[QE-users] Optimization does not converge

Thu Apr 4 15:45:03 CEST 2019

It is because you have an uneven number of electrons in your system. This
means you have an unpaired electron (so your system has a radical
character) which should not be described without a spin-polarized
calculation. But you're right this also means your system is paramagnetic.

Regards

Dominik

M.Sc. Dominik Voigt PhD Student
Münster University of Applied Sciences
Email: dv009200 at fh-muenster.de

> Dear Dominik
>
> Thank you very much for your reply.In fact, I added a hydroxyl group above
> the graphene sheet to build a simple hydroxylated graphene model,and the
> oxygen atom is directly above the carbon atom and the distance is about
> 1.45 angstroms.I want to know why I need to do spin polarization
> calculation for this system,is it because the presence of the hydroxyl
> group makes the graphene system magnetic?
>
>
> Wei gui
> School of Mechanical Engineering?Chongqing University, China
>
>> -----????-----
>> ???: dv009200 at fh-muenster.de
>> ????: 2019-04-04 20:18:15 (???)
>> ???: "Quantum Espresso users Forum" <users at lists.quantum-espresso.org>
>> ??:
>> ??: Re: [QE-users] Optimization does not converge
>>
>> I'm not sure but I think it has to do with the fact that you have an
>> unpaired electron in your system. You haven't defined the tot_charge of
>> your system, therefor the default value of tot_charge=0 means that you
>> have an OH radical adsorbed/bonded to the graphene layer. If that's
>> what
>> you want you should specify nspin and tot_magnetization. If you want
>> instead a hydroxy-ion (OH-) adsorbed on to the graphene layer you
>> should
>> set the tot_charge=-1.
>>
>> But as I said I'm not sure about this, so maybe there are some other
>> suggestions from users with more experience in this area of expertise?
>>
>> Best Regards
>>
>> Dominik
>>
>> M.Sc. Dominik Voigt PhD Student
>> Münster University of Applied Sciences
>> Email: dv009200 at fh-muenster.de
>>
>>
>> > Dear QE users,
>> > I am trying to optimize a single-layer graphene connected to a
>> hydroxyl
>> > group.After 48 scf cycles,the optimization result has never reached
>> the
>> > convergence value,the force of some atoms is always greater than the
>> > convergence threshold.But when I connect an epoxy group instead of a
>> > hydroxyl group on the graphene sheet, the optimization can reach
>> > convergence after 24 scf cycles.Does anyone know the reason for this?
>> > Any suggestions would be greatly appreciated.
>> > Thank you.
>> >
>> >
>> >  &control
>> >     calculation  = 'relax',
>> >     prefix='QJ1GO',
>> >     pseudo_dir = '/public/home/duan1/GuiWei/pseudo/',
>> >     outdir='/public/home/duan1/GuiWei/tempdir/'
>> >     tstress = .true.
>> >     tprnfor = .true.
>> >     etot_conv_thr=1.0D-4
>> >     forc_conv_thr=1.0D-3
>> > /
>> >  &system
>> >     ibrav= 0,
>> >     nat=66,
>> >     ntyp=3,
>> >
>> >     occupations='smearing',
>> >     smearing='mp',
>> >     degauss=0.02,
>> >
>> >
>> >     ecutwfc =40.0
>> >     ecutrho =320.0
>> >
>> >     vdw_corr='DFT-D'
>> >     london_s6 = 0.75
>> >
>> >
>> > /
>> > &electrons
>> >     conv_thr =  1.0d-8
>> >     mixing_beta = 0.2
>> >     mixing_mode = 'local-TF'
>> >     mixing_ndim=16
>> >     electron_maxstep=200
>> > /
>> > &IONS
>> >   ion_dynamics='bfgs'
>> > /
>> > CELL_PARAMETERS angstrom
>> > 19.680000000000003       0.000000000000010       0.000000000000000
>> >  0.000000000000000       8.521689973238882       0.000000000000000
>> >  0.000000000000000       0.000000000000000      25.000000000000000
>> > ATOMIC_SPECIES
>> > C  12.0107   C.pbe-rrkjus.UPF
>> > O   16.00    O.pbe-rrkjus.UPF
>> > H   1.00     H.pbe-rrkjus.UPF
>> > ATOMIC_POSITIONS  crystal
>> >   C   0.0000000000000000   0.0000000000000000   0.2164000000000000
>> >   C   0.1250000000000000  -0.0000000000000000   0.2164000000000000
>> >   C   0.0625000000000000   0.2499999999999999   0.2164000000000000
>> >   C   0.0000000000000000   0.4999999999999999   0.2164000000000000
>> >   C   0.2500000000000000  -0.0000000000000002   0.2164000000000000
>> >   C   0.1875000000000000   0.2499999999999999   0.2164000000000000
>> >   C   0.1250000000000000   0.4999999999999998   0.2164000000000000
>> >   C   0.0624999999999998   0.7499999999999989   0.2164000000000000
>> >   C   0.3750000000000000  -0.0000000000000002   0.2164000000000000
>> >   C   0.3125000000000000   0.2500000000000000   0.2164000000000000
