Re: [Pw_forum] Question regarding how nonlinear core correction PPs are treated in PWscf

[Paolo Giannozzi]

No. The Hartree potential is a linear function(al) of the charge density.
The "unscreening" procedure (that is: subtracting out the Hartree potential
generated by the core electrons) done at the end of the pseudopotential
generation is sufficient.

Paolo

On Tue, May 12, 2015 at 12:02 AM, Stephen Weitzner  wrote:

> Dear users/developers of Quantum–ESPRESSO,
>
> I have a question regarding nonlinear core corrected pseudopotentials and
> the way energies are computed in PWscf.
>
> What I understand by reading Prof. Dal Corso’s notes (
> http://people.sissa.it/~dalcorso/lectures/lecture_pseudo_sb_2009.pdf) is
> that the nonlinear core correction determines the local potential by using
> the total charge density (core + valence) to compute the
> exchange-correlation potential [V_XC(r)]. However, the local potential
> [V_loc(r)]  depends also on the Hartree potential [V_H(r)] and is computed
> as: V_loc(r) = V_eff(r) – V_H(r) – V_XC(r). So my question is, does the
> nonlinear core correction implemented in PWscf also use the total charge
> density to compute the Hartree potential?
>
> Any insight/clarification you could provide would be greatly appreciated.
>
> Thank you for your time,
>
> Stephen Weitzner
> ––
> PhD Candidate
> Department of Materials Science and Engineering
> N-334 Millennium Science Complex
> The Pennsylvania State University
> University Park, PA 16802
>
>
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Re: [Pw_forum] Negative Polarization !!!

[Mostafa Youssef]

Hi Mojtaba,

Polarization is a vector, so negative or positive just indicate its direction. 
So no worries about negative polarization. But in periodic boundary conditions 
you may still need to add (subtract) multiples of the polarization quantum in 
order to get the "reasonable" value of the spontaneous polarization of the 
material.

A favorite of mine which go over some of these difficulties is this  paper:

http://journals.aps.org/prb/abstract/10.1103/PhysRevB.71.014113


Mostafa Youssef
MIT


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[Pw_forum] Question regarding how nonlinear core correction PPs are treated in PWscf

[Stephen Weitzner]

Dear users/developers of Quantum–ESPRESSO,

I have a question regarding nonlinear core corrected pseudopotentials and the 
way energies are computed in PWscf. 

What I understand by reading Prof. Dal Corso’s notes 
(http://people.sissa.it/~dalcorso/lectures/lecture_pseudo_sb_2009.pdf 
) is that 
the nonlinear core correction determines the local potential by using the total 
charge density (core + valence) to compute the exchange-correlation potential 
[V_XC(r)]. However, the local potential [V_loc(r)]  depends also on the Hartree 
potential [V_H(r)] and is computed as: V_loc(r) = V_eff(r) – V_H(r) – V_XC(r). 
So my question is, does the nonlinear core correction implemented in PWscf also 
use the total charge density to compute the Hartree potential? 

Any insight/clarification you could provide would be greatly appreciated.

Thank you for your time,

Stephen Weitzner
––
PhD Candidate
Department of Materials Science and Engineering
N-334 Millennium Science Complex
The Pennsylvania State University
University Park, PA 16802

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[Pw_forum] Phonon- Negative frequencies

[Sohail Ahmad]

Dear QE user,

While calculating phonon dispersion of ZrS2 monolayer, i am getting negative 
eigen values.
Though i have taken every care of convergence, q mesh and k points but all in 
vain.
Pls have a look at my input files mentioned below.Output file is attached.
Any suggestions are highly appreciated.


