ABINIT Discussion Forums

Dear all
I use in the tutorial of elastic and piezoelectric properties, then I completed of dataset 1 was the ground-state geometry of PbTiO3
and completed dataset 2,3 and I get *_DS3_DDB when I ran in anaddb code I have a warning see below
piezo9 : WARNING -
Acoustic sum rule violation met : the eigenvalues of accoustic mode
are too large at Gamma point
Increase cutoff energy or k-points sampling.
The three eigenvalues are: 1.337316E-04 6.583204E-05 1.338816E-04

So, when I increase cutoff about from 30---->60 Ha I have also a warning above.

Please help me
Abdulmutta

Hello,

Did you try increasing the k-point sampling also ?
If so, it would be better to post your input file so that we can better help you ...

David

Dear David
Thank you for your reply
This my input files see below
# PbTiO3 : computation of the total energy
# Response function calculation for:
# * rigid-atom elastic tensor
# * rigid-atom piezoelectric tensor
# * interatomic force constants at gamma
# * Born effective charges

ndtset 3

# Set 1 : Initial self-consistent run

iscf1 5
kptopt1 1
tolvrs1 1.0d-18 #need excellent convergence of GS quantities for RF runs


# Set 2 : Calculate the ddk wf's - needed for piezoelectric tensor and
# Born effective charges in dataset 3

getwfk2 -1
iscf2 -3 #this option is needed for ddk
kptopt2 2 #use time-reversal symmetry only for k points
nqpt2 1 #one wave vector will be specified
qpt2 0 0 0 #need to specify gamma point
rfelfd2 2 #set for ddk wf's only
rfdir2 1 1 1 #full set of directions needed
tolwfr2 1.0d-20 #only wf convergence can be monitored here

# Set 3 : response-function calculations for all needed perturbations

getddk3 -1
getwfk3 -2
iscf3 5
kptopt3 2 #use time-reversal symmetry only for k points
nqpt3 1
qpt3 0 0 0
rfphon3 1 #do atomic displacement perturbation
rfatpol3 1 5 #do for all atoms
rfstrs3 3 #do strain perturbation
rfdir3 1 1 1 #the full set of directions is needed
tolvrs3 1.0d-10 #need reasonable convergence of 1st-order quantities

#Definition of the planewave basis set
ecut 60.0
ecutsm 0.5
dilatmx 1.05

#Definition of the k-point grid
ngkpt 6 6 6
nshiftk 4
shiftk 0.5 0.5 0.5
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0 0.5

#Definition of the SCF procedure
iscf 5
ntime 1000
nstep 1000
diemac 12.0
prtvol 3

#Gives the number of bands, explicitely (do not take the default)
nband 25 # For an insulator (if described correctly as an
# insulator by DFT), conduction bands should not
# be included in response-function calculations


Please help
Abdulmutta

Search the forum for other posts on ASR:
1) turn on ASR correction with the anaddb asr input variable
2) your pseudopotentials are responsible for the ASR breaking. Try changing one at a time to see which one it is. Otherwise also see the PhD of Philippe Ghosez on BaTiO3 - he looks at ASR breaking in particular.

matthieu

Dear matthieu
After that, I try with your suggestion I had warning
and then I changing my pp files I also got it see below
piezo9 : WARNING -
Acoustic sum rule violation met : the eigenvalues of accoustic mode
are too large at Gamma point
Increase cutoff energy or k-points sampling.

I tries 1 mount ago I didn't know how is it going, caused my machine had PC i7 4 core
please help me

Abdulmutta

See viewtopic.php?f=10&t=318