[Pw_forum] sc effective pot in atomic code

Mahmoud Payami Shabestari mpayami at aeoi.org.ir
Mon Aug 21 10:11:59 CEST 2017

Dear Nicola,

Thank you very much for your prompt reply.
I remember that in HSE functional the long-range parts of HF and PBE are 
assumed to cancel each other, but a long-range term E_x(PBE) still remains:
E_xc(HSE)= a*E_x(HF,SR) + (1-a)*E_x(PBE,SR) + E_x(PBE,LR) + E_c(PBE)

Now, you mean that the potential corresponding to E_x(PBE,LR) term also 
decays exponentially because it is based on E_x(uniform). OK, I understand 
it. Thanks for that.

Best regards,

-----Original Message-----
From: Nicola Marzari <nicola.marzari at epfl.ch>
To: PWSCF Forum <pw_forum at pwscf.org>, Mahmoud Payami Shabestari 
<mpayami at aeoi.org.ir>
Date: Mon, 21 Aug 2017 09:22:33 +0200
Subject: Re: [Pw_forum] sc effective pot in atomic code

Dear Mahmoud,

I do not know much (well, anything) about the atomic code, so not sure
if what you are printing is correct.

Independently from this, not only lda and pbe should indeed decay
exponentially (as the charge density does), but also hse, since it the
exchange it has is only short-range (my guess, never looked at this).


On 21/08/2017 06:50, Mahmoud Payami Shabestari wrote:
> Dear QE users and developers,
> Kindly, I am interested in comparing the asymptotic behaviors of V_eff
> or V_xc for different xc functionals using the "atomic" code.
> I added a few lines at the end of "new_potential.f90" file in order to
> write grid%r(i),vnew(i,1),vnew(i,2) in a file.
> Since in a hybrid functional we have for example:
> E_xc = a*E_x(exact) + (1-a)*E_x(local) + E_c(local),
> one expects an asymptotic behavior of "-2*a/r" for the xc potential.
> However, I noticed that:
> a) for HSE and PBE inputs they generate the same potentials and ae 
> b) both lda and pbe potentials decay exponentially.
> Question:
> Did I use the correct target file for writing down the xc potential? How
> can I explain the exponential decays of those functioals (if I have
> chosen the right target)?
> Best regards,
> Mahmoud Payami,
> _______________________________________________
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> Pw_forum at pwscf.org
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Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
http://theossrv1.epfl.ch/Main/Contact http://nccr-marvel.ch/en/project
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