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1.3.DistortionModes
27
Server[21].Notethattoloadthestructuralinformationtheinputfilecan
beintheformofaCIF(CrystallographicInputFile),orelseenteredman-
ually.So,forexample,supposeweloadthestructurefilefortheBaTiO
3
tetragonalstructureasthehettotype.Firstwehavetomakesurethatthe
transformationmatrixissetupas
ª
«
«
«
¬
100
010
001
º
»
»
»
¼
Thenfollowingtheprocedurethroughyoufinallydiscoveragreatdeal
ofinformationafterthesymmetrymodeanalysis(atomicshifts,globalshift
etc)includingthetable
Atoms
Ba1
Ti1
O1
WP
1b
3c
1a
GM4-(2)
GM4-(1)
GM4-(1)
Modes
whereWParetheWyckofpositionsofeachatomtypeinthearistotype
structure.Weseethattheprogramhasautomaticallyfoundthatthedis-
tortionmodeisGM4-.Similarly,supposeweenterthefollowingasthe
hettotypeforthestructurewithtiltsystema
0a0c-
#SpaceGroupITAnumber
140
#Latticeparameters
5.85.88.4909090
#Numberofindependentatomsintheasymmetricunit
4
#[atomtype][number][WP][x]
[y]
[z]
Ba
1
4b
0.5
0.0
0.25
Ti
1
4c
0.0
0.0
0.0
O
1
4a
0.0
0.0
0.25
O
2
8h
0.220.280.0
andthetransformationmatrices
ª
«
«
«
¬
1
1
0
-
1
0
10
0
2
º
»
»
»
¼
+
ª
«
«
«
¬
12
12
12
/
/
/
º
»
»
»
¼