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["Dr. Savita Pundalik" <psavita@crlindia.com>]

Hello,

Thanks for your suggestion, I shall try that.

Regards
Savita Pundlik

-----Original Message-----
From: Fabien Bruneval [mailto:fabien.bruneval@cea.fr]
Sent: Wed 4/9/2008 12:58 PM
To: forum@abinit.org
Subject: Re: [abinit-forum] Band Gap calculations on Alumina

Dear Dr. Pundalik,

You should be able to determine from the log file, where exactly the
code stopped. I guess it is in the dataset 2.
The problem is that the screening and then the sigma calculations
require a regular k-point grid.
In your input, the k-point grid looks quite weird:

ngkpt 4 4 4

nshiftk 1

shiftk 0.5 0.5 0.0
       0.5 0.0 0.0
       0.0 0.5 0.0
       0.0 0.0 0.5

You set the number of shifts to 1 and then you provide 4 of them...
I advise you to use only one single shift. The shift being either 0.5
0.5 0.5 or 0. 0. 0. (if you want that the special points belong to the grid)

Have good GW calculations!

Fabien


Dr. Savita Pundalik wrote:
>
> Hello,
>
> I am trying to compute correct band gap in alpha-al2o3 using GW
> calculations.
> I did cell and geometry optimization for the rhombihedral structure
> with ecut 18 a.u.
> Thereafter I want to know the correct band gap.
> Since I am not very familiar, I have given some arbitrary inputs.
> The program stops during perhaps the dataset3. Is something wrong with
> the choice
> of k point in kptgw3?
>
> Thenks in advance for any help - Savita Pundlik : psavita@crlindia.com
>
> The input file and the error message follow:
> Input file -
> #  alumina : computation of the GW correction
> #
>
> 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)
> nband1      30         # Number of (occ and empty) bands to be computed
> istwfk1     32*1
> #kssform 3
>
> # Calculation of the screening (epsilon^-1 matrix)
> optdriver2  3        # Screening calculation
> getkss2     -1       # Obtain KSS file from previous dataset
> nband2      30       # Bands to be used in the screening calculation
> ecutwfn2    4.1      # Cut-off energy of the planewave set to
> represent the wavefunctions
> ecuteps2    5.6      # Cut-off energy of the planewave set to
> represent the dielectric matrix
> ppmfrq2    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
> #  -0.125    0.000    0.000
>   0.125    0.125    0.000
> bdgw3       14  15             # calculate GW corrections for bands
> from 14 to 15
>
>
> #Definition of the unit cell
>      acell    9.8198960592E+00  9.8198960592E+00  9.8198960592E+00 Bohr
>      rprim    5.4345588122E-01  0.0000000000E+00  8.3943773156E-01
>              -2.7172794061E-01  4.7064659897E-01  8.3943773156E-01
>              -2.7172794061E-01 -4.7064659897E-01  8.3943773156E-01
>
> #Definition of the atom types
> ntypat 2          # There is only one type of atom
> znucl 8 13          # 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 10                           # There are two atoms
> typat 1 1 1 1 1 1 2 2 2 2         # They both are of type 1, that is,
> Silicon.
> xred                              # This keyword indicate that the
> location of the atoms
>
>               5.5241111072E-01 -5.2411110717E-02  2.5000000000E-01
>               2.5000000000E-01  5.5241111072E-01 -5.2411110717E-02
>              -5.2411110717E-02  2.5000000000E-01  5.5241111072E-01
>              -5.5241111072E-01  5.2411110717E-02 -2.5000000000E-01
>              -2.5000000000E-01 -5.5241111072E-01  5.2411110717E-02
>               5.2411110717E-02 -2.5000000000E-01 -5.5241111072E-01
>               3.5278324003E-01  3.5278324003E-01  3.5278324003E-01
>               1.4721675997E-01  1.4721675997E-01  1.4721675997E-01
>              -3.5278324003E-01 -3.5278324003E-01 -3.5278324003E-01
>               8.5278324003E-01  8.5278324003E-01  8.5278324003E-01
>
> #Definition of the planewave basis set
> ecut  18.0         # Maximal kinetic energy cut-off, in Hartree
>
> #Definition of the k-point grid
> kptopt 1          # Option for the automatic generation of k points,
> taking
>                   # into account the symmetry
> #nkpt 10
> ngkpt 4 4 4
>
> nshiftk 1
>
> shiftk 0.5 0.5 0.0
>        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 SCF procedure
> nstep 10          # Maximal number of SCF cycles
> toldfe 1.0d-6     # Will stop when, twice in a row, the difference
>                   # between two consecutive evaluations of total energy
>                   # differ by less than toldfe (in Hartree)
> 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.
> iscf 5
>
>
>
>
> Error message -
> cchi0 : enter
>
>
>  wfrk in real space are in memory
>   use symmetries    =            0
>   use time reversal =  F
>   spectral method   =            0
>  calculating chi0(q,omega,G,G")
>
>  calculation status (    192 to be completed) :
>  cchi0 : ik =      1 /    192   is =  1  done by processor      0
>  cchi0 : ik =      2 /    192   is =  1  done by processor      0
>
>  cchi0 : ERROR -
>   kp=k-q-G0 not found
>  ik =    3 k =     0.125000    0.000000    0.125000
>  k-q =           0.250000    0.000000    0.000000
> -P-0000
> -P-0000  leave_new : decision taken to exit ...
> srun: error: n102: task[1,5]: Exited with exit code 1
> srun: Terminating job
> srun: error: n103: task14: Exited with exit code 1
> srun: error: n312: task67: Exited with exit code 1
> srun: error: n102: task0: Exited with exit code 1
>
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