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[zmq.lyao@gmail.com]

Dear abinit users:

We encounter a server problem when we perform the RF calculation.
The first step for Ground state calculation is OK. But in the second step for 
Response Function calculation d/dk, it is very difficulty to converge even 
after sever hundred cycles. The value of residm varied around 10-4 and 10-5, 
and is very far from tolwfr=1.0d-22. We do not know how to resolve the 
problem. Generally, what factors can affect the convergence for the Response 
Function calculation?
We appreciated for anyone who could give some help suggestion to figure out 
the problem. 

Bo Liu


The input file is attached below. 

ndtset  3
#Response Function calculation for LaBr3
#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            
   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,
    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       
 rfatpol3   1 8          
  rfelfd3   3            
   rfdir3   1 1 1                                                             
    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,
  tolvrs3   1.0d-8
    iscf3   5             # Self-consistent calculation, using algorithm 5

#Definition of the unit cell
acell  1.5788197427E+01  1.5788197427E+01  8.9547236657E+00
angdeg  90 90 120 

#Definition of the atom types
ntypat 2         
znucl 35 57    
                         
#Definition of the atoms
spgroup 176
natom 8 
#natrd 4
typat 1 1 1 1 1 1 2 2 
#typat 1 2 

      xred    2.8849128174E-01  9.1452153238E-01  7.5000000000E-01
              6.2603025064E-01  7.1150871826E-01  7.5000000000E-01
              9.1452153238E-01  6.2603025064E-01  2.5000000000E-01
              8.5478467616E-02  3.7396974936E-01  7.5000000000E-01
              3.7396974936E-01  2.8849128174E-01  2.5000000000E-01
              7.1150871826E-01  8.5478467616E-02  2.5000000000E-01
              3.3333333333E-01  6.6666666667E-01  2.5000000000E-01
              6.6666666667E-01  3.3333333333E-01  7.5000000000E-01

#Definition of the planewave basis set
ecut 40.0

#Definition of the k-point grid
kptopt 1         
ngkpt    4 4 6       
nshiftk 1                     
shiftk 0.0 0.0 0.5

#Definition of the SCF procedure
nstep 20000         
diemac 12.0