I'm using the Teter's extended norm-conserving PPs (downloaded from the page of abinit) and the VCA scheme to calculate the phonon structure of (Sr1-xBax)TiO3. The GS+RF files for (Sr0.5Ba0.5)TiO3 is
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ndtset 37
# dataset1: usual ground-state calculation
getwfk1 0 # cancel default
kptopt1 1 # GS calculation
nqpt1 0 # cancel default
tolvrs1 1.0d-18 # SCF stopping criterion
rfphon1 0 # cancel default
# dataset2: response function calculation of d/dk
rfelfd2 2 # activate the calculation of d/dk perturbation
rfdir2 1 1 1 # perturbation in x-,y-,z-directions
rfphon2 0 # cancel default
qpt2 0.0 0.0 0.0 # Gamma point
kptopt2 2 # using only time symmetry
iscf2 -3 # the non self-consistent method to calculate d/dk
tolwfr2 1.0d-22 # Must use tolwfr for non self-consistent calculations
tolvrs2 0.0 # cancel default
# dataset3: response function calculation
qpt3 0.0 0.0 0.0 # Gamma point
getddk3 2
kptopt3 2 # using only time symmetry
rfelfd3 3 # electric-field perturbation
# dataset4-37: q-vectors
nqpt 1 # using only one point per dataset
qpt4 0.12500000000000D+00 0.00000000000000D+00 0.00000000000000D+00
qpt5 0.25000000000000D+00 0.00000000000000D+00 0.00000000000000D+00
qpt6 0.37500000000000D+00 0.00000000000000D+00 0.00000000000000D+00
qpt7 0.50000000000000D+00 0.00000000000000D+00 0.00000000000000D+00
qpt8 0.12500000000000D+00 0.12500000000000D+00 0.00000000000000D+00
qpt9 0.25000000000000D+00 0.12500000000000D+00 0.00000000000000D+00
qpt10 0.37500000000000D+00 0.12500000000000D+00 0.00000000000000D+00
qpt11 0.50000000000000D+00 0.12500000000000D+00 0.00000000000000D+00
qpt12 0.25000000000000D+00 0.25000000000000D+00 0.00000000000000D+00
qpt13 0.37500000000000D+00 0.25000000000000D+00 0.00000000000000D+00
qpt14 0.50000000000000D+00 0.25000000000000D+00 0.00000000000000D+00
qpt15 0.37500000000000D+00 0.37500000000000D+00 0.00000000000000D+00
qpt16 0.50000000000000D+00 0.37500000000000D+00 0.00000000000000D+00
qpt17 0.50000000000000D+00 0.50000000000000D+00 0.00000000000000D+00
qpt18 0.12500000000000D+00 0.12500000000000D+00 0.12500000000000D+00
qpt19 0.25000000000000D+00 0.12500000000000D+00 0.12500000000000D+00
qpt20 0.37500000000000D+00 0.12500000000000D+00 0.12500000000000D+00
qpt21 0.50000000000000D+00 0.12500000000000D+00 0.12500000000000D+00
qpt22 0.25000000000000D+00 0.25000000000000D+00 0.12500000000000D+00
qpt23 0.37500000000000D+00 0.25000000000000D+00 0.12500000000000D+00
qpt24 0.50000000000000D+00 0.25000000000000D+00 0.12500000000000D+00
qpt25 0.37500000000000D+00 0.37500000000000D+00 0.12500000000000D+00
qpt26 0.50000000000000D+00 0.37500000000000D+00 0.12500000000000D+00
qpt27 0.50000000000000D+00 0.50000000000000D+00 0.12500000000000D+00
qpt28 0.25000000000000D+00 0.25000000000000D+00 0.25000000000000D+00
qpt29 0.37500000000000D+00 0.25000000000000D+00 0.25000000000000D+00
qpt30 0.50000000000000D+00 0.25000000000000D+00 0.25000000000000D+00
qpt31 0.37500000000000D+00 0.37500000000000D+00 0.25000000000000D+00
qpt32 0.50000000000000D+00 0.37500000000000D+00 0.25000000000000D+00
qpt33 0.50000000000000D+00 0.50000000000000D+00 0.25000000000000D+00
qpt34 0.37500000000000D+00 0.37500000000000D+00 0.37500000000000D+00
qpt35 0.50000000000000D+00 0.37500000000000D+00 0.37500000000000D+00
qpt36 0.50000000000000D+00 0.50000000000000D+00 0.37500000000000D+00
qpt37 0.50000000000000D+00 0.50000000000000D+00 0.50000000000000D+00
# dataset4-37: q-vector phonon calculations (default for all datasets)
getwfk 1 # read wavefunction from dataset 1
kptopt 3 # using only time symmetry
rfphon 1 # do phonon response
rfatpol 1 5 # treat displacements of all atoms
rfdir 1 1 1 # all directions
tolvrs 1.0d-8 # convergence criterion
# iscf 5 # (default) self-consistent algorithm
iscf 7 # work around of scfcge cannot converge problem
# common input variables
# lattice parameters
acell 3*7.47 # cell parameters
rprim 1.0 0.0 0.0
0.0 1.0 0.0
0.0 0.0 1.0
# definition of alchemical psps and atom types
npsp 4 # 4 psps to be loaded
ntypat 3 # 3 types: Ti, O, Sr/Ba
znucl 22 8 38 56 # weight of Ti, O, Sr/Ba
ntypalch 1 # one atom will be alchemical
mixalch 0.50 0.50 # Sr-50% / Ba-50%
# definition of atoms
natom 5 # number of atoms
typat 1 2 2 2 3 # Ti, O, O, O, Sr/Ba
xred
0.5 0.5 0.5 # Ti
0.5 0.5 0.0 # O
0.5 0.0 0.5 # O
0.0 0.5 0.5 # O
0.0 0.0 0.0 # Sr/Ba
# definition of bands
nband 20 # define nband for non-SCF convergence
# definition of XC
ixc 3 # Ceperley-Alder XC
# definition of SCF calculation
nstep 100 # Maximal number of SCF calculation
diemac 9.0 # dielectric
# definition of energy cut-off
ecut 45 # energy cut-off
# definition of kpoints
ngkpt 8 8 8 # number of grid points for k-points generation
nshiftk 1 # non FCC or BCC lattice
shiftk 0.5 0.5 0.5
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The input file for anaddb is
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!Input file for the ifc code. Analysis of the DDB
!Flags
ifcflag 1 ! Interatomic force constant flag
!Wavevector grid number 1 (coarse grid, from DDB)
brav 1 ! Bravais Lattice : 1-S.C., 2-F.C., 3-B.C., 4-Hex.)
