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Posted: **Tue Aug 31, 2010 8:37 pm**

Hi,
Anybody have a POSCAR for alpha-quartz that they could share with me?
Thank you very much,
torey

Posted: **Tue Aug 31, 2010 9:38 pm**

Positions and lattice vectors for various structures of Si02 (including the alpha structure) can be found at

http://cst-www.nrl.navy.mil/lattice/struk/sio2.html

Cheers,
/Dan
<span class='smallblacktext'>[ Edited Tue Aug 31 2010, 11:40PM ]</span>

Posted: **Wed Sep 01, 2010 7:39 am**

What are you size?because you need tell me

Posted: **Tue Sep 07, 2010 4:32 pm**

I'm trying to model a 2x2x2 conventional cell. Thanks, and thanks Dan!

Posted: **Thu Sep 09, 2010 8:20 am**

If you are doing defect calculations, then maybe an orthorhombicly projected alpha quartz cell would be the best thing.

Posted: **Thu Jan 20, 2011 7:45 pm**

Hi, I'm trying to set up a POSCAR for alpha-quartz, with a=b=9.826 ang and c=10.810 ang. For angles, alpha=beta=90, gamma=120.
I have Cartesian coordinates for the atoms (there are 24 Si and 48 O) but I do not know how to set up the lattice vectors when the angles are different.
Can anyone help?
Thank you,
torey