[QE-users] Non-converging vc-relaxation calculation

[Robert Stanton]

Dear Stephen,

    Not that this will necessarily affect your convergence issues, but note
that it appears you may have mistakenly written ecutwfc twice, and that
your ecutrho will be defaulting to only 200Ry as opposed to what appears to
be the intended 500. Just letting you know in case you've got a system
converged for 50/500 cutoffs, not sure if it will help the current issue in
your system.

Kind Regards,
Robert Stanton
Clarkson University

On Thu, Jul 16, 2020 at 8:39 AM Mona Asadinamin <Mona.a at uga.edu> wrote:

> Dear Stephen;
>
> You might want to try a smaller mixing_beta. The default is 0.7.
>
>
> Best regards;
>
>
> Mona Asadi Namin
>
> Graduate student
>
> Center for simulational physics
>
> University of Georgia
>
> --------------------------------------
>
> Email:mona.a at uga.ed <mona.a at uga.edu>u <mona.a at uga.edu>
>
>
>
> ------------------------------
> *From:* users <users-bounces at lists.quantum-espresso.org> on behalf of
> Stephen Zhang <lolzen at berkeley.edu>
> *Sent:* Thursday, July 16, 2020 4:01 AM
> *To:* Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
> *Subject:* [QE-users] Non-converging vc-relaxation calculation
>
> [EXTERNAL SENDER - PROCEED CAUTIOUSLY]
>
> Hi everyone,
>
> I've encountered the issue of my vc-relax calculation not converging. Here
> is my input,
> ############################################################
> &control
>     calculation = 'vc-relax'
>     prefix = 'CoSnS'
>     outdir = './outdir'
>     pseudo_dir = '/home/stephen/qe-6.5/SSSP_precision_pseudos'
>     etot_conv_thr = 1e-6
>     forc_conv_thr = 1e-5
> /
> &system
>     ibrav=5, celldm(1) =10.16896836537393, celldm(4) = 0.4980629252775897,
>     nat=7, ntyp=7,
>     ecutwfc=50,
>     ecutwfc=500,
>     occupations='smearing',smearing='gaussian',degauss=0.1,
>     nspin=2,
>     starting_magnetization(1) = 0.24,
>     starting_magnetization(2) = 0.25,
>     starting_magnetization(3) = 0.3,
>     starting_magnetization(4) = 0.02,
>     starting_magnetization(5) = 0.04,
>     starting_magnetization(6) = 0.09,
>     starting_magnetization(7) = 0.01,
> /
> &electrons
>     conv_thr=1e-9
> /
> &ions
> /
> &cell
>     cell_dofree='ibrav'
> /
> ATOMIC_SPECIES
>  Co1  58.933195 Co.pbe-spn-kjpaw_psl.0.3.1.UPF
>  Co2  58.933195 Co.pbe-spn-kjpaw_psl.0.3.1.UPF
>  Co3  58.933195 Co.pbe-spn-kjpaw_psl.0.3.1.UPF
>  Sn4  118.71 Sn.pbe-dn-kjpaw_psl.1.0.0.UPF
>  Sn5  118.71 Sn.pbe-dn-kjpaw_psl.1.0.0.UPF
>  S6  32.065 S.pbe-n-kjpaw_psl.1.0.0.UPF
>  S7  32.065 S.pbe-n-kjpaw_psl.1.0.0.UPF
> ATOMIC_POSITIONS {crystal_b}
>  Co1 0.5000 0.0000 0.0000
>  Co2 0.0000 0.5000 0.0000
>  Co3 0.0000 0.0000 0.5000
>  Sn4 0.5000 0.5000 0.5000
>  Sn5 0.0000 0.0000 0.0000
>  S6 0.7195 0.7195 0.7195
>  S7 0.2805 0.2805 0.2805
> K_POINTS (automatic)
>   3 3 3 0 0 0
> #####################################################################3
> A recurring problem I've seen is that the scf accuracy will decrease to a
> certain point and then jump up again. According to the pw_user_guide
> <https://www.quantum-espresso.org/Doc/pw_user_guide.pdf> this is due to
> the fact that I am using few k-points and have a metallic material. The
> guide recommends the following:
>
> Usually one can solve the problem by adding a few empty bands and a small
> broadening
>
> However, I'm not sure on how to do either. Do i just increase the nbnd
> number and increase the degauss value?
>
> Thank you,
> Stephen
>
> --
> *University of California, Berkeley*
> *Department of Letter and Sciences*
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