[Pw_forum] End of SCF - convergence NOT achieved

[Ben Palmer]

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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