The ABINIT Users Mailing List ( CLOSED )

[Prasenjit Sen <prasen@mri.ernet.in>]

Hello users:
    I am trying to get familiar with doing electron-phonon calculations
with density functional perturbation theory using ABINIT. As a test case,
I am trying to work out el-ph properties of bulk Al (same as the tutotrial
telphon in the Tutorial). Of course the runs with the set of files
distributed with ABINIT (telphon_1-5) go on fine. When I try improve on
the input parameters, I run into the following problem.

I increase ecut to 450 eV, set ngkpt 16 16 16, and for response function
calculation use a 4x4x4 q-grid. The g.s. and response function
calculations converge. The phonon band structure calculated with anaddb
also works out correctly. But while I try to do an el-ph calculation using
anaddb, the Eliashberg Tc does not converge, though MacMillan Tc seems to
converge.

Here are the corresponding lines from the log file. Please note that the
information that Eliashberg Tc does not converge is printed only in the
log file (std output), and not in the main output file.
===========================
eliashberg_1d : Tc not converged.   0.424775375941627       /= 1
 Eliashberg Tc nonetheless =   1.842976348995707E-015  (Ha) =
  5.819652073374399E-010  (K)
  eliashberg_1d : end
===============================
The MacMillan Tc is printed as:
===========
 mka2f: isotropic lambda =     3.773693E-01
 mka2f: omegalog  =     1.133614E-03 (Ha)     3.579667E+02 (Kelvin)
 mka2f: input mustar =     1.360000E-01
 mka2f: MacMillan Tc =     1.015034E-06 (Ha)     3.205221E-01 (Kelvin)
  mka2f : end
=============
My questions are the following.

1. Can one trust the el-ph coupling results (*_A2F file, say) when
Eliashberg Tc has not converged?

2. Which parameters should I focus on if I need to converge Eliashberg Tc?

I am including the input files for the GS and RF calculations
(Almetelph1_1.in), the input file for el-ph calculation (Almetelph1_4.in).

Thanks in advance,

   Prasenjit Sen

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#
#  the sequence of datasets makes the ground states and
#   all of the explicit perturbations of the single
#   Al atom in all directions, for the irreducible
#   qpoints in a 4x4x4 grid.
#
ndtset 33
jdtset 1   2 3 4 5   6 7 8 9   10 11 12 13  14 15 16 17  18 19 20 21  22 23 
24 25  26 27 28 29   30 31 32 33

#
# DATASET 1 : make ground state wavefunctions and density
# 
iscf 3
kptopt1 3
tolwfr1 1.0d-20
prtden1 1
nline1 8    ! This is to expedite the convergence of higher-lying bands

#
#  qpoint Gamma
#
#  DATASET 2: construct the wavefunctions at k+q (same as at k,
#     but kept for similarity to the other qpoints).
#
iscf2    -3   tolwfr2  1.0d-15 getden2  1             kptopt2  3 nqpt2  1 
qpt2   0.0 0.0 0.0
#
#  DATASET 3,4,5: perturbation at q=Gamma along reduced direction 1,2,3
#
rfatpol3  1 1 rfdir3  1 0 0 rfphon3  1 tolvrs3   1.0e-8 getwfk3  1 getwfq3   
2 kptopt3  3 nqpt3  1 qpt3   0.0 0.0 0.0
rfatpol4  1 1 rfdir4  0 1 0 rfphon4  1 tolvrs4   1.0e-8 getwfk4  1 getwfq4   
2 kptopt4  3 nqpt4  1 qpt4   0.0 0.0 0.0
rfatpol5  1 1 rfdir5  0 0 1 rfphon5  1 tolvrs5   1.0e-8 getwfk5  1 getwfq5   
2 kptopt5  3 nqpt5  1 qpt5   0.0 0.0 0.0

