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[<manhquank9@gmail.com>]

Dear Abinit users

I am learning about the band gap of TiO2. I have read the GW approximation
tutorial and have finished it. But when I tested with TiO2, there are some
problems

1. When only add only nbandkss -1 to get KSS file, abinit only read input 
file,
stop and return no error

# Computation of the total energy

#Definition of the k-point grids
kptopt 1          # Option for the automatic generation of k points, taking
into account the symmetry
nshiftk 1
shiftk 0.5 0.5 0.5
ngkpt 2 2 2
nbandkss -1

#Definition of the unit cell
acell 8.6814 8.6814 5.5917         

#Definition of the atom types
ntypat 2          # There is only one type of atom
znucl 22 8       # 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.
                        

#Definition of the atoms
natom 6           # There are six atoms
typat 1 1 2 2 2 2       
xangst 0.000 0.000 0.000
       2.297 2.297 1.480
       1.400 1.400 0.000
       3.194 3.194 0.000
       0.897 3.697 1.480
       3.697 0.897 1.480
#Definition of the planewave basis set
ecut  40.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
nstep 100         # Maximal number of SCF cycles
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.
toldfe 1e-6
ixc 11

Second, when I only change some numbers from the tgw1_9.in (Tutorial) just to
fit with TiO2, abinit only read input file, stop and return no error

# Calculation of the GW correction to the direct band gap in Gamma
# Dataset 1: ground state calculation
# Dataset 2: calculation of the kss file
# Dataset 3: calculation of the screening (epsilon^-1 matrix for W)
# Dataset 4: calculation of the Self-Energy matrix elements (GW corrections)

ndtset      4

kptopt   1            # Option for the automatic generation of k points
ngkpt    2 2 2        # Density of k points

# Dataset1: usual self-consistent ground-state calculation
# Definition of the k-point grid
nkpt1    3
nshiftk1  1
shiftk1  0.5 0.5 0.5  # This grid is the most economical
prtden1  1              # Print out density


# Dataset2: calculation of kss file
# Definition of k-points
nkpt2    14                # A set of 14 k-points containing Gamma
nshiftk2  4
shiftk2  0.0 0.0 0.0    # This grid contains the Gamma point
         0.0 0.5 0.5
         0.5 0.0 0.5
         0.5 0.5 0.0
istwfk2  14*1                    # Option needed for Gamma
iscf2    -2             # Non self-consistent calculation
getden2  -1             # Read previous density file
nband2   40
nbandkss2 100           # Number of bands to store in KSS file

# Dataset3: Calculation of the screening (epsilon^-1 matrix)
optdriver3  3        # Screening calculation
getkss3     -1       # Obtain KSS file from previous dataset
nband3      40       # Bands to be used in the screening calculation
ecutwfn3    3.6      # Planewaves to be used to represent the wavefunctions
ecuteps3    6.0      # Dimension of the screening matrix
ppmfrq3    16.7 eV  # Imaginary frequency where to calculate the screening

# Dataset4: Calculation of the Self-Energy matrix elements (GW corrections)
optdriver4  4        # Self-Energy calculation
getkss4     -2       # Obtain KSS file from dataset 1
getscr4     -1       # Obtain SCR file from previous dataset
nband4      100      # Bands to be used in the Self-Energy calculation
ecutwfn4    5.0      # Planewaves to be used to represent the wavefunctions
ecutsigx4   6.0      # Dimension of the G sum in Sigma_x
                     # (the dimension in Sigma_c is controlled by npweps)
nkptgw4      1                # number of k-point where to calculate the GW
correction
kptgw4                       # k-points
  0.000    0.000    0.000    # (Gamma)
bdgw4       24  25             # calculate GW corrections for bands from 4 to 
5

#Definition of the unit cell
acell 8.6814 8.6814 5.5917         

#Definition of the atom types
ntypat 2          # There is only one type of atom
znucl 22 8          # 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.

#Definition of the atoms
natom 6           # There are six atoms
typat 1 1 2 2 2 2       
xangst 0.000 0.000 0.000
       2.297 2.297 1.480
       1.400 1.400 0.000
       3.194 3.194 0.000
       0.897 3.697 1.480
       3.697 0.897 1.480

#Definition of the planewave basis set
ecut  40.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
nstep 100         # Maximal number of SCF cycles
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.
toldfe  1.0d-6

# Use only symmorphic operations
symmorphi 0

# This line added when defaults were changed (v5.3) to keep the previous, old
behaviour
  iscf 5

And third, I have used Abinit in Linux and Windows and tried to do the GW
Tutorial, but sometimes, Abinit run and stop without error. Do abinit have 
some
bugs with GW approximation?

Best regarded
Quan Phung Manh
-- 
Quan Phung Manh
Khoa Hoa hoc - Dai hoc Khoa hoc tu nhien
ĐT: 0906263816