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[<wxw079000@utdallas.edu>]

Dear all,

I tried to calculate the GaAs(001) surface by using GW approximation. But it
stopped when it finished
the second the error message is:too large difference in the number of
electrons. The following is the output file and input files. by the way, for
the test purpose, I used very low accurate parameter control. 

Any kind of advice is appreciated. Thanks.

####output file ######

timing point number   70
-cpu time  =       0.62 seconds
-real time =       0.62 seconds


 fermi : total number of electrons =    32

 fermi : input and calculated number of electrons differ by   4.00000000

 fermi : ERROR -
  Found too large difference in the number of electrons

 leave_new : decision taken to exit ...

##### input file ####
ndtset      4

kptopt   1            # Option for the automatic generation of k points
chkprim 0

# Dataset1: usual self-consistent ground-state calculation
# Definition of the k-point grid
ngkpt1   2 4 1        # Density of k points
nshiftk1 2
shiftk1 0.5 0.0 0.0
       0.0 0.5 0.0
prtden1  1         # Print out density

# Dataset2: calculation of kss file
# Definition of k-points
ngkpt2   2 4  1     # Density of k points
nshiftk2 2
shiftk2 0.0 0.0 0.0
       0.5 0.5 0.0

iscf2    -2             # Non self-consistent calculation
getden2  -1             # Read previous density file
nband2   14
nbandkss2 50        # Number of bands to store in KSS file
 prtvol2=2
istwfk2  8*1

# Dataset3: Calculation of the screening (epsilon^-1 matrix)
optdriver3  3        # Screening calculation
getkss3     -1       # Obtain KSS file from previous dataset
nband3      50      # Bands to be used in the screening calculation
ecutwfn3    3.0      # Planewaves to be used to represent the wavefunctions
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       50     # Bands to be used in the Self-Energy calculation
ecutwfn4    3.0      # Planewaves to be used to represent the wavefunctions
ecutsigx4   3.0      # 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
 0.0 0.0 0.0
prtdos4 3
bdgw4   16 17
acell  3*10.686
rprim  1.0  -1.0  0.0   # FCC primitive vectors (to be scaled by acell)
       0.5  0.5  0.0
       0.0  0.0  2.769

# Definition of the atom types
ntypat  2         # There is only one type of atom
znucl   31 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 8           # There are two atoms
typat  4*1 4*2        # They both are of type 1, that is, Silicon.
xred              # Reduced coordinate of atoms
     #0.0  0.0  0.0
     #0.5 0.0 0.0
      0.0 0.0 0.3611448
      0.5 0.0 0.3611448
      0.25 0.50 0.1805724
      0.75 0.50 0.1805724
      0.00 0.50 0.0902862
      0.50 0.50 0.0902862
      0.250 0.0 0.2708586
      0.750 0.0 0.2708586

# Definition of the planewave basis set (at convergence 16 Rydberg 8 Hartree)
ecut 4.0          # Maximal kinetic energy cut-off, in Hartree

# Use only symmorphic operations
symmorphi 0
nstep   50        # Maximal number of SCF cycles
diemac  13.00     # 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
  ixc 7 7
######### end input file ############