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["Yanqing Zheng" <yqzheng1@sh163.net>]

Dear Zeming,
Set nband to be 56.
Wish it help.

Good luck!

Yanqing Zheng, Ph.D.
Shanghai Institute of Ceramics,
Chinese Academy of Sciences
Jiading, 201800, Shanghai
P. R. China
E-mail: yqzheng@sh163.net
Fax no.: +86 21 59927184

Dear all, 
   I am trying the Response-function calculation of the effect of an 
homogeneous electric field.  For the first step GS calculation, it is easy to 
reach tolvrs=  1.00E-18 and converged. But, for the second step, a 
non-self-consistent response-function computation of the d/dk perturbation, 
it seems that it is very difficult to converge. After 70 steps, the maximum 
residual only reached about 2E-04 (>>tolwfr= 1.0E-22) and oscillated around 
this value. The tutorial and help of Abinit said it should be use a very 
small tolwfr value. So, I'd like to know how to select a suitable tolwfr for 
different system in RF calcualtion and what input variables influence the 
convergence mostly. Anyone have any suggestion to speed convergence? Thanks 
in advance.

regards,
Zeming
---------------------------
The input file is as follows.
#Response-function calculation, with q=0

  ndtset  3

#Ground state calculation
  kptopt1   1             # Automatic generation of k points, taking
                          # into account the symmetry
  tolvrs1   1.0d-18       # SCF stopping criterion
    iscf1   5             # Self-consistent calculation, using algorithm 5

#Response Function calculation : d/dk
  rfelfd2   2             # Activate the calculation of the d/dk perturbation
   rfdir2   1 1 1                                
    nqpt2   1
     qpt2   0.0 0.0 0.0   # This is a calculation at the Gamma point

  getwfk2   -1            # Uses as input the output wf of the previous 
dataset

  kptopt2   2             # Automatic generation of k points,
                          # using only the time-reversal symmetry to decrease
                          # the size of the k point set.

    iscf2  -3             # The d/dk perturbation must be treated 
                          # in a non-self-consistent way
  tolwfr2   1.0d-22      # Must use tolwfr for non-self-consistent 
calculations
                          

#Response Function calculation : electric field perturbation and phonons
  rfphon3   1        #the calculation of the atomic dispacement perturbations
 rfatpol3   1 24           # All the atoms will be displaced
  rfelfd3   3            
  rfdir3   1 1 1         # All directions                       
  nqpt3   1
  qpt3   0.0 0.0 0.0   # This is a calculation at the Gamma point
  getwfk3   -2            # Uses as input wfs the output wfs of the dataset 1
  getddk3   -1            # Uses as input ddk wfs the output of the dataset 2

  kptopt3   2             # Automatic generation of k points,
                          # using only the time-reversal symmetry to decrease
                          # the size of the k point set.
  tolvrs3   1.0d-8
    iscf3   5             # Self-consistent calculation, using algorithm 5 



#Definition of the unit cell
acell 15.09060  15.09060  9.76535        # This is lattice constant
angdeg 90 90 90

#Definition of the atom types
ntypat 4          
znucl 38 12 14 8   
                                                  
                         
#Definition of the atoms
spgroup 113 #  P-421m
chkprim=0

natom 24 
brvltt=0
natrd 6
nband 80

typat 1 2 3 4 4 4   
xred                                
0.33869   0.16131   0.50958 
0.00000   0.00000   0.00000 
0.13924   0.36076   0.95060 
0.50000   0.00000   0.14329 
0.14160   0.35840   0.25931 
0.07613   0.19200   0.80587 
      
ecut 40  # Maximal kinetic energy cut-off, in Hartree


#Definition of the k-point grid

ngkpt  4 4 4
nshiftk 1         # of the reciprocal space (that form a BCC lattice !),
shiftk 0.50 0.50 0.50

#Definition of the SCF procedure
nstep 70          # Maximal number of SCF cycles
diemac 2.0