[Pw_forum] Restart from previous run

[BARRETEAU Cyrille]

Dear Sylwia

The idea of the Force theorem (implemented by Alexander Smogunox in QE) is more or less to treat the SOC as a small perturbation.
The  total energy (or rather its variation) is given by the band energy term after a single diagonalization (with SOC but starting from scf potential without SOC)
This is explained in:
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.205409

In addition this band energy term can be decomposed in atomic/orbital contributions as also explained in
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.247203


Best wishes

Cyrille
========================
Cyrille Barreteau
CEA Saclay, IRAMIS, SPEC Bat. 771
91191 Gif sur Yvette Cedex, FRANCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+33 1 69 08 38 56 /+33  6 47 53 66 52  (mobile)
email:     cyrille.barreteau at cea.fr
Web:     http://iramis.cea.fr/Pisp/cyrille.barreteau/
========================
________________________________
De : pw_forum-bounces at pwscf.org [pw_forum-bounces at pwscf.org] de la part de Sylwia Golab [Sylwia.Golab at fis.agh.edu.pl]
Envoyé : mardi 13 février 2018 17:14
À : pw_forum at pwscf.org
Objet : Re: [Pw_forum] Restart from previous run

Dear Mr Paulatto and Mr Gianozzi,

thank you for your replies.
In example with Force Theorem there are fully-relativistic nscf calculations based on  scalar-relativistic scf calculations. As far as I know, scf potential should be also calculated with SOC to get correct potential. Am I wrong?

I tried to use the 'filepot' parameter and it seems to work (e.g. I did not get errors), but with this parameter the scf cycle was only of 1 iteration shorter than "normal" scf cycle with SOC.

Best wishes,
Sylwia


------------------------------

Message: 7
Date: Wed, 7 Feb 2018 21:58:01 +0100
From: Paolo Giannozzi <p.giannozzi at gmail.com>
Subject: Re: [Pw_forum] Restart from previous run
To: PWSCF Forum <pw_forum at pwscf.org>
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    <CAPMgbCvNdJMJwkcw85==5yrn3nj_VUNpsK7V-gVHKK1=tnEHZg at mail.gmail.com>
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On Wed, Feb 7, 2018 at 8:13 PM, Lorenzo Paulatto <paulatz at gmail.com> wrote:

> 1) when one want to include SOC. It would be great if one could start
> > from potential already calculated without SOC instead of potential of
> > free atoms. Is it possible just by mode 'restart'?
>
> no
>

It might be actually possible. Something similar is used in one of the
examples
(PP/examples/ForceTheorem_example)


> but increasing the number of k-points may increase the number of plane
> waves,

which would break reading the potential in G-space.
>

actually it is the charge density that is read. The G-vector grid for the
charge density
should not depend upon the number of k-points.

If I remember correctly the new file format writes in G-space, the old one
> used real

space, but I'm not 100% sure.
>

correct

Paolo
--
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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