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The space groups listed in this file are known by their name: an uppercase copy of the classical name. They are often followed by a comment which include their reference number in the international table and can precise the origin choice.
Sometimes there are short entries for space group of high symetry which are restricted to some of the most symetrical Wickoff position, by example FM3M_AB is a restricted entry of the group Fm3m valid for the Wickoff positions a and b only.
Please return the mistakes found in the distributed file. Entry can be added by users in the file. When a group is encountered in the input file, the program first scans its internal table read in the data file then if no match is found it scans the default up to the first name matching the definition.
variable | value | comment |
SymName | string whithout spaces | The first character of the string has to be among (P, I, F, A, B, C, R)
according
to the kind of Bravais Lattice or to be the symbol * reserved to
complement of a 3-D group in modulated structure.
After the identifier, a comment beginning with # is allowed till the end of line. |
System | C | Cubic |
Q | Tetragonal (Quadratic) | |
H | Hexagonal (Laue classes 6/m and 6/mmm | |
R | Trigonal (Laue classes 3 and 3m - hexagonal axis) | |
T | Trigonal (Laue classes 3 and 3m - rhombohedral axis) | |
O | Orthorhombic | |
L | Monoclinic (unique axis a) | |
M | Monoclinic (unique axis b) | |
N | Monoclinic (unique axis c) | |
A | Anortic (Triclinic) | |
* | complement for displacive modulation | |
Holohedral | 0 | if the group is not holohedral (eg 3 or 4/m) |
1 | if the group is holohedral | |
SymCenter | 0 | the group has no symmetry center at the origin. |
1 | the group is centrosymmetric at the origin, in this case, only the operations belonging to the factor group G/I have to be declared. | |
NSymOps | Integer | number of symmetry operations to be read |
- x,y,z;
- -x,z+2/3,y
The symmetry operations are separated by a semicolumn or by a linefeed.
The only valid translation are given using simple ratio (up to 12).
P21/C #13 axe b M 1 1 2 x,y,z; -x,1/2+y,1/2-z; FD3M_E #227 Fd-3m orig -3m (wickoff sites : a, b, c, d, and e only) C 1 1 4 x, y, z; x, 1/4-y, 1/4-z; 1/4-x, y, 1/4-z; 1/4-x, 1/4-y, z;
sginfo
as shown in the following example by doing some
cut and paste.
sginfo
can be found at http://www.csb.yale.edu/sginfo
$ sginfo -xyz P2/c # sginfo -xyz P2/c Space Group 13:b1 C2h^4 P2/c:b1 = P12/c1 -P 2yc Point Group 2/m Laue Group 2/m Monoclinic Unique Axis y Order 4 Order P 4 s.i.Vector Modulus 1 0 0 2 0 1 0 2 0 0 1 2 #List 2 x, y, z -x, y, -z+1/2 $ sginfo -xyz Pm-3m # sginfo -xyz Pm-3m Space Group 221 Oh^1 Pm-3m -P 4 2 3 Point Group m-3m Laue Group m-3m Cubic Order 48 Order P 48 s.i.Vector Modulus 1 1 1 2 #List 24 x, y, z -y, x, z -x, -y, z y, -x, z x, -z, y x, -y, -z x, z, -y z, y, -x -x, y, -z -z, y, x ....
# input for spacegroup CMMA O 1 1 4 X, Y, Z; -X, -Y+1/2, Z; -X, Y+1/2, -Z; X, -Y, -Z *_CMMA #complement * 1 0 4 X+1/2; -X+1/2; X+1/2; -X+1/2
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