[Pw_forum] Phonon calculation crash in orthorhombic cell.

[Eyvaz Isaev]

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
> ----------------------
> 
> 
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> 


-------------------------------------------------------------------
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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