[Pw_forum] Aluminium EPC at X

Amit Kumar amit76.india at gmail.com
Sun Mar 25 19:58:12 CEST 2007


   Respected Users,

   I'm very much confused with the results of the electron-phonon coupling
of Aluminium
   at X-point.  You can see a large discrepancy in the results of Example
No. 7.
   I hope developers  have checked  their  results  carefully  before
keeping them on the web and
   they must have some clarification of the above anomaly.
   Someone can get some total value of lamda (say 0.38 for Al) by
manipulating some input  parameters
   in 100 ways.
   However it does not imply al the ways are correct. Sometime some correct
results might be accidental.
   So developers should check every part of the results carefully and
mention all the details in their
   published paper instead of   just giving an experimentally closed value
of  lambda.

   Check  out the discrepancy even in the example given by developers.
::::::::::::::::

   OLd version ::::

        electron-phonon interaction  ...

     Gaussian Broadening:   0.010 Ry, ngauss=   1
     DOS =  1.571147 states/spin/Ry/Unit Cell at Ef=  8.320258 eV
     double delta at Ef = 11.225648
     lambda( 1)=  0.159075   gamma=  8.614118 GHz
     lambda( 2)=  0.159075   gamma=  8.614118 GHz
     lambda( 3)=  0.003155   gamma=  0.507699 GHz
     Gaussian Broadening:   0.020 Ry, ngauss=   1
     DOS =  2.063779 states/spin/Ry/Unit Cell at Ef=  8.335249 eV
     double delta at Ef = 18.003706
     lambda( 1)=  0.227168   gamma= 16.158565 GHz
     lambda( 2)=  0.227168   gamma= 16.158565 GHz
     lambda( 3)=  0.186119   gamma= 39.344107 GHz
     Gaussian Broadening:   0.030 Ry, ngauss=   1
     DOS =  2.225322 states/spin/Ry/Unit Cell at Ef=  8.330057 eV
     double delta at Ef = 16.640984
     lambda( 1)=  0.192523   gamma= 14.766136 GHz
     lambda( 2)=  0.192523   gamma= 14.766136 GHz
     lambda( 3)=  0.205460   gamma= 46.832277 GHz
     Gaussian Broadening:   0.040 Ry, ngauss=   1
     DOS =  2.326737 states/spin/Ry/Unit Cell at Ef=  8.319465 eV
     double delta at Ef = 14.664131
     lambda( 1)=  0.176025   gamma= 14.116094 GHz
     lambda( 2)=  0.176025   gamma= 14.116094 GHz
     lambda( 3)=  0.151743   gamma= 36.164371 GHz
     Gaussian Broadening:   0.050 Ry, ngauss=   1
     DOS =  2.437502 states/spin/Ry/Unit Cell at Ef=  8.308700 eV
     double delta at Ef = 13.504805
     lambda( 1)=  0.157223   gamma= 13.208493 GHz
     lambda( 2)=  0.157223   gamma= 13.208493 GHz
     lambda( 3)=  0.127499   gamma= 31.832929 GHz
     Gaussian Broadening:   0.060 Ry, ngauss=   1
     DOS =  2.540670 states/spin/Ry/Unit Cell at Ef=  8.300510 eV
     double delta at Ef = 12.914118
     lambda( 1)=  0.139587   gamma= 12.223180 GHz
     lambda( 2)=  0.139587   gamma= 12.223180 GHz
     lambda( 3)=  0.123908   gamma= 32.245781 GHz
     Gaussian Broadening:   0.070 Ry, ngauss=   1
     DOS =  2.612585 states/spin/Ry/Unit Cell at Ef=  8.295170 eV
     double delta at Ef = 12.624523
     lambda( 1)=  0.127008   gamma= 11.436544 GHz
     lambda( 2)=  0.127008   gamma= 11.436544 GHz
     lambda( 3)=  0.124915   gamma= 33.427891 GHz
     Gaussian Broadening:   0.080 Ry, ngauss=   1
     DOS =  2.651928 states/spin/Ry/Unit Cell at Ef=  8.291972 eV
     double delta at Ef = 12.510074
     lambda( 1)=  0.119464   gamma= 10.919196 GHz
     lambda( 2)=  0.119464   gamma= 10.919196 GHz
     lambda( 3)=  0.127255   gamma= 34.566893 GHz
     Gaussian Broadening:   0.090 Ry, ngauss=   1
     DOS =  2.669093 states/spin/Ry/Unit Cell at Ef=  8.290116 eV
     double delta at Ef = 12.474088
     lambda( 1)=  0.115291   gamma= 10.605987 GHz
     lambda( 2)=  0.115291   gamma= 10.605987 GHz
     lambda( 3)=  0.130520   gamma= 35.683264 GHz
     Gaussian Broadening:   0.100 Ry, ngauss=   1
     DOS =  2.674519 states/spin/Ry/Unit Cell at Ef=  8.288962 eV
     double delta at Ef = 12.456417
     lambda( 1)=  0.112978   gamma= 10.414299 GHz
     lambda( 2)=  0.112978   gamma= 10.414299 GHz
     lambda( 3)=  0.134292   gamma= 36.789272 GHz



    And check the
    Newer  Version  :::::::::



     .     Diagonalizing the dynamical matrix

     q = (    0.000000000   0.000000000   1.000000000 )

 **************************************************************************
     omega( 1) =       6.150074 [THz] =     205.145746 [cm-1]
     omega( 2) =       6.150074 [THz] =     205.145746 [cm-1]
     omega( 3) =       9.705764 [THz] =     323.751591 [cm-1]
 **************************************************************************
     electron-phonon interaction  ...

