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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hi,

1) Why do you expect LDA to give you the correct bad gap ?
2) Are 10 scf steps enough to converge your calculation ?
3) How do you calculate the band gap ?

regards

PMA

On 5/1/07, taoj0003@ntu.edu.sg <taoj0003@ntu.edu.sg> wrote:
> Dear abinit user
>
> I used abinit to calcualte the band structure of rutile tio2. The band gap I 
> get is around 5.3eV(9.17179-3.90134), while the experiment value is around 
> 3.2eV. I am very confused about this. Can any me help me check my input file?
> Also the appropate output file is given. (The kpt I am giving is called #17, 
> but I confirm I checked all the kpt.) btw, the pseudopotetials I am using are 
> ti_ps.abinit.paw.lda and o_ps.abinit.paw.lda.nocore. I am always thinking 
> maybe it's the pseudopotetials. Can any one help check this?
> -----------------
> input file
> ------------------
> ndtset 2
>
> #Dataset 1 : usual self-consistent calculation
> kptopt1 1
> ngkpt1  4 4 6
> prtden1  1
> toldfe1  1.0d-6
>
> #Dataset 2 : the band structure
> iscf2    -2
> getden2  -1
> kptopt2  -2
> nband2   32
> ndivk2     18 14
> kptbounds2
>              0.0  0.5  0.5   # R point
>              0.0  0.0  0.0 # Gamma point
>              0.5  0.5  0.0 # M point
>
> tolwfr2  1.0d-12
> enunit2  1             # Will output the eigenenergies in eV
>
> acell 2*4.595 2.9589 angstrom
> ntypat 2
> znucl 22 8
>
> natom 6
> typat 1 1 2 2 2 2
> xred
>   0.00000000  0.00000000   0.00000000      #Ti
>   0.50000000  0.50000000   0.50000000      #Ti
>   0.30530000  0.30530000   0.00000000      #O
>   -0.30530000 -0.30530000  0.00000000      #O
>   0.80530000  0.19470000   0.50000000      #O
>   0.19470000  0.80530000   0.50000000      #O
>
> #Definition of the planewave basis set
> ecut 20.0         # Maximal kinetic energy cut-off, in Hartree
>
> #Definition of the SCF procedure
> nstep 10          # Maximal number of SCF cycles
> diemac 2.0
>
> -------------------------------
> the output file:
> -----------------------------
> kpt#  17, nband= 32, wtk=  1.00000, kpt=  0.0000  0.0556  0.0556 (reduced 
> coord)
>  -58.25568 -58.24540 -22.95254 -22.95190 -22.41545 -22.41462 -22.33658 
> -22.24695  -14.01464 -12.73354 -11.18070 -11.17093  -1.71983  -0.89610  
> -0.83583   0.58022    0.58350   2.02542   2.04408   2.50084   3.33573   
> 3.51918   3.52216   3.90134           9.17179   9.49369  10.42985  10.81380  
> 10.81895  12.04120  13.00632  13.58343


--
Pierre-Matthieu Anglade