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I am trying to get the phonon frequencies of an insulator. I used the trf2_1.in template and am working with 10 datasets. Dataset 2 does not converge. I had given nsteps = 30 . Other datasets have converged total energies. Though I waas able to run till the Anaddb part, the phonon frequencies generated were all absurd. I have attached the input file that I am working with. Could you please tell me where I am wrong? Thanks in advance. Uma

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Crystalline cgN : computation of the phonon spectrum

ndtset 10
#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
getddk1 0
optdriver1 0
rfelfd1 0
tolwfr1 0

#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 2.50000000E-01 0.00000000E+00 0.00000000E+00
qpt5 5.00000000E-01 0.00000000E+00 0.00000000E+00
qpt6 2.50000000E-01 2.50000000E-01 0.00000000E+00
qpt7 2.50000000E-01 2.50000000E-01 2.50000000E-01
qpt8 -2.50000000E-01 2.50000000E-01 2.50000000E-01
qpt9 5.00000000E-01 5.00000000E-01 2.50000000E-01
qpt10 5.00000000E-01 5.00000000E-01 5.00000000E-01



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-22 # Use wave function residual criterion instead
getwfk2 1
getddk2 0
optdriver 1
tolvrs2 0
#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
getwfk3 1
tolwfr 0
#Sets 4-10 : Finite-wave-vector phonon calculations (defaults for all datasets)
getddk 0
getwfk 1 # Use GS wave functions from dataset1
kptopt4 3 # Need full k-point set for finite-Q response
kptopt5 3
kptopt6 3
kptopt7 3
kptopt8 3
kptopt9 3
kptopt10 3
rfphon 1 # Do phonon response
rfelfd 0
rfatpol 1 4 # 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

#######################################################################
#Common input variables

#Definition of the unit cell
acell 3.8037 3.8037 3.8037 angstrom
rprim -0.5000000000000000 0.5000000000000000 0.5000000000000000
0.5000000000000000 -0.5000000000000000 0.5000000000000000
0.5000000000000000 0.5000000000000000 -0.5000000000000000

#Definition of the atom types
ntypat 1 # There is one type of atom
znucl 7.0 # 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.

#Definition of the atoms
:
Definition of the atoms
natom 4 # There are 4 atoms
typat 1 1 1 1 # 4 atoms of the same type .
xred 0.17000000000000017 0.1700000000000017 0.1700000000000017
0.5000000000000000 0.0000000000000000 0.3299999999999983
0.0000000000000000 0.3299999999999983 0.5000000000000000
0.3299999999999983 0.5000000000000000 0.0000000000000000

#Gives the number of band, explicitely (do not take the default)
nband 20

#Exchange-correlation functional

ixc 11 # GGA, Perdew-Burke-Ernzerhof GGA functional

#Definition of the planewave basis set

ecut 500 eV # Maximal kinetic energy cut-off, in eV

#Definition of the k-point grid
ngkpt 8 8 8
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 5 # Self-consistent calculation, using algorithm 5
nstep 30 # Maximal number of SCF cycles
diemac 3.0d0 # 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.
# add to conserve old < 6.7.2 behavior for calculating forces at each SCF step
optforces 1

I was able to arrive at the convergence by reducing diemac to 2.0 and increasing nsteps to 3000.
Uma