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Dear Sylwia<br>
<br>
The idea of the Force theorem (implemented by Alexander Smogunox in QE) is more or less to treat the SOC as a small perturbation.<br>
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)<br>
This is explained in: <br>
<a href="https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.205409" target="_blank">https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.205409</a><br>
<br>
In addition this band energy term can be decomposed in atomic/orbital contributions as also explained in<br>
<a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.247203" target="_blank">https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.247203</a><br>
<br>
<br>
<div>Best wishes<br>
<br>
Cyrille<br>
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<div style="font-family:Tahoma; font-size:13px"><b>Cyrille Barreteau</b><br>
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<div style="font-family:Tahoma; font-size:13px"><font size="2"><font face="Times New Roman">CEA Saclay<span style="background-color:white"></span></font><font face="Times New Roman">,
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</span></font>91191 Gif sur Yvette Cedex<span style="background-color:white"></span>, FRANCE
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6 47 53 66 52 (mobile) </font></font></font> </font></font></font><br>
<font face="Times New Roman">email: cyrille.barreteau@cea.fr </font><font face="Times New Roman"><br>
Web: <a href="http://iramis.cea.fr/Pisp/cyrille.barreteau/" tabindex="0">http://iramis.cea.fr/Pisp/cyrille.barreteau/</a></font><font size="2"><br>
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<div id="divRpF877708" style="direction: ltr;"><font size="2" face="Tahoma" color="#000000"><b>De :</b> pw_forum-bounces@pwscf.org [pw_forum-bounces@pwscf.org] de la part de Sylwia Golab [Sylwia.Golab@fis.agh.edu.pl]<br>
<b>Envoyé :</b> mardi 13 février 2018 17:14<br>
<b>À :</b> pw_forum@pwscf.org<br>
<b>Objet :</b> Re: [Pw_forum] Restart from previous run<br>
</font><br>
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<div>Dear Mr Paulatto and Mr Gianozzi,<br>
<br>
thank you for your replies. <br>
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?<br>
<br>
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.<br>
<br>
Best wishes,<br>
Sylwia<br>
<br>
<br>
------------------------------<br>
<br>
Message: 7<br>
Date: Wed, 7 Feb 2018 21:58:01 +0100<br>
From: Paolo Giannozzi <p.giannozzi@gmail.com><br>
Subject: Re: [Pw_forum] Restart from previous run<br>
To: PWSCF Forum <pw_forum@pwscf.org><br>
Message-ID:<br>
<CAPMgbCvNdJMJwkcw85==5yrn3nj_VUNpsK7V-gVHKK1=tnEHZg@mail.gmail.com><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
On Wed, Feb 7, 2018 at 8:13 PM, Lorenzo Paulatto <paulatz@gmail.com> wrote:<br>
<br>
> 1) when one want to include SOC. It would be great if one could start<br>
> > from potential already calculated without SOC instead of potential of<br>
> > free atoms. Is it possible just by mode 'restart'?<br>
><br>
> no<br>
><br>
<br>
It might be actually possible. Something similar is used in one of the<br>
examples<br>
(PP/examples/ForceTheorem_example)<br>
<br>
<br>
> but increasing the number of k-points may increase the number of plane<br>
> waves,<br>
<br>
which would break reading the potential in G-space.<br>
><br>
<br>
actually it is the charge density that is read. The G-vector grid for the<br>
charge density<br>
should not depend upon the number of k-points.<br>
<br>
If I remember correctly the new file format writes in G-space, the old one<br>
> used real<br>
<br>
space, but I'm not 100% sure.<br>
><br>
<br>
correct<br>
<br>
Paolo<br>
-- <br>
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,<br>
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>
Phone +39-0432-558216, fax +39-0432-558222<br>
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