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[Hua Bao <hbao@purdue.edu>]

Dear Michel Cote,

Thank you for your suggestion.
I should have posted the input file here. I don't know why it doesn't work.

Below is the input file.

ndtset 2
xangst        0.0000000000E+00  0.0000000000E+00  0.0000000000E+00
             0.0000000000E+00  0.0000000000E+00  2.0099967960E+00
            -6.4731367782E-49  0.0000000000E+00  7.5046032040E+00
             0.0000000000E+00  1.8921000000E+00  2.3786500000E+00
             0.0000000000E+00  1.8921000000E+00  3.6865320396E-01
             0.0000000000E+00  1.8921000000E+00  4.3886467960E+00
             1.8921000000E+00  1.8921000000E+00  4.7573000000E+00
             1.8921000000E+00  1.8921000000E+00  6.7672967960E+00
             1.8921000000E+00  0.0000000000E+00  7.1359500000E+00
             1.8921000000E+00  3.2365683891E-49  9.1459467960E+00
             1.8921000000E+00  1.8921000000E+00  2.7473032040E+00
             1.8921000000E+00  0.0000000000E+00  5.1259532040E+00     



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 15.0         # 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 #Z

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

Michel Cote wrote:
> Hello,
>
> Since I cannot analyze your input file, you should really include it 
> in your question to the forum, I can suggest to change the convergence 
> factor. For band structure calculations starting from a well-converged 
> density, it is better to use tolwfr and set it to a small value. If 
> you use another convergence criterion, it might converge well the 
> lower bands but not the upper bands.
>
> Michel
>
>
> Le 07-07-09 à 17:04, hbao@purdue.edu <mailto:hbao@purdue.edu> a écrit :
>
> > Dear all,
> > I am using abinit to calculate band structure of anatase TiO2. The 
> > band gap is good and trends is good too. However, the bands are not 
> > smooth curves. Instead, they are fluctuating, especially at higher 
> > energy levels. What might be the reason for that?
>
> _____________________________________
> Michel Cote
> Departement de physique
> Universite de Montreal
> emai: Michel.Cote@umontreal.ca <mailto:Michel.Cote@umontreal.ca>
> web: http://www.phys.umontreal.ca/~michel_cote 
> <http://www.phys.umontreal.ca/%7Emichel_cote>