Bilbao Crystallographic Server XML output Space group representations

Representations of Space Groups

To obtain the representations for a given k-vector and given space group in XML form you have to give the command

GET /cgi-bin/cryst/xml/nph-get_doc?p=irreps&g=group&k=kvec

where

• group -- is the group number in ITA, followed by a letter that specifies the setting that is used in case that there are two conventional settings.
  The letters are: b|c for the unique axis, o|t where o corresponds to origin choice one and t -- to origin choice two, and [rh]=h|r for rhombohedral and hexagonal axes.
• kvec contains the necesary data in the form [x,y,z,label,basis]
• x,y,z are the values for the three coordinates of the k-vector, label is the k-vector label, and basis is p - primitive, c - centered dual, or a - adjusted coefficients.

NOTE: By now the program uses the default choice for the group setting when there is more than one conventional setting.

For example if you want to obtain the representations for the k vector with label GM and coordinates (0,0,0) of the group 012( C 2/m) you have to do the following:

GET /cgi-bin/cryst/xml/nph-get_doc?p=irreps&g=12&k=0,0,0,GM,p

The output you will obtain has the following form:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE bcs_group PUBLIC "bcs_group" "www.cryst.ehu.es/cryst/dtd/bcs_group.dtd">

<bcs_group><!-- Bilbao Crystallographic Server (www.cryst.ehu.es) -->
<group number="12" symbol=" C 2/m"><!-- Irreps of the group 12 ( C 2/m) [unique axis b] -->
<kvec label="GM" basis="p">
<xyz>0, 0, 0</xyz>
<genpositions>
<genpos>
<mat>
<row>[ 1 0 0  ][ 0  ]</row>
<row>[ 0 1 0  ][ 0  ]</row>
<row>[ 0 0 1  ][ 0  ]</row>
</mat>
</genpos>
<genpos>
<mat>
<row>[ -1 0 0  ][ 0  ]</row>
<row>[ 0 1 0  ][ 0  ]</row>
<row>[ 0 0 -1  ][ 0  ]</row>
</mat>
</genpos>
<genpos>
<mat>
<row>[ -1 0 0  ][ 0  ]</row>
<row>[ 0 -1 0  ][ 0  ]</row>
<row>[ 0 0 -1  ][ 0  ]</row>
</mat>
</genpos>
<genpos>
<mat>
<row>[ 1 0 0  ][ 0  ]</row>
<row>[ 0 -1 0  ][ 0  ]</row>
<row>[ 0 0 1  ][ 0  ]</row>
</mat>
</genpos>
/genpositions>
<irreps num="4">
<repr name="GM1" dim="1">
<mat>
<row>[ (1.000,  0.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,  0.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,  0.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,  0.0)  ]</row>
</mat>
</repr>
<repr name="GM2" dim="1">
<mat>
<row>[ (1.000,  0.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,  0.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,180.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,180.0)  ]</row>
</mat>
</repr>
<repr name="GM3" dim="1">
<mat>
<row>[ (1.000,  0.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,180.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,  0.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,180.0)  ]</row>
</mat>
</repr>
<repr name="GM4" dim="1">
<mat>
<row>[ (1.000,  0.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,180.0)  ]</row>
</mat>
<mat>
<row>[ (1.000,180.0)  ]</row>
</mat>
<mat>
<row>[ (1.000, -0.0)  ]</row>
</mat>
</repr>
</irreps><!-- end of the list -->
</kvec>
</group>
</bcs_group>

For more information about the program and the data in the output, see the REPRES Users' manual.