[QE-users] DFT+U can not converge
Giuseppe Mattioli
giuseppe.mattioli at ism.cnr.it
Wed Dec 19 12:30:51 CET 2018
Dear Liang Xiongyi
In my opinion, your initial structure is possibly wrong or missing
necessary saturation (i.e. twofold-coordinated P atoms on the surface
and P=O free terminations, which are likely unstable in gas phase).
However, and generally speaking, if your calculation is going
somewhere not so far from convergence, you can overcome a difficult
initial step by using this very useful switch:
scf_must_converge=.false.
Coupled with a suitable electron_maxstep variable, it will calculate
forces and move atoms when scf ends. If the structure is meaningful
and not wrong (and this may not be the case) in a few steps you should
recover an acceptably smooth convergence.
HTH
Giuseppe
LEUNG Clarence <liangxy123 at hotmail.com> ha scritto:
> Dear QEusers,
>
> When I use QE6.3 to perform DFT+U to relax a slab, it is very
> difficult to converge and even can not converge (more than 300 scf
> steps). Thanks for your suggestion in advances.
>
> The input file is:
>
> &CONTROL
> calculation='relax',
> nstep = 200 ,
> wf_collect = .true. ,
> etot_conv_thr = 3.5D-6 ,
> forc_conv_thr = 4.0D-4,
> /
>
> &SYSTEM
> ibrav=0,
> celldm(1)=9.6431795847d0,
> nat=109,
> ntyp=3,
> ecutwfc=60,
> ecutrho=480,
> input_dft='PBE',
> occupations='smearing',
> smearing = 'gaussian' ,
> degauss = 0.01 ,
> nspin = 2 ,
> starting_magnetization(1) = 0.5 ,
> lda_plus_u = .true. ,
> Hubbard_U(1) = 3.32 ,
> vdw_corr = dft-d3 ,
> /
> &ELECTRONS
> conv_thr=1d-05,
> mixing_beta=0.3d0,
> mixing_mode ='local-TF',
> electron_maxstep = 600 ,
> /
> &IONS
> /
> &CELL
> /
>
> ATOMIC_SPECIES
> Co 58.933200d0 Co.pbe-spn-rrkjus_psl.0.3.1.UPF
> O 15.999400d0 O.pbe-n-rrkjus_psl.1.0.0.UPF
> P 30.973800d0 P.pbe-n-rrkjus_psl.1.0.0.UPF
>
> ATOMIC_POSITIONS {crystal}
> O 0.175510868 0.823201091 0.004041902 0 0 0
> Co 0.752963028 0.655948399 0.004313566 0 0 0
> O 0.301125723 0.416151961 0.004879997 0 0 0
> Co 0.846799898 0.775755648 0.005275182 0 0 0
> Co 0.346800351 0.275755641 0.005275204 0 0 0
> O 0.392474471 0.135359341 0.005670234 0 0 0
> Co 0.940637166 0.895562903 0.006236666 0 0 0
> O 0.518089326 0.728310212 0.006508330 0 0 0
> O 0.902313840 0.059368885 0.017959393 0 0 0
> O 0.807187857 0.964594997 0.020457557 0 0 0
> O 0.036878250 0.705581722 0.023890599 0 0 0
> P 0.893919682 0.538810250 0.026242849 0 0 0
> Co 0.451343782 0.481124665 0.033750041 0 0 0
> O 0.028914218 0.314809876 0.034323347 0 0 0
> P 0.323165643 0.700374526 0.044655886 0 0 0
> O 0.412931350 0.644218586 0.045243797 0 0 0
> O 0.180081232 0.532598515 0.046685149 0 0 0
> O 0.551818853 0.324973894 0.062282695 0 0 0
> O 0.318968869 0.213353805 0.063724007 0 0 0
> P 0.408734429 0.157197863 0.064311920 0 0 0
> O 0.702985853 0.542762514 0.074644459 0 0 0
> Co 0.280556437 0.376447725 0.075217763 0 0 0
> P 0.837980537 0.318762141 0.082724954 0 0 0
> O 0.695021832 0.151990660 0.085077236 0 0 0
> O 0.924712372 0.892977386 0.088510276 0 0 0
> O 0.829586379 0.798203506 0.091008410 0 0 0
> O 0.213810893 0.129262179 0.102459474 0 0 0
> Co 0.791263053 0.962009487 0.102731138 0 0 0
> O 0.339425748 0.722213050 0.103297569 0 0 0
> Co 0.885099923 0.081816736 0.103692754 0 0 0
> Co 0.385100377 0.581816730 0.103692776 0 0 0
> O 0.430774496 0.441420429 0.104087807 0 0 0
> Co 0.978937191 0.201623991 0.104654238 0 0 0
> O 0.556389351 0.034371300 0.104925902 0 0 0
> O 0.940613865 0.365429972 0.116376965 0 0 0
> O 0.845487883 0.270656085 0.118875129 0 0 0
