I am calculating the phonon spectrum in TiSe2. It is HCP structure. I want to know how to calculate the phonon at q= 1/3 0 0 of this structure.
the following is my input file. Thank you.
Crystalline TiSe2 : computation of the phonon spectrum
ndtset 22
#Set 1 : ground state self-consistency
getwfk1 0 # Cancel default
kptopt1 1 # Automatic generation of k points, taking
# into account the symmetry
nqpt1 0 # Cancel default
tolvrs1 1.0d-18 # SCF stopping criterion (modify default)
rfphon1 0 # Cancel default
ecutsm1 0.5
dilatmx1 1.05
#Q vectors for all datasets
#Complete set of symmetry-inequivalent qpt chosen to be commensurate
with kpt mesh so that only one set of GS wave functions is needed.
#Generated automatically by running GS calculation with kptopt=1,
nshift=0, shiftk=0 0 0 (to include gamma) and taking output kpt set
file as qpt set. Set nstep=1 so only one iteration runs.
nqpt 1 # One qpt for each dataset (only 0 or 1 allowed)
# This is the default for all datasets and must
# be explicitly turned off for dataset 1.
qpt2 0.00000000000000D+00 0.00000000000000D+00 0.00000000000000D+00
qpt3 0.00000000000000D+00 0.00000000000000D+00 0.00000000000000D+00
qpt4 0.25000000000000D+00 0.00000000000000D+00 0.00000000000000D+00
qpt5 1/3 0.00000000000000D+00 0.00000000000000D+00
qpt6 0.50000000000000D+00 0.00000000000000D+00 0.00000000000000D+00
qpt7 0.25000000000000D+00 0.25000000000000D+00 0.00000000000000D+00
qpt8 1/3 1/3 0.00000000000000D+00
qpt9 0.00000000000000D+00 0.00000000000000D+00 0.25000000000000D+00
qpt10 0.25000000000000D+00 0.00000000000000D+00 0.25000000000000D+00
qpt11 1/3 0.00000000000000D+00 0.25000000000000D+00
qpt12 0.50000000000000D+00 0.00000000000000D+00 0.25000000000000D+00
qpt13 -0.25000000000000D+00 0.00000000000000D+00 0.25000000000000D+00
qpt14 -1/3 0.00000000000000D+00 0.25000000000000D+00
qpt15 0.25000000000000D+00 0.25000000000000D+00 0.25000000000000D+00
qpt16 1/3 1/3 0.25000000000000D+00
qpt17 0.00000000000000D+00 0.00000000000000D+00 0.50000000000000D+00
qpt18 0.25000000000000D+00 0.00000000000000D+00 0.50000000000000D+00
qpt19 1/3 0.00000000000000D+00 0.50000000000000D+00
qpt20 0.50000000000000D+00 0.00000000000000D+00 0.50000000000000D+00
qpt21 0.25000000000000D+00 0.25000000000000D+00 0.50000000000000D+00
qpt22 1/3 1/3 0.50000000000000D+00
#Set 2 : Response function calculation of d/dk wave function
iscf2 -3 # Need this non-self-consistent option for d/dk
kptopt2 2 # Modify default to use time-reversal symmetry
rfphon2 0 # Cancel default
rfelfd2 2 # Calculate d/dk wave function only
tolwfr2 1.0d-15 #-22 Use wave function residual criterion instead
#Set 3 : Response function calculation of Q=0 phonons and electric field pert.
getddk3 2 # d/dk wave functions from last dataset
kptopt3 2 # Modify default to use time-reversal symmetry
rfelfd3 3 # Electric-field perturbation response only
#Sets 4-15 : Finite-wave-vector phonon calculations (defaults for all datasets)
getwfk 1 # Use GS wave functions from dataset1
kptopt 3 # Need full k-point set for finite-Q response
rfphon 1 # Do phonon response
rfatpol 1 3 # Treat displacements of all atoms
rfdir 1 1 1 # Do all directions (symmetry will be used)
tolvrs 1.0d-8 # This default is active for sets 3-10
#####################################################################
#Definition of the unit cell
acell 6.697189 6.697189 12.6498
rprim 1 0 0 # In tutorials 1 and 2, these primitive vectors
-1/2 0.8660254037844387 0 # (to be scaled by acell) were 1 0 0 0 1 0 0 0 1
0 0 1 # that is, the default.
#Definition of the atom types
ntypat 2 # There is only one type of atom
znucl 22 34 # The keyword “znucl” refers to the atomic number of the
# possible type(s) of atom. The pseudopotential(s)
# mentioned in the “files” file must correspond
# to the type(s) of atom. Here, the type are Ti and Se.
pp_dirpath “$ABI_PSPDIR” # This is the path to the directory were
# pseudopotentials for tests are stored
#pseudos “JTH-LDA-atomicdata-1.1/ATOMICDATA/Ti.LDA_PW-JTH.xml, JTH-LDA-atomicdata-1.1/ATOMICDATA/Se.LDA_PW-JTH.xml”
pseudos “JTH-PBE-atomicdata-1.1/ATOMICDATA/Ti.GGA_PBE-JTH.xml, JTH-PBE-atomicdata-1.1/ATOMICDATA/Se.GGA_PBE-JTH.xml”
# Name and location of the pseudopotential
#Definition of the atoms
natom 3 # There are three atoms
typat 1 2 2 # The first is of type 1 (Ti), the second is the type 2 (Se)ey both are of type 1, that is, Silicon.
xred 0.0 0.0 0.0
1/3 2/3 0.2312
2/3 1/3 0.7688
#Gives the number of band, explicitely (do not take the default)
nband 20
vdw_xc 6
#Definition of the planewave basis set
ecut 20.0 # Maximal kinetic energy cut-off, in Hartree
pawecutdg 35.0
pawxcdev 0
occopt 7
tsmear 0.001
#Definition of the k-point grid
#kptopt 1
# Option for the automatic generation of k points, taking
# into account the symmetry
ngkpt 8 8 8 # This is a 2x2x2 grid based on the primitive vectors
nshiftk 1 # of the reciprocal space (that form a BCC lattice !),
# repeated four times, with different shifts :
shiftk 0.0 0.0 0.5
# In cartesian coordinates, this grid is simple cubic, and
# actually corresponds to the
# so-called 4x4x4 Monkhorst-Pack grid
#Definition of the SCF procedure
nstep 500 # Maximal number of SCF cycles
#toldfe 1.0d-6 # Will stop when, twice in a row, the difference
# between two consecutive evaluations of total energy
# differ by less than toldfe (in Hartree)
# This value is way too large for most realistic studies of materials
diemac 12.0 # Although this is not mandatory, it is worth to
# precondition the SCF cycle. The model dielectric
# function used as the standard preconditioner
# is described in the “dielng” input variable section.
# Here, we follow the prescription for bulk silicon.