[QE-users] Good convergence in one system, but bad convergence in a similar system.

Dan Gil dan.gil9973 at gmail.com
Mon May 7 16:09:55 CEST 2018


Hi,

I am running pw.x simulations with a slab of quartz (Si-O2) plus one
molecule of water (H2O). I am varying the distance between the quartz and
the water and minimizing the energy to obtain the electron density. For
some simulations, this runs perfectly fine. But for a range of distances,
the simulation is not converging.

I am running version 5.2.1.

Here is an example input for a simulation that did not converge:
&control
    calculation='scf',
    wf_collect = .true. ,
    outdir = 'bulkQuartz' ,
    restart_mode = 'restart' ,
    pseudo_dir = 'pseudo' ,
    disk_io = 'low' ,
    verbosity = 'low' ,
    max_seconds = 100000 ,
 /
 &system
    ibrav = 4 ,
    celldm(1)=19.174,
    celldm(3)=11,
    nat = 99 ,
    ntyp = 3 ,
    ecutwfc = 40.0,
    ecutrho = 400.0,
    smearing='mp',
    occupations='smearing',
    degauss=0.03,
 /
 &electrons
    diagonalization='david',
    conv_thr = 1.d-9,
    mixing_mode = 'plain',
    mixing_beta = 0.3,
 /
 &ions
 /
ATOMIC_SPECIES
Si   28.086 Si.pbe-n-rrkjus_psl.0.1.UPF
O    15.9994  O.pbe-n-rrkjus_psl.0.1.UPF
H     1.0008  H.pbe-rrkjus_psl.0.1.UPF
ATOMIC_POSITIONS crystal
Si       0.258687845   0.020629154   0.102019210
Si      -0.019888278   0.217277596   0.135661396
Si      -0.255311356  -0.249612076   0.118530505
O        0.216500358   0.131658292   0.109534141
O        0.105223826   0.186083494   0.128659197
O        0.264534959  -0.168589142   0.143893618
O       -0.226733650  -0.091440817   0.112415255
O       -0.094524332  -0.210925541   0.123877363
O        0.093345754  -0.085570018   0.095442520
Si       0.757637856   0.017698785   0.102996627
Si       0.499261195   0.247760755   0.133810675
Si       0.260502898  -0.231081580   0.118523575
O        0.715128665   0.136375843   0.108242265
O        0.614018644   0.199922131   0.127663208
O        0.377640707   0.099030305   0.140774042
O        0.292700056  -0.078156587   0.111965605
O        0.414396516  -0.210945055   0.124328613
O        0.577963780  -0.097510873   0.096335619
Si       0.246470371   0.510075455   0.102784084
Si      -0.008350761   0.743445657   0.133843274
Si      -0.243372898   0.263323249   0.118704908
O        0.222512928   0.641672436   0.108318043
O        0.110306465   0.704860221   0.126807033
O       -0.115606042   0.588684590   0.140894836
O       -0.207914965   0.421714663   0.112788923
O       -0.098241029   0.274413059   0.125535627
O        0.089954168   0.409350420   0.095091556
Si       0.228636707  -0.015515213   0.148652077
Si      -0.000570920   0.240108188   0.180788870
Si      -0.238830414  -0.233101222   0.164455135
O        0.188814156   0.105300171   0.155401485
O        0.129580597   0.211975161   0.174891343
O       -0.103849604   0.085600484   0.188142180
O       -0.197719806  -0.075671535   0.157544568
O       -0.081306989  -0.212395019   0.169818898
O        0.059546539  -0.110377315   0.142459206
Si       0.740429584   0.504294772   0.102333982
Si       0.498815103   0.741901797   0.134296099
Si       0.248787099   0.256703622   0.119466045
O        0.690620417   0.619909718   0.108736776
O        0.615675562   0.693188124   0.128587271
O        0.372773731   0.591011105   0.141039660
O        0.272376153   0.410198382   0.112966911
O        0.413019149   0.304455349   0.124924356
O        0.584007175   0.392416303   0.095402910
Si       0.758429580   0.021916104   0.148368885
Si       0.497195902   0.241475081   0.180701057
Si       0.256420844  -0.246383404   0.165486299
O        0.696874500   0.124690779   0.154915749
O        0.627049328   0.207421194   0.175351188
O        0.389596957   0.095713470   0.188773822
O        0.286106670  -0.081604242   0.160344849
O        0.420928926  -0.211470046   0.169927370
O        0.605226550  -0.102009143   0.141361730
Si       0.230900257   0.494107246   0.150078925
Si      -0.002502177   0.742290132   0.180741181
Si      -0.245952687   0.256039707   0.165008027
O        0.185533611   0.602815647   0.157314135
O        0.131608578   0.714161757   0.175650111
O       -0.109986238   0.584469784   0.187280614
O       -0.213559651   0.414224396   0.159154408
O       -0.089358513   0.275030823   0.170099821
O        0.075256561   0.370294522   0.143692679
Si       0.739384104   0.504889521   0.149819448
Si       0.501511397   0.743531243   0.180792889
Si       0.252716537   0.245693266   0.164465906
O        0.692669670   0.623114374   0.155320753
O        0.632713148   0.718738485   0.174634131
O        0.390256052   0.587279847   0.187506439
O        0.287331354   0.401942568   0.158203482
O        0.413978743   0.277476084   0.169723547
O        0.591741413   0.389802030   0.142457721
O        0.075025371   0.394019373   0.189188206
O        0.585313746   0.402337676   0.188308620
O        0.586281012   0.898771216   0.188916607
O        0.079369486   0.894756829   0.189163605
H        0.279938155   0.524595442   0.186664674
H        0.554383154   0.470114112   0.184420140
H        0.559654896   0.970318831   0.185076636
H        0.054346688   0.968508631   0.185624074
H        0.048603107   0.467541718   0.185794537
H       -0.222446062   0.525660848   0.186700053
H        0.277389445   0.032971149   0.187895233
H       -0.214394328   0.027904448   0.187751258
O        0.412416352   0.098886746   0.094609920
O        0.902446164   0.097353509   0.094335582
O        0.893185184   0.601781350   0.094504311
O        0.414681469   0.606997644   0.095511698
H        0.486522220   0.570599213   0.098078251
H        0.523150719   0.275802926   0.095532467
H        1.020421053   0.445893853   0.097845531
H        1.027748221  -0.046877912   0.098118747
H        0.513764581  -0.217924054   0.096610529
H        0.509415048  -0.057382202   0.098654295
H       -0.039562544  -0.290584834   0.096265488
H       -0.030986477   0.209885972   0.095356879
H        0.003452399   0.090676042   0.305               # Does not
converge from 0.305 to 0.355.
H        0.090676042   0.003452399   0.305               # Everything else
I tried (0.205 to 0.280 and also 0.455) converged.
O        0.105871559   0.105871559   0.305
K_POINTS automatic
1 1 1 1 1 1

