I'm a new user of abinit and I am now doing the test an exercise, I want to repeat the previous work of H3S bcc cubic structure,the structure should be dynamical stability but when I calculated the phonon after geometry relaxation at 200 GPa , the phonon frequency at q point 0.5 0.5 0.5 was negative frequencies about -300 cm-1, and I cannot get rid of it , please help me to find the reason.
First I do the geometry relaxation :
Code: Select all
#Dataset of opt and occupation
#=============================
occopt 6
tsmear 0.001
optcell 2
ionmov 2
tolmxf 1.0d-14
ntime 1000000
dilatmx 2.00
ecutsm 0.5
strprecon 0.1
strtarget -6.797858d-3 -6.797858d-3 -6.797858d-3 0 0 0
# Definition of the unit cell
#=============================
acell 3*4.8813129966E+00
rprim -0.5 0.5 0.5
0.5 -0.5 0.5
0.5 0.5 -0.5
#Definition of the atoms types
#=============================
ntypat 2
znucl 1 16
natom 4
typat 1 1 1 2
#tolvrs 1.0d-20
xred 5.00000000000000E-01 5.00000000000000E-01 0.00000000000000E+00
0.00000000000000E+00 5.00000000000000E-01 5.00000000000000E-01
5.00000000000000E-01 0.00000000000000E+00 5.00000000000000E-01
0.00000000000000E+00 0.00000000000000E+00 0.00000000000000E+00
#Definition of the k-point grid
#==========================================
kptopt 1
ngkpt 32 32 32
nshiftk 1
shiftk 0 0 0
#Definition of the SCF procedure
#==========================================
#iscf 5
ecut 40
nband 15
toldff 1.0d-15
#diemac 3.0
nstep 100000
#Definition of the outfile information
#==========================================
prtwf 0
and than I used the new acell to run the phonon freq for 3 perticular q points Gamma point 0 0 0 and point 0.25 0.25 0.25 and point 0.5 0.5 0.5
Code: Select all
# Crystalline AlAs : computation of the phonon spectrum
ndtset 5
#Set 1 : ground state self-consistency
occopt 6
tsmear 0.001
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
#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 0.00000000E+00 0.00000000E+00 0.00000000E+00
qpt3 0.00000000E+00 0.00000000E+00 0.00000000E+00
qpt4 5.00000000E-01 5.00000000E-01 5.00000000E-01
qpt5 2.50000000E-01 2.50000000E-01 2.50000000E-01
#Set 2 : Response function calculation of d/dk wave function
#
iscf2 -3 # Need this non-self-consistent option for d/dk
kptopt2 3 # Modify default to use time-reversal symmetry
rfphon2 0 # Cancel default
rfelfd2 2 # Calculate d/dk wave function only
tolwfr2 1.0d-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 3 # Modify default to use time-reversal symmetry
rfelfd3 3 # Electric-field perturbation response only
#Sets 4-10 : 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 4 # Treat displacements of all atoms
rfdir 1 1 1 # Do all directions (symmetry will be used)
tolvrs 1.0d-18 # This default is active for sets 3-10
#######################################################################
#Common input variables
#Definition of the unit cell
acell 3*4.8813129966E+00 This is equivalent to 10.61 10.61 10.61
rprim -0.5 0.5 0.5 # In lessons 1 and 2, these primitive vectors
0.5 -0.5 0.5 # (to be scaled by acell) were 1 0 0 0 1 0 0 0 1
0.5 0.5 -0.5 # that is, the default.
#Definition of the atom types
ntypat 2 # There are two types of atom
znucl 1 16 # 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, type 1 is the Aluminum,
# type 2 is the Arsenic.
#Definition of the atoms
natom 4 # There are two atoms
typat 1 1 1 2 # The first is of type 1 (Al), the second is of type 2 (As).
xred 5.0000000000E-01 5.0000000000E-01 0.0000000000E+00
0.0000000000E+00 5.0000000000E-01 5.0000000000E-01
5.0000000000E-01 0.0000000000E+00 5.0000000000E-01
0.0000000000E+00 0.0000000000E+00 0.0000000000E+00
#Gives the number of band, explicitely (do not take the default)
nband 15
#Exchange-correlation functional
# ixc 1 # LDA Teter Pade parametrization
#Definition of the planewave basis set
ecut 40 # Maximal kinetic energy cut-off, in Hartree
#Definition of the k-point grid
ngkpt 24 24 24
nshiftk 1 # Use one copy of grid only (default)
shiftk 0.0 0.0 0.0 # This gives the usual fcc Monkhorst-Pack grid
#Definition of the SCF procedure
iscf 7 # Self-consistent calculation, using algorithm 5
nstep 100000 # Maximal number of SCF cycles
# diemac 9.0 # 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.
# The dielectric constant of AlAs is smaller that the one of Si (=12).
# add to conserve old < 6.7.2 behavior for calculating forces at each SCF step
optforces 1
#%%<BEGIN TEST_INFO>
#%% [setup]
#%% executable = abinit
#%% test_chain = trf2_1.in, trf2_3.in, trf2_4.in, trf2_5.in, trf2_6.in, trf2_7.in
#%% [files]
#%% files_to_test =
#%% trf2_1.out, tolnlines= 14, tolabs= 5.000e-05, tolrel= 5.000e-04, fld_options=-medium
#%% psp_files = 13al.981214.fhi, 33as.pspnc
#%% [paral_info]
#%% max_nprocs = 2
#%% [extra_info]
#%% authors =
#%% keywords = NC, DFPT
#%% description =
#%%<END TEST_INFO>
I got imaginary freq at 0.5 0.5 0.5 about -300 cm -1 and I really don't know what to do
Thank you very much