[CP2K-user] [CP2K:13917] Poisson solver for big-slab system

[Lucas Lodeiro]

Thanks a lot professor Hutter for your little course of solvers. About the
vacuum, I tried to avoid it due to the habit of the PW basis programs that
I used years ago... but it is very good behavior in CP2K.
Regards

El vie., 18 sept. 2020 a las 5:54, <hut... at chem.uzh.ch> escribió:

> Hi
>
> a few remarks:
>
> for a 2d system you can use either a 3d or 2d Poisson solver.
> If your system is symmetric or only has a small dipole orthogonal
> to the slab you can use 3d system with a large enough vacuum space.
> For largeer dipoles there is also the dipole correction term.
> Remember that in CP2K the overhead of using vacuum space is rather small.
>
> For the 2d case there are several options. ANALYTIC, MT and Wavelet.
> Wavelet requires the slab to be in the xz plane.
> The convergence should not depend on the choice of solver. If it is
> slow, you probably have another problem. I would choose ANALYTIC, and
> WAVELET as the second choice.
>
> Implicit solvers are for very specific applications. I don't see how
> they relate to your system.
>
> 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: 09/18/2020 05:57AM
> Subject: [CP2K:13916] Poisson solver for big-slab system
>
> Hi all,
> I want to do an AIMD over a big slab (2D) system, which has 50 A of
> thickness. First of all I am performing SCF calculations to get the best
> and faster way to compute the SCF cycles, but the convergence is not yet
> fast enough as I need to run AIMD.
> As my system is big, I try to not use a 3D periodic setup to avoid a lot
> of vacuum space... I tried with ANALYTIC solver, it is stable but requires
> a lot of iterations.
> I see the IMPLICIT one, but I do not know what are specific conditions for
> each solver...
> In the case of MT I know I need a double system-size cell, and that is not
> applicable  here. The WAVELET solver needs thinner vacuum space, what is
> wonderful, but it does not work with FFTW (somebody knows if FFTSG are
> slower?), and the most important thing, are not translational invariants
> which is important for the MD.
>
> I need some insights over solvers.
>
> Regards - Lucas Lodeiro
>
>
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