> O 0.075178275 0.011642810 0.122308171 0 0 0
> P 0.932219708 0.844871338 0.124660421 0 0 0
> Co 0.489643808 0.787185753 0.132167613 0 0 0
> O 0.067214244 0.620870964 0.132740919 0 0 0
> P 0.361354279 0.006083789 0.142115621
> O 0.446802131 0.950135511 0.145110715
> O 0.214381915 0.837791409 0.146887224
> O 0.593110221 0.629859448 0.161855388
> O 0.355569602 0.519337757 0.162613913
> P 0.444333889 0.463046511 0.162481449
> O 0.733915313 0.849462282 0.171314557
> Co 0.331397450 0.684149370 0.174777754
> P 0.880835007 0.624048906 0.181575275
> O 0.729016571 0.457586972 0.184340848
> O 0.943694570 0.199413194 0.185888622
> O 0.842699539 0.103890146 0.188690045
> O 0.246376254 0.435621465 0.201025875
> Co 0.819907469 0.267437250 0.200281311
> O 0.371654672 0.028624679 0.201597106
> Co 0.919293748 0.386217687 0.198228118
> Co 0.408991643 0.881622266 0.208931455
> O 0.502982285 0.747275057 0.201700410
> Co 0.015942502 0.506736170 0.203798000
> O 0.581988259 0.338815157 0.205761317
> O 0.989082264 0.670263393 0.214923633
> O 0.891588821 0.575388161 0.217463006
> O 0.102116329 0.316952504 0.225311380
> P 0.946018990 0.150667428 0.220957196
> Co 0.509889754 0.092572883 0.231027714
> O 0.087929910 0.910622245 0.254736182
> P 0.390071467 0.310008795 0.243522265
> O 0.475452219 0.253683339 0.241349488
> O 0.235229551 0.143749020 0.238654386
> O 0.612387032 0.940393783 0.254302766
> O 0.441611912 0.824444770 0.264038723
> P 0.540200975 0.770461487 0.260363655
> O 0.761099937 0.156388759 0.269996408
> Co 0.350068981 0.991380761 0.270128489
> P 0.873321153 0.936340371 0.286294166
> O 0.833246668 0.765227606 0.276230271
> O -0.000361722 0.500532992 0.288698932
> O 0.881119075 0.405321157 0.282221320
> O 0.360000301 0.737045056 0.298351129
> Co 0.882972312 0.575549749 0.299644501
> O 0.422605865 0.327653597 0.304586136
> Co 0.978817281 0.686215697 0.299070830
> Co 0.413208161 0.191270814 0.293687127
> O 0.508789991 0.058470538 0.306778792
> Co 0.104885226 0.777001345 0.337018699
> O 0.655258778 0.642479617 0.299146914
> O -0.013826595 0.991404406 0.298780328
> O 0.795664337 0.914010571 0.342626007
> O 0.182057906 0.620327437 0.315087245
> P -0.025531312 0.449691921 0.318993246
> Co 0.536676633 0.394337417 0.322803232
> O 0.111523355 0.238614584 0.330445421
> P 0.458259125 0.623697091 0.344422574
> O 0.563543106 0.565239764 0.345713118
> O 0.245933114 0.438564927 0.345886633
> O 0.755827316 0.261536514 0.398125722
> O 0.347085887 0.142061029 0.350995120
> P 0.418798485 0.087516712 0.363471914
> O 0.760091719 0.450332386 0.364446953
> Co 0.425302156 0.268828519 0.364933404
> P 1.000978059 0.228830728 0.389926937
> O 0.665322447 0.083338404 0.398947262
> O 0.175348426 0.819170270 0.393432843
> O 0.972375724 0.715594688 0.364967608
> O 0.192491280 0.055768375 0.386972733
> Co 0.947698792 0.864533921 0.380242742
> O 0.461116896 0.646777652 0.398656956
> Co -0.128695091 0.044030025 0.349922760
> Co 0.459662371 0.500794114 0.364054027
>
>
> K_POINTS {automatic}
> 3 3 1 0 0 0
>
> CELL_PARAMETERS {alat}
> 1.000000000000d0 0.000000000000d0 0.000000000000d0
> -0.125138500246d0 5.222389311845d0 0.000000000000d0
> 0.000000000000d0 0.000000000000d0 4.847983163860d0
>
> LIANG Xiongyi
> CIty University of Hong Kong
GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
Via Salaria Km 29,300 - C.P. 10
I-00015 - Monterotondo Scalo (RM)
Mob (*preferred*) +39 373 7305625
Tel + 39 06 90672342 - Fax +39 06 90672316
E-mail: <giuseppe.mattioli at ism.cnr.it>
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