间超共轭和重杂化理论可以解释这些氢键的形成机制。
Natural bond orbital analysis shows that these H-bonds can be interpreted with the theory of inter-and intra-molecular hyperconjugation and rehybridization.
对稀有气体化合物的分子结构分别用“价层电子对互斥理论”、“价键理论”和“分子轨道理论”进行了分析处理。
This paper analyzes shell electron pair repulsion theory , valence-bond theory and molecular orbital theory on molecular structure of noble gas compounds.
用杂化轨道理论和分子轨道理论阐明了氮的氧化物成键类型，给出了分子空间构型及结构数据的解释。
The spatial configurations and bonding effects of Oxides of Nitrogen were explained by using the Valence-shell Electron Repulsion Theory, Hybrid-orbital Theory and Molecular orbital Theory.
我们在形成一个分子时要做的就是，把这两个轨道放到一起，这样我们有他们的原子核，两个原子核，它们之间的距离为键长。
What we're going to do in forming a molecule is just bring these two orbitals close together such that now we have their nucleus, the two nuclei, at a distance apart that's equal to the bond length.
而在分子轨道理论里，我要告诉你们的时，我们任为电子分布在整个分子中，它们不仅仅是和，一个原子或者一个键有关。
Whereas in molecular orbital theory, what I'm telling you is instead we understand that the electrons are spread all over the molecule, they're not just associated with a single atom or a single bond.
另外，我们介绍了自然键轨道(NBO)方法，这种方法在成键分析中显示越来越重要的作用，并能够结合用于DFT方法中。
In addition, we introduced the natural bond orbital (NBO) methods, which is increasingly important in bonding analysis and can be used for DFT methods.
利用群论的方法及定域键的观点可以把轨道对称守恒原理表述为键对称守恒规律。
The conservation principle of orbital symmetry may be represented as conservation law of bond symmetry, by means of group theory and the point of view of the localized bonds.
通过CO分子接近表面时各分子轨道能量本征值的变化，讨论了各轨道的成键、反键特征。
The bonding and antibonding character for the CO valence level have also been studied by analysis of the variations of the molecular eigenvalues when the CO molecule approaches the surface.
通过CO分子接近表面时各分子轨道能量本征值的变化，讨论了各轨道的成键、反键特征。
The bonding and antibonding character for the CO valence level have also been studied by analysis of the variations of the molecular eigenvalues when the CO molecule approaches the surface.
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