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[matthieu verstraete <Matthieu.Verstraete@ulg.ac.be>]

---------- Forwarded message ----------
From: matthieu verstraete <Matthieu.Verstraete@ulg.ac.be>
Date: Thu, Dec 17, 2009 at 11:15 AM
Subject: Re: [abinit-forum] phonons in cubic ZrO2
To: forum@abinit.org


How much are you breaking the acoustic sum rule at the Gamma point?
You should try with rfasr 1 in abinit, and then also with asr=1 or 2
in anaddb

Matthieu

PS: if your qpoint grid is a subgrid of your k-point grid (eg 4x4x4q
for 12x12x12k), you don't need to do the WFQ calculation, just specify
getwfk.

also, no need for rfdir?3   1 1 1  - rfdir only has meaning for rf 
calculations.

On Thu, Dec 17, 2009 at 10:00 AM,  <ilukacevic@fizika.unios.hr> wrote:
> Dear colleagues.
>
> I am trying to reproduce the phonon calculations done by [1] and [2] in the
> cubic ZrO2. However, I am unable to reproduce the phonon frequencies 
> correctly:
>
> 1] I do not reproduce the soft optical mode at the X ponit of the BZ.
> 2] I do not reproduce the degeracy of the 2 acoustic modes at the X point.
> 3] All 3 acoustic modes are unstable in my calcs at the X point.
>
> This is an insert from the one of my outputs for the phonons at the X point
>
>  Phonon frequencies in cm-1    :
> - -5.078229E+02 -4.244537E+02 -1.864653E+02  3.341160E+02  3.655486E+02
> -  4.372096E+02  6.722486E+02  7.056660E+02  7.798493E+02
>
>
> I am using Teters' LDA psps for Zr and O (from abinit web site) which 
> include
> 12 and 6 valence electrons respectively. I have checked the convergence with
> respect ot ecut and ngkpt until phonon freq. are converged under 1 cm^-1. I 
> do
> not obtain any serious warning in my calcs, except that the last occ is 2.00
> (but I think that does not influence the result since cubic ZrO2 is an
> isolator).
>
> I would appreciate any hints and help concernig this problem. An example of 
> my
> input files is given bellow. I am using abinit 5.8.4 on a Linux Debian 
> cluster.
>
> Thank you all in advance.
>
> Yours
> Igor Lukacevic
>
>
> Refs
>
> [1] Phys. Rev. Lett. 81, 3297 (1998)
> [2] Phys. Rev. Lett. 78, 4063 (1997)
>
>
> Input file
>
> #ZrO2 crystal; fcc
> #phonons at X point
>
>  ndtset     4
>  acell      3*9.46
>
>  #DATASET 1
>  prtden?1  1
>  kptopt?1  1
>  tolvrs?1  1.0d-19
>  nstep?1   80
>
>  #DATASET 2
>  iscf?2   -2
>  nqpt?2    0
>  getwfk?2 -1
>  getden?2 -1
>  tolwfr?2  1.0d-20
>  nstep?2   400
>
>  #DATASET 3
>  getden?3 -2
>  getwfk?3 -1
>  iscf?3   -2
>  nqpt?3    1
>  qpt?3     0.50d0  0.50d0  0.0d0
>  rfdir?3   1 1 1
>  tolwfr?3  1.0d-20
>  nstep?3   400
>
> #DATASET 4
>  getwfk?4 -2
>  getwfq?4 -1
>  nqpt?4    1
>  qpt?4     0.50d0  0.50d0  0.0d0    #X point on the fcc BZ
>  rfatpol?4 1  2
>  rfdir?4   1 1 1
>  rfphon?4  1
>  tolvrs?4  1.0d-6
>  nstep?4   25
>
> #Common data****************
>
>  ixc       3
>  kptopt    3
>  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*10
>   ecut     40
>
> #structure
>
>  angdeg    90  90  90
>  brvltt   -1
>  occopt    1
>  ntime     30
>  nstep     40
>  spgroup   225
>  natom     3
>  nband     12
>  ntypat    2
>  typat     1 2 2
>  xred      0.00  0.00  0.00
>            0.25  0.25  0.25
>            0.25  0.25  0.75
>  znucl     40 8 8
>
>    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
>
>  timopt    2
>



--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. Matthieu Verstraete

Universite de Liège
Institut de Physique, Bat. B5, 3/7
Allée du 6 aout, 17
B- 4000 Sart Tilman, Liège
Belgium

Associate member European Theoretical Spectroscopy Facility (ETSF
http://www.etsf.eu)

Phone : +32 4 366 90 17
Fax   : +32 4 366 36 29

Mail : matthieu.verstraete@ulg.ac.be
         matthieu.jean.verstraete@gmail.com



-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. Matthieu Verstraete

Universite de Liège
Institut de Physique, Bat. B5, 3/7
Allée du 6 aout, 17
B- 4000 Sart Tilman, Liège
Belgium

Associate member European Theoretical Spectroscopy Facility (ETSF
http://www.etsf.eu)

Phone : +32 4 366 90 17
Fax   : +32 4 366 36 29

Mail : matthieu.verstraete@ulg.ac.be
          matthieu.jean.verstraete@gmail.com