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[Eamonn Murray <emurray@physics.rutgers.edu>]

It seems that you have 32 electrons but nband2 is set to 14. That's
giving you the four missing electrons.


On Mon, 2008-05-19 at 18:23 +0200, wxw079000@utdallas.edu wrote:
> 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 ############