[QE-users] Disable final scf cycle in vc-relax

[Lorenzo Paulatto]

> Dear all,
> thank you for your replies. The fix suggested by Paolo works fine for me.
> I am performing DFT+U calculations and the best way for me to converge 
> them is to restart a partly converged scf calculation. However, the 
> final scf run of the vc-relax calculation cannot be run in this way, 
> thus does not converge at all... If you have more elegant ideas for that 
> problem, I am glad to hear them.

I think if you manually set nr1, nr2 and nr3 (and nr1s, nr2s, nr3s if 
using ecutrho) you *may* be able to do an nscf calculation at the end 
even after using the Paolo's trick. The cutoff at which this calculation 
will be run is different than the initial one.

hth

> 
> Best regards,
> Malte Sachs
> 
> Am 05.02.20 um 17:28 schrieb Bidault, Xavier:
>> My guess is that the cutoff is too short. If the volume has changed a 
>> lot after the relaxation, the initial number of planewaves no more 
>> fits that volume. I think the final scf cycle is meant to assess this, 
>> in order to check if the cutoff (and the planewaves number related to 
>> this volume) if still valid and relevant.
>>
>> Xavier Bidault
>>
>> ------------------------------------------------------------------------
>> *From:* users <users-bounces at lists.quantum-espresso.org> on behalf of 
>> Paolo Giannozzi <p.giannozzi at gmail.com>
>> *Sent:* Wednesday, February 5, 2020 10:22 AM
>> *To:* Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
>> *Subject:* Re: [QE-users] Disable final scf cycle in vc-relax
>> There is no way to disable the last scf step from input. You may 
>> easily do that by modifying PW/src/move_ions.f90: change lines 153 and 
>> 160 to
>>                  ions_status = 0
>> and the code will not execute the last step (neither the one with 
>> nonzero magnetization nor the one with the final cell).
>> Note however that you cannot run a non-scf calculation starting from 
>> the data of the variable-cell optimization and that convergence 
>> trouble in the last step won't go away in a new calculation.
>>
>> Paolo
>>
>>
>>
>> On Wed, Feb 5, 2020 at 3:56 PM Malte Sachs 
>> <malte.sachs at chemie.uni-marburg.de 
>> <mailto:malte.sachs at chemie.uni-marburg.de>> wrote:
>>
>>     Dear all,
>>
>>     I often have scf-convergence problems at the final scf cycle of a
>>     vc-relax calculation. Is there an easy way to disable this step of
>>     the
>>     calculation (e.g. a hidden keyword) to save some computer time?
>>
>>     Thank you and best regards,
>>
>>     Malte Sachs
>>
>>     -- 
>>     Malte Sachs
>>     Anorganische Chemie, Fluorchemie
>>     Philipps-Universität Marburg
>>     Hans-Meerwein-Straße 4
>>     35032 Marburg (Paketpost: 35043 Marburg)
>>     Tel.: +49 (0)6421 28 - 25 68 0
>>     http://www.uni-marburg.de/fb15/ag-kraus/
>>
>>
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>>
>>
>> -- 
>> 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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> 
> 
> -- 
> Malte Sachs
> Anorganische Chemie, Fluorchemie
> Philipps-Universität Marburg
> Hans-Meerwein-Straße 4
> 35032 Marburg (Paketpost: 35043 Marburg)
> Tel.: +49 (0)6421 28 - 25 68 0
> http://www.uni-marburg.de/fb15/ag-kraus/
> 
> 
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
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-- 
Lorenzo Paulatto - Paris