[Pw_forum] Problem with relaxing large system

[Pascal Boulet]

Dear Nkosinathi,

Strictly speaking, your calculation does not crash: it ends up after the maximum number of SCF steps is reached. I had a look at the structure and I have a few remarks.

1. Is it normal that the Al-Al distances are 2.8 angstroms long? It seems a bit of a large distance to me, but I may be wrong.
2. For ultrasoft pseudopotential I would suggest to use 10*ecutwfc for the charge density cutoff (see ecutrho).
3. It is possible that your system is metallic. Do you use electron smearing in your calculation? If not I would try it (see smearing=‘cold' and degauss=0.02).
4. It is very unlikely that the water molecules are aligned the way they are in the input. They should form hydrogen bonds together and interactions with the solid. This may also explain why the density is hard to converge: the input coordinates are probably very far from the " solution ". If you can " improve "  the starting structure it would facilitate the converge.

Hope this help a bit,
Best regards
Pascal

Le 17 juil. 2015 à 09:17, Nkosinathi Malaza <nuttymalaza at gmail.com> a écrit :

> Dear All,
> 
> I need assistance with relaxing the system of Al and H2O, the system has 123 atoms with ESM=bc3. The input file runs until it crashes, what can be the problem?
> 
> I have attached the output file.
> 
> Kind regards
> 
> N. Malaza
> Wits University
> Johannesburg 
> South Africa
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--
Pascal Boulet - MCF HDR, Resp. L1 MPCI - DEPARTEMENT CHIMIE
Aix-Marseille Université - ST JEROME - Avenue Escadrille Normandie Niemen - 13013 Marseille
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