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[<us_sophie.green@yahoo.com>]

Dear all,

I am beening troubled with some mistakes in GW calculation. The follows is
mistake and warning message in the log file:

scfcge: WARNING -
  Potential-based CG line minimization has trouble to converge.
  The algorithm is restarted with more secure parameters.
 scfcge: actual    20-9-1   1.5928E-01 -4.654626213488E+00  1.5508E-13
 scfcge: predict           -1.1244E+00 restart the algorithm
 scfcge:
 scfcge: start    20-10-0   0.0000E+00 -4.654626213488E+00  1.5508E-13


scfcge : ERROR -
  Potential-based CG line minimization not converged after 13 restarts.
  Action : read the eventual warnings about lack of convergence.
  Some might be relevant. Otherwise, raise nband.

#############################################
I have increased the nband in the input file, but the error message still
appeared.

The input file is as follows:

ndtset      4
kptopt   1            # Option for the automatic generation of k points
ngkpt    12 12 12        # Density of k points

nkpt1    468
nshiftk1  1
shiftk1  0.5 0.5 0.5  # This grid is the most economical
prtden1  1         # Print out dens

nkpt2  468
nshiftk2  1
shiftk2  0.5 0.5 0.5  # This grid is the most economical
istwfk2  468*1
iscf2    -2             # Non self-consistent calculation
getden2  -1             # Read previous density file
nband2   13
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      100       # Bands to be used in the screening calculation
ecutwfn3    40.0      # Planewaves to be used to represent the wavefunctions
ecuteps3    40.0      # 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
getkss4     -2       # Obtain KSS file from dataset 1
getscr4     -1       # Obtain SCR file from previous dataset
nband4      25      # Bands to be used in the Self-Energy calculation
ecutwfn4    35.0      # Planewaves to be used to represent the wavefunctions
ecutsigx4    30.0      # 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
    0.25   0.25    0.25
bdgw4       6  7             # calculate 
ecut 70.0          # Maximal kinetic energy cut-off, in Hartree

# Use only symmorphic operations
symmorphi 0

# Definition of the SCF procedure
nstep   30        # 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-8

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

##########################################
If anyone has such experience, please instruct me. Thanks in advance.