[Pw_forum] Regarding ph.x

[Bahadır SALMANKURT]

Dear Manu,

Increasing ecut may be useful. Also conv_thr is high, reduce it to 1D-10
which is good for phonon calculation. For &inputph, add the following;

*alpha_mix(1) = 0.3 *

I always use alpha_mix(1) as 0.3 or 0.5 when I have converge problem. Default
value is 0.7.

Bests



2016-06-08 23:23 GMT+03:00 Manu Hegde <mhegde at uwaterloo.ca>:

> Hello All,
>
> I was trying to calculate phonon dispersion in PbTIO3, my SCF calculations
> went well, but I am struggling with ph.x. It is taking long time to
> converge. Any suggestions to  improve the input and make it faster?.
>
>  Both SCF and Phonon input are below, please have a look.
>
>
> &CONTROL
>                  calculation = 'scf' ,
>                 restart_mode = 'from_scratch' ,
>                       outdir = '/home/user/espresso-5.3.0/PBTIO/' ,
>                   pseudo_dir = '/home/user/espresso-5.3.0/pseudo/' ,
>                       prefix = 'perov',
>                           tstress = .true.,
>                          tprnfor = .true.,
>                        verbosity = 'high',
>  /
>  &SYSTEM
>
>                            A = 3.97,
>                        space_group = 221,
>                          nat = 3,
>                         ntyp = 3,
>                      ecutwfc = 30.0 ,
>
>  /
>  &ELECTRONS
>                     conv_thr = 1D-6,
>                    mixing_beta=0.3
>  /
> ATOMIC_SPECIES
>    Pb  207.20000  Pb.pz-d-van.UPF
>    Ti   47.86700  Ti.pz-sp-van_ak.UPF
>     O   15.99940  O.pz-van_ak.UPF
> ATOMIC_POSITIONS crystal_sg
>    Pb  1a
>    Ti  1b  0.5
>     O  0.5 0.5 0.0
> K_POINTS automatic
>   8 8 8   0 0 0
>
>
> Phonon input
>
>
> phonons of PbTio at grid
> &inputph
>         prefix = 'perov'
>
>         ldisp = .true.,
>         fildyn = 'pbtio.dyn',
>         amass(1) = 207.2,
>         amass(2) = 47.867,
>         amass(3) = 15.9994
>         outdir = '/home/user/espresso-5.3.0/PBTIO/'
>         nq1 = 4,
>         nq2 = 4,
>         nq3 = 4,
>         tr2_ph = 1.0d-12,
> /
>
>
>
> Thanks and Regards,
> Manu
> University of Waterloo
>
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>



-- 

Bahadır SALMANKURT
Ph.D. Candidate
Department of Physics, Sakarya University, TURKEY
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