[Wien] Partial Occupancy/Origin Shift

[Travis Sefzik]

Thank you Dr. Sharat this does help.  What I ended up doing is using 
CRYSTAL98 to give me a structure and used the output to plug into my 
.struct file.  What you have sent me certainly seems easier to deal 
with - I also liked the cryst.ehu.es sit.

Xavier - I thank you also for all of your help.

-Travis



On Feb 27, 2005, at 11:06 PM, Dr. Sharat Chandra wrote:

> Dear Travis
>
> The conventional positions for the 152 spgr are:
>
> Multiplicity Wyckoff  Site      Coordinates
>              letter   symmetry
>
> 6 c  1	(x,y,z),(-y,x-y,z+1/3),(-x+y,-x,z+2/3),(y,x,-z),
> 	(x-y,-y,-z+2/3),(-x,-x+y,-z+1/3)
> 3 b .2.	(x,0,5/6),(0,x,0.16667),(-x,-x,1/2)
> 3 a .2.	(x,0,1/3),(0,x,2/3),(-x,-x,0)
>
> When shifted by 0.5,0.5,0.5, these yield
>
> 6 c  1	(x-1/2,y-1/2,z-1/2),(-y-1/2,x-y-1/2,z-0.16667),
> 	(-x+y-1/2,-x-1/2,z-0.16667),(y-1/2,x-1/2,-z-1/2),
> 	(x-y-1/2,-y-1/2,-z-0.16667),(-x-1/2,-x+y-1/2,-z-0.16667)
> 3 b .2.	(x-1/2,-1/2,1/3),(-1/2,x-1/2,2/3),(-x-1/2,-x-1/2,1)
> 3 a .2.	(x-1/2,-1/2,-0.16667),(-1/2,x-1/2,+0.16667),(-x-1/2,-x-1/2,1/2)
>
> And, when shifted by 0,0,1/3
>
> 6 c  1	(x,y,z-1/3),(-y,x-y,z),(-x+y,-x,z+1/3),(y,x,-z-1/3),
> 	(x-y,-y,-z+1/3),(-x,-x+y,-z)
> 3 b .2.	(x,0,0.5),(0,x,0.83333),(-x,-x,0.16667)
> 3 a .2.	(x,0,0),(0,x,1/3),(-x,-x,2/3)
>
>
> As you can see there is not much change except that the coordinates 
> have
> been reduced by 0.5,0.5,0.5 or 0,0,1/3 everywhere. In this sense, there
> should not be any difference in the band structures you calculate with 
> the
> shifted and unshifted coordinates. If you want more information, please
> visit the site http://www.cryst.ehu.es/cryst/get_wp.html for finding 
> out
> the general coordinates and Wyckoff positions of the space groups.
>
> Hope this solves the proble.
>
> Regards
> Sharat
>
> On Sun, 27 Feb 2005, Travis Sefzik wrote:
>
>> Xavier,
>>
>> Thanks again for the help.
>>
>> The problem stems from a paper by Jurgen Glinnemann in '92 (Z
>> KRISTALLOGR 198 (3-4): 177-212 1992).  He had reported structures of
>> high pressure GeO2 (however using spc.gr. 152 and origin shift of 1/3c
>> contrary to what Sowa (Z KRISTALLOGR 184: 257-268 1988)had done
>> previously).  I was really hoping to use these structures but have
>> never taken the time to work through the math within crystallography.
>>
>> I have a plan that will hopefully keep me from further investigating
>> the intricacies of crystallography ... but it would be great to plug
>> Glinnemann's numbers into WIEN directly.
>
>
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---
Travis Sefzik
Grandinetti Group
Chemistry Department
The Ohio State University
100 W. 18th Ave.
Columbus, OH 43210

phone: (614) 292-8064
fax: (614) 292-0559
email: tsefzik at chemistry.ohio-state.edu