ABINIT Discussion Forums

Dear Abinit Users,
Good Mornings to all...
I have performed the tutorial for electron phonon coupling constants...
It works well..and got the results...for coupling constants...
in this tutorial it contains natom=1,
But when we applied for two atom systems...it...works well up to step 3 (Extraction and merging of the electron-phonon matrix elements using MRGGKK.)
but for step-4 (calculation of electron-phonon by anaddb code) it show..the error
read_gkk : ERROR-
gkk element 4 1 1 2 was not found by symmetry operations on the irreducible perturbations and qpoints given

leave_new : decision taken to exit ...

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

=== Build Information ===
Version : 6.0.1
Build target : x86_64_linux_gnu4.4
Build date : 20100223
*************************************************************************************************
we have read all the FAQ files and archives and forum posts..and tried to get overcome this error but not get success..
Here we have used the step1.in file as below...
in this file we have intentionally keep ecut and ngkpt for just solving the error and saving the time..but these is not the cause the error..

########################################################
# Note that the q-point grid must be a sub-grid of the k-point grid (here 4x4x4)
ndtset 4
# DATASET 1 : make ground state wavefunctions and density
######################################################
tolwfr1 1.0d-14
nline1 8 # This is to expedite the convergence of higher-lying bands
rfphon1 0 # for DS1 do _not_ do perturbation
nqpt1 0 # for DS1 do _not_ do perturbation
prtwf1 1 # need GS wavefunctions for further runs
getwfk1 0
qpt2 0.0 0.0 0.0
qpt3 0.5 0.0 0.0
qpt4 0.5 0.5 0.0
# general data for all phonon calculations:
###############################################
rfatpol 1 2
rfdir 1 1 1
rfphon 1
prtwf 0 # for response function runs, do not keep first order wavefunctions
tolvrs 1.0e-5
getwfk 1
nqpt 1
prepgkk 1 # force all perturbations to be calculated for q-points considered
prtgkk 2 # print out GKK files containing electron-phonon coupling
ngkpt 4 4 4
kptopt 3 # keep all k-points. Also for ground state, because of eventual transport calculations
# use a centered grid for the kpoints: obligatory for el-ph for the moment
############################################################
nshiftk 1
shiftk 0.0 0.0 0.0
ecut 4.0
acell 3*8.37716
spgroup 225
brvltt -1
angdeg 90 90 90
nband 16
# include metallic occupation function with a small smearing
#######################################################
occopt 3
tsmear 0.001
natom 2
typat 1 2
xred 0.00 0.00 0.00
0.5 0.5 0.5
nstep 800
ntypat 2
znucl 12 7

###########################
The anaddb input (step-4.in) file as below...
##########################

# turn on calculation of the electron-phonon quantities
elphflag 1
telphint 2
# Minimalistic kpoint grid - needed for tetrahedron method
################################################
kptrlatt 4 0 0 0 4 0 0 0 4
ngkpt 4 4 4
elphsmear 0.01
mustar 0.136
nqpath 7
qpath
0.0 0.0 0.0
1/2 1/2 0.0
1 1 1
1/2 1/2 1/2
1/2 1/2 0.0
1/2 3/4 1/4
1/2 1/2 1/2
prtnest 1 # print the nesting function along the q-path specified by qpath
# note that the k-grid defined by kptrlatt must be orthogonal in reciprocal space
# moreover off-diagonal elements are not allowed
# i.e kprtlatt = (1 0 0 0 1 1 0 -1 1 ) will not work
# Minimalistic qpoint grid
ngqpt 2 2 2
# impose acoustic sum rule in a symmetric way
asr 2
dipdip 1
# bravais lattice necessary
brav 1
# qpt grid
nqshft 1
q1shft 0.0 0.0 0.0
ifcflag 1
ifcana 1
# ifc for all atoms?
natifc 0
atifc 1 2 3
# print dielectric matrix with freq dependence
dieflag 1 # was 0
# print out eigenvectors and symmetrize dyn matrix
eivec 1
#Wavevector list number 1 (Reduced coordinates and normalization factor)
nph1l 1
qph1l 0.00000000E+00 0.00000000E+00 0.00000000E+00 1
# This line added when defaults were changed (v5.3) to keep the previous, old behaviour
symdynmat 1
#################################################################

if somebody knows where we are doing mistakes...please suggest.....

Hoping for positive reply...
With Best Regards,
Sanjay D Gupta
Junior Research fellow
Department of Physics
Bhavnagar University

Your input files look ok. The first thing you should check is that the irreducible q-points have not changed for the new system. As you have a different point group from Al this is probably the case, and you may need additional q. You can also turn off the el-ph calculation, run anaddb for phonon bands, and see if that works (in which case the q-points are sufficient).

very interested to know the results of your calculations, though. Bear in mind that for non-metallic systems the el-ph integrals will all be 0!

Multi-atom el-ph has been used extensively, so it has to work.

matthieu

Respected Sir,
Matthieu, Thank you very much for kind reply..
I got the complete final run by anaddb code the error was in the selection of q-points
Thanks once again to point out my mistake.