[Pw_forum] Phonon calculation crash in orthorhombic cell.

[Miriam Marques]

  Thank you very much Eyvaz.

  It has been a long time since I used this code and I had forgotten this
parameter effects.
  I will reduce the alpha_mix(1) parameter as you suggested.
  Best regards,

Miriam.

----------------------
Miriam Marques
School of Physics
University of Edinburgh
-----------------------


Quoting Eyvaz Isaev <eyvaz_isaev at yahoo.com>:

> Hi Miriam,
>
> Did you try reduce alpha_mix(1)  parameter in your
> phonon calculations?
> By default it is 0.7.
>
> Bests,
> Eyvaz.
>
> --- Miriam Marques <mmarques at staffmail.ed.ac.uk>
> wrote:
>
>>
>>   Dear PWSCF users,
>>
>>   I am trying to perform a phonon calculation on a
>> uniform grid of
>> q-points for an orthorhombic metallic structure.
>>
>> First, I did the scf calculation for a 16x16x16
>> Monkhorst-Pack grid
>> and tried to calculate phonons on a uniform (4x4x4)
>> grid via ldisp,
>> but the program phonon stopped with the error "end
>> of self consistent
>> calculation. No convergence has been achieved" in
>> the representation 4
>> (mode 4) of the first q point different from gamma.
>> (I am using
>> tr2_ph=1.0d-12)
>> Surprisingly, when I did the scf calculation for a
>> 13x13x13
>> Monkhorst-Pack grid and then the phonon calculation
>> via ldisp on a
>> 4x4x2 grid, the program ran (it crashed again when I
>> tried the 4X4x8
>> grid).
>>
>> I attached the input for the first case.
>>
>>    # self-consistent calculation
>>      cat > pcmcm.scf.in << EOF
>>   &control
>>      calculation='scf'
>>      restart_mode='from_scratch',
>>      pseudo_dir = '$PSEUDO_DIR/',
>>      outdir='$TMP_DIR/',
>>      prefix='pcmcm'
>>      tprnfor = .true.
>>      tstress = .true.
>>   /
>>   &system
>>      ibrav=  9, celldm(1) =6.089228715122, celldm(2)
>> =0.86757351,
>> celldm(3)= 2.5838341, nat=  4, ntyp= 1, nbnd= 20,
>> ecutwfc = 30.0,
>> ecutrho=300, occupations='smearing',
>> smearing='methfessel-paxton',
>> degauss=0.02
>>   /
>>   &electrons
>>      diagonalization='david'
>>      mixing_beta = 0.7
>>      conv_thr = 1.0D-10
>> /
>> ATOMIC_SPECIES
>>   P  30.973761 P.pw91-n-van.UPF
>> ATOMIC_POSITIONS crystal
>>   P 0.0000000000 0.0000000000 0.00000000000
>>   P 0.0000000000 0.0000000000 0.50000000000
>>   P 0.0000000000 0.0000000000 0.25000000000
>>   P 0.0000000000 0.0000000000 0.75000000000
>> K_POINTS {automatic}
>> 16 16 16 0 0 0
>> EOF
>>      $ECHO "  running the scf calculation for
>> P...\c"
>>      $PW_COMMAND < pcmcm.scf.in > pcmcm.scf.out
>>      $ECHO " done"
>>
>> # phonon calculation on a (4 4 4) uniform grid of
>> q-points
>> cat > pcmcm.ph.in << EOF
>> phonons of cmcm P
>>   &inputph
>>    tr2_ph=1.0d-12,
>>    prefix='pcmcm',
>>    ldisp=.true.,
>>    nq1=4, nq2=4, nq3=4
>>    amass(1)=30.973761,
>>    outdir='$TMP_DIR/',
>>    fildyn='pcmcm.dyn',
>>   /
>> EOF
>> $ECHO "  running the phonon calculation at
>> Gamma...\c"
>> $PH_COMMAND < pcmcm.ph.in > pcmcm.ph.out
>>
>>
>>
>> Thank you very much for your help,
>>
>> Miriam.
>>
>> ----------------------
>> Miriam Marques
>> School of Physics
>> University of Edinburgh
>> ----------------------
>>
>>
>> _______________________________________________
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>>
>
>
> -------------------------------------------------------------------
> Prof. Eyvaz Isaev,
> Theoretical Physics Department, Moscow State Institute of Steel &   
> Alloys, Russia, and
> Condensed Matter Theory Group, Uppsala University, Sweden   
> Eyvaz.Isaev at fysik.uu.se, eyvaz_isaev at yahoo.com
>
>
>
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