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

Title: Band Gap calculations on Alumina

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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