beta=0.1 is still pretty large, try reducing it before testing anything else. I've already seen systems where you have to go below beta=0.01 to get convergence, so that would be the first thing to do in this case in my opinion.

Hello Juan Andres De la Rosa Abad

I tried to replicate your calculation, but there are soe informations missing. You didn't describe your unit cell nor the atomic positions. It would be very helpful if you do it, so we could check how your calculation is going

Best regards,

Ricardo Tadeu

Ricardo Tadeu Maia

This is the complete input:

&control

calculation='scf'

prefix='nio'

pseudo_dir = './'

outdir='./out'

verbosity='high'

/

&system

ibrav = 0,

nat = 8,

ntyp = 2,

ecutrho = 400

ecutwfc = 50

nspin = 2,

tot_magnetization = 0.0

occupations = 'smearing'

smearing = 'cold'

degauss = $degauss

starting_magnetization(1) = 2.7777777778d-01

starting_magnetization(2) = 2.7777777778d-01

! starting_magnetization(3) = 1.0000000000d-01

/

&electrons

mixing_beta = $beta

electron_maxstep = 80

mixing_mode = 'local-TF'

mixing_ndim = 10

diagonalization = 'cg'

/

&ions

/

ATOMIC_SPECIES

Ni 58.693 Ni.pbesol-spn-kjpaw_psl.1.0.0.UPF

O 16.000 O.pbesol-n-kjpaw_psl.1.0.0.UPF

ATOMIC_POSITIONS angstrom

Ni 0.000 0.000 2.084

Ni 0.000 0.000 6.253

Ni 1.286 1.414 0.000

Ni 1.286 1.414 4.168

O 2.572 0.000 0.000

O 2.572 0.000 4.168

O 1.286 1.414 2.084

O 1.286 1.414 6.253

CELL_PARAMETERS angstrom

2.572 0.0 0.0

0.0 2.828 0.0

0.0 0.0 18.2526

K_POINTS {automatic}

15 15 5 0 0 0

!HUBBARD {ortho-atomic}

U Ni1-3d 7.0339

U Ni2-3d 7.0339

There are some things you must change.

First, in the lines degauss = $degauss and mixing_beta = $beta , you must set a number for both, so I made:

degauss = 0.02

mixing_beta = 0.7

Also, you must change smearing = 'cold' to

smearing = 'gaussian'

Now SCF calculation works. It takes a while to converge, so my task now is to try to make a correspondent input that may lead to a faster calculation. Could you show me the structure you wanted to study, like a CIF or something else that elucidate the structure?

Ricardo Tadeu Maia Thank you a lot. Your suggestions make the simulation converge. I will use this parameter to simulate an heterojunction. Which parameter do you suggest modifying to create a faster simulation?

Juan Andres De la Rosa Abad , I'm glad it worked. So, about the calculation being faster, check this other question I was discussing:

https://www.researchgate.net/post/Elastic_property_calculation_in_QE

I explained that in a SCF calculation with beryllium, I had two kinds of input, one with incorrect symmetry and one with correct symmetry. When you do a calculation with less symmetry than you could, it takes a lot more time to conclude. It means that we should take advantage of symmetry of our systems. This is what I want to do, a proper input with as much symmetry as we can get. I will come after with one or two different inputs so we can discuss what suits you better.

Check this input of a slab made using Burai software. It's more symmetric, and much faster than the previous.

Ricardo Tadeu Maia, Thanks for the new input. I was relaxing the previous structure, and the input generated news configurations, but it reached a point where it did not converge. Do you have any suggestions?

Juan Andres De la Rosa Abad , I think I would try the new input to be optimized. I just worked in that previous input just to make it work, not that it was completely correct. Also, you had a 15 15 5 mesh, which is very dense. Do you really need that much?

The new SCF input with 4 4 1 mesh finishes SCF in 8 minutes for me. The previous input, in 1 hour, wasn't even close to the end. I really think you should try the newer.

Also, when you do the optimization process, do you specify " cell_dofree = 'ibrav' "? If you don't, QE will mess your symmetry completely.

Ricardo Tadeu Maia, I used a more dense mesh because I found on the internet that a higher mesh value could help to converge. I will try with the new input. I am just performing a 'relax' calculation. I will update you when I have some results. Thanks.