 tr2_ph = 1.0d-15,
 ldisp = .true.,
 nq1 = 6, nq2 = 6, nq3 = 1,
 amass(1) = 91.22,
 amass(2) = 32.06,
 prefix = 'ZrS2m',
 outdir = './OUT',
fildyn = 'ZrS2m.dyn',
/


  calculation = 'scf',
  restart_mode = 'from_scratch',
  prefix = 'ZrS2m',
  pseudo_dir = '/home/sohail/Espresso/espresso-5.0.1/pseudo',
  outdir = './OUT',
  verbosity = 'high',
  tprnfor = .true.,
  tstress = .true.,
  etot_conv_thr = 1.0d-5,
  forc_conv_thr = 1.0d-4,
  nstep = 500,
 /
 
  ibrav = 4, a = 3.75, b = 3.75, c = 15.0,
  nat = 3, ntyp = 2,
  ecutwfc = 75,
  ecutrho = 300,
  nosym = .FALSE.
  occupations = 'fixed',
 /
 
  mixing_beta = 0.7,
  conv_thr = 1.0d-15,
 /
ATOMIC_SPECIES
Zr  91.22  Zr.pbe-mt_fhi.UPF
S   32.06  S.pbe-mt_fhi.UPF
ATOMIC_POSITIONS {Angstrom}
Zr  0.0  0.0  0.0
S  -0.00018  2.113679346  1.38397
S   1.830500018  1.056839657 -1.38397
K_POINTS AUTOMATIC
12 12 1 1 1 1

phonons.xmgr
Description: Binary data
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[Pw_forum] Negative Polarization !!!

[Mojtaba Mirseraji]

Dear All

If we have a negative total polarization (by nscf+lberry),has it meaning?
This happens, for example, in strain study of tetragonal perovskites.
if it has meaning, what does it mean, physically?
I have some problem with negative polarization 

Regards

Mojtaba Mirseraji
Ph.D. Candidate
Theoretical Condensed Matter Physics
Arak University
I.R.IRAN
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Re: [Pw_forum] Electron-phonon matrix calculation and elph.#iq.#irr.xml

[Paolo Giannozzi]

If I remember correctly, the calculation contains a division by the
frequency that becomes singular for the three zero-frequency acoustic modes
at q=0. Their coefficients are known to be zero anyway so they are ignored,
I think.

Paolo

On Mon, May 11, 2015 at 5:15 AM, Jaehong Park  wrote:

>
> At gamma point(q-point), there are only 6 irreps and thus 6
> elph.1.#irr.xml files where #irr runs from 1 to 6 due to degeneracy,
>
>
However, where q-point!=0 without such degeneracy, there are 9 irreps and
> corresponding 9  elph.#iq.#irr.xml  files.
>
> Tel :  +82-2-958-6653
>
> Mobile : +82-10-5481-5143
>
> E-mail : catina...@snu.ac.kr
>
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Re: [Pw_forum] implementation of DFT-D3

[Behnaz Bagheri]

Thanks,

Behnaz

With kind regards,
Behnaz Bagheri Varnousfaderani
PhD Candidate
Department of Mathematics and Computer Science
Centre for Analysis,Scientific Computing, and Applications W
Institute for Complex Molecular Systems
Technical University of Eindhoven

On Mon, May 11, 2015 at 3:57 PM, Paolo Giannozzi 
wrote:

> DFT-D3 is not currently implemented. I don't know if anybody is working on
> it. The comments contained in Modules/mm_dispersion.f90 should give some
> clues on what has to be done.
>
> Paolo
>
> On Mon, May 11, 2015 at 2:02 PM, Behnaz Bagheri <
> behnaz.bagher...@gmail.com> wrote:
>
>> Dear all,
>>
>> Does anybody know whether DFT-D3 has been implemented in PWscf or not
>> yet? If not, is anybody implementing it?
>>
>> Thank you,
>> Behnaz
>>
>> ---
>> With kind regards,
>> Behnaz Bagheri Varnousfaderani
>> PhD Candidate
>> Department of Mathematics and Computer Science
>> Centre for Analysis,Scientific Computing, and Applications W
>> Institute for Complex Molecular Systems
>> Technical University of Eindhoven
>>
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Re: [Pw_forum] implementation of DFT-D3

[Paolo Giannozzi]

DFT-D3 is not currently implemented. I don't know if anybody is working on
it. The comments contained in Modules/mm_dispersion.f90 should give some
clues on what has to be done.