     Gaussian Broadening:   0.010 Ry, ngauss=   0
     DOS =  2.640036 states/spin/Ry/Unit Cell at Ef=  8.292189 eV
     lambda( 1)=  0.1693   gamma=   16.15 GHz
     lambda( 2)=  0.1696   gamma=   16.18 GHz
     lambda( 3)=  0.1515   gamma=   35.98 GHz
     Gaussian Broadening:   0.020 Ry, ngauss=   0
     DOS =  2.665783 states/spin/Ry/Unit Cell at Ef=  8.295265 eV
     lambda( 1)=  0.1342   gamma=   12.92 GHz
     lambda( 2)=  0.1376   gamma=   13.25 GHz
     lambda( 3)=  0.1441   gamma=   34.55 GHz
     Gaussian Broadening:   0.030 Ry, ngauss=   0
     DOS =  2.664312 states/spin/Ry/Unit Cell at Ef=  8.294084 eV
     lambda( 1)=  0.1197   gamma=   11.51 GHz
     lambda( 2)=  0.1231   gamma=   11.85 GHz
     lambda( 3)=  0.1466   gamma=   35.14 GHz
     Gaussian Broadening:   0.040 Ry, ngauss=   0
     DOS =  2.668351 states/spin/Ry/Unit Cell at Ef=  8.290682 eV
     lambda( 1)=  0.1148   gamma=   11.06 GHz
     lambda( 2)=  0.1181   gamma=   11.39 GHz
     lambda( 3)=  0.1470   gamma=   35.28 GHz
     Gaussian Broadening:   0.050 Ry, ngauss=   0
     DOS =  2.672172 states/spin/Ry/Unit Cell at Ef=  8.286936 eV
     lambda( 1)=  0.1125   gamma=   10.85 GHz
     lambda( 2)=  0.1156   gamma=   11.16 GHz
     lambda( 3)=  0.1485   gamma=   35.71 GHz
     Gaussian Broadening:   0.060 Ry, ngauss=   0
     DOS =  2.674722 states/spin/Ry/Unit Cell at Ef=  8.283275 eV
     lambda( 1)=  0.1107   gamma=   10.70 GHz
     lambda( 2)=  0.1135   gamma=   10.96 GHz
     lambda( 3)=  0.1508   gamma=   36.29 GHz
     Gaussian Broadening:   0.070 Ry, ngauss=   0
     DOS =  2.675808 states/spin/Ry/Unit Cell at Ef=  8.279572 eV
     lambda( 1)=  0.1093   gamma=   10.57 GHz
     lambda( 2)=  0.1116   gamma=   10.78 GHz
     lambda( 3)=  0.1533   gamma=   36.91 GHz
     Gaussian Broadening:   0.080 Ry, ngauss=   0
     DOS =  2.675785 states/spin/Ry/Unit Cell at Ef=  8.275659 eV
     lambda( 1)=  0.1082   gamma=   10.46 GHz
     lambda( 2)=  0.1099   gamma=   10.63 GHz
     lambda( 3)=  0.1558   gamma=   37.51 GHz
     Gaussian Broadening:   0.090 Ry, ngauss=   0
     DOS =  2.675260 states/spin/Ry/Unit Cell at Ef=  8.271439 eV
     lambda( 1)=  0.1072   gamma=   10.36 GHz
     lambda( 2)=  0.1086   gamma=   10.49 GHz
     lambda( 3)=  0.1582   gamma=   38.07 GHz
     Gaussian Broadening:   0.100 Ry, ngauss=   0
     DOS =  2.674736 states/spin/Ry/Unit Cell at Ef=  8.266876 eV
     lambda( 1)=  0.1063   gamma=   10.27 GHz
     lambda( 2)=  0.1074   gamma=   10.37 GHz
     lambda( 3)=  0.1603   gamma=   38.57 GHz


     Number of q in the star =    3
     List of q in the star:
          1   0.000000000   0.000000000   1.000000000
          2   1.000000000   0.000000000   0.000000000
          3   0.000000000   1.000000000   0.000000000




    One can easily notice that the above 2 results are not the same.
    Moreover,  the results  are not well converged.

     Please tell me
     which value will you say the correct one????????

     Gaussian Broadening:   0.090 Ry, ngauss=   0
     DOS =  2.675260 states/spin/Ry/Unit Cell at Ef=  8.271439 eV
     lambda( 3)=  0.1582   gamma=   38.07 GHz

     Gaussian Broadening:   0.080 Ry, ngauss=   0
     DOS =  2.675785 states/spin/Ry/Unit Cell at Ef=  8.275659 eV
     lambda( 3)=  0.1558   gamma=   37.51 GHz


     The value of lambda  :   0.1470     or  0.1558   or   0.1582
      are not  the same.

     By the way,  manipulating the input parameters carefully  one can
easily get  the
     total value of lambda very close to the experimental one  in the both
version.

     Looking forward to your kind explanation.

     Regards,
     Amit
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