[Pw_forum] Geometry optimization does not converge

Gunther Jegert guntherjegert at mytum.de
Mon Sep 21 14:56:48 CEST 2009


Dear all,

 

I am quite new to the PWscf community and currently I am trying to do a
geometry relaxation for a SiO2-slab with 84 atoms, where I introduced an
Oxygen vacancy. Things went pretty well for the neutral slab with vacancy.
However, when I try to charge the vacancy by removing an electron, I run
into problems. Starting from the relaxed geometry of the neutral vacancy,
the BFGS algorithm does not converge anymore. I end up with the following
error:

 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%

     from bfgs : error #         1

     bfgs history already reset at previous step

 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%

 

stopping ...

       

This error has been discussed several times in the forum (f. i.
(http://www.democritos.it/pipermail/pw_forum/2007-January/005834.html))and
I, of course, checked the archives for propositions how to solve the
problem. Following Stefano’s
(http://www.democritos.it/pipermail/pw_forum/2007-January/005840.html) and
Axel’s
(http://www.democritos.it/pipermail/pw_forum/2007-January/005843.html)
suggestions, I varied the energy cutoff between 40 – 60 Ry and kept the
density ten times higher. I added some additional unoccupied states and a
smearing. I also increased the conv_thr for the electrons up to 1D-11. I
even tried different starting geometries. However, I always end up with a
too high force in the order of 1D-2 (forc_conv_thr = default). 

 

Might I still have problems with too noisy energies due to insufficient
scf-convergence or inaccurate forces or do I just have a stupid beginner’s
mistake in my input?

 

Below, I have added an exemplary input file. I would be grateful, if you
could have a look on it and check it. Any suggestion of you is very, very
welcome!

 