Paolo

On Mon, May 11, 2015 at 2:02 PM, Behnaz Bagheri 
wrote:

> Dear all,
>
> Does anybody know whether DFT-D3 has been implemented in PWscf or not yet?
> If not, is anybody implementing it?
>
> Thank you,
> Behnaz
>
> ---
> With kind regards,
> Behnaz Bagheri Varnousfaderani
> PhD Candidate
> Department of Mathematics and Computer Science
> Centre for Analysis,Scientific Computing, and Applications W
> Institute for Complex Molecular Systems
> Technical University of Eindhoven
>
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[Pw_forum] implementation of DFT-D3

[Behnaz Bagheri]

Dear all,

Does anybody know whether DFT-D3 has been implemented in PWscf or not yet?
If not, is anybody implementing it?

Thank you,
Behnaz

---
With kind regards,
Behnaz Bagheri Varnousfaderani
PhD Candidate
Department of Mathematics and Computer Science
Centre for Analysis,Scientific Computing, and Applications W
Institute for Complex Molecular Systems
Technical University of Eindhoven
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Re: [Pw_forum] Visualizing charge density (pp.x)

[Brandon Nguyen]

Thank you!

Sent from my iPhone

> On May 10, 2015, at 7:52 PM, plgong  wrote:
> 
> hi, you can try xcryden software. 
> Good luck!
> 在2015-05-11 05:15:52，plgongplg...@theory.issp.ac.cn写道：
> 
> What is the recommended program to use in order to visualize charge density 
> acquired from using pp.x?
> 
> 
> 
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Re: [Pw_forum] (no subject)

[saswata halder]

Thank you sir,

I'll try and do it as soon as possible

On Mon, May 11, 2015 at 2:31 PM, George Amolo  wrote:
> Hello Saswata,
>
> Good day. It will be nice if you attach the input script so that members of
> the forum can help you.
>
> george
> University of Eldoret, Kenya
>
> On Mon, May 11, 2015 at 11:39 AM, saswata halder  wrote:
>>
>> Dear Users,
>>
>> I am sort of a beginner in quantum espresso and i am working with a
>> perovskite system. I have tried both scf and relax calculations for
>> SrTiO3. the forces are shown to be zero. But i am quite unsure about
>> the value of pressure that is optimum for a relaxed structure.
>>
>> I request you to please help me on this matter.
>> I apologize if my question is ill-framed.
>>
>> Thanking you,
>>
>> Saswata Halder.
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Re: [Pw_forum] (no subject)

[George Amolo]

Hello Saswata,

Good day. It will be nice if you attach the input script so that members of
the forum can help you.

george
University of Eldoret, Kenya

On Mon, May 11, 2015 at 11:39 AM, saswata halder  wrote:

> Dear Users,
>
> I am sort of a beginner in quantum espresso and i am working with a
> perovskite system. I have tried both scf and relax calculations for
> SrTiO3. the forces are shown to be zero. But i am quite unsure about
> the value of pressure that is optimum for a relaxed structure.
>
> I request you to please help me on this matter.
> I apologize if my question is ill-framed.
>
> Thanking you,
>
> Saswata Halder.
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[Pw_forum] (no subject)

[saswata halder]

Dear Users,

I am sort of a beginner in quantum espresso and i am working with a
perovskite system. I have tried both scf and relax calculations for
SrTiO3. the forces are shown to be zero. But i am quite unsure about
the value of pressure that is optimum for a relaxed structure.

I request you to please help me on this matter.
I apologize if my question is ill-framed.

Thanking you,

Saswata Halder.
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