[gpaw-users] Convergence Problem with Core-Hole Calculations

[Mathias Ljungberg]

Hi Hongliang,

First of all your system is charged. Because of a the core hole you  
need to put charge=-1 to get an extra electron in the valence band -if  
that is what you want. Maybe this is the reason the dipole correction  
does not work. If you have a neutral system I think mixed periodic  
boundary conditions should work as well. Anyway, the convergence of  
the total energy of the core hole state is pretty sensitive to the  
grid spacing and size of the box, I attach some plots of tests I did  
for a water molecule (without any dipole correction). The first plot  
shows the convergence with grid spacing and the XAS case has got an  
extra electron in the valence band, XPS does not. The second plot  
shows the convergence with box size. If you are looking for relative  
shifts maybe you can get away with less converged parameters. One more  
thing, to get reliable total energies you should use a spin polarized  
calculation.


Best Regards,
Mathias







On May 19, 2010, at 3:39 AM, Hongliang Xin wrote:

> Here is the input file and output. I am not exactly calculating the  
> delta Kohn-Sham energy. I am trying to evaluate the final state  
> effect of core-level shift. I am not very convinced about what I am  
> doing though. I just thought that the calculated delta energy should  
> be converged with respect to vacuum space. For some reason, it did  
> not allow me to put non-periodic on z direction with core-hole.
>
> Any suggestions would be very helpful.
>
> Thanks,
>
> Hongliang
>
> On Tue, May 18, 2010 at 6:56 PM, Mathias Ljungberg <mathias.ljungberg at physto.se 
> > wrote:
> Hi Hongliang,
>
> Can you send a script that illustrates your problem, including the  
> text output? I think the delta Kohn-Sham energy should converge  
> without the dipole correction.
>
> Best Regards,
> Mathias Ljungberg
>
>
>
>
> On May 18, 2010, at 9:56 PM, Hongliang Xin wrote:
>
>> Dear All,
>>
>> I have been experiencing the convergence problem with the core-hole  
>> calculations. Without dipole correction, the delta Kohn-Sham energy  
>> is not converging with respect to the vacuum space. Adding dipole  
>> correction as instructed before, the SCF convergence is very very  
>> fluctuating due to the WFS problem as mentioned on previous Dipole  
>> Correction question. I have tried to reduce the spacing to 0.15, or  
>> change the mode to "lcao", and the problem is still there.
>>
>> Any suggestions with this situation would be highly appreciated.
>>
>>
>> Thanks,
>>
>> Hongliang
>>
>> -- 
>> Hongliang Xin
>> Ph.D. Candidate
>> Dept. of Chemical Engineering
>> University of Michigan
>> 3166 HH Dow
>> 2300 Hayward
>> Ann Arbor, MI 48109
>> Phone: (734) 647-8051
>> E-mail: hxin at umich.edu
>> _______________________________________________
>> gpaw-users mailing list
>> gpaw-users at listserv.fysik.dtu.dk
>> https://listserv.fysik.dtu.dk/mailman/listinfo/gpaw-users
>
>
>
>
> -- 
> Hongliang Xin
> Ph.D. Candidate
> Dept. of Chemical Engineering
> University of Michigan
> 3166 HH Dow
> 2300 Hayward
> Ann Arbor, MI 48109
> Phone: (734) 647-8051
> E-mail: hxin at umich.edu
> < 
> OAgfcc 
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