Electron microscopy
 
4mm Point Group
- Practical Electron Microscopy and Database -
- An Online Book -
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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
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Table 3003 list all the space groups which have point group 4mm.

Table 3003. All space groups which have point group 4mm.
Space Group Patterson Space Group Number of Symmetry Operators Crystal System Laue Class Lattice Type
P4mm 123 8 Tetragonal 4/mmm P
P4bm 123 8 Tetragonal 4/mmm P
P42cm 123 8 Tetragonal 4/mmm P
P42nm 123 8 Tetragonal 4/mmm P
P4cc 123 8 Tetragonal 4/mmm P
P4nc 123 8 Tetragonal 4/mmm P
P42mc 123 8 Tetragonal 4/mmm P
P42bc 123 8 Tetragonal 4/mmm P
I4mm 139 16 Tetragonal 4/mmm I
I4cm 139 16 Tetragonal 4/mmm I
I41md 139 16 Tetragonal 4/mmm I
I41cd 139 16 Tetragonal 4/mmm I

In 4mm, σ1 and σ3 are related by the 90° rotation of 4­fold axis as shown in Figure 3003a. There are two obvious sets of mirror planes which are σ13 and σ24. These two sets are not equivalent as the operation of the rotation axis will never match the two sets to the same location. Therefore, this is group 4mm.

4mm point group

Figure 3003a. 4mm point group.

 

 

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