[Pw_forum] question about elphonon calculation

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Dear All Users,
     I was trying to calculate the el-ph coupling.And I followed just as the
example 07 did.
    First I run a dense scf calculation and then a scf calculation.
    Sencond I run the phonon calculation and it got error message.
    I attached the input of mine and the error message below.Although from
the error message I thought there should be a phonon calculation before the
elph calculation.But it run the elph calculation directely after the scf run
have been done in example07 .
   I wonder that should I need a phonon calculation before the el-ph
calculation after the scf run. And if the answer is yes, why it do not run
in example07.

Have a nice day
Deng Pan
Nanjing University

elph.in
 MgB2-elph
&inputph
  amass(1)= 24.3,
  amass(2)= 10.8,
  prefix='MgB2'
  tr2_ph=1.0d-14,
  alpha_mix(1)=0.5,
  iverbosity=1,
  fildyn='/MgB2/elph/test/MgB2.dyn',
  outdir='/tmp1/',
  ldisp=.true,
  nq1=4,nq2=4,nq3=4,
  elph=.true./
  fildvscf='/MgB2/elph/test/MgB2dv'
 /

and the error message
     task #         3
     from phq_readin : error #         1
     El-ph needs a DeltaVscf file
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