[Pw_forum] Slow calculation of (5, 5) CNT transmission and complex bands.
Gabriele Sclauzero
gabriele.sclauzero at epfl.ch
Tue Aug 2 11:35:50 CEST 2011
Hello,
Il giorno 28/lug/2011, alle ore 23.03, chengyu yang ha scritto:
> 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.
Your value of ngper is quite large for this kind of calculations, you can't afford it without using a lot of processors in a parallel calculation. Moreover, as far as I know the calculation of the complex bands is not completely parallelized at the moment, hence if your leads have a very large cross section and contain really a lot of atoms, I'm afraid that the calculation is hardly feasible with the current implementation.
In your case, the calculation should be feasible with 8-16 processors in parallel (if nodes have enough memory), but only if you use USPP, so that you will be able to reduce the ecutwfc down to 30-35 Ry.
In the PWcond input file I would reduce epsproj to 10^-5 or 10^-6, depending on the level of accuracy required (but you should do a small test on this).
HTH
GS
> 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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§ Gabriele Sclauzero, EPFL SB ITP CSEA
PH H2 462, Station 3, CH-1015 Lausanne
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