ngqpt 8 8 8 ! Monkhorst-Pack indices
nqshft 1 ! number of q-points in repeated basic q-cell
q1shft 3*0.0
!Effective charges
asr 1 ! Acoustic Sum Rule. 1 => imposed asymetrically
chneut 1 ! Charge neutrality requirement for effective charges.
!Interatomic force constant info
dipdip 1 ! Dipole-dipole interaction treatment
!Phonon band structure output for band2eps - See note near end for
! dealing with gamma LO-TO splitting issue.
eivec 4
!Wavevector list number 1 (Reduced coordinates and normalization factor)
nph1l 51 ! number of phonons in list 1
qph1l 0.0000 0.0000 0.0000 1.0 !(gamma point:[000])
0.0500 0.0000 0.0000 1.0
0.1000 0.0000 0.0000 1.0
0.1500 0.0000 0.0000 1.0
0.2000 0.0000 0.0000 1.0
0.2500 0.0000 0.0000 1.0
0.3000 0.0000 0.0000 1.0
0.3500 0.0000 0.0000 1.0
0.4000 0.0000 0.0000 1.0
0.4500 0.0000 0.0000 1.0
0.5000 0.0000 0.0000 1.0 !(X point:1/2[100])
0.5000 0.0500 0.0000 1.0
0.5000 0.1000 0.0000 1.0
0.5000 0.1000 0.0000 1.0
0.5000 0.1500 0.0000 1.0
0.5000 0.2000 0.0000 1.0
0.5000 0.2500 0.0000 1.0
0.5000 0.3000 0.0000 1.0
0.5000 0.3500 0.0000 1.0
0.5000 0.4000 0.0000 1.0
0.5000 0.4500 0.0000 1.0
0.5000 0.5000 0.0000 1.0 !(M point:1/2[110])
0.5500 0.5500 0.0000 1.0
0.6000 0.6000 0.0000 1.0
0.6500 0.6500 0.0000 1.0
0.7000 0.7000 0.0000 1.0
0.7500 0.7500 0.0000 1.0
0.8000 0.8000 0.0000 1.0
0.8500 0.8500 0.0000 1.0
0.9000 0.9000 0.0000 1.0
0.9500 0.9500 0.0000 1.0
1.0000 1.0000 0.0000 1.0 !(gamma point:[110])
1.0500 1.0500 0.0500 1.0
1.1000 1.1000 0.1000 1.0
1.1500 1.1500 0.1500 1.0
1.2000 1.2000 0.2000 1.0
1.2500 1.2500 0.2500 1.0
1.3000 1.3000 0.3000 1.0
1.3500 1.3500 0.3500 1.0
1.4000 1.4000 0.4000 1.0
1.4500 1.4500 0.4500 1.0
1.5000 1.5000 0.5000 1.0 !(R point:[110]+1/2[111])
1.5000 1.5000 0.4500 1.0
1.5000 1.5000 0.4000 1.0
1.5000 1.5000 0.3500 1.0
1.5000 1.5000 0.3000 1.0
1.5000 1.5000 0.2500 1.0
1.5000 1.5000 0.2000 1.0
1.5000 1.5000 0.1500 1.0
1.5000 1.5000 0.1000 1.0
1.5000 1.5000 0.0500 1.0
1.5000 1.5000 0.0000 1.0 !(M point:[110]+1/2[110])
!Wavevector list number 2 (Cartesian directions for non-analytic gamma phonons)
!The output for this calculation must be cut-and-pasted into the
! t59_out.freq file to be used as band2eps input to get proper LO-TO
! splitting at gamma. Note that gamma occurrs twice.
nph2l 1 ! number of directions in list 2
qph2l 1.0 0.0 0.0 0.0
# This line added when defaults were changed (v5.3) to keep the previous, old behaviour
symdynmat 0
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The phonon structure is in the attachment as .in file which actually is .eps file
Sr0.5Ba0.5TiO3_phonon.in- (46.71 KiB) Downloaded 248 times
The result is good except for the M point compared with the paper by X. Gonze and K. M. Rabe[http://arxiv.org/abs/cond-mat/0004464].
In their paper, there is a plateau with imaginary frequency along Gamma-X-M (Figure 1) while a plateau with real frequency is observed in our calculation.
Any help is welcomed!