24小时热门版块排行榜

返回列表

当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖

lyl163com

金虫 (正式写手)

CMEI: 2
应助: 4 (幼儿园)
金币: 703.7
帖子: 919
在线: 436.2小时
虫号: 860823

[交流] 【请教】结构解析时都有哪些判断原子是否定错的方法

结构解析时都有哪些判断原子是否定错的方法

回复此楼

» 猜你喜欢

» 本主题相关价值贴推荐，对您同样有帮助:

请教单晶结构解析中原子定义问题已经有7人回复
用什么方法确定四元合金原子排列结构已经有7人回复
急求帮助：共聚水凝胶的结构和彼此之间的相互作用力的判断表征方法手段有哪些啊已经有7人回复
计算晶体怎样减少键长键角的相对误差？怎样确定中心原子周围键的键组成？已经有4人回复
急需赛默飞世尔ICE 3500原子吸收仪各个角度照片及内部结构，操作方法已经有3人回复
【讨论】刃型位错的柏氏矢量的确定问题（三角结构排列的原子）已经有12人回复
【求助】24个Mg原子，即hcp结构，结果里面出现很大的warning，怎么回事已经有19人回复
【求助】在结构优化时怎样固定大量原子？已经有5人回复
【求助】结构优化时如何将原子位置固定在原胞内已经有9人回复
【请教】晶体解析如何确定原子种类？已经有15人回复

» 抢金币啦！回帖就可以得到:
查看全部散金贴

1楼2011-03-31 12:19:13

已阅回复此楼关注TA 给TA发消息送TA红花 TA的回帖

xujun16

银虫 (著名写手)

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