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[<zhouy6@rpi.edu>]

Hi dear all,

I'm trying to calculate the GW correction at the K-point (0, 0.4157, 0.4157),
and I tried to use "standard" procedure by using ngkpt and nshiftk and shiftk
in the second DATASET.

but I kept seeing this error, seems that the "standard" method only works for
those grid points, not for an irregular k-point.

 cchi0 : ERROR -
  kp=k-q-G0 not found
 ik =    1 k =    -0.125000   -0.084300    0.040700
 k-q =          -0.375000   -0.252900    0.122100

 leave_new : decision taken to exit ...


Could someone help me find out what the problem is?

Thanks

Yu Zhou

============
here is my input file:

ndtset      4

kptopt   1
ngkpt    4 4 4

# Dataset1: usual self-consistent ground-state calculation
nshiftk1 4
shiftk1  0.5 0.5 0.5
         0.5 0.0 0.0
         0.0 0.5 0.0
         0.0 0.0 0.5
prtden1  1


# Dataset2: calculation of kss file
nshiftk2 4 
shiftk2  0.0 1.6628 1.6628
         0.0 2.1628 2.1628
         0.5 1.6628 2.1628
         0.5 2.1628 1.6628
istwfk2  60*1
iscf2    -2
getden2  -1
nband2   9
nbandkss2 -1

# Dataset3: Calculation of the screening (epsilon^-1 matrix)
optdriver3  3
getkss3     -1
nband3      25
ecutwfn3    3.6
ecuteps3    6.0
ppmfrq3    16.7 eV

# Dataset4: Calculation of the Self-Energy matrix elements (GW corrections)
optdriver4  4
getkss4     -2
getscr4     -1
nband4      100
ecutwfn4    5.0
ecutsigx4    6.0

nkptgw4      1
kptgw4
  0.000    0.4157    0.4157
bdgw4       4  5


# Definition of the unit cell: fcc
acell  3*10.217        # 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  1         # There is only one type of atom
znucl 14          # 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 1        # They both are of type 1, that is, Silicon.
xred              # Reduced coordinate of atoms
      0.0  0.0  0.0
      0.25 0.25 0.25

# Definition of the planewave basis set (at convergence 16 Rydberg 8 Hartree)
ecut 8.0          # Maximal kinetic energy cut-off, in Hartree

# Use only symmorphic operations
symmorphi 0

# Definition of the SCF procedure
nstep   10        # 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.
tolwfr  1.0d-10   

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