[Pw_forum] Convergence threshold

[Sergey Lisenkov]

Dear Carlo,

 Thank you very much for your response. 

>do the dots mean that the code performs other iterations after the message 
>"End of self-consistent calculation" ??? Can you post the complete output 
>file and the details of your input ?

I mean that code performs other iterations but the convergence is already achieved:

Please, look in output:

convergence threshold     =      1.0E-08 

After first scf loop:

     total energy              =  -304.04955368 ryd
     estimated scf accuracy    <     0.00000003 ryd

     iteration # 12     ecut=    38.00 ryd     beta=0.30
     Davidson diagonalization (with overlap)
     ethr =  3.33E-11,  avg # of iterations =  2.0

     total cpu time spent up to now is    663.40 secs

     End of self-consistent calculation

          k = 0.0625 0.0000 0.0000 (69280 PWs)   bands (ev):

   -14.3985 -14.1020 -14.1014 -13.4128 -13.4127 -12.9699 -12.8594 -12.8592
   -12.8567 -12.8560  -8.9009  -8.6354  -8.6344  -8.2400  -8.2399  -7.4494
    -7.4493  -6.9773  -6.7669  -6.7669  -6.5989  -6.5972  -6.5658  -6.5612
    -5.8985  -5.8984  -5.6890  -5.4801  -5.4794  -5.2608  -4.7019  -4.7017
    -4.5606  -4.5575  -4.5170  -4.5165  -4.4484  -4.3031  -4.1997  -4.1993

          k = 0.1875 0.0000 0.0000 (69344 PWs)   bands (ev):

   -14.3210 -14.0308 -14.0302 -13.3701 -13.3701 -13.1341 -12.9893 -12.9886
   -12.8983 -12.8982  -8.6196  -8.4586  -8.4574  -8.3730  -8.3729  -7.7287
    -7.7285  -6.9513  -6.7173  -6.7131  -6.4254  -6.4241  -6.3997  -6.3996
    -5.6185  -5.5852  -5.5850  -5.5652  -5.5640  -5.3769  -4.7220  -4.6945
    -4.6914  -4.6360  -4.6358  -4.5810  -4.4900  -4.4896  -4.2428  -4.2424

          k = 0.3125 0.0000 0.0000 (69432 PWs)   bands (ev):

   -14.1698 -13.8926 -13.8920 -13.3965 -13.2910 -13.2910 -13.2086 -13.2080
   -12.9727 -12.9725  -8.4728  -8.4727  -8.1564  -8.1550  -8.1399  -8.0547
    -8.0546  -7.0152  -7.0120  -6.9517  -6.0979  -6.0968  -5.8711  -5.8710
    -5.5557  -5.5555  -5.5537  -5.4814  -5.2734  -5.2598  -5.2596  -4.9107
    -4.9078  -4.8003  -4.6664  -4.6659  -4.5314  -4.5311  -4.3216  -4.3212

          k = 0.4375 0.0000 0.0000 (69512 PWs)   bands (ev):

   -13.9537 -13.6973 -13.6967 -13.6846 -13.4578 -13.4572 -13.1886 -13.1885
   -13.0721 -13.0720  -8.4579  -8.4579  -8.3125  -8.3124  -7.7879  -7.7860
    -7.5834  -7.3939  -7.3914  -7.1285  -5.7016  -5.6654  -5.6642  -5.6545
    -5.4581  -5.4557  -5.3745  -5.3744  -5.2871  -5.1394  -5.1393  -5.1283
    -5.1258  -5.0494  -5.0430  -5.0422  -4.4686  -4.4684  -4.4092  -4.4088

!    total energy              =  -304.04955370 ryd
     estimated scf accuracy    <        2.8E-09 ryd


But after third and next scf loop:

...
     total energy              =  -304.04986379 ryd
     estimated scf accuracy    <     0.00000238 ryd

     iteration #  8     ecut=    38.00 ryd     beta=0.30
     Davidson diagonalization (with overlap)
     ethr =  2.98E-09,  avg # of iterations =  3.3

     total cpu time spent up to now is   2657.46 secs

     total energy              =  -304.04986469 ryd
     estimated scf accuracy    <     0.00000074 ryd

     iteration #  9     ecut=    38.00 ryd     beta=0.30
     Davidson diagonalization (with overlap)
     ethr =  9.26E-10,  avg # of iterations =  2.0

     total cpu time spent up to now is   2705.26 secs

     total energy              =  -304.04986483 ryd
     estimated scf accuracy    <     0.00000048 ryd

     iteration # 10     ecut=    38.00 ryd     beta=0.30
     Davidson diagonalization (with overlap)
     ethr =  5.97E-10,  avg # of iterations =  2.3

