warning in the process to get DDB file  [SOLVED]

mgrddb, anaddb, cut3d, electron-phonon coupling,...

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warning in the process to get DDB file

Postby jlwindy » Tue Jan 22, 2019 5:21 pm

dear all
l use VCA mehtod to compute the elastic and piezoelectic constant of PZT as the tutorial indicated.In the second step, l find some warning.
1.Alchemical pseudopotential with nlcc!
2. Density went too small (lower than xc_denpos) at 27629 points
and was set to xc_denpos = 1.00E-14. Lowest was -0.34E+02.
Likely due to too low boxcut or too low ecut for pseudopotential core charge.
3. Alchemical crystals are not fully supported by the netcdf format
Important parameters (e.g. znucl, symbols) are not written with the correct value
4.input nkpt=256 not equal disk file nkpt=160
5. input kptopt= 2 /= disk file kptopt= 1
6.Restart of self-consistent calculation need translated wavefunctions.
7.nstep 60 was not enough SCF cycles to converge.
8. WARNING : still subject to testing - especially symmetries.
Did the warnings have much impact on the outcome?hHow to remove this warning?
My pseudopotential is ONCVPSP-PBE-PDv0.4.
My input file

ndtset 3

# Set 1 : Initial self-consistent run

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

optdriver1 0

# 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
optdriver2 1
# Set 3 : response-function calculations for all needed perturbations

getddk3 -1
getwfk3 -2
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
optdriver3 1
#Common input data

# Here is a default value, for automatic testing : suppress it and fill the previous line
acell 7.8195376106E+00 7.6804731029E+00 7.8158140311E+00
rprim 9.9999084672E-01 -2.6428541435E-19 -4.2786066027E-03
6.1232339957E-17 1.0000000000E+00 0.0000000000E+00
-1.3440657856E-02 6.1763458541E-17 9.9990967028E-01

#Definition of the atom types and atoms
npsp 4
znucl 82 8 40 22
ntypat 3
ntypalch 1

mixalch 0.52 0.48
natom 5

typat 1 2 2 2 3
#Starting approximation for atomic positions in REDUCED coordinates
#based on ideal tetrahedral bond angles

# Here is a set of default values, for automatic testing : suppress it and fill the previous line
xred 5.7985553951E-02 5.4187599351E-19 -6.4812601329E-02
4.7095252908E-01 4.8629243633E-19 5.2032924011E-01
-1.2118344632E-02 5.0000000000E-01 5.2214654756E-01
4.6928549538E-01 5.0000000000E-01 3.7931124251E-03
5.1389476621E-01 5.0000000000E-01 4.7854370124E-01

#Definition of the plane wave basis set
ecut 30 # Maximum kinetic energy cutoff (Hartree)
ecutsm 0.5 # Smoothing energy needed for lattice paramete
# optimization. This will be retained for
# consistency throughout.
pawecutdg 36
#Definition of the k-point grid
kptopt 1 # Use symmetry and treat only inequivalent points
ngkpt 8 8 8 # 4x4x4 Monkhorst-Pack grid
nshiftk 1 # Use one copy of grid only (default)
shiftk 0.0 0.0 0.5 # This choice of origin for the k point grid
# preserves the hexagonal symmetry of the grid,
# which would be broken by the default choice.

#Definition of the self-consistency procedure
diemac 4.0 # Model dielectric preconditioner
nstep 60 # Maxiumum number of SCF iterations
# enforce calculation of forces at each SCF step
optforces 1

Thanks for your reading.Looking forward for your help.
Best wishes.
Posts: 32
Joined: Tue Jan 08, 2019 5:11 pm

Re: warning in the process to get DDB file  [SOLVED]

Postby mverstra » Wed Jan 23, 2019 11:17 am


warnings 1,2,4,5 are not a big deal (the negative charge is a bit huge but it might be due to the alchemy or just the initial iterations)

3 - well, depends if you use the netcdf file, of course...

7 - you need more iterations - how bad it is depends on where you got to. You should always check convergence anyway!

8 - no idea which part of the code this is in. You can check with a simpler example (low cutoffs, nband and nkpt) whether the results are the same as with nsym 1
Matthieu Verstraete
University of Liege, Belgium
Posts: 637
Joined: Wed Aug 19, 2009 12:01 pm

Re: warning in the process to get DDB file

Postby jlwindy » Sat Jan 26, 2019 10:47 am

dear mverstra
Thanks for your help
Best regards
Posts: 32
Joined: Tue Jan 08, 2019 5:11 pm

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