[QE-users] vc-relax Convergence problem with 'TS' VdW correction
Paolo Giannozzi
p.giannozzi at gmail.com
Sat Oct 13 18:46:34 CEST 2018
I don't think a tighter convergence threshold will fix the problem here:
there is a mismatch between forces and energies. This calculation uses
- Tkatchenko-Scheffler corrections
- in a spin-polarized case
- in a variable-cell calculation
Assuming that there is no problem without TS, it would be helpful to know
whether the problem is due to spin polarization, to variable cell, to both,
or to none.
PG
On Fri, Oct 12, 2018 at 9:32 PM Nicola Marzari <nicola.marzari at epfl.ch>
wrote:
>
> First I would try to have a much, much tighter convergence threshold
> than conv_thr = 1.0d-6; I think we use as a standard 0.2d-9 times
> the number of atoms - so in your case 4.0d-9, rather than
> 1.0d-6. If your selfconsistency is poor, your forces are noisy, and the
> relaxation slow.
>
> I also note that there is a variable called
> ts_vdw_econv_thr ; not sure what it does, but seems relevant.
>
> nicola
>
>
>
>
> On 12/10/2018 16:36, Hooman Yaghoobnejad Asl wrote:
> > Dear all,
> > I'm experiencing a problem with total force minimization when
> > the vdw_corr = 'TS' is used. Without the vdw_corr option, force
> > minimization completes smoothly, as shown below:
> >
> > Total force = 0.144455 Total SCF correction = 0.002938
> > Total force = 0.096620 Total SCF correction = 0.004258
> > Total force = 0.023833 Total SCF correction = 0.000694
> > Total force = 0.013572 Total SCF correction = 0.000196
> > Total force = 0.013176 Total SCF correction = 0.000775
> > Total force = 0.013520 Total SCF correction = 0.001316
> > Total force = 0.013322 Total SCF correction = 0.000670
> > Total force = 0.013164 Total SCF correction = 0.000897
> > Total force = 0.013634 Total SCF correction = 0.000800
> > Total force = 0.016822 Total SCF correction = 0.000639
> > Total force = 0.015558 Total SCF correction = 0.000354
> > Total force = 0.012359 Total SCF correction = 0.000858
> > Total force = 0.009014 Total SCF correction = 0.000322
> > Total force = 0.007140 Total SCF correction = 0.000338
> > Total force = 0.006073 Total SCF correction = 0.000556
> > Total force = 0.005047 Total SCF correction = 0.000465
> > Total force = 0.004639 Total SCF correction = 0.000050
> > Total force = 0.003113 Total SCF correction = 0.000382
> > Total force = 0.002225 Total SCF correction = 0.000268
> > Total force = 0.001698 Total SCF correction = 0.000156
> > Total force = 0.001505 Total SCF correction = 0.000372
> > Total force = 0.001422 Total SCF correction = 0.000244
> > Total force = 0.001442 Total SCF correction = 0.000420
> > However, after implementing the VdW correction, it seems that the forces
> > cannot be minimized further even after 200 ionic steps:
> >
> > Total force = 0.146620 Total SCF correction = 0.003488
> > Total force = 0.108842 Total SCF correction = 0.004843
> > Total force = 0.069519 Total SCF correction = 0.000923
> > Total force = 0.016339 Total SCF correction = 0.002655
> > Total force = 0.015353 Total SCF correction = 0.001041
> > Total force = 0.016188 Total SCF correction = 0.000361
> > Total force = 0.016350 Total SCF correction = 0.000832
> > Total force = 0.015878 Total SCF correction = 0.001654
> > Total force = 0.016273 Total SCF correction = 0.000560
> > Total force = 0.016349 Total SCF correction = 0.000406
> > Total force = 0.015879 Total SCF correction = 0.001403
> > .
> > .
> > .
> > .
