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[occupierliu@yahoo.com.cn]

Dear abinit user:
    When I try to calculate the total energy of two atoms at ground state, 
the abinis version 4.4.3 break off undesignedly. The error message in the log 
file is:
  vtowfk : BUG   For istwf_k=2, observed the following element of evec :
    3    1             nan             nan
  with a non-negligible imaginary part.
  Action : contact ABINIT group.

 Delivered    6 WARNINGs and   0 COMMENTs to log file.

 leave_new : decision taken to exit ...

with warnings like: 
 scfcge: WARNING -
  Potential-based CG line minimization has trouble to converge.
  The algorithm is restarted with more secure parameters.

I've changed the iscf from default 5 to 3, but it didn't work.
Do I need to change some parameters? I appreciate any advice.



Input file:
# C-O potential energy calculation
#

#Definition of the unit cell
acell: 40 34 34   # The keyword "acell" refers to the
                  # lengths of the primitive vectors (in Bohr)

#Definition of the atom types
ntypat 2          # There is only one type of atom
znucl 8 6         # 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 Hydrogen.
nband 10
getwfk -1                         

#Definition of the atoms
natom 2           # There are two atoms
typat 1 2         # They both are of type 1, that is, Hydrogen
xcart             
  -3.85 20.0 20.0    
   3.85 20.0 20.0    
#Definition of the planewave basis set
ecut 30.0         # Maximal plane-wave kinetic energy cut-off, in Hartree

#Definition of the k-point grid
nkpt 1            # Only one k point is needed for isolated system,
                  # taken by default to be 0.0 0.0 0.0

#Definition of the SCF procedure
#iscf  3 
nstep 1000         # Maximal number of SCF cycles
toldfe 1.0d-12   # Will stop when, twice in a row, the difference 
                  # between two consecutive evaluations of total energy 
                  # differ by less than toldfe (in Hartree) 
diemac 1.0        # Although this is not mandatory, it is worth to
                  # precondition the SCF cycle. The model dielectric
diemix 0.5        # function used as the standard preconditioner
                  # is described in the "dielng" input variable section.
                  # Here, we follow the prescriptions for molecules 
                  # in a big box