[Pw_forum] slow speed of D3 code

[david yang]

Hi all,
  I am calculating anharmonic IFCS for Si on a 3x3x3 supercell
on 32 processor.

But the calculation seems to be very slow ,it takes 250 hours
for calculating IFCs  at a particular point(e.g on X,L,or
any arbitrary point).

If there is any trick by which I can speed up my calculation .


thanking you



with regards
David
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[Pw_forum] some help on D3 code

[david yang]

Hi all ,

I am using D3 code for anharmonic terms calcualtion for ZnO.

But during final step (while executing D3.x  command ) it showing me error

 task # 0
 from d3_readin : error # 1
 US not implemented
===


My input file looks as

 &control
calculation='scf'
restart_mode='from_scratch',
!pseudo_dir='directory where ps
!outdir='directory where large files are written/'
pseudo_dir='./',
outdir='./'
prefix='ZnO',
!ldisp=.true.
 /
 &system
ibrav=4, celldm(1)=9.826575141,celldm(3)=1.625,nat=4, ntyp=2,
ecutwfc =16.0
 /
 &electrons
conv_thr =  1.0d-8
mixing_beta = 0.7
 /
ATOMIC_SPECIES
 Zn 65.39Zn.pbe-van.UPF
 O  15.9994  O.pbe-van_ak.UPF
ATOMIC_POSITIONS
Zn 0.   0.6667  0.
Zn 0.6667   0.  0.5000
O  0.   0.6667  0.3750
O  0.6667   0.  0.8750
K_POINTS {automatic}
3 3 3 0 0 0

and D3 file is

Anharm at Q1
&inputph
   prefix = 'ZnO',
   fildrho = 'ZnO.drho_Q1',
   fild0rho = 'ZnO.drho_Q1',
   amass(1) = 65.39,
   amass(2) = 15.9994,
   outdir = './',
   fildyn = 'ZnO.anh_Q1',
 /
0.0 0.0 0.0


I believe that this error is related to pseudo potential and i tried
changing pseudo potential but nothing is working .

Can any give me quick  suggestion  on this matter.


Thanks in advance



regards
David Yang
NTU
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[Pw_forum] Regarding anharmonic IFCs

[david yang]

Dear Users and developers of Quantum espresso,
   I have some question regarding D3 code .

I am interested in Anharmonic properties of crystals and for that i am
using D3 code of quantum espresso while going through the source code i
figured out that present version of quantum espresso calculates Anharmonic
IFCs only for q=0,q' and q" .
So that mean that quantum espresso  gives us anharmonic IFCs in reciprocal
space something like phi(0,q',q') where phi denotes anharmonic IFC.

I have two questions on this

(1)--Whether my understanding is correct?
(2)--For my work i need anharmonic IFCs in real space means phi(0,l,l')
I known that this can be done by taking inverse Fourier transform of
phi(0,q',-q') , but i am clue less after this .
Can anyone give me hint that how to proceed for inverse Fourier transform
...



I will be great-full to all of you.
Awaiting for responses



Thanks a lot





With warm regards
David yang
NTU
Singapore
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