[Pw_forum] VC-Relax taking too long on a 4-atom system

[Elliot Menkah]

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Hello Juanjo,

Thank you for the information.
I've read and made the necessary corrections.

Thanks for the insight.


Kind Regards,
Elliot

On 10/22/2014 02:50 PM, Juanjo Meléndez wrote:
> Hi Elliot
>
> Assuming that you calibrated correctly both cutoff, ecutrho and the ZB
> sampling, I have a few suggestions which could help you:
>
> 1) Are you sure about the value at "celldm(1)" and about your atomic
> positions? Take into account that your are using the {alat} switch, which
> means that you are providing cartesian coordinates in units of the
lattice
> parameter. You should also check the CELL_PARAMETERS card.
>
> 2) Change "nat=1" by "nat=4", because these are the atoms that your unit
> cell actually contains.
>
> 3) Do not use "nosym=.true.", because your system has some symmetries
that
> may simplify the calculations.
>
> 4) Do not use "dipfield" for your calculations. See the input data
> description for an explanation.
>
> Hope these suggestions help you. Additionally, I would not use so many
> cycles (10^6 is a lot!). Convergence should be achieved in less than (or
> about) 100 cycles. If you force a high number of cycles, you will not
> realize whether there is something wrong in your starting model...
>
> Good luck
>
> Juanjo
>
>
> Juan J. Meléndez
> Associate Professor
> Department of Physics · University of Extremadura
> Avda. de Elvas, s/n 06006 Badajoz (Spain)
> Phone: +34 924 28 96 55
> Fax: +34 924 28 96 51
> Email: melendez at unex.es
> Web: http://materiales.unex.es/miembros/personal/jj-melendez/Index.html
>
>
>
> -----Mensaje original-----
> From: Elliot Menkah
> Sent: Wednesday, October 22, 2014 4:04 PM
> To: pw_forum at pwscf.org
> Subject: [Pw_forum] VC-Relax taking too long on a 4-atom system
>
> Hi Everyone,
> I'm trying to determine a lattice parameter in a study and I'm running a
> vc-relax calculation.
> It's just a 4-atom bulk ferromagnetic nickel system yet my calculation
> has been running for over 5hrs already on a 16 core resource.
>
> It's presently on ' iteration #*** '
>
> Is there anything wrong with the setup of the job?
>
> Shouldn’t the job have completed by now?
>
> Could you please peruse and vet my input file for any possibles reasons
> why it's so if it shouldn’t be?
>
> What could be affecting the convergence?
>
>
> Thank you
>
>
>
>
> Kind Regards,
>
> Elliot
>


- -- 
Elliot S. Menkah
Research Student - Computational Chemistry/ Computational Material Science
Theoretical and Computational Chemistry
Dept. of Chemistry
Kwame Nkrumah UNiversity of Sci. and Tech.
Kumasi
Ghana

Tel: +233 243-055-717

Alt Email: elliotsmenkah at gmail.com
           elliotsmenkah at hotmail.com

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