[Pw_forum] Converged SCF total energies different in 6.0/6.1/6.2

[WF]

Dear all,

In tests a normal DFT calculations with Si, I noticed that QE 6.0 and 6.1
gives exactly same total energy with 6.0 and 6.1 (-15.75190880 Ry), but with
QE 6.2.1, the total energy is -15.75191309Ry. I tested this on two different
machines with different compilers, the results are the same across all of
them (at least to last digit). I did some tests on larger systems also and
found even larger difference. This 1e-5 Ry order of difference is not
negligible. Is there anything introduced in 6.2 leads to this difference?
Thanks very much.

 

Best regards,

Feng

 

The input file is attached:





calculation='scf'

outdir='./tmp'

prefix='si'

wf_collect = .true.,

/



ibrav=2,

celldm(1) = 10.263,

nat=2,

ntyp= 1,

ecutwfc = 40,

/



mixing_mode='plain'

mixing_beta = 0.7,

conv_thr =  1.0d-10,

/

ATOMIC_SPECIES

Si  1.0 Si_ONCV_PBE-1.1.upf

ATOMIC_POSITIONS {alat}

Si 0.00 0.00 0.00

Si 0.25 0.25 0.25

K_POINTS (automatic)

4 4 4 0 0 0

==

 

 

--

Dr. Feng Wu

Postdoctoral researcher

Department of Chemistry and Biochemistry

University of California, Santa Cruz

Phone: 831-459-2874

 

 

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[Pw_forum] k-mesh vs q-mesh

[A. Jain]

Hi All,

I have a query regarding selecting the size of q-grids to use when 
trying to obtain phonon dispersion. Obviously there is a difference 
between k-mesh and q-mesh as they are used to calculate different 
properties, as referenced in this thread from 2012: 
http://qe-forge.org/pipermail/pw_forum/2012-January/097425.html.

However my question is, how do we know the quality of a q-mesh that we 
have selected? Is that simply from the phonon dispersion and asking 
matdyn to calculated frequencies at a phonon point not in the grid then 
checking to see how well it fits, or is there another way where complete 
phonon frequencies do not have to be calculated to determine the quality 
of a q-mesh?

Also adding onto that, when selecting a q-mesh how does one go about it? 
Is it ok to simply use the same grid size as that of the k-mesh (if not, 
how come?) and can the size of the k-mesh used give any clues as to what 
size q-mesh to use?

Best,

Apoorv Jain
PhD Student
Department of Chemical Engineering and Biotechnology
University of Cambridge
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[Pw_forum] The influence of mixing_beta in scf calculation and alpha_mixing in phonon calculation

[黄志硕]

Dear all users,

When encountering the convergence problems, the most suggested thing is to 
change the mixing parameters in scf calculation. But I wonder if changing 
mixing data (mixing_beta in scf calculation, and alpha_mixing in phonon 
calculation) could influence the accurate of the results, like total energy, 
Fermi level?

Best regards
Zhishuo Huang

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Re: [Pw_forum] error- dE0s is positive which should never happen

[Saif Ullah]

Dear Bhushan,

It means that you have already achieved (nearly achieved) the convergence
as can be concluded from the following sentence by prof. Paolo
(This kind of errors invariably happens when you are very close

to the minimum and you have some numerical noise on forces. It
is useless in my opinion to insist: your system is sufficiently
relaxed


Paolo)

I'm surely not a QE expert but when I have this kind of problem, I usually
change (a bit) the positions of few atoms and do a relax calculation
following by an scf-calc.

