[Pw_forum] Phonon calculation of Silicene: ph.x

[Ari P Seitsonen]

Dear Neelesh,

   Adding to the answer of Jagdish, there is a fixed dimension:

qe-6.2/Modules/parameters.f90:       npk    = 40000,  &! max number of k-points

(This in version 6.2)
As pointed our in the previous answer, the number of actual k points will 
be reduced significantly if you do not apply k point beyond one value in 
the direction without periodicity (assuming that you have indeed a 
single, isolated layer in question).

     Greetings,

        apsi

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   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
     Ecole Normale Supérieure (ENS), Département de Chimie, Paris
     Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Thu, 11 Jan 2018, Jagdish verma wrote:

> Dear Neelesh,
> 
> I don't know about the error. But in scf input , I think you should have 36 36 1 0 0 0 k grid because silicene  has 2D structure. It will
> decrease k points in scf.out. Please correct me if I said anything wrong. 
> 
> On Thu, Jan 11, 2018 at 5:50 PM, NEELESH GUPTA <rse2017003 at iiita.ac.in> wrote:
>       Dear All ,
>        
> I'm trying to perform a phonon calculation of silicne using using ph.x on QE v 6.0.
> 
> I running this simulation using parallelzation
> mpirun -np 32 -hostfile machine ph.x -ndiag4  -nk 2 <ph.in> ph.out
> 
> 
> 
> Error generated...
> 
>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>      Error in routine set_kplusq (23976):
>      too many k points
>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> 
>      stopping ...
> 
> :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
> 
> ##I have done the scf calculation is done with k-points
>   36  36  36  0 0 0
> 
> ##  Detailed paramters
>   ibrav=4,
>   celldm(1)=7.3321373633d0, celldm(3)=12.8865979381d0,
>   nat=2,
>   ntyp=1,
> 
> 
> ## the ph code is....
> Ph
>  &inputph
>     prefix='calc'
>     outdir='Xe',
>     fildyn='calc.dyn',
>     tr2_ph=1.0d-16,
>     alpha_mix=0.7,
>     verbosity='high',
>     ldisp=.true.,
>     epsil= .false.
>     trans=.true,
>     nq1=4,nq2=4,nq3=1,
> 
> 
> 
> I have tried with -nimage in mpi run  but it stops and in crash files it shows error of too many k-points. 
> 
> Thanks in advance!
> 
> 
> 
> Warm regards
> Neelesh Gupta
> Research Scholar,ECE
> 
> 
> 
> 
> 
> 
> 
> 
> 
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> 
> 
> --
> With best regards,
> Jagdish Verma,
> 
> 
> 
>