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[matthieu verstraete <matthieu.jean.verstraete@gmail.com>]

I can't see much wrong, apart possibly from occopt, which you have set
to 3 (metallic). Probably for this reason the ddk has not been
included in the ddb file: check for ipert=4 idir=1,2,3.

Try with an insulator value for occopt.

Matthieu

On Tue, Mar 24, 2009 at 3:29 PM, matthieu verstraete
<matthieu.jean.verstraete@gmail.com> wrote:
> Hello Tao,
>
> this is indeed very strange, and you should definitely have an LO-TO
> splitting. Do you have the convergence information for the DDK run?
> Could it be that it did not converge? The rest of your input looks
> quite correct. You might send a tarball of all the outputs, if they
> are not too heavy.
>
> Cheers
>
> Matthieu
>
> On Mon, Mar 23, 2009 at 6:05 PM,  <gaotaoscu@hotmail.com> wrote:
>> Dear All,
>>
>> When I try to reproduce the TO-LO splitting for CaF2 (original paper: 
>> PHYSICAL
>> REVIEW B vol68, 195123,2003),I got no LO-TO splitting in my calculation.
>> According to the experiments and the theoretical calculation, there should 
>> have
>> a TO-LO splitting in Gamma point for CaF2, but my input file is not able 
>> to let
>> these kind of slitting. my version is abinit-5.4.4p, and pseudopotential is
>> '20ca.pspnc' and '9f.pspnc'. Below is my setting for the DDB and phonon 
>> parts,
>> and the related output, any comments or suggestion is appreciated.
>>
>> 1,Generation of the derivative databases,
>> # Crystalline CaF2 : computation of the phonon spectrum
>>
>>   ndtset   10
>>  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
>>
>>     nqpt   1            # One qpt for each dataset (only 0 or 1 allowed)
>>
>>     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   5.00000000E-01  2.50000000E-01  0.00000000E+00
>>     qpt8  -2.50000000E-01  2.50000000E-01  0.00000000E+00
>>     qpt9   5.00000000E-01  5.00000000E-01  0.00000000E+00
>>     qpt10 -2.50000000E-01  5.00000000E-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   2          # Modify default to use time-reversal symmetry
>>  rfphon2   0          # Cancel default
>>  rfelfd2   2          # Calculate d/dk wave function only
>>  tolvrs2   0.0        # Cancel default for d/dk
>>  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   2          # 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 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
>>
>> #Common input variables
>> #Definition of the unit cell
>>    acell   3*10.3232         # This is equivalent to   10.61 10.61 10.61
>>    rprim   0.0  0.5  0.5   # In lessons 1 and 2, these primitive vectors
>>            0.5  0.0  0.5   # (to be scaled by acell) were 1 0 0  0 1 0  0 
>> 0 1
>>            0.5  0.5  0.0   # that is, the default.
>>
>> #Definition of the atom types
>>   ntypat   2         # There are two types of atom
>>    znucl   20 9     # 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   3         # There are two atoms
>>    typat   1 2 2       # The first is of type 1 (Al), the second is of 
>> type 2
>> (As).
>>    xred                      # will follow, one triplet of number for each
>> atom
>>         0.0  0.0  0.0      # Triplet giving the REDUCED coordinate of atom 
>> 1.
>>         1/4  1/4  1/4      # Triplet giving the REDUCED coordinate of atom 
>> 2.
>>         3/4  3/4  3/4               # Note the use of fractions (remember 
>> the
>> limited
>>
>> #Gives the number of band, explicitely (do not take the default)
>>    nband   11
>>    occopt  3
>> #Exchange-correlation functional
>>
>>      ixc   1             # LDA Teter Pade parametrization
>>
>> #Definition of the planewave basis set
>>
>>     ecut   26.0           # Maximal kinetic energy cut-off, in Hartree
>>
>> #Definition of the k-point grid
>>    ngkpt   4  4  4
>>  nshiftk   4              # Use one copy of grid only (default)
>>   shiftk   0.0 0.0 0.5    # This gives the usual fcc Monkhorst-Pack grid
>>            0.0 0.5 0.0
>>            0.5 0.0 0.0
>>            0.5 0.5 0.5
>>
>> #Definition of the SCF procedure
>>    iscf     7        # Self-consistent calculation, using algorithm 5
>>    nstep   1500      # Maximal number of SCF cycles
>>    diemac   9.0      # Although this is not mandatory, it is worth to
>>                      # precondition the SCF cycle. The model dielectric
>>
>> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>> 2,computation of phonon band structures
>>
>> !Input file for the ifc code. Analysis of the CaF2 DDB
>> !Flags
>>  ifcflag   1     ! Interatomic force constant flag
>>
>> !Wavevector grid number 1 (coarse grid, from DDB)
>>  brav    2      ! Bravais Lattice : 1-S.C., 2-F.C., 3-B.C., 4-Hex.)
>>  ngqpt   4  4  4   ! 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    80      ! number of phonons in list 1
>>
>>  qph1l       0.00000000E+00  0.00000000E+00  0.00000000E+00  1.0
>>              5.00000000E-02  2.50000000E-02  2.50000000E-02  1.0
>>              1.00000000E-01  5.00000000E-02  5.00000000E-02  1.0
>>                  .........................................
>>              5.00000000E-01  4.50000000E-01  5.50000000E-01  1.0
>>              5.00000000E-01  4.75000000E-01  5.25000000E-01  1.0
>>              5.00000000E-01  5.00000000E-01  5.00000000E-01  1.0
>>
>> !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
>> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>> 3, output of LO-TO splitting.
>>     ........................................................
>>  Treat the second list of vectors
>> -begin at tcpu      0.470  and twall      0.957 sec
>>  Phonon at Gamma, with non-analyticity in the
>>  direction (cartesian coordinates)  1.00000  0.00000  0.00000
>>  Phonon energies in Hartree :
>>   0.000000E+00  0.000000E+00  0.000000E+00  1.634493E-03  1.634494E-03
>>   1.634498E-03  1.962988E-03  1.962988E-03  1.962990E-03
>>  Phonon frequencies in cm-1    :
>> -  0.000000E+00  0.000000E+00  0.000000E+00  3.587298E+02  3.587300E+02
>> -  3.587309E+02  4.308260E+02  4.308260E+02  4.308265E+02
>> +Total cpu time      0.470  and wall time      0.959 sec
>>  anaddb : the run completed succesfully.
>>
>> Regards,
>>
>> Tao
>>
>
>
>
> --
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Dr. Matthieu Verstraete
>
> European Theoretical Spectroscopy Facility (ETSF)
> Dpto. Fisica de Materiales,
> U. del Pais Vasco,
> Centro Joxe Mari Korta, Av. de Tolosa, 72,   Phone: +34-943018393
> E-20018 Donostia-San Sebastian, Spain        Fax  : +34-943018390
>
> Mail : matthieu.jean.verstraete@gmail.com
> http://www-users.york.ac.uk/~mjv500
>



-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Matthieu Verstraete

European Theoretical Spectroscopy Facility (ETSF)
Dpto. Fisica de Materiales,
U. del Pais Vasco,
Centro Joxe Mari Korta, Av. de Tolosa, 72,   Phone: +34-943018393
E-20018 Donostia-San Sebastian, Spain        Fax  : +34-943018390

Mail : matthieu.jean.verstraete@gmail.com
http://www-users.york.ac.uk/~mjv500