[Pw_forum] which criterion does not meet during relax progresss

[xu yuehua]

Hi, all

I relaxed a system, my relaxation criterion is
 etot_conv_thr=1.D-5
 forc_conv_thr=1.D-4,
and conv_thr    = 1.D-8 ,

and in my output file,  i see the force_conv_thr is met, and the conv_thr
seems also met.
for in the last relaxation step, the printed information is :


*!    total energy              =    -551.13047812 Ry
     Harris-Foulkes estimate   =    -551.13047807 Ry
     estimated scf accuracy    <          2.4E-11 Ry

     The total energy is the sum of the following terms:

     one-electron contribution =   -2144.14675345 Ry
     hartree contribution      =    1097.77738769 Ry
     xc contribution           =    -134.85772630 Ry
     ewald contribution        =     630.09661393 Ry

     convergence has been achieved in   9 iterations

     Forces acting on atoms (Ry/au):

     atom   1 type  2   force =     0.00006652    0.00001074    0.00001717
     atom   2 type  1   force =    -0.00001149   -0.00003650    0.00002296
     atom   3 type  1   force =     0.00002092    0.00003527    0.00001095
     atom   4 type  2   force =    -0.00006106   -0.00005036    0.00002893
     atom   5 type  1   force =     0.00012199   -0.00005785   -0.00011993
     atom   6 type  1   force =    -0.00005472    0.00002358    0.00009707
     atom   7 type  2   force =     0.00003025    0.00003532    0.00004727
     atom   8 type  1   force =     0.00001390    0.00009541    0.00000283
     atom   9 type  1   force =    -0.00007213   -0.00012498   -0.00005854
     atom  10 type  2   force =    -0.00000989   -0.00001883   -0.00002476
     atom  11 type  1   force =     0.00002862   -0.00010630    0.00001950
     atom  12 type  1   force =     0.00000813    0.00006367   -0.00002737
     atom  13 type  2   force =    -0.00010953    0.00005997    0.00012796
     atom  14 type  1   force =     0.00012468    0.00004819    0.00006199
     atom  15 type  1   force =    -0.00003227   -0.00002568   -0.00012529
     atom  16 type  2   force =     0.00000131    0.00002155    0.00006799
     atom  17 type  1   force =     0.00002056    0.00002091    0.00006192
     atom  18 type  1   force =    -0.00004895   -0.00000474   -0.00012101
     atom  19 type  2   force =    -0.00000208   -0.00000446    0.00003292
     atom  20 type  1   force =    -0.00003014    0.00001046    0.00005040
     atom  21 type  1   force =    -0.00000665    0.00000012   -0.00002565
     atom  22 type  2   force =     0.00004366    0.00001375   -0.00003139
     atom  23 type  1   force =     0.00001038    0.00000199   -0.00004611
     atom  24 type  1   force =     0.00000001   -0.00002044    0.00003004
     atom  25 type  2   force =    -0.00000668   -0.00002989    0.00007813
     atom  26 type  1   force =     0.00003097   -0.00004437    0.00003757
     atom  27 type  1   force =     0.00001552    0.00000595   -0.00005710
     atom  28 type  2   force =     0.00001236    0.00004340    0.00012950
     atom  29 type  1   force =    -0.00002372    0.00002505   -0.00007569
     atom  30 type  1   force =     0.00003122    0.00000291    0.00000276
     atom  31 type  2   force =    -0.00001390   -0.00010264   -0.00009180
     atom  32 type  1   force =     0.00004590    0.00003207    0.00003011
     atom  33 type  1   force =    -0.00002671    0.00005738   -0.00001122
     atom  34 type  2   force =    -0.00001380   -0.00001243   -0.00005321
     atom  35 type  1   force =    -0.00002033    0.00001199    0.00006508
     atom  36 type  1   force =     0.00001161   -0.00000439   -0.00003033
     atom  37 type  2   force =    -0.00008127    0.00002129    0.00005130
     atom  38 type  1   force =    -0.00004667   -0.00008260   -0.00004117
     atom  39 type  1   force =     0.00000793    0.00013767   -0.00000675
     atom  40 type  2   force =     0.00001123   -0.00004604    0.00006549
     atom  41 type  1   force =     0.00003825    0.00001125   -0.00000180
     atom  42 type  1   force =    -0.00005610    0.00001922   -0.00008202
     atom  43 type  2   force =    -0.00001184    0.00000509   -0.00002456
     atom  44 type  1   force =    -0.00005112   -0.00001419    0.00000597
     atom  45 type  1   force =     0.00009312   -0.00000567   -0.00002162
     atom  46 type  2   force =    -0.00002442   -0.00003492    0.00009560
     atom  47 type  1   force =    -0.00005855    0.00002530   -0.00010962
     atom  48 type  1   force =     0.00008502   -0.00001219   -0.00005446

     Total force =     0.000643     Total SCF correction =     0.000037*
**
*entering subroutine stress ...

          total   stress  (Ry/bohr**3)                   (kbar)     P=
-1.92
  -0.00001798   0.00000011   0.00000000         -2.64      0.02      0.00
   0.00000011  -0.00001708   0.00000001          0.02     -2.51      0.00
   0.00000000   0.00000001  -0.00000407          0.00      0.00     -0.60


     The maximum number of steps has been reached.

     End of BFGS Geometry Optimization*

 Ie.  the code saying *The maximum number of steps has been reached.* the
relaxation is not convergence. I am puzzled the  etot_conv_thr does not meet
?? The etot_conv_thr  is not high, and the nstep is already 200.  try a
lower etot_conv_thr?

i wish someone could have a look at the output. Thanks a lot !





-- 
Yuehua Xu
Group of Computational Condensed Matter Physics,
National Laboratory of Solid State Microstructures and Department of
Physics,
Nanjing University,
 Nanjing 210093,
 P. R. China
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