- - - - -

And the output of the last few steps before max_cpu time is reached:
     iteration #149     ecut=    40.00 Ry     beta=0.30
     Davidson diagonalization with overlap
     ethr =  8.11E-07,  avg # of iterations =  1.0

     negative rho (up, down):  8.983E-03 0.000E+00

     total cpu time spent up to now is    96700.7 secs

     total energy              =   -2222.09469556 Ry
     Harris-Foulkes estimate   =   -2222.09477676 Ry
     estimated scf accuracy    <       0.00452085 Ry

     iteration #150     ecut=    40.00 Ry     beta=0.30
     Davidson diagonalization with overlap
     ethr =  8.11E-07,  avg # of iterations =  1.0

     negative rho (up, down):  8.982E-03 0.000E+00

     total cpu time spent up to now is    97153.1 secs

     total energy              =   -2222.09453313 Ry
     Harris-Foulkes estimate   =   -2222.09469588 Ry
     estimated scf accuracy    <       0.00440438 Ry

     iteration #151     ecut=    40.00 Ry     beta=0.30
     Davidson diagonalization with overlap
     ethr =  8.11E-07,  avg # of iterations =  1.0

     negative rho (up, down):  8.992E-03 0.000E+00

     total cpu time spent up to now is    97606.0 secs

     total energy              =   -2222.09363527 Ry
     Harris-Foulkes estimate   =   -2222.09453414 Ry
     estimated scf accuracy    <       0.00423049 Ry

     iteration #152     ecut=    40.00 Ry     beta=0.30
     Davidson diagonalization with overlap

     Maximum CPU time exceeded

 - - - - -

Best Regards,

Dan Gil
PhD Student
Department of Chemical and Biomolecular Engineering
Case Western Reserve University
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20180507/3d42d7c5/attachment.html>


More information about the users mailing list