> > Total force = 0.015866 Total SCF correction = 0.001214
> > Total force = 0.016279 Total SCF correction = 0.000263
> > Total force = 0.016351 Total SCF correction = 0.000394
> > Total force = 0.015879 Total SCF correction = 0.000394
> > Total force = 0.016277 Total SCF correction = 0.001323
> > Total force = 0.016347 Total SCF correction = 0.000194
> > Total force = 0.015878 Total SCF correction = 0.000606
> > I was wondering if anyone can make a comment on this? I'm using QE 6.2
> > on a cluster. Input copied below:
> > &CONTROL
> > title = 'Li0.5NiO2 NCPP FM VdW ' ,
> > calculation = 'vc-relax' ,
> > max_seconds = 86300 ,
> > ! wf_collect = .true. ,
> > outdir = '/' ,
> > wfcdir = '/' ,
> > pseudo_dir = '/scratch/05246/pseudo/' ,
> > !restart_mode = 'restart' ,
> > prefix = 'LNO' ,
> > disk_io = 'low' ,
> > verbosity = 'high' ,
> > nstep = 200 ,
> > /
> > &SYSTEM
> > ibrav = 0,
> > celldm(1) = 1.889726,
> > nat = 21,
> > ntyp = 3,
> > ecutwfc = 80 ,
> > ecutrho = 320 ,
> > occupations = 'smearing' ,
> > degauss = 0.001 ,
> > smearing = 'gaussian' ,
> > nspin = 2 ,
> > starting_magnetization(1) = 0.25,
> > vdw_corr = 'TS' ,
> > /
> > &ELECTRONS
> > electron_maxstep = 500,
> > conv_thr = 1.0d-6 ,
> > /
> > &IONS
> > /
> > &CELL
> > /
> > CELL_PARAMETERS {alat}
> > 5.790000 0.000000 0.000000
> > -1.447500 2.507144 0.000000
> > 0.000000 0.000000 14.221000
> > ATOMIC_SPECIES
> > Ni 58.69000 Ni_ONCV_PBE-1.0.upf
> > O 15.99000 O_ONCV_PBE-1.0.upf
> > Li 6.94000 Li_ONCV_PBE-1.0.upf
> > ATOMIC_POSITIONS crystal
> > O 0.000000 0.000000 0.232000
> > O 0.000000 0.000000 0.768000
> > O 0.333333 0.333333 0.565333
> > O 0.333333 0.333333 0.101333
> > O 0.166667 0.666667 0.898667
> > O 0.166667 0.666667 0.434667
> > Ni 0.000000 0.000000 0.500000
> > Ni 0.333333 0.333333 0.833333
> > Ni 0.166667 0.666667 0.166667
> > Li 0.166667 0.666667 0.666667
> > O 0.500000 0.000000 0.232000
> > O 0.500000 0.000000 0.768000
> > O 0.833333 0.333333 0.565333
> > O 0.833333 0.333333 0.101333
> > O 0.666667 0.666667 0.898667
> > O 0.666667 0.666667 0.434667
> > Ni 0.500000 0.000000 0.500000
> > Ni 0.833333 0.333333 0.833333
> > Ni 0.666667 0.666667 0.166667
> > Li 0.500000 0.000000 0.000000
> > Li 0.833333 0.333333 0.333333
> > K_POINTS automatic
> > 4 8 2 0 0 0
> >
> > Thank you
> > P.S. I benchmarked the wf cut-off energy vs binary oxides for each metal
> > and 80 Ry gave values comparable to 320 Ry.
> >
> > --
> > *Hooman Yaghoobnejad
> > *
> > *PhD, Department of Chemistry
> > *
> > *Missouri University of Science and Technology
> > *
> > *Rolla, MO 65409
> > *
> > *USA*
> >
> >
> > _______________________________________________
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> > users at lists.quantum-espresso.org
> > https://lists.quantum-espresso.org/mailman/listinfo/users
> >
>
>
> --
> ----------------------------------------------------------------------
> 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
> _______________________________________________
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--
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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