[QE-users] npool

Andrew Xu andrewaccount at gmail.com
Wed Jan 6 00:15:28 CET 2021


Hi users,

Does npool need to divide the number of k-points after symmetry operations
are performed? In a tutorial I saw online (
https://materials.prace-ri.eu/497/7/QE__main_strategies_of_parallelization_and_levels_of_parallelisms.pdf):
"By definition, npools must be a divisor of the total number of k-points."

In a calculation I ran (relevant output below), I accidentally sent npool =
16, which does not divide the total number of k points after symmetry
operations (35), but I got no errors. Am I misunderstanding something here?

Best,
Andrew

------------------------------

     Parallel version (MPI & OpenMP), running on      80 processor cores
     Number of MPI processes:                80
     Threads/MPI process:                     1
     K-points division:     npool     =      16
     R & G space division:  proc/nbgrp/npool/nimage =       5
     Reading input from pw_oncv_pbe0.in

     Current dimensions of program PWSCF are:
     Max number of different atomic species (ntypx) = 10
     Max number of k-points (npk) =  40000
     Max angular momentum in pseudopotentials (lmaxx) =  3

     IMPORTANT: XC functional enforced from input :
     Exchange-correlation      = PBE0 ( 6  4  8  4 0 0)
     EXX-fraction              =        0.25
     Any further DFT definition will be discarded
     Please, verify this is what you really want


     Subspace diagonalization in iterative solution of the eigenvalue
problem:
     a serial algorithm will be used

     EXX: setup a grid of 512 q-points centered on each k-point
     (set verbosity='high' to see the list)

     Parallelization info
     --------------------
     sticks:   dense  smooth     PW     G-vecs:    dense   smooth      PW
     Min         194     194     58                 4548     4548     756
     Max         196     196     59                 4550     4550     759
     Sum         973     973    293                22743    22743    3791



     bravais-lattice index     =            1
     lattice parameter (alat)  =       7.1240  a.u.
     unit-cell volume          =     361.5528 (a.u.)^3
     number of atoms/cell      =            4
     number of atomic types    =            2
     number of electrons       =        46.00
     number of Kohn-Sham states=           26
     kinetic-energy cutoff     =      60.0000  Ry
     charge density cutoff     =     240.0000  Ry
     cutoff for Fock operator  =     240.0000  Ry
     convergence threshold     =      1.0E-08
     mixing beta               =       0.7000
     number of iterations used =            8  plain     mixing
     Exchange-correlation      = PBE0 ( 6  4  8  4 0 0)
     EXX-fraction              =        0.25
...

     atomic species   valence    mass     pseudopotential
        O              6.00    15.99940     O ( 1.00)
        W             28.00   183.85000     W ( 1.00)

     48 Sym. Ops., with inversion, found



   Cartesian axes

     site n.     atom                  positions (alat units)
         1           W   tau(   1) = (   0.0000000   0.0000000   0.0000000
 )
         2           O   tau(   2) = (   0.0000000   0.5000000   0.0000000
 )
         3           O   tau(   3) = (   0.5000000   0.0000000   0.0000000
 )
         4           O   tau(   4) = (   0.0000000   0.0000000   0.5000000
 )

     number of k points=    35
                       cart. coord. in units 2pi/alat
        k(    1) = (   0.0000000   0.0000000   0.0000000), wk =   0.0039062
        k(    2) = (   0.0000000   0.0000000   0.1250000), wk =   0.0234375
        k(    3) = (   0.0000000   0.0000000   0.2500000), wk =   0.0234375
        k(    4) = (   0.0000000   0.0000000   0.3750000), wk =   0.0234375
        k(    5) = (   0.0000000   0.0000000  -0.5000000), wk =   0.0117188
        k(    6) = (   0.0000000   0.1250000   0.1250000), wk =   0.0468750
        k(    7) = (   0.0000000   0.1250000   0.2500000), wk =   0.0937500
        k(    8) = (   0.0000000   0.1250000   0.3750000), wk =   0.0937500
        k(    9) = (   0.0000000   0.1250000  -0.5000000), wk =   0.0468750
        k(   10) = (   0.0000000   0.2500000   0.2500000), wk =   0.0468750
        k(   11) = (   0.0000000   0.2500000   0.3750000), wk =   0.0937500
        k(   12) = (   0.0000000   0.2500000  -0.5000000), wk =   0.0468750
        k(   13) = (   0.0000000   0.3750000   0.3750000), wk =   0.0468750
        k(   14) = (   0.0000000   0.3750000  -0.5000000), wk =   0.0468750
        k(   15) = (   0.0000000  -0.5000000  -0.5000000), wk =   0.0117188
        k(   16) = (   0.1250000   0.1250000   0.1250000), wk =   0.0312500
        k(   17) = (   0.1250000   0.1250000   0.2500000), wk =   0.0937500
        k(   18) = (   0.1250000   0.1250000   0.3750000), wk =   0.0937500
        k(   19) = (   0.1250000   0.1250000  -0.5000000), wk =   0.0468750
        k(   20) = (   0.1250000   0.2500000   0.2500000), wk =   0.0937500
        k(   21) = (   0.1250000   0.2500000   0.3750000), wk =   0.1875000
        k(   22) = (   0.1250000   0.2500000  -0.5000000), wk =   0.0937500
        k(   23) = (   0.1250000   0.3750000   0.3750000), wk =   0.0937500
        k(   24) = (   0.1250000   0.3750000  -0.5000000), wk =   0.0937500
        k(   25) = (   0.1250000  -0.5000000  -0.5000000), wk =   0.0234375
        k(   26) = (   0.2500000   0.2500000   0.2500000), wk =   0.0312500
        k(   27) = (   0.2500000   0.2500000   0.3750000), wk =   0.0937500
        k(   28) = (   0.2500000   0.2500000  -0.5000000), wk =   0.0468750
        k(   29) = (   0.2500000   0.3750000   0.3750000), wk =   0.0937500
        k(   30) = (   0.2500000   0.3750000  -0.5000000), wk =   0.0937500
        k(   31) = (   0.2500000  -0.5000000  -0.5000000), wk =   0.0234375
        k(   32) = (   0.3750000   0.3750000   0.3750000), wk =   0.0312500
        k(   33) = (   0.3750000   0.3750000  -0.5000000), wk =   0.0468750
        k(   34) = (   0.3750000  -0.5000000  -0.5000000), wk =   0.0234375
        k(   35) = (  -0.5000000  -0.5000000  -0.5000000), wk =   0.0039062

     Dense  grid:    22743 G-vectors     FFT dimensions: (  36,  36,  36)

     Estimated max dynamical RAM per process >   14760.85MB

     Estimated total allocated dynamical RAM > 1180867.90MB
....
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