[Pw_forum] End of SCF - convergence NOT achieved

[Nicola Marzari]

1) yes

2) read the document


On 29/06/2017 15:43, Ben Palmer wrote:
> Hi Nicola,
> 
> Thank you, I will have a look at that now.  I'm using the 1.0.0 version
> of the pslibrary at the moment.  Would you recommend that I switch to 0.3.1?
> 
> Thank you,
> 
> Ben
> 
> 
> On 28/06/17 13:31, Nicola Marzari wrote:
>>
>> In addition to Tom very good suggestions, I'd strongly recommend using
>> pslibrary 0.3.1 (paw, or ultrasoft), with 90 Ry and dual of 12.
>>
>> See here for extensive testing of the pseudos:
>> https://infoscience.epfl.ch/record/216845?ln=en
>>
>> 			nicola
>>
>>
>> On 28/06/2017 14:14, Tom Daff wrote:
>>> Hi Ben
>>>    > It would probably be helpful to see your input file, as there are many
>>> difficulties with iron and it could be any one of them!
>>>
>>> What magnetism are you using? FCC iron is most stable in antiferromagnetic
>>> double layer spin state (unless you are willing to look into spin-spiral),
>>> and around the equilibrium volume there is a crossover in stability of the
>>> high-spin and low-spin ferromagnetic states and I've found it difficult to
>>> get convergence if you are off with the starting spin.
>>>
>>> I've found that mixing_beta = 0.1, with the default mixing scheme gives me
>>> the most efficient convergence, and increasing the number of k-points can
>>> sometimes help too.
>>>
>>> Tom Daff
>>>
>>> University of Cambridge
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On
>>> Behalf Of Ben Palmer
>>> Sent: 28 June 2017 08:32
>>> To: PWSCF Forum <pw_forum at pwscf.org>
>>> Subject: [Pw_forum] End of SCF - convergence NOT achieved
>>>
>>> Hi Everyone,
>>>
>>> I'm trying to run a scf and vc-relax calculation for FCC Iron (nspin = 2).
>>> I've managed to do this for a 4 atom example (although the final scf
>>> calculation did fail: Error in routine ggen (138): smooth g-vectors missing
>>> !).  When I scale up to 32 atoms, it fails to converge.
>>>
>>> I've increased the number of steps to 250, used Plain, TF and local-TF
>>> modes, changed the mixing mode, beta and ndim.  I've also tried increasing
>>> nbnds and changing the starting magnetisation and celldm(1).
>>>
>>> The structure looks fine and I'm using the output from the 4 atom vc-relax
>>> calculation (scaled up 2x2x2).
>>>
>>> I wanted to ask if anyone has any suggestions on what I could try in order
>>> to get the calculation to converge?
>>>
>>> Thank you.
>>>
>>> Ben Palmer
>>>
>>> student @ University of Birmingham
>>>
>>>
>>>
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>>
> 
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-- 
----------------------------------------------------------------------
Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
http://theossrv1.epfl.ch/Main/Contact http://nccr-marvel.ch/en/project