#
#  qpoint 1/4 0 0
#
#  DATASET 6: construct the wavefunctions at k+q
#
iscf6    -3 tolwfr6  1.0d-15 getden6  1  kptopt6  3 nqpt6  1 qpt6   0.25 0.0 
0.0
#
#  DATASET 7,8,9: perturbation along reduced direction 1,2,3
#
rfatpol7  1 1 rfdir7  1 0 0 rfphon7  1 tolvrs7   1.0e-8 getwfk7  1 getwfq7   
6 kptopt7  3 nqpt7  1 qpt7   0.25 0.0 0.0
rfatpol8  1 1 rfdir8  0 1 0 rfphon8  1 tolvrs8   1.0e-8 getwfk8  1 getwfq8   
6 kptopt8  3 nqpt8  1 qpt8   0.25 0.0 0.0
rfatpol9  1 1 rfdir9  0 0 1 rfphon9  1 tolvrs9   1.0e-8 getwfk9  1 getwfq9   
6 kptopt9  3 nqpt9  1 qpt9   0.25 0.0 0.0

#
#  qpoint X= 1/2 0 0
#
#  DATASET 10: construct the wavefunctions at k+q
#
iscf10   -3  tolwfr10 1.0d-15 getden10 1 kptopt10 3 nqpt10 1 qpt10  0.5 0.0 
0.0
#
#  DATASET 11,12,13: perturbation along reduced direction 1,2,3
#
rfatpol11 1 1 rfdir11 1 0 0 rfphon11 1 tolvrs11  1.0e-8 getwfk11 1 getwfq11 
10 kptopt11 3 nqpt11 1 qpt11  0.5 0.0 0.0
rfatpol12 1 1 rfdir12 0 1 0 rfphon12 1 tolvrs12  1.0e-8 getwfk12 1 getwfq12 
10 kptopt12 3 nqpt12 1 qpt12  0.5 0.0 0.0
rfatpol13 1 1 rfdir13 0 0 1 rfphon13 1 tolvrs13  1.0e-8 getwfk13 1 getwfq13 
10 kptopt13 3 nqpt13 1 qpt13  0.5 0.0 0.0

#
#  qpoint X= 1/4 1/4 0
#
#  DATASET 14: construct the wavefunctions at k+q
#
iscf14   -3  tolwfr14 1.0d-15 getden14 1 kptopt14 3 nqpt14 1 qpt14  0.25 0.25 
0.0
#
#  DATASET 15,16,17: perturbation along reduced direction 1,2,3
#
rfatpol15 1 1 rfdir15 1 0 0 rfphon15 1 tolvrs15  1.0e-8 getwfk15 1 getwfq15 
14 kptopt15 3 nqpt15 1 qpt15  0.25 0.25 0.0
rfatpol16 1 1 rfdir16 0 1 0 rfphon16 1 tolvrs16  1.0e-8 getwfk16 1 getwfq16 
14 kptopt16 3 nqpt16 1 qpt16  0.25 0.25 0.0
rfatpol17 1 1 rfdir17 0 0 1 rfphon17 1 tolvrs17  1.0e-8 getwfk17 1 getwfq17 
14 kptopt17 3 nqpt17 1 qpt17  0.25 0.25 0.0

#
#  qpoint X= 1/2 1/4 0
#
#  DATASET 18: construct the wavefunctions at k+q
#
iscf18   -3  tolwfr18 1.0d-15 getden18 1 kptopt18 3 nqpt18 1 qpt18  0.5 0.25 
0.0
#
#  DATASET 19,20,21: perturbation along reduced direction 1,2,3
#
rfatpol19 1 1 rfdir19 1 0 0 rfphon19 1 tolvrs19  1.0e-8 getwfk19 1 getwfq19 
18 kptopt19 3 nqpt19 1 qpt19  0.5 0.25 0.0
rfatpol20 1 1 rfdir20 0 1 0 rfphon20 1 tolvrs20  1.0e-8 getwfk20 1 getwfq20 
18 kptopt20 3 nqpt20 1 qpt20  0.5 0.25 0.0
rfatpol21 1 1 rfdir21 0 0 1 rfphon21 1 tolvrs21  1.0e-8 getwfk21 1 getwfq21 
18 kptopt21 3 nqpt21 1 qpt21  0.5 0.25 0.0

