[Pw_forum] Slow calculation of (5, 5) CNT transmission and complex bands.

chengyu yang chengyu.young at gmail.com
Thu Jul 28 23:03:52 CEST 2011


Dear All,
         I am trying to calculate the complex bands and the transmission of
a (5,5) defectless carbon nanotube using PWCOND.x, however, the calculation
process is very slow and I can see it kind of stopped at the point:  ngper,
shell number =         2809         299.
         My input files are like this:


##################################################################################
scf input file:

&CONTROL
                 calculation = 'scf' ,
                restart_mode = 'from_scratch' ,
                       prefix = '55' ,
 /
 &SYSTEM
                       ibrav = 6,
                   celldm(1) = 21.764541128,celldm(3)=0.213765379
                         nat = 20,
                        ntyp = 1,
                     ecutwfc = 75 ,
 /
 &ELECTRONS
                    conv_thr = 1.0d-8 ,
                 mixing_beta = 0.7 ,
 /
ATOMIC_SPECIES
    C   12.01100  C.pz-vbc.UPF

ATOMIC_POSITIONS angstrom

  C        3.409595     0.000000    -1.231179
  C        3.113484     1.389805    -1.231179
  C        2.758420     2.004110    -0.000000
  C        1.701954     2.954436    -0.000000
  C        1.053623     3.242718    -1.231179
  C       -0.359664     3.390572    -1.231179
  C       -1.053623     3.242718    -0.000000
  C       -2.283903     2.531625    -0.000000
  C       -2.758420     2.004110    -1.231179
  C       -3.335768     0.705684    -1.231179
  C       -3.409595     0.000000    -0.000000
  C       -3.113484    -1.389805    -0.000000
  C       -2.758420    -2.004110    -1.231179
  C       -1.701954    -2.954436    -1.231179
  C       -1.053623    -3.242718     0.000000
  C        0.359664    -3.390572     0.000000
  C        1.053623    -3.242718    -1.231179
  C        2.283903    -2.531625    -1.231179
  C        2.758420    -2.004110     0.000000
  C        3.335768    -0.705684     0.000000




K_POINTS automatic
 1 1 5 0 0 0


###############################################################################

pwcond.in file:


&inputcond
    prefixl='55'
    band_file ='bands.cnt55'
    ikind=0
    energy0=4.d0
    denergy=-0.1d0
    ewind=3.d0
    epsproj=1.d-4
    delgep = 1.d-9
    cutplot = 3.d0
 /
    1
    0.0 0.0 1.0
    5

###########################################################
and the output file:

     GEOMETRY:

     lattice parameter (a_0)   =      21.7645  a.u.
     the volume                =    2203.8697 (a.u.)^3
     the cross section         =     473.6953 (a.u.)^2
     l of the unit cell        =       0.2138 (a_0)
     number of atoms/cell      =           20
     number of atomic types    =            1

     crystal axes: (cart. coord. in units of a_0)
               a(1) = (  1.0000  0.0000  0.0000 )
               a(2) = (  0.0000  1.0000  0.0000 )
               a(3) = (  0.0000  0.0000  0.2138 )


   Cartesian axes

     site n.     atom                  positions (a_0 units)
          1           C   tau(  1)=(  0.2960  0.0000  0.1069  )
          2           C   tau(  2)=(  0.2703  0.1207  0.1069  )
          3           C   tau(  3)=(  0.2395  0.1740  0.2138  )
          4           C   tau(  4)=(  0.1478  0.2565  0.2138  )
          5           C   tau(  5)=(  0.0915  0.2816  0.1069  )
          6           C   tau(  6)=( -0.0312  0.2944  0.1069  )
          7           C   tau(  7)=( -0.0915  0.2816  0.2138  )
          8           C   tau(  8)=( -0.1983  0.2198  0.2138  )
          9           C   tau(  9)=( -0.2395  0.1740  0.1069  )
         10           C   tau( 10)=( -0.2896  0.0613  0.1069  )
         11           C   tau( 11)=( -0.2960  0.0000  0.2138  )
         12           C   tau( 12)=( -0.2703 -0.1207  0.2138  )
         13           C   tau( 13)=( -0.2395 -0.1740  0.1069  )
         14           C   tau( 14)=( -0.1478 -0.2565  0.1069  )
         15           C   tau( 15)=( -0.0915 -0.2816  0.2138  )
         16           C   tau( 16)=(  0.0312 -0.2944  0.2138  )
         17           C   tau( 17)=(  0.0915 -0.2816  0.1069  )
         18           C   tau( 18)=(  0.1983 -0.2198  0.1069  )
         19           C   tau( 19)=(  0.2395 -0.1740  0.2138  )
         20           C   tau( 20)=(  0.2896 -0.0613  0.2138  )

     nr1s                      =          120
     nr2s                      =          120
     nr3s                      =           27
     nrx1s                     =          120
     nrx2s                     =          120
     nrx3s                     =           27
     nr1                       =          120
     nr2                       =          120
     nr3                       =           27
     nrx1                      =          120
     nrx2                      =          120
     nrx3                      =           27

 _______________________________
  Radii of nonlocal spheres:

     type       ibeta     ang. mom.          radius (a_0 units)
          C       1         0                    0.0593
----- General information -----

