[交流] 【请教】结构解析时都有哪些判断原子是否定错的方法

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1楼2011-03-31 12:19:13

lyl163com

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Originally posted by cluster8676 at 2011-03-31 12:44:35:
主要是看温度因子

那看温度因子，有没有判断的依据呢！或者是不是有表可查！比如O原子的温度因子一般是多少之类的！

3楼2011-03-31 13:32:05

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cluster8676

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lyl163com(金币+5): 2011-03-31 17:10:44

主要是看温度因子

2楼2011-03-31 12:44:35

lijunjie84

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lyl163com(金币+2): 2011-03-31 17:10:57

U值，键长键角是否合理，

4楼2011-03-31 14:57:11

xujun16

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lyl163com(金币+3): 2011-03-31 19:45:12

结构解析时都有哪些判断原子是否定错的方法?
Re: in general, isotropic displacement parameters, eg. B factor or U factor. (Uiso=Biso/78.96). (anisotropic atomic displacement parameters also work.)

For inorganic ionic crystals and intermetallic compounds the typical range of B's is ~0.5 to ~1.0A; for other inorganic and many coordination compounds B varies from ~1 to ~3A, while for organic and organometallic compounds and for solvent or other intercalated non-bonded molecules or atoms this range extends from ~3 to ~10A or higher. If you isotropic displacement parameters in this range are reasonable.

      Hence, if the B becomes unphysical during the LS refinement, this usually means that the improper type of an atom has been placed in the suspicious site. There are two possibilities:

   (1) if the chemical element placed in a certain pisition has fewer electrons than is should, then during the refinement its diaplacement parameters becomes negative or much lower than those of the correctly placed atoms;

   (2) When the site has too many electrons than it really does, displacement parameters of the corresponding atom will be unusually high during the refinement.

Maybe helpful!
Reference: Fundamentals of Powder diffraction and Structural Characterization of Materials Vitalij K. Pecharsky 2003

5楼2011-03-31 19:20:49