[Pw_forum] q-mesh breaks symmetry

[BENYAHIA NEZHA]

I'd like to calculate phonon frequencies of compound InAs on the 
Wurtzite structure, using the input files that i pasted below, the Scf 
calculation was done normally, however phonons calculation crashes and 
display me this error message on the output file.

 



     This q-mesh breaks symmetry!

     Try to choose different nq1, nq2, nq3

     You can also continue by setting search_sym=.false.

     but be careful because q2r will not work



 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

     Error in routine q_points (1):

     q-mesh breaks symmetry

 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%



When i took (nq1, nq2, nq3)=(4 4 4) it worked, but according to my knowledge when we are on the wurtzite structure nq1=nq2≠nq3. I'd like also to understand how to choose (nq1, nq2, nq3). I really appreciate if anyone can help me to find out the problems.

  

input files:

 &control

    calculation='scf'

    restart_mode='from_scratch',

    tstress = .true.

    tprnfor = .true.

    prefix='InAs2h',

    pseudo_dir = '/home/InAs.lda/Pseudo',

    outdir='/home/InAs.lda/Temp'

 /

 &system

    ibrav=  4, celldm(1) =8.00,celldm(3) =1.633, nat= 4, ntyp= 2,

    ecutwfc =60.0,

 /

 &electrons

    diagonalization='david'

    conv_thr =1.0e-7

    mixing_beta = 0.7

 /

ATOMIC_SPECIES

 In   114.818 In.PZ.UPF

 As   74.9216 As.PZ.UPF

ATOMIC_POSITIONS crystal

In  0.00000000 0.00000000 0.00000000

In  0.33333333 0.66666667 0.50000000

As  0.00000000 0.00000000 0.37500000

As  0.33333333 0.66666667 0.87500000

  

K_POINTS (automatic)

 4 4 3 1 1 1

  

phonons of InAs

 &inputph

  tr2_ph=1.0d-14,

  prefix='InAs',

  ldisp=.true.,

  nq1=4, nq2=4, nq3=3

  amass(1)=114.818,

  amass(2)=74.9216,

    outdir='/home/InAs.lda/Temp/',

  fildyn='InAs.dyn',

 /

  
 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20140421/f3038938/attachment.html>