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pengfei0724

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[求助] 紧急求助:I2/a(No.15)空间群的具体情况

我想请问各位大侠,单斜晶系是不是只有底心或简单结构,没有体心结构,但是I2/a(No.15)空间群确实是属于单斜晶系的,这到底是为什么啊,在座的各位有谁了解这个空间群的具体情况没?包括晶体结构,原子位置等信息,谢谢各位啦!

[ Last edited by pengfei0724 on 2011-6-20 at 23:28 ]
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bible2

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【答案】应助回帖

I 2/c 1 1


--------------------------------------------------------------------------------

Space group number: 15

Schoenflies symbol: C2h^6

Hermann-Mauguin symbol: I 2/c 1 1

Unique axis: a

Cell choice: 3

Hall symbol: -I 2xc



Number of lattice translations: 2

Space group is centric.

Number of representative symmetry operations: 2

Total number of symmetry operations: 8



Parallelepiped containing an asymmetric unit:

  0<=x<=1/2; 0<=y<=1/4; 0<=z<1



List of symmetry operations:


Matrix  Rotation-part type  Axis direction  Screw/glide component  Origin shift  
x,y,z  1 - - -  
x,-y,-z+1/2  2 [1,0,0] (0,0,0) (0,0,1/4)  
-x,-y,-z  -1 - - (0,0,0)  
-x,y,z-1/2  -2 [1,0,0] (0,0,-1/2) (0,0,0)  
x+1/2,y+1/2,z+1/2  1 - - -  
x+1/2,-y+1/2,-z+1  2 [1,0,0] (1/2,0,0) (0,1/4,1/2)  
-x+1/2,-y+1/2,-z+1/2  -1 - - (1/4,1/4,1/4)  
-x+1/2,y+1/2,z  -2 [1,0,0] (0,1/2,0) (1/4,0,0)  


Change-of-basis matrix:  -y,x,y+z
               Inverse:  y,-x,x+z

List of Wyckoff positions:

Wyckoff letter  Multiplicity  Site symmetry
point group type  Representative special position operator  
f 8 1 x,y,z  
e 4 2 x,0,1/4  
d 4 -1 1/4,-1/4,3/4  
c 4 -1 1/4,-1/4,1/4  
b 4 -1 1/2,0,0  
a 4 -1 0,0,0  


Additional generators of Euclidean normalizer:
  Number of structure-seminvariant vectors and moduli: 2   
    Vector    Modulus
   (1, 0, 0)     2
   (0, 1, 0)     2

--------------------------------------------------------------------------------
Copyright 2003 by Jiawei Wang. All rights reserved.          Jiawei Wang  Laboratory of Soft Matter Physics (LSMP)  Institute of Physics, Chinese Academy of Sciences  No.8 South Street 3, Zhong Guan Cun  P.O. Box 603, Beijing 100080, P.R. China  Tel: +86-10-82649083  E-mail: jwwang@cryst.iphy.ac.cn
2楼2011-06-21 07:53:49
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