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

Check your ground state output to see what the spectrum looks like. I
suspect you will find the system actually is metallic.

If not, it happens quite frequently that a perturbation makes it
metallic, especially if the gap is very small. This makes convergence
quite difficult (you might try changing diemac for the phonon runs, I
think iprcel does not work for RF). You could also try to change
occopt for the phonon runs, but again you will find it refuses to
allow the LO-TO splitting calculation at some point... If your system
has a large gap none of this should be happening. Check geometries and
compostition etc... Maybe the pseudopotentials have a ghost state...

Which dataset is crashing?

Matthieu



On Fri, Apr 3, 2009 at 12:43 PM,  <gaotaoscu@hotmail.com> wrote:
> Dear All,
>
> I get some contradictory suggestions from the phonon calculation error
> displayed in ABINIT. On the one hand, my oxide compund(insulator) request 
> the
> 'occopt 1', otherwise there will have no LO-TO splitting. However, when the
> 'occopt 1' option were filled in the input file, the calculation error will
> suggest you to 'change occopt, consistently, in GS and RF calculations'. 
> Will
> you have any suggestion on this problem? Thank you very much in advance.
>
> Best,
>
> Tao
>
> PS, here is my input file. and error displayed.
> 1) input file,
> # Crystalline : 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
>  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
>    acell   3*10.349007457  Bohr         # 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 is tow type of atom
>   znucl ---   ---      # The keyword "znucl" refers to the atomic number of
> the
>
> #Definition of the atoms
>   natom 3           # There are two atoms
>   typat 1 2 2         # They both are of type 1, that is, Silicon.
>   xred              # This keyword indicate that the location of the atoms
>                  # 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   12
>    occopt 1
> #Exchange-correlation functional
>
>      ixc   11             # LDA Teter Pade parametrization
>
> #Definition of the planewave basis set
>
>     ecut   28.0
> #Definition of the k-point grid
>    ngkpt   4  4  4
>    nshiftk   4              # Use one copy of grid only (default)
>    shiftk 0.5 0.5 0.5
>          0.5 0.0 0.0
>          0.0 0.5 0.0
>          0.0 0.0 0.5
>
> #Definition of the SCF procedure
>     iscf   7          # Self-consistent calculation, using algorithm 5
>     nline  15
>    nstep   1000         # Maximal number of SCF cycles
>   diemac   12.0        # Although this is not mandatory, it is worth to
>                       # precondition the SCF cycle. The model dielectric
>
> 2) error displayed,
>
>     iter   2DEtotal(Ha)        deltaE(Ha) residm    vres2
>  scfcv3, nstep=        1000
>
>  getcut: wavevector=  0.0000  0.0000  0.0000  ngfft=  36  36  36
>         ecut(hartree)=     28.000   => boxcut(ratio)=   2.06526
>  scfcv3, nstep=        1000
> -P-0000  occeig : ERROR -
> -P-0000   In a non-metallic case (occopt<3), for a RF calculation,
> -P-0000   if the eigenvalues are degenerate, the occupation numbers must 
> also
> be degenerate.
> -P-0000   However, the following pair of states gave :
> -P-0000   k -state, band number   9, occ=    2.000000E+00, eigenvalue=
> -2.507767E-01,
> -P-0000   kq-state, band number  10, occ=    0.000000E+00, eigenvalue=
> -2.507767E-01.
> -P-0000   Action : change occopt, consistently, in GS and RF calculations.
> -P-0000
> -P-0000  leave_new : decision taken to exit ...
> -P-0000  leave_new : synchronization done...
> -P-0000  leave_new : exiting...
>



-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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