----- Complex band structure calculation -----

     nrx                       =          120
     nry                       =          120
     nz1                       =           11


     energy0               =         4.0E+00
     denergy               =        -1.0E-01
     nenergy               =          5
     ecut2d                =         7.5E+01
     ewind                 =         3.0E+00
     epsproj               =         1.0E-04


     number of k_|| points=    1
                       cryst. coord.
        k(    1) = (   0.0000000   0.0000000), wk =   1.0000000
----- Information about left lead -----

     nocros                   =           10
     noins                    =           10
     norb                     =           30
     norbf                    =           30
     nrz                      =           27

      iorb      type   ibeta   ang. mom.   m       position (a_0)
        1        1       1        0        1   taunew(   1)=(  0.2395
0.1740  0.0000)
        2        1       1        0        1   taunew(   2)=(  0.1478
0.2565  0.0000)
        3        1       1        0        1   taunew(   3)=( -0.0915
0.2816  0.0000)
        4        1       1        0        1   taunew(   4)=( -0.1983
0.2198  0.0000)
        5        1       1        0        1   taunew(   5)=( -0.2960
0.0000  0.0000)
        6        1       1        0        1   taunew(   6)=( -0.2703
-0.1207  0.0000)
        7        1       1        0        1   taunew(   7)=( -0.0915
-0.2816  0.0000)
        8        1       1        0        1   taunew(   8)=(  0.0312
-0.2944  0.0000)
        9        1       1        0        1   taunew(   9)=(  0.2395
-0.1740  0.0000)
       10        1       1        0        1   taunew(  10)=(  0.2896
-0.0613  0.0000)
       11        1       1        0        1   taunew(  11)=(  0.2960
0.0000  0.1069)
       12        1       1        0        1   taunew(  12)=(  0.2703
0.1207  0.1069)
       13        1       1        0        1   taunew(  13)=(  0.0915
0.2816  0.1069)
       14        1       1        0        1   taunew(  14)=( -0.0312
0.2944  0.1069)
       15        1       1        0        1   taunew(  15)=( -0.2395
0.1740  0.1069)
       16        1       1        0        1   taunew(  16)=( -0.2896
0.0613  0.1069)
       17        1       1        0        1   taunew(  17)=( -0.2395
-0.1740  0.1069)
       18        1       1        0        1   taunew(  18)=( -0.1478
-0.2565  0.1069)
       19        1       1        0        1   taunew(  19)=(  0.0915
-0.2816  0.1069)
       20        1       1        0        1   taunew(  20)=(  0.1983
-0.2198  0.1069)
       21        1       1        0        1   taunew(  21)=(  0.2395
0.1740  0.2138)
       22        1       1        0        1   taunew(  22)=(  0.1478
0.2565  0.2138)
       23        1       1        0        1   taunew(  23)=( -0.0915
0.2816  0.2138)
       24        1       1        0        1   taunew(  24)=( -0.1983
0.2198  0.2138)
       25        1       1        0        1   taunew(  25)=( -0.2960
0.0000  0.2138)
       26        1       1        0        1   taunew(  26)=( -0.2703
-0.1207  0.2138)
       27        1       1        0        1   taunew(  27)=( -0.0915
-0.2816  0.2138)
       28        1       1        0        1   taunew(  28)=(  0.0312
-0.2944  0.2138)
       29        1       1        0        1   taunew(  29)=(  0.2395
-0.1740  0.2138)
       30        1       1        0        1   taunew(  30)=(  0.2896
-0.0613  0.2138)
    k slab    z(k)  z(k+1)     crossing(iorb=1,norb)
    1   0.0000 0.0079 0.0079   111111111100000000000000000000
    2   0.0079 0.0158 0.0079   111111111100000000000000000000
    3   0.0158 0.0238 0.0079   111111111100000000000000000000
    4   0.0238 0.0317 0.0079   111111111100000000000000000000
    5   0.0317 0.0396 0.0079   111111111100000000000000000000
    6   0.0396 0.0475 0.0079   111111111100000000000000000000
    7   0.0475 0.0554 0.0079   111111111111111111110000000000
    8   0.0554 0.0633 0.0079   111111111111111111110000000000
    9   0.0633 0.0713 0.0079   000000000011111111110000000000
   10   0.0713 0.0792 0.0079   000000000011111111110000000000
   11   0.0792 0.0871 0.0079   000000000011111111110000000000
   12   0.0871 0.0950 0.0079   000000000011111111110000000000
   13   0.0950 0.1029 0.0079   000000000011111111110000000000
   14   0.1029 0.1108 0.0079   000000000011111111110000000000
   15   0.1108 0.1188 0.0079   000000000011111111110000000000
   16   0.1188 0.1267 0.0079   000000000011111111110000000000
   17   0.1267 0.1346 0.0079   000000000011111111110000000000
   18   0.1346 0.1425 0.0079   000000000011111111110000000000
   19   0.1425 0.1504 0.0079   000000000011111111110000000000
   20   0.1504 0.1583 0.0079   000000000011111111111111111111
   21   0.1583 0.1663 0.0079   000000000011111111111111111111
   22   0.1663 0.1742 0.0079   000000000000000000001111111111
   23   0.1742 0.1821 0.0079   000000000000000000001111111111
   24   0.1821 0.1900 0.0079   000000000000000000001111111111
   25   0.1900 0.1979 0.0079   000000000000000000001111111111
   26   0.1979 0.2058 0.0079   000000000000000000001111111111
   27   0.2058 0.2138 0.0079   000000000000000000001111111111

        k(    1) = (   0.0000000   0.0000000), wk =   1.0000000

 ngper, shell number =         2809         299
####################################################################################
the output file stopped  there, and I couldn't see the process. Maybe it
takes long time cause I found it took 1 hour to calculate a transmission.
I don't quite understand the parameters setting, I have adjusted the ewind,
epsproj, nzl, according to the postings on this forum. However,
the result seemed not change.

I appreciate everyone who could give me some advice.
Thank you!

Regards.

Chengyu Yang
Material Science and Engineering,
 University of Central Florida, USA
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