#
#  qpoint X= -1/4 1/4 0
#
#  DATASET 22: construct the wavefunctions at k+q
#
iscf22   -3  tolwfr22 1.0d-15 getden22 1 kptopt22 3 nqpt22 1 qpt22  -0.25 
0.25 0.0
#
#  DATASET 23,24,25: perturbation along reduced direction 1,2,3
#
rfatpol23 1 1 rfdir23 1 0 0 rfphon23 1 tolvrs23  1.0e-8 getwfk23 1 getwfq23 
22 kptopt23 3 nqpt23 1 qpt23  -0.25 0.25 0.0
rfatpol24 1 1 rfdir24 0 1 0 rfphon24 1 tolvrs24  1.0e-8 getwfk24 1 getwfq24 
22 kptopt24 3 nqpt24 1 qpt24  -0.25 0.25 0.0
rfatpol25 1 1 rfdir25 0 0 1 rfphon25 1 tolvrs25  1.0e-8 getwfk25 1 getwfq25 
22 kptopt25 3 nqpt25 1 qpt25  -0.25 0.25 0.0

#
#  qpoint X= 1/2 1/2 0
#
#  DATASET 26: construct the wavefunctions at k+q
#
iscf26   -3  tolwfr26 1.0d-15 getden26 1 kptopt26 3 nqpt26 1 qpt26  0.5 0.5 
0.0
#
#  DATASET 27,28,29: perturbation along reduced direction 1,2,3
#
rfatpol27 1 1 rfdir27 1 0 0 rfphon27 1 tolvrs27  1.0e-8 getwfk27 1 getwfq27 
26 kptopt27 3 nqpt27 1 qpt27  0.5 0.5 0.0
rfatpol28 1 1 rfdir28 0 1 0 rfphon28 1 tolvrs28  1.0e-8 getwfk28 1 getwfq28 
26 kptopt28 3 nqpt28 1 qpt28  0.5 0.5 0.0
rfatpol29 1 1 rfdir29 0 0 1 rfphon29 1 tolvrs29  1.0e-8 getwfk29 1 getwfq29 
26 kptopt29 3 nqpt29 1 qpt29  0.5 0.5 0.0

#
#  qpoint X= -1/4 1/2 1/4
#
#  DATASET 30: construct the wavefunctions at k+q
#
iscf30   -3  tolwfr30 1.0d-15 getden30 1 kptopt30 3 nqpt30 1 qpt30  -0.25 0.5 
0.25
#
#  DATASET 31,32,33: perturbation along reduced direction 1,2,3
#
rfatpol31 1 1 rfdir31 1 0 0 rfphon31 1 tolvrs31  1.0e-8 getwfk31 1 getwfq31 
30 kptopt31 3 nqpt31 1 qpt31  -0.25 0.5 0.25
rfatpol32 1 1 rfdir32 0 1 0 rfphon32 1 tolvrs32  1.0e-8 getwfk32 1 getwfq32 
30 kptopt32 3 nqpt32 1 qpt32  -0.25 0.5 0.25
rfatpol33 1 1 rfdir33 0 0 1 rfphon33 1 tolvrs33  1.0e-8 getwfk33 1 getwfq33 
30 kptopt33 3 nqpt33 1 qpt33  -0.25 0.5 0.25

#
#  Common data
#

#
#  the kpoint grid is minimalistic to keep the calculation
#   manageable.
#
ngkpt 16 16 16

#
#  as is the kinetic energy cutoff
#
ecut 450.0  eV

#
#  use a centered grid for the kpoints
#
nshiftk 1
shiftk 0.0 0.0 0.0
acell 3*7.5
rprim 
 0.0 0.5 0.5
 0.5 0.0 0.5
 0.5 0.5 0.0
nband 6

#
#  include metallic occupation function with a small smearing
#
occopt 7
tsmear 0.001
natom 1
typat 1
xred 0.00 0.00 0.00
nstep 300
ntypat 1 
znucl 13 
# turn on calculation of the electron-phonon quantities
elphflag 1

# Path in reciprocal space along which the phonon linewidths
#  and band structure will be calculated
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

# Coulomb pseudopotential parameter
mustar 0.136

# Minimalistic qpoint grid
ngqpt 4 4 4

#  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 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