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[javier.torres@unito.it]

Dear Abinit Users 

I performed a response function calculation in order to get the phonons at 
gamma point of AgB2... For this I used the optimized gometry of my system, 
performed with ionmov 2 and optcell 2 as you can see in the attached files, 
the obtained lattice parameters correspond to a stress tensor with components 
smaller than 10^-8, the atomic coordinates were not optimized because the 
atoms are special positions...  

The result of the phonon calculation with this geometry is a set of freqs 
with very negative values of about -46 cm^-1 ... How can I get the adequate 
geometry of my system to get the true frequencies???

Kind regards

F. T.

OPT...
# Hexagonal Primitive (P6/mmm) AgB2 GS SHIFTK  0 0 0 
# Geometric block
spgroup  191
acell   5.4424112657  5.4424112657  6.6707332527  #Experimental Values Lal
angdeg  90 90 120
ntypat  2
znucl   47 5
natom   3
typat   1 2 2
xred
        0.0 0.0 0.0
        1/3 2/3 1/2
        2/3 1/3 1/2
#
# OPTCELL
#
ionmov   2
optcell  2    #try opcell 2 too!!!
tolmxf   1.0d-5
ntime    50
dilatmx  1.2
strfact  10
#
# Methods and Parameters
#
intxc    0         #better for fft changed  disable for RF calc
occopt   7         #added for metalic occupation Gaussian smearing 
tsmear   0.01      #convergence
brav     4         #added for hexagonal lattice
ixc      1
ecut     30.0
ecutsm   0.5
ngkpt    10 10 10       #16x16x16 exceeds the limit of memory allocation with 
kopt=2
frzfermi 1
nshiftk  1
shiftk   0.0 0.0 0.0
#
# SCF defined in each dataset
#
nstep     1000
#
# DS_1 gs and density calculation
#
iscf     3
kptopt   1
kptgen   1
toldfe   1.0d-12   #important for freqcalc
#irdwfk  1



Phon...

# Hexagonal Primitive (P6/mmm) AgB2 GS SHIFTK  0 0 0 
ndtset 2
# Geometric block
spgroup  191
acell   5.6504357844  5.6504357843  7.5478571140 
angdeg  90 90 120
ntypat  2
znucl   47 5
natom   3
typat   1 2 2
xred
        0.0 0.0 0.0
        1/3 2/3 1/2
        2/3 1/3 1/2
#
# Methods and Parameters
#
intxc    0         #better for fft changed  disable for RF calc
occopt   7         #added for metalic occupation Gaussian smearing 
tsmear   0.01      #convergence
brav     4         #added for hexagonal lattice
ixc      1
ecut     43.0
ecutsm   0.5
ngkpt    10 10 10       #16x16x16 exceeds the limit of memory allocation with 
kopt=2
#frzfermi 1
nshiftk  1
shiftk   0.0 0.0 0.0
#
# SCF defined in each dataset
#
nstep     1000
#
# DS_1 gs and density calculation
#
iscf1     3
kptopt1   1
kptgen1   1
tolwfr1   1.0d-20   #important for freqcalc
#irdwfk1   1
#
# DS_2 whole phonon
#
  rfphon2   1            # Will consider phonon-type perturbation
 rfatpol2   1 3          # Only the first atom is displaced
   rfdir2   1 1 1        # Along the first reduced coordinate axis
    nqpt2   1            # One wavevector is to be considered
     qpt2   0 0 0        # This wavevector is q=0 (Gamma)
  kptopt2   2            # Automatic generation of k points, taking
                        # into account the time-reversal symmetry only
  tolvrs2   1.0d-10       # SCF stopping criterion
    iscf2   3            # Self-consistent calculation, using algorithm 3
  getwfk2   -1            # Read the ground-state wavefunctions