[Pw_forum] symmetry Sq=-q+G in Quantum Espresso-5.0.2 patched

[Maksim Markov]

Dear all,

In Quantum Espresso-5.0.3 release it is written that

"Fixed in this version:

PHonon: the recently introduced symmetry Sq=-q+G has still some problem:
currently disabled".

But when I compute phonons of Bismuth with QE-5.0.3 patched version I have
3 Sym.Ops. (with q-> -q+G) instead of 2 Sym.Ops. (no q-> -q+G) with
QE-4.1. This leads to fantastic phonon frequencies:

for example at q =2*pi/a (-0.238418000; 0.00; 0.00) I have

a) Quantum Espresso-4.1

     Number of q in the star =    6
     List of q in the star:
          1  -0.238418000   0.000000000   0.000000000
          2   0.119209000  -0.206476045   0.000000000
          3   0.119209000   0.206476045   0.000000000
          4   0.238418000   0.000000000   0.000000000
          5  -0.119209000   0.206476045   0.000000000
          6  -0.119209000  -0.206476045   0.000000000

     Diagonalizing the dynamical matrix

     q = (   -0.238418000   0.000000000   0.000000000 )

 **************************************************************************
     omega( 1) =       0.462172 [THz] =      15.416501 [cm-1]
     omega( 2) =       0.874193 [THz] =      29.160135 [cm-1]
     omega( 3) =       1.167513 [THz] =      38.944289 [cm-1]
     omega( 4) =       2.546953 [THz] =      84.957785 [cm-1]
     omega( 5) =       2.882297 [THz] =      96.143731 [cm-1]
     omega( 6) =       2.906512 [THz] =      96.951452 [cm-1]
 **************************************************************************

     Mode symmetry, C_2  (2)    point group:

     omega(  1 -  1) =         15.4  [cm-1]   --> B
     omega(  2 -  2) =         29.2  [cm-1]   --> B
     omega(  3 -  3) =         38.9  [cm-1]   --> A
     omega(  4 -  4) =         85.0  [cm-1]   --> A
     omega(  5 -  5) =         96.1  [cm-1]   --> B
     omega(  6 -  6) =         97.0  [cm-1]   --> A

 **************************************************************************


b) Quantum Espresso-5.0.3 patched
     Number of q in the star =    6
     List of q in the star:
          1  -0.238418000   0.000000000   0.000000000
          2   0.119209000  -0.206476045   0.000000000
          3   0.119209000   0.206476045   0.000000000
          4   0.238418000   0.000000000   0.000000000
          5  -0.119209000   0.206476045   0.000000000
          6  -0.119209000  -0.206476045   0.000000000

     Diagonalizing the dynamical matrix

     q = (   -0.238418000   0.000000000   0.000000000 )

 **************************************************************************
     omega( 1) =      -1.085582 [THz] =     -36.211103 [cm-1]
     omega( 2) =       0.607194 [THz] =      20.253825 [cm-1]
     omega( 3) =       0.971936 [THz] =      32.420309 [cm-1]
     omega( 4) =       2.752515 [THz] =      91.814003 [cm-1]
     omega( 5) =       3.038656 [THz] =     101.358649 [cm-1]
     omega( 6) =       3.262554 [THz] =     108.827080 [cm-1]
 **************************************************************************

     Mode symmetry, C_2  (2)    point group:

     omega(  1 -  1) =        -36.2  [cm-1]   --> B
     omega(  2 -  2) =         20.3  [cm-1]   --> A
     omega(  3 -  3) =         32.4  [cm-1]   --> B
     omega(  4 -  4) =         91.8  [cm-1]   --> A
     omega(  5 -  5) =        101.4  [cm-1]   --> A
     omega(  6 -  6) =        108.8  [cm-1]   --> B

 **************************************************************************

Were the symmetries really disabled and in which routine?

With best regards,

Maksim Markov, Doctorant
Laboratoire des Solides Irradies
Ecole Polytechnique

Route de Saclay
91128 Palaiseau

tel: +33 1 69 33 44 97