Regards
Saif

Saif Ullah
Departamento de Física
Instituto de Ciências Exatas - ICE
Universidade Federal de Juiz de Fora - UFJF
Juiz de Fora - MG - Brazil - CEP 36036-330
sul...@fisica.ufjf.br
Cell# +55 32 9110-7851
https://www.researchgate.net/profile/Saif_Ullah41

On Tue, Dec 19, 2017 at 11:43 AM, B S Bhushan  wrote:

> Dear Dr. Saif,
>
> I have through this link before posting the error. However, I could not
> find a solution to my problem there.
>
>
> On Tue, Dec 19, 2017 at 6:07 PM, Saif Ullah  wrote:
>
>> It is a well-known error.
>>
>> The following links may be helpful.
>> http://qe-forge.org/pipermail/pw_forum/2014-September/105225.html
>> https://www.mail-archive.com/pw_forum@pwscf.org/msg29759.html
>>
>> Regards
>> Saif
>>
>>
>> On Tue, Dec 19, 2017 at 7:38 AM, B S Bhushan 
>> wrote:
>>
>>> Dear experts...
>>>
>>> I have received this following error when I was trying to optimize a
>>> doped graphene sheet.
>>>
>>> 
>>> %%
>>>  Error in routine bfgs (1):
>>>  dE0s is positive which should never happen
>>>  %%%
>>> %%%
>>>
>>> Please suggest me how to avoid this error.
>>>
>>> Thank you very much for your precious time and knowledge.
>>>
>>> Sincerely,
>>> B S Bhushan,
>>> Ph.D Scholar,
>>> ABV-IIITM Gwalior, India.
>>>
>>>
>>>
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>>
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Re: [Pw_forum] Pw_forum Digest, Vol 125, Issue 13

[Lorenzo Paulatto]

On 20/12/17 08:58, Anuja Chanana wrote:
> Thanks.
> Is it possible to read merged two output files in Xcrysden?
> Looking forward to a reply.

Why don't you try?

kind regards


-- 
Lorenzo Paulatto - Paris
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Re: [Pw_forum] Pw_forum Digest, Vol 125, Issue 13

[Anuja Chanana]

Thanks.
Is it possible to read merged two output files in Xcrysden?
Looking forward to a reply.




Thanks and Regards
Dr. Anuja Chanana
Research Associate
Materials Theory Lab - Prof. Umesh Waghmare
Theoretical Sciences Unit,
Jawaharlal Nehru Centre for Advanced Scientific Research,
Jakkur Bangalore-560064
an...@jncasr.ac.in
https://www.researchgate.net/profile/Anuja_Chanana



>8. Re: Merging output files (Lorenzo Paulatto)
>
>
> Message: 6
> Date: Tue, 19 Dec 2017 13:57:09 +0530
> From: Anuja Chanana 
> Subject: [Pw_forum] Merging output files
> To: pw_forum@pwscf.org
> Message-ID:
>  a...@mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Dear QE,
> Is there a way to merge various output files in espresso and observe the
> results of the merged output file in Xcrysden?
>
> Looking forward to a reply.
>
> Thanks and Regards
> Dr. Anuja Chanana
> Research Associate
> Jawaharlal Nehru Centre for Advanced Scientific Research,
> Jakkur Bangalore-560064
>
>
>
>
>
>
>
>
> Message: 8
> Date: Tue, 19 Dec 2017 11:17:32 +0100
> From: Lorenzo Paulatto 
> Subject: Re: [Pw_forum] Merging output files
> To: PWSCF Forum 
> Message-ID:
>  gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> cat file1 file2 > file_merged
>
> Kind regards
>
> --
> Lorenzo Paulatto
> Written on a virtual keyboard with real fingers
>
> On Dec 19, 2017 10:14, "Anuja Chanana"  wrote:
>
> > Dear QE,
> > Is there a way to merge various output files in espresso and observe the
> > results of the merged output file in Xcrysden?
> >
> > Looking forward to a reply.
> >
> > Thanks and Regards
> > Dr. Anuja Chanana
> > Research Associate
> > Jawaharlal Nehru Centre for Advanced Scientific Research,
> > Jakkur Bangalore-560064
> >
> >
> >
> >
> >
> >  Sent with Mailtrack
> >  ndnaehgpjlnokgebbaldlmgkapkpjkkb?utm_source=gmail_
> medium=signature_campaign=signaturevirality>
> >
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> End of Pw_forum Digest, Vol 125, Issue 13
> *
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