[Pw_forum] Enquiry about phonon calculation

[saswata halder]

Dear all,

I am trying to perform a phonon calculation of Sr2MgWO6 double
perovskite having Fm3m symmetry. I have relaxed the system using the
following input file:

&CONTROL
    calculation='vc-relax',
    restart_mode='from_scratch',
    prefix='SM'
    pseudo_dir = '/home/quantum/quantum/potentials/',
    outdir='./'
    tstress=.true.
    tprnfor=.true.
    verbosity='high'
    wf_collect=.true.
    nstep=1000
    etot_conv_thr=1.0D-7
    forc_conv_thr=1.0D-4
    disk_io='default'
 /
 &SYSTEM
    ibrav = 2, celldm(1) =15.0329, nat = 10, ntyp= 4,
    ecutwfc = 80.0,  occupations='fixed',
 /
 &ELECTRONS
    diagonalization='david'
    mixing_mode='plain',
    mixing_beta = 0.7D0
    conv_thr =  1.0D-4
    electron_maxstep=500
 /
&IONS
    ion_dynamics='bfgs'
/
&CELL
    cell_dynamics='bfgs',
    press=0.0,
    cell_factor=2.5
    press_conv_thr=0.002,
/
ATOMIC_SPECIES
 Sr  87.620  Sr.pbe-mt_fhi.UPF
 Mg  24.305  Mg.pbe-mt_fhi.UPF
 W  183.840  W.pbe-mt_fhi.UPF
 O   15.999  O.pbe-mt_fhi.UPF
ATOMIC_POSITIONS crystal
 Sr 0.25  0.25  0.25
 Sr 0.75  0.75  0.75
 Mg 0.50  0.00  0.00
 W  0.00  0.00  0.00
 O  0.245 0.00  0.00
 O  0.755 0.00  0.00
 O  0.00  0.245 0.00
 O  0.00  0.755 0.00
 O  0.00  0.00  0.245
 O  0.00  0.00  0.755
K_POINTS automatic
 7 7 7   1 1 1


After relaxing I have started the phonon calculations using the
following input parameters:

phonons of ST at Gamma
 &inputph
  tr2_ph=1.0d-14,
  prefix='ST',
  epsil=.true.,
  amass(1)=87.620,
  amass(2)=24.3050
  amass(3)= 183.84,
  amass(4)=15.999,
  outdir='./'
  fildyn='ST.dynG',
 /
0.0 0.0 0.0

Now as the electric field calculations are being performed the
following line is being shown:

"ik   1 ibnd  25 linter: root not converged  0.310E-07
     kpoint   1 ibnd  25 solve_e: root not converged  0.666E-01"

Could anyone please suggest what it means and how can i converge this?

Thanking you,

Saswata Halder.

Bose Institute.