[Pw_forum] Problem in SCF convergence

[Cococcioni Matteo]

Besides checking the cutoffs, you could try to lower the convergence treshold for the first scf calculation to make sure that forces and stresses are not totally crazy (actually, you should be sure they are converged with cutoffs too). Also, it could make sense to lower the initial trust radius. If you get not so accurate forces and stresses and the amplitude for the first move of ions and cell is too big your system could end up in a crazy configuration (it moves by much in the wrong direction) for which the scf cycle on charge density is not easy to converge.

Best,

Matteo



On Feb 21, 2018, at 5:05 PM, Thomas Brumme <thomas.brumme at uni-leipzig.de<mailto:thomas.brumme at uni-leipzig.de>> wrote:

Dear Bibhas Manna,

without any inputfile we can only guess what might be wrong. The cutoffs
seem to be a good - at least for the start; you should always check that those
are enough for your specific calculation.

My guess would be: you should consider using smearing for the occupations,
but without input... Why are you using the old 5.1 version?

Kind regards

Thomas


On 21.02.2018 15:52, Bibhas Manna wrote:
Dear QE users,

I am using PWSCF v.5.1 for vc-relaxing a graphene sheet with platinum atom adsorbed on it. The very first SCF cycle successfully converges after 18 iterations but the problem arises with the immediate next SCF cycle which is not converging even after 100 iterations.

I am using ecutwfc of 45 Ry and ecutrho of 400 Ry for pseudo potentials types :
H.pbe-van_ak.UPF
C.pbe-van_ak.UPF
Pt.pbe-n-kjpaw_psl.0.1.UPF


Could anyone please suggest me what may be the wrong with my code..


Any help in this regard is highly appreciable.

Thanks and regards.
Bibhas Manna
Research Scholar
IIT Kharagpur, India.



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Dr. rer. nat. Thomas Brumme
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
Leipzig University
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email: thomas.brumme at uni-leipzig.de<mailto:thomas.brumme at uni-leipzig.de>


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Matteo Cococcioni
Theory and Simulation of Materials
École Polytechnique Fédérale de Lausanne






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