The ABINIT Users Mailing List ( CLOSED )

[Xavier Gonze <xavier.gonze@uclouvain.be>]

Dear Igor,

You do not mention your pseudopotential.
It is very important to use a Zr pseudopotential with semi-core state.
If I remember correctly, the one that had been used in the paper you  
mention
is the one in the table http://www.abinit.org/downloads/psp-links/psp-links/lda_ex 
 .

Also, please note that the DDB that had lead to this paper is actually
provided in the ABINIT package :
tests/v2/Input/t22.ddb.in.gz

You might find there interesting information about the parameters of  
the real calculation that was done...
Best wishes,
Xavier


On 12 Jan 2010, at 10:21, Igor Lukacevic wrote:

> Dear colleagues,
>
> I am having problems in reproducing the phonon dispersions in the  
> rocksalt phase of ZrO2 wrt the results obtained in F. Detraux et  
> al., prl 81, 3297 (1998):
>
> 1] I obtain many imaginary frequencies.
> 2] Acoustic mode(s) go imaginary, while the optical mode is the  
> unstable one.
>
> They have been using ecut 30 Ha and ngkpt 3*4, while I used ecut 60  
> Ha and ngkpt 3*6. Both psuedos have the same number of valence  
> electrons.
>
> I'm using abinit 5.8.4p, and I correct the output of mrgdbb (acell  
> and rprim) to be able to use brav=2 option in anaddb. My calcs  
> converge without warnings. I'm sending the inputs and the plot bellow.
>
> Could anyone give me a clue why this happens and how to improve my  
> calcs?
>
> Thank you all in advance!
>
> Yours,
>
> Igor Lukacevic
>
>
>
> ==================================
> RF phonon input
>
> # Crystalline ZrO2 - fluorite - cubic fcc - Fm-3m #225 : computation  
> of the phonon spectrum
>
>    ndtset   18
> #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
>
> #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   1.66666667E-01  0.00000000E+00  0.00000000E+00
>      qpt5   3.33333333E-01  0.00000000E+00  0.00000000E+00
>      qpt6   5.00000000E-01  0.00000000E+00  0.00000000E+00
>      qpt7   1.66666667E-01  1.66666667E-01  0.00000000E+00
>      qpt8   3.33333333E-01  1.66666667E-01  0.00000000E+00
>      qpt9   5.00000000E-01  1.66666667E-01  0.00000000E+00
>      qpt10 -3.33333333E-01  1.66666667E-01  0.00000000E+00
>      qpt11 -1.66666667E-01  1.66666667E-01  0.00000000E+00
>      qpt12  3.33333333E-01  3.33333333E-01  0.00000000E+00
>      qpt13  5.00000000E-01  3.33333333E-01  0.00000000E+00
>      qpt14 -3.33333333E-01  3.33333333E-01  0.00000000E+00
>      qpt15  5.00000000E-01  5.00000000E-01  0.00000000E+00
>      qpt16  5.00000000E-01  3.33333333E-01  1.66666667E-01
>      qpt17 -3.33333333E-01  3.33333333E-01  1.66666667E-01
>      qpt18 -3.33333333E-01  5.00000000E-01  1.66666667E-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 4-17 : 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*9.46
>    angdeg   90  90  90
>    brvltt  -1
>   spgroup   225
>
> #Definition of the atom types
>    ntypat   2
>     znucl   40 8 8
>
> #Definition of the atoms
>     natom   3
>     typat   1 2 2
>
>      xred   0.00  0.00  0.00
>             0.25  0.25  0.25
>             0.75  0.75  0.75
>
> #Gives the number of band, explicitely (do not take the default)
>     nband   14
>
> #Exchange-correlation functional
>
>       ixc   3
>
> #Definition of the planewave basis set
>
>      ecut   60
>
> #Definition of the k-point grid
>   nshiftk   4
>   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
>   ngkpt     3*6
>
> #Definition of the SCF procedure
>     iscf    7              # Use Pulay mixing sheme for SCF cycle
> npulayit    10             # Number of Pulay iterations
