[Wien] Generating struct from space group and coordinates

[Gavin Abo]

I did this rather quickly. So you will have to double check if it looks 
correct or not.


It looks like both your lattice parameters and atomic positions are in 
the R-3 hexagonal setting.  So enter in SETSTRU [ 
http://www.cryst.ehu.es/cryst/setstru.html ]:


# Comments start with #
# Space Group ITA number
148
# Lattice parameters
6.8275 6.8275 20.5619 90 90 120
# Number of independent atoms in the asymmetric unit
3
# [atom type] [number] [WP] [x] [y] [z]
Te 1 - 0.00367 0.36633 0.08513
Ge 2 - 0       0       0.059
Cr 3 - 0       0       0.3302


Click Transform Structure


Select R-3: h for initial and R-3:r for Final.  Then, SETSTRU should 
output the rhombohedral settings:


Final Setting: R-3:r (148)148 #R-3:r
7.9066 7.9066 7.9066 51.16 51.16 51.16
3
Te    1    -    0.088800    0.447790    -0.281200
Ge    2    -    0.059000    0.059000    0.059000
Cr    3    -    0.330200    0.330200    0.330200

In StructGen, select 148_R-3 for the spacegroup.


Enter the "hexagonal" for the lattice parameters:


a = 6.8275 ang, b = 6.8275 ang, c = 20.5619 ang, alpha = 90 deg, beta = 
90 deg, gamma = 120 deg


For the atomic positions, enter the inequivalent "rhombohedral" positions:


Te 0.088800    0.447790    -0.281200
Ge 0.059000    0.059000    0.059000
Cr 0.330200    0.330200    0.330200


After you save the structure and come back and view in StructGen again, 
take note of the StructGen message under Inequivalent Atoms:

"positions must be specified in rhombohedral coordinates"


See if the structure looks okay now (for example in XCrySDen or VESTA).

Reference: 
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg12704.html

On 11/12/2017 8:55 AM, Md. Fhokrul Islam wrote:
>
> Dear Wien2k users,
>
>
> I am trying to build the struct file of Cr2Ge2Te6 crystal from space 
> group and atomic position using w2web.
> I have obtained the information about this crystal from springer database
> http://materials.springer.com/isp/crystallographic/docs/sd_1622000
>
> Space group: 148 (R-3 h)
> Lattice constants a, b, c:  0.68275 (nm), 0.68275 (nm), 2.05619 (nm)
> Angle alpha, beta, gamma:  90, 90, 120
>
> atom  Wychoff           x         y                z
> Te   18f 0.00367 0.36633 0.08513
> Ge      6c 0         0       0.059
> Cr    6c 0 0         0.3302
>
> But if I use the coordinates of each of these three atoms and space 
> group in w2web, I don't get the correct crystal structure.
> Although I have managed to get the structure from other online sources 
> but I am wondering if anyone can tell me how can
> I use these info to generate the structure usingw2web.
>
>
> Thanks,
> Fhokrul
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