Questions about the section Mixing in the XAS calculation

marci marc... at
Thu Jan 28 13:21:49 UTC 2010


At the moment only the direct mixing is possible with XAS
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

On Jan 28, 2:08 pm, zh <vale... at> 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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