The ABINIT Users Mailing List ( CLOSED )

[Alex Huang <alex.zhen.huang@gmail.com>]

Dear users and developers-

I am calculating Response Function of Graphene Nanoribbon. Seems the SCF
calculation is hard to converge. Can you help me look at why is it?

Thanks for helping
Warnings-
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
 scfcge: WARNING -
  Potential-based CG line minimization has trouble to converge.
  The algorithm is restarted with more secure parameters.
 scfcge: actual    13-6-1   4.1250E-01 -4.501096672356E+01  7.9239E-01
 scfcge: predict           -6.6216E-01 restart the algorithm
 scfcge:
 scfcge: start     13-7-0   0.0000E+00 -4.501096672356E+01  7.9239E-01
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$


#######################################################
 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.
##################### ####################################

Input file is listed below

# Crystalline AlAs : computation of the phonon spectrum

   ndtset   10
#Set 1 : ground state self-consistency

  getwfk1   0            # Cancel default
  kptopt1   1            # Automatic generation of k points, taking
                         # into account the symmetry
    nqpt1   0            # Cancel default
  tolvrs1   1.0d-18      # SCF stopping criterion (modify default)
  rfphon1   0            # Cancel default
 
#Q vectors for all datasets

#Complete set of symmetry-inequivalent qpt chosen to be commensurate
# with kpt mesh so that only one set of GS wave functions is needed.
#Generated automatically by running GS calculation with kptopt=1,
# nshift=0, shiftk=0 0 0 (to include gamma) and taking output kpt set
# file as qpt set. Set nstep=1 so only one iteration runs.

     nqpt   1            # One qpt for each dataset (only 0 or 1 allowed)
                         # This is the default for all datasets and must
                         #  be explicitly turned off for dataset 1.
      qpt2     0.00000000E+00  0.00000000E+00  0.00000000E+00
      qpt3     0.00000000E+00  0.00000000E+00  0.00000000E+00
      qpt4     0.00000000E+00  0.00000000E+00  6.25000000E-02
      qpt5     0.00000000E+00  0.00000000E+00  1.25000000E-01
      qpt6     0.00000000E+00  0.00000000E+00  1.87500000E-01
      qpt7     0.00000000E+00  0.00000000E+00  2.50000000E-01
      qpt8     0.00000000E+00  0.00000000E+00  3.12500000E-01
      qpt9     0.00000000E+00  0.00000000E+00  3.75000000E-01
      qpt10    0.00000000E+00  0.00000000E+00  4.37500000E-01
      qpt11    0.00000000E+00  0.00000000E+00  5.00000000E-01

#Set 2 : Response function calculation of d/dk wave function 

    iscf2   -3         # Need this non-self-consistent option for d/dk
  kptopt2   2          # Modify default to use time-reversal symmetry
  rfphon2   0          # Cancel default
  rfelfd2   2          # Calculate d/dk wave function only
  tolvrs2   0.0        # Cancel default for d/dk
  tolwfr2   1.0d-22    # Use wave function residual criterion instead

#Set 3 : Response function calculation of Q=0 phonons and electric field pert.

  getddk3   2          # d/dk wave functions from last dataset
  kptopt3   2          # Modify default to use time-reversal symmetry
  rfelfd3   3          # Electric-field perturbation response only

#Sets 4-10 : Finite-wave-vector phonon calculations (defaults for all 
datasets)

   getwfk   1          # Use GS wave functions from dataset1
   kptopt   3          # Need full k-point set for finite-Q response
   rfphon   1          # Do phonon response
  rfatpol   1 2 3 4 5 6 7 8    # Treat displacements of all atoms
    rfdir   1 1 1      # Do all directions (symmetry will be used)
   tolvrs   1.0d-8     # This default is active for sets 3-10

#######################################################################
#Common input variables

#Definition of the unit cell
    acell  60.36 16.08 8.04         # This is equivalent to   10.61 10.61 
10.61
    angdeg 90 90 90
#    rprim   0.0  0.5  0.5   # In lessons 1 and 2, these primitive vectors 
#            0.5  0.0  0.5   # (to be scaled by acell) were 1 0 0  0 1 0  0 0 
1

#            0.5  0.5  0.0   # that is, the default.

#Definition of the atom types
   ntypat   1         # There are two types of atom
    znucl   6     

#Definition of the atoms
    natom   8         # There are two atoms
    typat   1 1 1 1 1 1 1 1     # The first is of type 1 (Al), the second is 
of
type 2 (As).
                       
     xred   0.462  0.5  0.000
            0.538  0.5  0.000
            0.462  0.5  0.333
            0.538  0.5  0.333
            0.500  0.5  0.500
            0.577  0.5  0.500
            0.500  0.5  0.833
            0.577  0.5  0.833
#Gives the number of band, explicitely (do not take the default)
    nband   40         

#Exchange-correlation functional

      ixc   1           
     ecut   25.0           # Maximal kinetic energy cut-off, in Hartree

#Definition of the k-point grid
    ngkpt   1  1  16          
  nshiftk   1              # Use one copy of grid only (default)
                           # changed by Alex from 4 to 1
   shiftk   0.0 0.0 0.5    # This gives the usual fcc Monkhorst-Pack grid
                        

#Definition of the SCF procedure
     iscf   5          # Self-consistent calculation, using algorithm 5
    nstep   100         # Maximal number of SCF cycles
   diemac   9.0