[CP2K:4531] Questions about the section Mixing in the XAS calculation

marcella Iannuzzi marc... at pci.uzh.ch
Tue Aug 6 20:15:57 CEST 2013


Hi Ali

mixing in G-space and smearing wrk with GAPW and with XAS since quite a while
regards
marcella

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Marcella Iannuzzi              Phone : ++41 44 635 4479
Physical Chemistry Institute   FAX   : ++41 44 635 6838
University of Zurich               E-mail:  marc... at pci.uzh.ch
Winterthurerstrasse 190
CH-8057 Zurich, Switzerland
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On Aug 6, 2013, at 3:05 PM, Ali Akbari wrote:

> Hi Marcella, 
> 
> It has been a quite while since this post was written. However, it seems to me that it's not yet 
> implemented completely (for Kerker it works). I was especially interested in Pulay mixing. Is there
> any way to use it in XAS (of course with GAPW approach)?     
> 
> Many thanks,
> Ali
> 
> 
> 
> 
> 
> 
> 
> On Thursday, 28 January 2010 15:21:49 UTC+2, marci wrote:
> Hi,
> At the moment only the direct mixing is possible with XAS
> calculations,
> g-space mixing in combination  with GAPW calculations need some
> additional changes that are not implemented yet.
> The plan is to have this extension relatively soon.
> kind regards
> Marcella
> 
> 
> 
> On Jan 28, 2:08 pm, zh <vale... at gmail.com> wrote:
> > 1). In the manual of cp2k,  it mentions that there are a couple of
> > optional charge mixing methods for the XAS calculations. However, from
> > the source code,i.e., xas_tp_scf.F, it is found that only the
> > "DIRECT_P_MIXING" is indeed supported, as shown in followings
> > ....
> > 421        IF (scf_env%mixing_method.EQ.direct_mixing_nr) THEN
> > 422           CALL scf_env_density_mixing(scf_env%p_mix_new,&
> > 423                scf_env,scf_env%iter_delta,&
> > 424                qs_env=qs_env,diis=diis_step, error=error)
> > 425        ENDIF
> > ........
> >
> > Once the other mixing method (e.g., BROYDEN_MIXING, PULAY_MIXING) is
> > chosen in the self-consistent calculation of the ground state, the
> > self-consistent calculation for the excited state (e.g., DSCF, TP_HH
> > calculations) will stop in the first iteration step. This is observed
> > in my test calculations.  I want to confirm whether the above thing is
> > true or not.
> >
> > 2). If it is true, i.e., only the "DIRECT_P_MIXING" is indeed
> > supported for the self-consistent calculation of excited state for XAS
> > spectrum, how can we modify the source code to enable other mixing
> > methods for XAS calculations? Is it easy do such thing? Actually,
> > these charge mixing methods are already implemented in
> > "qs_gspace_mixing.F".  Wish someone  give  me some hints.
> 
> 
> 
> 
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