&CONTROL

                 calculation = 'relax' ,

                restart_mode = 'restart' ,

                      outdir = '/home/PWscf/SiO2_84_Ovacp1_relax/output//' ,

                  pseudo_dir = '/home/PWscf/pseudo//' ,

                       nstep = 200 ,

 /

 &SYSTEM

                       ibrav = 0,

                         nat = 83,

                        ntyp = 3,

                     ecutwfc = 60 ,

                     ecutrho = 600 ,

                       nelec = 409 ,

                        nbnd = 220,

                 occupations = 'smearing' ,

                     degauss = 0.05 ,

                    smearing = 'methfessel-paxton' ,

                       nspin = 2 ,

 /

 &ELECTRONS

                    conv_thr = 1.D-9 ,

                 mixing_beta = 0.1 ,

                 mixing_mode = 'local-TF' ,

                 mixing_ndim = 10 ,

 /

 &IONS

                ion_dynamics = 'bfgs' ,

           pot_extrapolation = 'second_order' ,

           wfc_extrapolation = 'second_order' ,

 /

CELL_PARAMETERS hexagonal 

    17.414330330    6.200601079    0.000000000 

     0.000000000   13.777142870    0.000000000 

     0.000000000    0.000000000   42.588738040 

ATOMIC_SPECIES

    O   15.99900  O.pbe-van_bm.UPF 

   Si   28.08600  Si.pbe-n-van.UPF 

    H    1.00794  H.pbe-van_bm.UPF 

ATOMIC_POSITIONS crystal 

H        0.442138619   0.127580299   0.242115140

H        0.896137968   0.169119175   0.231615489

H        0.145279030   0.729466154   0.185318477

H        0.568527920   0.766728712   0.198838355

H        0.457668337   0.648606147   0.882235439

H        0.943934588   0.667149402   0.882893664

H        0.230323559   0.332247876   0.847403349

H        0.718571406   0.319187862   0.839952063

O        0.364677524   0.489280841   0.306670494

O        0.867635321   0.478867163   0.284064758

O        0.147367650   0.236115994   0.598026320

O        0.649640819   0.240794516   0.584731050

O        0.006278921   0.852123145   0.451026193

O        0.505597281   0.853373705   0.451280302

O        0.272809908   0.659725422   0.767916947

O        0.779049125   0.652527075   0.765357869

O        0.012328673   0.412490052   0.389290845

O        0.531224781   0.403102299   0.404465186

O        0.301626474   0.205319075   0.698724798

O        0.781065101   0.224772715   0.689991966

O        0.399409099   0.024956692   0.247297497

O        0.872257458   0.051528049   0.239846197

O        0.165316856   0.807508121   0.552180617

O        0.674267803   0.814813814   0.545851753

O        0.371769306   0.230668120   0.470840104

O        0.874075269   0.237128242   0.461296955

O        0.140604238   0.045485854   0.762585096

O        0.636783689   0.032316531   0.746475796

O        0.227654885   0.869784726   0.305080065

O        0.732727431   0.858504650   0.301584259

O        0.016547404   0.618236231   0.612079200

O        0.499871866   0.635111488   0.584920922

O        0.352145267   0.087370571   0.364285089

O        0.869168592   0.063942036   0.358940555

O        0.147949565   0.833154474   0.667584191

O        0.651280724   0.772724044   0.662149348

O        0.227434967   0.645403363   0.208182128

O        0.662565566   0.668667284   0.208416304

O        1.017204746   0.453226494   0.506583053

O        0.136606701   0.247643881   0.288287407

O        0.625203555   0.236268317   0.300390560

O        0.422870566   0.005178966   0.601178945

O        0.910961373  -0.002707092   0.599445140

O        0.049445293   0.422821214   0.745842272

O        0.533616582   0.415059161   0.741837098

O        0.279059613   0.620877043   0.456332047

O        0.772220558   0.616326195   0.445880739

O        0.077686441   0.628262425   0.307134784

O        0.592714281   0.614412248   0.320651893

O        0.355511589   0.386483961   0.603007628

O        0.861212384   0.386623507   0.596590250

O        0.217865803   0.001430950   0.458554135

O        0.719084261   0.003380876   0.451700786

O       -0.012841619   0.805524587   0.760936012

O        0.491588382   0.790461355   0.759417041

O        0.491159178   0.549730308   0.851262651

O        0.986487073   0.567079624   0.852990171

O        0.287151091   0.251418691   0.815141144

O        0.774113742   0.233345538   0.808313178

Si       0.022946405   0.442457010   0.317456331

Si       0.529681143   0.438905148   0.330234749

Si       0.304976291   0.200078045   0.627530596

Si       0.808520928   0.210558149   0.619785676

Si       0.161464516   0.828055173   0.481008952

Si       0.671356418   0.820865731   0.473400870

Si       0.445482049   0.605073868   0.781879032

Si       0.948636471   0.613116893   0.782529738

Si       0.279447583   0.058249921   0.300110703

Si       0.777972225   0.052171461   0.299130437

Si       0.059696263   0.813964553   0.608786133

Si       0.566523466   0.812843443   0.600031241

Si       0.193805384   0.233036488   0.756882342

Si       0.681560751   0.226501789   0.748830087

Si       0.408990216   0.420762023   0.452805513

Si       0.920407319   0.429512363   0.449897638

Si       0.222030251   0.663241013   0.280168453

Si       0.713290716   0.659481955   0.277387702

Si       0.010118971   0.426126379   0.578196606

Si       0.500224259   0.418800498   0.580296470

Si       0.362955019   0.035259574   0.433753945

Si       0.867091171   0.039993888   0.429863970

Si       0.137475224   0.836500083   0.740406223

Si       0.640529374   0.813508387   0.734302882

K_POINTS

  2

   0.2500000000000000   0.2500000000000000   0.0000000000000000
0.500000000000000

   0.2500000000000000  -0.2500000000000000   0.0000000000000000
0.500000000000000

 

 

Best wishes

Gunther

 

_________________________________
Dipl.-Phys. Gunther Jegert
Lehrstuhl für Nanoelektronik
Technische Universität München
Gebäude N8, Raum 1820

Theresienstraße 90
80333 München

 

Phone: +49 89 289 25370
Mail:     <mailto:bernhard.fabel at tum.de> guntherjegert at mytum.de

Web:    <http://www.nano.ei.tum.de/> http://www.nano.ei.tum.de
_________________________________

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20090921/4f54be13/attachment.html>


More information about the users mailing list