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[Hua Bao <hbao@purdue.edu>]

Dear Konstantin Rushchanskii and all,

Thank you for your suggestions.
I have two more questions here.
1.After I changed the ecut to 30, the band structure became 
unreasonable. I didn't see any band gap for the anatase TiO2. And it is 
supposed to have  a gap of 3.2eV even with LDA functional. Then what is 
the possible the problems here?

2. I checked the force result and find some forces are exactly zero. See 
below. It seems not correct here. What may lead to this result?
   1      0.00000000000000     0.00000000000000     0.00000000000000
   2      0.00000000000000     0.00000000000000     0.00748690006424
   3      0.00000000000000     0.00000000000000    -0.00748690006424
   4      0.00000000000000     0.00000000000000     0.00000000000000
   5      0.00000000000000     0.00000000000000    -0.00748690006424
   6      0.00000000000000     0.00000000000000     0.00748690006424
Thanks,
Hua

Input file,


ndtset 2
xangst        .......
ntypat 2                   
znucl 22 8
   
#Definition of the unit cell
acell  3.7842 3.7842 9.5146  angstrom  

#Definition of the atoms
natom 12           
typat  1 2 2 1 2 2 1 2 1 2 2 2        

#Definition of the planewave basis set
ecut 30.0         # Maximal kinetic energy cut-off, in Hartree
chkprim 0

#Dataset 1
kptopt1 1
ngkpt1 4 4 4
prtden1 1
toldfe1 1.0d-6
#Dataset 2
#Definition of the k-point grid
iscf2 -2
getden2 -1
kptopt2 -7                  # taken by default to be 0.0 0.0 0.0
nband2 64
ndivk2 21 21 21 21 21 21 21
kptbounds2  0.0 0.0 0.0 #gamma
          0.5 0.0 0.0 #X
          0.5 0.0 0.5 #R
          0.0 0.0 0.5 #Z
          0.0 0.0 0.0 #gamma
          0.5 0.5 0.0 #M
          0.5 0.5 0.5 #A
          0.0 0.0 0.5 #5

tolwfr2 1.0d-12
enunit2 1
prteig2 1
#Definition of the SCF procedure
nstep 100          # Maximal number of SCF cycles



Konstantin Rushchanskii wrote:
> Dear Hua Bao,
> > ecut 15.0         # Maximal kinetic energy cut-off, in Hartree
> ecut 15 Ha is very low for Ti and for O.
>
> If you use TM's pspnc pseudopotentials from abinit.org, the simplest 
> way to find the minimal cutoff is to look for the maximal value of 
> e99.9 parameter in the header of pseudopotential files.
> In your case it is 28.075 (the cut-off energy for p-orbital of oxygen).
>
> Regards,
> KR