[Pw_forum] ibrav=2 and space_group=202: input coordinate misunderstood

[Musil Félix]

Dear QE developers,

I am running the following input file and the resulting output has changed the non equivalent scaled atomic coordinates (see highlighted in yellow). I compared with space group 224 with ibrav=1 and these scaled coordinates do match. Is there a reason for this particular behavior ?

Please find attached an input file to reproduce this behavior.

Cheers,

Felix Musil

QE INPUT:

&CONTROL
  calculation = "scf"
  outdir = "./out/"
  prefix = "qe"
  pseudo_dir = "/scratch/musil/run_qe/pseudo/SSSP_acc_PBE/"
  restart_mode = "from_scratch"
  verbosity = "high"
  wf_collect = .false.
/
&SYSTEM
  ecutrho = 40.00000
  ecutwfc = 10.00000
  ibrav = 2
  nat = 1
  nbnd = 57
  ntyp = 1
  occupations = "smearing"
  smearing = "cold"
  degauss = 0.010000
  space_group = 202
  A = 11.740480817708141
/
&ELECTRONS
  conv_thr = 0.10000000
/
ATOMIC_SPECIES
  Si  28.0855  Si.pbe-n-rrkjus_psl.1.0.0.UPF
ATOMIC_POSITIONS  crystal_sg
  Si    0.80567873  0.49498614 0.00500792

QE OUTPUT:

     Program PWSCF v.6.1 (svn rev. 13369) starts on 15Sep2017 at 18:33: 4

     This program is part of the open-source Quantum ESPRESSO suite
     for quantum simulation of materials; please cite
         "P. Giannozzi et al., J. Phys.:Condens. Matter 21 395502 (2009);
          URL http://www.quantum-espresso.org",
     in publications or presentations arising from this work. More details at
     http://www.quantum-espresso.org/quote

     Parallel version (MPI), running on     8 processors
     R & G space division:  proc/nbgrp/npool/nimage =       8
     Reading input from /scratch/musil/data/check_input_errors/sg_202-f_0-0/qe.in
.
.
.

     celldm(1)=  22.186293  celldm(2)=   0.000000  celldm(3)=   0.000000
     celldm(4)=   0.000000  celldm(5)=   0.000000  celldm(6)=   0.000000

     crystal axes: (cart. coord. in units of alat)
               a(1) = (  -0.500000   0.000000   0.500000 )
               a(2) = (   0.000000   0.500000   0.500000 )
               a(3) = (  -0.500000   0.500000   0.000000 )

.
.
.

   Crystallographic axes

     site n.     atom                  positions (cryst. coord.)
         1           Si  tau(   1) = (  0.7043430  0.3056728  0.6842995  )
         2           Si  tau(   2) = (  0.3056728  0.7043430  0.3056847  )
         3           Si  tau(   3) = (  0.3056847  0.6842995  0.3056728  )
         4           Si  tau(   4) = (  0.6842995  0.3056847  0.7043430  )
         5           Si  tau(   5) = (  0.6842995  0.3056728  0.3056847  )
         6           Si  tau(   6) = (  0.3056847  0.7043431  0.6842995  )
         7           Si  tau(   7) = (  0.3056728  0.6842995  0.7043431  )
         8           Si  tau(   8) = (  0.7043431  0.3056847  0.3056728  )
         9           Si  tau(   9) = (  0.3056847  0.3056728  0.7043430  )
        10           Si  tau(  10) = (  0.6842995  0.7043430  0.3056728  )
        11           Si  tau(  11) = (  0.7043430  0.6842995  0.3056847  )
        12           Si  tau(  12) = (  0.3056728  0.3056847  0.6842995  )
        13           Si  tau(  13) = (  0.2956570  0.6943272  0.3157005  )
        14           Si  tau(  14) = (  0.6943272  0.2956570  0.6943153  )
        15           Si  tau(  15) = (  0.6943153  0.3157005  0.6943272  )
        16           Si  tau(  16) = (  0.3157005  0.6943153  0.2956570  )
        17           Si  tau(  17) = (  0.3157005  0.6943272  0.6943153  )
        18           Si  tau(  18) = (  0.6943153  0.2956569  0.3157005  )
        19           Si  tau(  19) = (  0.6943272  0.3157005  0.2956569  )
        20           Si  tau(  20) = (  0.2956569  0.6943153  0.6943272  )
        21           Si  tau(  21) = (  0.6943153  0.6943272  0.2956570  )
        22           Si  tau(  22) = (  0.3157005  0.2956570  0.6943272  )
        23           Si  tau(  23) = (  0.2956570  0.3157005  0.6943153  )
        24           Si  tau(  24) = (  0.6943272  0.6943153  0.3157005  )



Félix Musil
Doctoral Assistant - Ph.D Student

EPFL STI IMX COSMO
LABORATORY OF COMPUTATIONAL SCIENCE AND MODELLING
Institute of Materials Science and Engineering
MXG 319
Station 12
CH-1015 Lausanne
Switzerland

E-mail: felix.musil at epfl.ch
http://cosmo.epfl.ch/
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