>   nnsclo    4              # Number of non-self consistent loops
>    nline    8              # Number of line minimisations
>
>   diemac    4
>
>
> ==================================
> anaddb input
>
> !Input file for the anaddb code. Analysis of the SiO2 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   3*6    ! 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   71     ! number of phonons in list 1
>
>   qph1l   0.0000  0.0000  0.0000   1.0    !(gamma point)
>           0.0375  0.0375  0.0750   1.0
>           0.0750  0.0750  0.1500   1.0
>           0.1125  0.1125  0.2250   1.0
>           0.1500  0.1500  0.3000   1.0
>           0.1875  0.1875  0.3750   1.0
>           0.2250  0.2250  0.4500   1.0
>           0.2625  0.2625  0.5250   1.0
>           0.3000  0.3000  0.6000   1.0
>           0.3375  0.3375  0.6750   1.0
>           0.3750  0.3750  0.7500   1.0    !(K point)
>           0.3875  0.3875  0.7750   1.0
>           0.4000  0.4000  0.8000   1.0
>           0.4125  0.4125  0.8250   1.0
>           0.4250  0.4250  0.8500   1.0
>           0.4375  0.4375  0.8750   1.0
>           0.4500  0.4500  0.9000   1.0
>           0.4625  0.4625  0.9250   1.0
>           0.4750  0.4750  0.9500   1.0
>           0.4875  0.4875  0.9750   1.0
>           0.5000  0.5000  1.0000   1.0    !(X point)
>           0.5500  0.5500  1.0000   1.0
>           0.6000  0.6000  1.0000   1.0
>           0.6500  0.6500  1.0000   1.0
>           0.7000  0.7000  1.0000   1.0
>           0.7500  0.7500  1.0000   1.0
>           0.8000  0.8000  1.0000   1.0
>           0.8500  0.8500  1.0000   1.0
>           0.9000  0.9000  1.0000   1.0
>           0.9500  0.9500  1.0000   1.0
>           1.0000  1.0000  1.0000   1.0    !(gamma point)
>           0.9500  0.9500  0.9500   1.0
>           0.9000  0.9000  0.9000   1.0
>           0.8500  0.8500  0.8500   1.0
>           0.8000  0.8000  0.8000   1.0
>           0.7500  0.7500  0.7500   1.0
>           0.7000  0.7000  0.7000   1.0
>           0.6500  0.6500  0.6500   1.0
>           0.6000  0.6000  0.6000   1.0
>           0.5500  0.5500  0.5500   1.0
>           0.5000  0.5000  0.5000   1.0    !(L point)
>           0.5000  0.4500  0.5000   1.0
>           0.5000  0.4000  0.5000   1.0
>           0.5000  0.3500  0.5000   1.0
>           0.5000  0.3000  0.5000   1.0
>           0.5000  0.2500  0.5000   1.0
>           0.5000  0.2000  0.5000   1.0
>           0.5000  0.1500  0.5000   1.0
>           0.5000  0.1000  0.5000   1.0
>           0.5000  0.0500  0.5000   1.0
>           0.5000  0.0000  0.5000   1.0    !(X point)
>           0.5000  0.0250  0.5250   1.0
>           0.5000  0.0500  0.5500   1.0
>           0.5000  0.0750  0.5750   1.0
>           0.5000  0.1000  0.6000   1.0
>           0.5000  0.1250  0.6250   1.0
>           0.5000  0.1500  0.6500   1.0
>           0.5000  0.1750  0.6750   1.0
>           0.5000  0.2000  0.7000   1.0
>           0.5000  0.2250  0.7250   1.0
>           0.5000  0.2500  0.7500   1.0    !(W point)
>           0.5000  0.2750  0.7250   1.0
>           0.5000  0.3000  0.7000   1.0
>           0.5000  0.3250  0.6750   1.0
>           0.5000  0.3500  0.6500   1.0
>           0.5000  0.3750  0.6250   1.0
>           0.5000  0.4000  0.6000   1.0
>           0.5000  0.4250  0.5750   1.0
>           0.5000  0.4500  0.5500   1.0
>           0.5000  0.4750  0.5250   1.0
>           0.5000  0.5000  0.5000   1.0    !(L point)
>
> !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
> # This line added when defaults were changed (v5.3) to keep the  
> previous, old behaviour
>   symdynmat 0
> <ZrO2_rocksalt_phon.eps>