[CP2K-user] [CP2K:14393] AIMD+Hybrid-Functionals, How to set the MTS and E_box?

[Lucas Lodeiro]

Thanks professor Hutter,
It is so clarifier this example, with it I can to compute RESPA
calculations and reproduce the figure 4 in the implementation paper. As you
mention, the first comment in the example input is wrong, The order is
inverted.
Just to clarify the RESPA calculations for other users:
The principal task is to set a multiple force_eval section as:

&MULTIPLE_FORCE_EVALS
   FORCE_EVAL_ORDER 1 2
&END

Then you have to define two FORCE_EVAL sections with all typical
information for a calculation, if you use ADMM, put in both force eval
sections the auxiliary basis set file, if not, there will be problems. The
first FORCE_EVAL is the "outer" calculation, which is computed in the "long
step time", meanwhile, the second FORCE_EVAL is the "inner" and computed in
the "short step time". The hybrid ave to be the first, and the GGA the
second, but if you put in reverse order, it works but compute a GGA MD, and
a hybrid calculation for he short steps.
Finally, you have to put in MOTION/MD section:

    &RESPA
       FREQUENCY 5
    &END RESPA

And define the time step, take care with it, because the time step defined
is the "long step time", which apply for the first (hybrid) force eval. The
second is computed in time steps of dt/n, where n is the frequency defined
above. For example to reproduce the figure 4 in the paper, I set time step
= 2.5 and frequency 5, then the hybrid is computed at each 2.5 fs and the
GGA evolves with a time step of 0.5 fs.

Regards!
Lucas Lodeiro

El lun, 14 dic 2020 a las 12:47, <hut... at chem.uzh.ch> escribió:

> Hi
>
> did you have a look into
>
> tests/QS/regtest-hfx-periodic/h2o-respa.inp
>
> I'm not sure if the comment in the input is correct.
>
> regards
>
> Juerg Hutter
> --------------------------------------------------------------
> Juerg Hutter                         Phone : ++41 44 635 4491
> Institut für Chemie C                FAX   : ++41 44 635 6838
> Universität Zürich                   E-mail: hut... at chem.uzh.ch
> Winterthurerstrasse 190
> CH-8057 Zürich, Switzerland
> ---------------------------------------------------------------
>
> -----cp... at googlegroups.com wrote: -----
> To: cp... at googlegroups.com
> From: "Lucas Lodeiro"
> Sent by: cp... at googlegroups.com
> Date: 12/13/2020 06:19AM
> Subject: [CP2K:14381] AIMD+Hybrid-Functionals, How to set the MTS and
> E_box?
>
> Hello,
> I am reading about how to speed up AIMD+hybrid-functional calculations. I
> explore different settings of the CP2K-HF section to accelerate the ERIs
> calculations. But reading this paper (
> https://aip.scitation.org/doi/10.1063/1.2931945), I see one more eps
> keyword, the epsilon_box, and I cannot find it in the manual (the
> Eps_schwarz and eps_storage are pretty clear).
>
> Also, the MTS section (multiple time step) shows that a very hge speed up
> using a mix between GGA and hybrid calculations for different frames. I
> want to do it, but it is not clear how to set up the MTS in the AIMD.In the
> HF sections there is no key for it. The only key related is RESPA, but is
> not clear to me how to activate and use it... I cannot find any example for
> this type of calculation.
>
> I am trying PBE0 calculation, and i do not know how MTS uses the XC
> section, because the X-GGA portion is 0.75, and in the non-hybrid frames,
> does it use the same X-GGA portion or it uses the full one?
>
> If somebody gives me some advice about it, I will appreciate it.
>
> Regards
> Lucas Lodeiro
>
>
>
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