     total cpu time spent up to now is   2756.29 secs

     total energy              =  -304.04986512 ryd
     estimated scf accuracy    <     0.00000001 ryd

     iteration # 11     ecut=    38.00 ryd     beta=0.30
     Davidson diagonalization (with overlap)
     ethr =  1.79E-11,  avg # of iterations =  3.5

     total cpu time spent up to now is   2806.19 secs

     total energy              =  -304.04986512 ryd
     estimated scf accuracy    <     0.00000001 ryd

     iteration # 12     ecut=    38.00 ryd     beta=0.30
     Davidson diagonalization (with overlap)
     ethr =  1.34E-11,  avg # of iterations =  2.0

     total cpu time spent up to now is   2857.51 secs

     total energy              =  -304.04986513 ryd
     estimated scf accuracy    <        4.6E-09 ryd             ! it should be enough

     iteration # 13     ecut=    38.00 ryd     beta=0.30
     Davidson diagonalization (with overlap)
     ethr =  5.79E-12,  avg # of iterations =  3.0

     total cpu time spent up to now is   2911.27 secs

     total energy              =  -304.04986513 ryd
     estimated scf accuracy    <        5.1E-09 ryd

     iteration # 14     ecut=    38.00 ryd     beta=0.30
     Davidson diagonalization (with overlap)
     ethr =  5.79E-12,  avg # of iterations =  2.3

     total cpu time spent up to now is   2961.01 secs

     End of self-consistent calculation

          k = 0.0625 0.0000 0.0000 (69280 PWs)   bands (ev):

   -14.4011 -14.1046 -14.1042 -13.4154 -13.4154 -12.9701 -12.8624 -12.8622
   -12.8577 -12.8571  -8.9136  -8.6463  -8.6455  -8.2410  -8.2408  -7.4448
    -7.4447  -6.9766  -6.7735  -6.7734  -6.5935  -6.5922  -6.5671  -6.5622
    -5.9090  -5.9088  -5.6854  -5.4780  -5.4773  -5.2569  -4.7024  -4.7023
    -4.5561  -4.5529  -4.5289  -4.5286  -4.4408  -4.3170  -4.1982  -4.1979

          k = 0.1875 0.0000 0.0000 (69344 PWs)   bands (ev):

   -14.3235 -14.0333 -14.0328 -13.3727 -13.3726 -13.1349 -12.9907 -12.9901
   -12.9015 -12.9013  -8.6317  -8.4685  -8.4675  -8.3742  -8.3741  -7.7266
    -7.7264  -6.9511  -6.7164  -6.7122  -6.4241  -6.4228  -6.4057  -6.4056
    -5.6147  -5.5927  -5.5925  -5.5644  -5.5633  -5.3739  -4.7342  -4.6914
    -4.6884  -4.6369  -4.6368  -4.5741  -4.4981  -4.4977  -4.2416  -4.2413

          k = 0.3125 0.0000 0.0000 (69432 PWs)   bands (ev):

   -14.1720 -13.8948 -13.8943 -13.3981 -13.2932 -13.2932 -13.2106 -13.2101
   -12.9762 -12.9761  -8.4740  -8.4739  -8.1645  -8.1632  -8.1508  -8.0543
    -8.0542  -7.0168  -7.0136  -6.9530  -6.0974  -6.0963  -5.8767  -5.8767
    -5.5549  -5.5540  -5.5530  -5.4772  -5.2831  -5.2649  -5.2647  -4.9087
    -4.9058  -4.7945  -4.6717  -4.6712  -4.5328  -4.5327  -4.3212  -4.3208

          k = 0.4375 0.0000 0.0000 (69512 PWs)   bands (ev):

   -13.9548 -13.6985 -13.6980 -13.6875 -13.4611 -13.4606 -13.1891 -13.1891
   -13.0773 -13.0772  -8.4586  -8.4586  -8.3133  -8.3132  -7.7937  -7.7919
    -7.5923  -7.3980  -7.3956  -7.1341  -5.7019  -5.6657  -5.6646  -5.6601
    -5.4571  -5.4548  -5.3795  -5.3795  -5.2818  -5.1441  -5.1440  -5.1273
    -5.1249  -5.0463  -5.0456  -5.0450  -4.4675  -4.4673  -4.4118  -4.4115

!    total energy              =  -304.04986513 ryd
     estimated scf accuracy    <        5.0E-10 ryd

     band energy sum           =   -46.52156332 ryd
     one-electron contribution =  -947.75987385 ryd
     hartree contribution      =   484.42869513 ryd
     xc contribution           =  -183.18402805 ryd
     ewald contribution        =   342.46534165 ryd

     convergence has been achieved

     Forces acting on atoms (Ry/au):
.....


May be i don't understand the process of scf calculations properly?

Best wishes,
  Sergey