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coolrainbow

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Originally posted by mchen10 at 2010-12-08 04:25:02:

actually B1 and B2 are equivalent, depends on way you define x and y. It will be B1 in one program and B2 in another sometimes, but both are right..

However, in the coordinate system defined within gaussview, it incorrectly identified the B1 and B2 states.
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31楼2010-12-08 08:06:39
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8tao7

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Originally posted by mchen10 at 2010-12-08 04:25:02:

actually B1 and B2 are equivalent, depends on way you define x and y. It will be B1 in one program and B2 in another sometimes, but both are right..

Yes, you are right. I found B1 in Gaussian, while B2 in ADF. Of course, the distribution of B1 and B2 orbitals is the same. When I rotated the system 45 degree in ADF, the B1 is output.
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32楼2010-12-08 08:06:51
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ykwang

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Originally posted by mchen10 at 2010-12-08 04:25:02:

actually B1 and B2 are equivalent, depends on way you define x and y. It will be B1 in one program and B2 in another sometimes, but both are right..

在讨论不可约表示的标记时,关于分子坐标系的选取并不是随意的,而是有普遍接受的规则可循,详见:M. 奥钦,H. H. 雅费 著,徐广智 译,《对称性、轨道和光谱》,科学出版社,1980, pp119-122。例如,对于H2O而言,分子平面规定为YZ面,而不能随意指定为XZ平面。按照这一约定,B1和B2是明确的。
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33楼2010-12-08 22:01:37
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mchen10

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Originally posted by ykwang at 2010-12-08 22:01:37:


在讨论不可约表示的标记时,关于分子坐标系的选取并不是随意的,而是有普遍接受的规则可循,详见:M. 奥钦,H. H. 雅费 著,徐广智 译,《对称性、轨 ...

please enlighten me, what is THE RULE?
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34楼2010-12-09 01:54:41
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ykwang

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Originally posted by mchen10 at 2010-12-09 01:54:41:
please enlighten me, what is THE RULE?

OK, I had thought that you may understand Chinese though you may not speak it. Concerning the rules about how to correctly assign the Cartesian coordinate axes to the symmetry ones of a molecule, please refer the following book:

"Symmetry, Orbitals and Spectra", Milton Orchin and  Hans H. Jaffe, John Wiley, 1971. [pp 119-122 in Chinese version. Sorry, I do not know the correct page numbers in English version of the book]
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35楼2010-12-09 09:09:07
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mchen10

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Originally posted by ykwang at 2010-12-09 09:09:07:


OK, I had thought that you may understand Chinese though you may not speak it. Concerning the rules about how to correctly assign the Cartesian coordinate axes to the symmetry ones of a molecul ...

Sorry for the inconvenience, it's just I cannot type Chinese in my office.

The problem here is: what on earth is the rule for choosing the plane? Is it simple enough that can be commonly accepted? Why popular programs don't always follow the rule even though they are commonly acknowledged? How about more complicated system with C2v symmetry?

Maybe you are right. But I am only be convinced with more proof and details. It is not possible that everyone will buy such book and read it.

[ Last edited by mchen10 on 2010-12-9 at 10:51 ]
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36楼2010-12-09 10:31:49
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ykwang

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Originally posted by mchen10 at 2010-12-09 10:31:49:
Sorry for the inconvenience, it's just I cannot type Chinese in my office.
The problem here is: what on earth is the rule for choosing the plane? Is it simple enough that can be commonly acc ...

首先针对程序的问题说几句:

量子化学程序包的主旨是解决复杂的计算问题,故在一些细节上做得并不好。具体能做到什么程度取决于程序员的专业素质,而不同程序包作者的专业素质却差别很大。你不能指望程序把一切都搞定,因为后续分析不是程序的问题,而是使用者的问题,完全把程序作为“黑箱”来使用是很危险的。

其次把上面提到的有关约定拷贝如下供参考:





[ Last edited by ykwang on 2010-12-9 at 16:53 ]
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37楼2010-12-09 16:52:12
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mchen10

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Originally posted by ykwang at 2010-12-09 16:52:12:


首先针对程序的问题说几句:

量子化学程序包的主旨是解决复杂的计算问题,故在一些细节上做得并不好。具体能做到什么程度取决于程序员的专业素质,而不同程序包作者的专业素质却差别很大。你不能指望程序把 ...

thanks

it surely clears the air a lot. it seems the rule takes care of the planar C2v molecules, but for non-planar ones the B1 and B2 are still arbitrary
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38楼2010-12-10 00:40:12
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ykwang

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Originally posted by mchen10 at 2010-12-10 00:40:12:
thanks
it surely clears the air a lot. it seems the rule takes care of the planar C2v molecules, but for non-planar ones the B1 and B2 are still arbitrary

对于非平面的C2v对称性的分子,惯例是将包含原子数最多的对称面选为YZ面(H2O只是这一要求的特例)。如果XZ面与YZ面包含相同数目的原子,则将包含重原子(非氢原子)数多的面选为YZ面。就我所知,Gaussian03/09是遵循这一规则的。
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39楼2010-12-10 06:04:51
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fineren

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学习了
40楼2010-12-10 12:18:39
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