Hi David,

On Wed, Mar 28, 2012 at 1:41 AM, David Lonie <[email protected]> wrote:
> On Tue, Mar 27, 2012 at 11:35 AM, Albert DeFusco <[email protected]> wrote:
>> David,
>>
>> After some playing around I was able to determine that SPGlib will generate 
>> the primitive lattice and basis atoms correctly for use in PWScf.  The 
>> avospg method reduceToPrimitive appears to work correctly only when I 
>> disable spg_refine_cell.  So far I have been unable to figure out what might 
>> be wrong between OBUnitCell::SetData and the Avogadro display.
>
> Interesting -- It sounds like refine cell may be converting the
> primitive cell back to a conventional cell?

Yes. It reduces to a conventional unit cell. A primitive lattice of a
conventional unit cell that has centring can be obtained by
multiplying a transformation matrix that is referred to the
International table of crystallography vol. A. Furthermore, when using
spg_refine_cell, the crystallographic axes are redefined in Cartesian
coordinates. So if the lattice vectors are stored in a 3x3 matrix in
Cartesian coordinates, they may be re-oriented. This re-orientation
does not happen in spg_find_primitive.

Togo


>
>> What I would like to do is use the spglib and avospg (crystallography 
>> extension) methods to determine the primitive lattice from my PWScf input 
>> generator.  The goal is have a button that will generate the PWScf input 
>> using either the generated primitive cell or take the displayed cell 
>> verbatim without changing the display.  Is it possible to connect the 
>> crystallography extension with a quantum input generator or should I 
>> re-implement the necessary methods in the PWScf input generator?
>
> This sounds like a nice feature! My suggestion here would be to move
> the avospg stuff into the main libavogadro library. That way both
> extensions could use the functionality without having to maintain two
> separate copies of spglib.
>
> Dave
>
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-- 
Atsushi Togo
http://atztogo.users.sourceforge.net/
[email protected]

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