>> >   C   0.2500000000000000   0.4999999999999999   0.2164000000000000
>> >   C   0.1875000000000000   0.7499999999999989   0.2164000000000000
>> >   C   0.5000000000000000  -0.0000000000000002   0.2164000000000000
>> >   C   0.4375000000000000   0.2500000000000000   0.2164000000000000
>> >   C   0.3750000000000000   0.4999999999999999   0.2164000000000000
>> >   C   0.3125000000000000   0.7499999999999988   0.2164000000000000
>> >   C   0.6250000000000000  -0.0000000000000004   0.2164000000000000
>> >   C   0.5625000000000000   0.2500000000000000   0.2164000000000000
>> >   C   0.5000000000000000   0.4999999999999999   0.2164000000000000
>> >   C   0.4375000000000000   0.7499999999999988   0.2164000000000000
>> >   C   0.7500000000000000  -0.0000000000000004   0.2164000000000000
>> >   C   0.6875000000000000   0.2499999999999999   0.2164000000000000
>> >   C   0.6250000000000000   0.4999999999999999   0.2164000000000000
>> >   C   0.5625000000000000   0.7499999999999988   0.2164000000000000
>> >   C   0.8750000000000000  -0.0000000000000004   0.2164000000000000
>> >   C   0.8125000000000000   0.2499999999999990   0.2164000000000000
>> >   C   0.7500000000000000   0.4999999999999999   0.2164000000000000
>> >   C   0.6875000000000000   0.7499999999999989   0.2164000000000000
>> >   C   0.9375000000000000   0.2499999999999990   0.2164000000000000
>> >   C   0.8750000000000000   0.5000000000000000   0.2164000000000000
>> >   C   0.8125000000000000   0.7499999999999988   0.2164000000000000
>> >   C   0.9375000000000000   0.7499999999999988   0.2164000000000000
>> >   C   0.0624999725702591   0.0833332967603452   0.2164000000000000
>> >   C  -0.0000000274297411   0.3333332967603450   0.2164000000000000
>> >   C   0.1874999725702590   0.0833332967603452   0.2164000000000000
>> >   C   0.1249999725702590   0.3333332967603450   0.2164000000000000
>> >   C   0.0624999725702589   0.5833332967603438   0.2164000000000000
>> >   C  -0.0000000274297409   0.8333332967603447   0.2164000000000000
>> >   C   0.3124999725702590   0.0833332967603452   0.2164000000000000
>> >   C   0.2499999725702590   0.3333332967603450   0.2164000000000000
>> >   C   0.1874999725702590   0.5833332967603448   0.2164000000000000
>> >   C   0.1249999725702590   0.8333332967603447   0.2164000000000000
>> >   C   0.4374999725702590   0.0833332967603452   0.2164000000000000
>> >   C   0.3749999725702590   0.3333332967603450   0.2164000000000000
>> >   C   0.3124999725702590   0.5833332967603448   0.2164000000000000
>> >   C   0.2499999725702590   0.8333332967603447   0.2164000000000000
>> >   C   0.5624999725702590   0.0833332967603451   0.2164000000000000
>> >   C   0.4999999725702591   0.3333332967603449   0.2164000000000000
>> >   C   0.4374999725702590   0.5833332967603438   0.2164000000000000
>> >   C   0.3749999725702590   0.8333332967603447   0.2164000000000000
>> >   C   0.6874999725702590   0.0833332967603451   0.2164000000000000
>> >   C   0.6249999725702590   0.3333332967603450   0.2164000000000000
>> >   C   0.5624999725702590   0.5833332967603447   0.2164000000000000
>> >   C   0.4999999725702591   0.8333332967603448   0.2164000000000000
>> >   C   0.8124999725702590   0.0833332967603451   0.2164000000000000
>> >   C   0.7499999725702590   0.3333332967603450   0.2164000000000000
>> >   C   0.6874999725702600   0.5833332967603440   0.2164000000000000
>> >   C   0.6249999725702590   0.8333332967603438   0.2164000000000000
>> >   C   0.9374999725702590   0.0833332967603450   0.2164000000000000
>> >   C   0.8749999725702590   0.3333332967603450   0.2164000000000000
>> >   C   0.8124999725702600   0.5833332967603438   0.2164000000000000
>> >   C   0.7499999725702590   0.8333332967603438   0.2164000000000000
>> >   C   0.9374999725702590   0.5833332967603438   0.2164000000000000
>> >   C   0.8749999725702601   0.8333332967603448   0.2164000000000000
>> >   O   0.5008325506691220   0.4975899051684459   0.2743438844378600
>> >   H   0.4505865611121930   0.4983293698599460   0.2875531708238770
>> > K_POINTS automatic
>> > 2  2  1  0  0  0
>> >
>> >
>> > Wei gui
>> > School of Mechanical Engineering?Chongqing University, China
>> >
>> >
>> >
>> > _______________________________________________
>> > users mailing list
>> > users at lists.quantum-espresso.org
>> > https://lists.quantum-espresso.org/mailman/listinfo/users
>>
>>
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