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:

In addition this band energy term can be decomposed in atomic/orbital 
contributions as also explained in

Best wishes

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)
De : [] de la part de 
Sylwia Golab []
Envoyé : mardi 13 février 2018 17:14
À :
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,


Message: 7
Date: Wed, 7 Feb 2018 21:58:01 +0100
From: Paolo Giannozzi <>
Subject: Re: [Pw_forum] Restart from previous run
To: PWSCF Forum <>
Content-Type: text/plain; charset="utf-8"

On Wed, Feb 7, 2018 at 8:13 PM, Lorenzo Paulatto <> 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

> 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.


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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