[QE-users] Wrong number of k-points?

[Laurens Siemons]

Thanks for the information and quick response.

Laurens

________________________________
Van: users <users-bounces at lists.quantum-espresso.org> namens Giovanni Cantele <giovanni.cantele at spin.cnr.it>
Verzonden: donderdag 31 januari 2019 10:15
Aan: Quantum Espresso users Forum
Onderwerp: Re: [QE-users] Wrong number of k-points?

The symmetry k -> -k is still present even though your system has no spatial symmetry. As such the number of k-points is halved.
Giovanni

PS from a quick google search I found for example this document you might find of help
https://people.sissa.it/~degironc/FIST/Slides/8%20Symmetry.pdf

On 31 Jan 2019, at 10:09, Laurens Siemons <laurenssiemons at hotmail.be> wrote:

Dear QE users,

I'm running a relax calculation and I encountered something that I do not understand in the output file. I used a 2 2 1 1 1 0 Monkhorst-Pack grid in my input file (which is shown below) but the output file tells me I only have 2 k-points:


       116           H   tau( 116) = (   3.8845153   0.8033970  -0.3177301  )
       117           H   tau( 117) = (   3.8658215   1.2769290  -0.3107519  )
       118           H   tau( 118) = (   4.1682098   1.0557090  -0.6030099  )

     number of k points=     2
                       cart. coord. in units 2pi/alat
        k(    1) = (   0.0000000   0.0833333  -0.0984507), wk =   1.0000000
        k(    2) = (   0.0000000   0.0833333   0.0984507), wk =   1.0000000

     Dense  grid:  5866317 G-vectors     FFT dimensions: ( 180, 160, 480)

     Smooth grid:  1484065 G-vectors     FFT dimensions: ( 108,  96, 320)

I would expect at least 4 k-point right? The system possesses no symmetry.

Thanks in advance,
Laurens Siemons,
PhD, University of Antwerp

&CONTROL
  calculation = 'relax'
  restart_mode = 'from_scratch'
  prefix = 'a101mpa1'
  tprnfor = .true.
  pseudo_dir = '/data/antwerpen/204/vsc20442/pseudo/pslibrary.1.0.0/wc/PSEUDOPOTENTIALS'
  outdir = '/scratch/antwerpen/204/vsc20442/TMP'
  wf_collect = .true.
  nstep = 100
/
&SYSTEM
  ibrav = 0
  A =    3.77449
  nat = 118
  ntyp = 5
  ecutwfc = 60
  ecutrho = 600
  spline_ps = .true.
/
&ELECTRONS
  electron_maxstep = 500
  diagonalization = 'david'
  conv_thr =  1.0d-10
  mixing_beta = 0.70
/
&IONS
  ion_dynamics = 'bfgs'
/
ATOMIC_SPECIES
   O   15.99900  O.wc-n-kjpaw_psl.1.0.0.UPF
  Ti   47.86700  Ti.wc-spn-kjpaw_psl.1.0.0.UPF
   H   1.0079    H.wc-kjpaw_psl.1.0.0.UPF
   C   12.0107   C.wc-n-kjpaw_psl.1.0.0.UPF
   P   30.973761 P.wc-n-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS {crystal}
Ti      0       0.000000        0.026316 0 0 0
Ti      2/3     0.000000        0.026316 0 0 0
Ti      1/3     0.000000        0.026316 0 0 0
Ti      1/6     1/2     0.026316 0 0 0
Ti      1/2     1/2     0.026316 0 0 0
Ti      5/6     1/2     0.026316 0 0 0
Ti      0       0.995856        0.266326
Ti      1/3     0.995856        0.266326
Ti      2/3     0.995856        0.266326
Ti      1/6     0.495856        0.266326
Ti      1/2     0.495856        0.266326
Ti      5/6     0.495856        0.266326
Ti      0       0.989202        0.145250
Ti      1/3     0.989202        0.145250
...
...
...
CELL_PARAMETERS {alat}
  0.000000000000000   3.000000000000000   0.000000000000000
  1.000000000000000  -0.000000000000000  -2.539341738883929
  8.550000000000001   0.000000000000000   0.000000000000000
K_POINTS {automatic}
2 2 1 1 1 0



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--

Giovanni Cantele, PhD

CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy

e-mail: giovanni.cantele at spin.cnr.it
            gcantele at gmail.com
Phone: +39 081 676910
Skype contact: giocan74
Web page: https://sites.google.com/view/giovanni-cantele

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