[gpaw-users] gpaw-users Digest, Vol 6, Issue 9

[Mathias Ljungberg]

On Jul 14, 2010, at 9:03 PM, Christian Glinsvad wrote:

> xiao.jianping at bccms.uni-bremen.de wrote:
>> The examples in gpaw website have three steps. The second step is to
>> obtain the energy scale between full core hole and no core hole
>> approximation. If this step is necessary for XAS calculation? I
>> skiped this step and set energy scale in plot.py directly, it should
>> work also. But I obtained the following error :
>>
>> " File
>> "/home/jxiao/localsoftware/GPAW_install/lib/python/gpaw/xas.py", line
>> 15, in __init__ assert wfs.gd.orthogonal AssertionError "
>>
>> Any suggestion? What meaning of this error?
>
> This means that the XAS code wasn't coded to handle non-orthogonal  
> unit
> cells. It doesn't necessarily mean that it wouldn't work (with some
> minor modifications), just that it's untested and will probably be  
> error
> prone in its current state.
>


It's the symmetry operations that are not implemented in XAS for non- 
orthogonal unit cells. If you don't have any symmetry you can just  
comment the assertation line and it should work... I'll see when I  
have time to take a look at this.

Concerning the energy scale you can instead plot the spectrum relative  
to the fermi level by subtracting the fermi level from the spectrum.  
To do the Delta Kohn Sham calculation to obtain the correct energy  
scale works best on isolated systems. For magnetic systems it is not  
very physical to fix the magnetic moment either, this is also most  
useful for small molecules to be able to put the extra electron in the  
correct spin orbital.

BTW,  you should only use one core hole in the calulation, a system  
with two  core holes is not what you want to calculate...

Best Regards
Mathias Ljungberg





> Regards
> Christian Glinsvad
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