The ABINIT Users Mailing List ( CLOSED )

[Riad Shaltaf <shaltaf@pcpm.ucl.ac.be>]

Dear Xiao Deng,

This is normal as you are trying to calculate the gap at k point that
does not exist in your KSS band structure. To calculate the GW
correction at specific k point, you must provide the LDA/GGA energies
and wavefunctions for that point, which is practically included in the
KSS file. The KSS file that you have calculated does not include Gamma
point. In order to include it you must avoid using shifted k point grid.
This is explained in the tutorial.

best regards

Riad

On Thu, 2006-09-14 at 17:17 +0800, Huiyong Deng wrote:
> Dear Abinit user,
>  
> Employing the GW approximation, these days, I've be calculating the
> InAs band gap (about 0.34eV). However, the calculation doesn't go on
> afer calculating the KSS files, and there is no tips about ERRORs.What
> 's wrong with me?  Can you help me? The input file and .files are as
> following. Thank you very much!
>  
> InAs. files
> --------------
> InAs.in
> InAs.out
> InAsi
> InAso
> InAs
> ../../abinit-4.6.5/Psps_for_tests/lda_fhi/49-In-4d.LDA.fhi
> ../../abinit-4.6.5/Psps_for_tests/lda_fhi/33-As.LDA.fhi
> ===========================
> InAs.in
> ---------------------------
> ndtset      3
> 
> # Definition of parameters for the calculation of the KSS file 
> nbandkss1   -1         # Number of bands in KSS file (-1 means the
> maximum possible)
> 
> kssform 1          #added
> 
> nband1      9         # Number of (occ and empty) bands to be computed
> istwfk1      10*1
> 
> #mpspso 1     #added
> 
> 
> # Calculation of the screening (epsilon^-1 matrix)
> optdriver2  3        # Screening calculation
> getkss2     -1       # Obtain KSS file from previous dataset
> nband2      17       # Bands to be used in the screening calculation
> ecutwfn2    2.1      # Cut-off energy of the planewave set to
> represent the wavefunctions 
> ecuteps2    3.6      # Cut-off energy of the planewave set to
> represent the dielectric matrix
> plasfrq2    16.7 eV  # Imaginary frequency where to calculate the
> screening
> 
> # Calculation of the Self-Energy matrix elements (GW corrections)
> optdriver3  4        # Self-Energy calculation
> getkss3     -2       # Obtain KSS file from dataset 1
> getscr3     -1       # Obtain SCR file from previous dataset
> nband3      30       # Bands to be used in the Self-Energy calculation
> ecutwfn3     5.0     # Planewaves to be used to represent the
> wavefunctions
> ecutsigx3     6.0     # Dimension of the G sum in Sigma_x
>                      # (the dimension in Sigma_c is controlled by
> npweps) 
> nkptgw3      1                # number of k-point where to calculate
> the GW correction
> kptgw3                       # k-points
>   0    0.000    0.000
> bdgw3       4  5             # calculate GW corrections for bands from
> 4 to 5
> 
> 
> # Data common to the three different datasets
> 
> # Definition of the unit cell: fcc
> acell  3*11.4        # This is equivalent to   10.217 10.217 10.217
> rprim  0.0  0.5  0.5   # FCC primitive vectors (to be scaled by acell)
>        0.5  0.0  0.5   
>        0.5  0.5  0.0
> 
> # Definition of the atom types
> ntypat  2         # There is only one type of atom
> znucl 49 33          # The keyword "znucl" refers to the atomic number
> of the 
>                   # possible type(s) of atom. The pseudopotential(s) 
>                   # mentioned in the "files" file must correspond
>                   # to the type(s) of atom. Here, the only type is
> Silicon.
>                          
> # Definition of the atoms
> natom 2           # There are two atoms
> typat  1 2        
> 
> xred              # Reduced coordinate of atoms 
>       0.0  0.0  0.0
>       0.25 0.25 0.25
> 
> 
> # Definition of the k-point grid 
> kptopt  1            # Option for the automatic generation of k
> points,
> nkpt    10
> ngkpt   4 4 4  
> nshiftk 4
> shiftk  0.5 0.5 0.5  # These shifts will be the same for all grids
>         0.5 0.0 0.0
>         0.0 0.5 0.0
>         0.0 0.0 0.5
> 
> # Use only symmorphic operations 
> symmorphi 0
> 
> # Definition of the planewave basis set (at convergence 16 Rydberg 8
> Hartree)
> ecut 23          # Maximal kinetic energy cut-off, in Hartree
> 
> # Definition of the SCF procedure 
> nstep   20        # Maximal number of SCF cycles
> toldfe  1.0d-6    # Will stop when this tolerance is achieved on total
> energy
> diemac  12.0      # Although this is not mandatory, it is worth to
>                   # precondition the SCF cycle. The model dielectric
>                   # function used as the standard preconditioner
>                   # is described in the "dielng" input variable
> section.
>                   # Here, we follow the prescription for bulk silicon.
> 
> 
> 
>  
> ===================
> Sincerely
> Xiao Deng
-- 
Riad Shaltaf                       UCL/SE/FSA/MAPR/PCPM
Tel: +32 (0)10 47 28 50            Bâtiment Boltzmann, a+1
Fax: +32 (0)10 47 34 52            1 place Croix du Sud
Mel: shaltaf@pcpm.ucl.ac.be        1348 Louvain-la-Neuve (Belgique)