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[Chao Cao <cao@qtp.ufl.edu>]

I don't know about this kind of material, but is it a highly correlated 
material? In that case, no DFT would give you correct band structure or 
DOS. You'll have to use LDA+U or GW correction. Since Se is chemically 
close to O, and TiO2 is typical Mott insulator, I would think it's very 
probable.

Chao Cao

tianmiao8287@163.com wrote:
> dear sir,
>     Last question(BaVSe3  band  gap) is my classmate who asks instead of 
> me.He don't understand my meaning.I am sorry about that.
> There is a problem puzzled me for a long time.The material is 
> BaV(1-x)Ti(x)S3.when x=0.8,it is a semiconductor.But the band gap I get is still zero,it is still metallic.I don't know why it is.By the way ,the  DOS still indicates that it is  metallic.The unmixing material is BaVS3,which is metallic.There are 10 atoms in a unit cell.The crystal structure is hexagonal.The space group is 194.The input file is as follows:
>
> # Computation of the band structure.
> # First, a SCF density computation, then a non-SCF band structure calculation.
>
> ndtset 2
> prtwf2 0
> #Dataset 1 : usual self-consistent calculation
> kptopt1 1          # Option for the automatic generation of k points,
>                    # taking into account the symmetry
> nshiftk1 1
> shiftk1  0.0 0.0 0.5
> ngkpt1  8 8 8 
> prtden1  1         # Print the density, for use by dataset 2
> toldfe1  1.0d-10
> nband1   60
> #Dataset 2 : the band structure
> iscf2    -2
> getden2  -1
> kptopt2  -7
> nband2   60
> ndivk2    50 50 50 50 50 50 50   # 10, 12 and 17 divisions of the 3 segments, 
> delimited
> nkpt2 351                       # by 4 points.
> prtvol2 10
> kptbounds2  0.0 0.0 0.0
>             1/3 1/3 0.0
>             1/2 0.0 0.0
>             0.0 0.0 0.0
>             0.0 0.0 0.5
>             1/3 1/3 0.5
>             0.5 0.0 0.5
>             0.0 0.0 0.5
> tolwfr2  1.0d-16
> enunit2  1             # Will output the eigenenergies in eV 
>
> #Definition of the unit cell
> acell 12.74053353 12.74053353 10.85836631      
> rprim  -sqrt(0.75)  1/2  0
>              0  -1    0
>               0      0      1
>
>
>
> npsp 4
> ntypat 3          # There is only one type of atom
> znucl 56 16 23 22                         
> ntypalch 1
> mixalch  0.2 0.8
> algalch 1
> ntyppure 2
> npspalch 2
>         
> #Definition of the atoms
> natom 10           # There are two atoms
> typat 1 1 2 2 2 2 2 2 3 3        
> xred       
>  1/3 2/3 3/4
>  2/3 1/3 1/4
>  5/6 2/3 3/4
>  1/3 1/6 3/4
>  5/6 1/6 3/4
>  2/3 5/6 1/4
>  1/6 1/3 1/4
>  1/6 5/6 1/4
>  0.0 0.0 1/2
>  0.0 0.0 0.0
> occopt 1
> #Definition of the planewave basis set
> ecut 55         # Maximal kinetic energy cut-off, in Hartree
>
> #Definition of the SCF procedure
> nstep 300          # Maximal number of SCF cycles
> diemac 12  
>