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[Sophie Green <us_sophie.green@yahoo.com>]

Hi,
I am troubled in the symmetry in abinit. My case is orthorgonal, with the space group cmca. But the output file shows it is monoclinic.  I checked the input variables, and I still don't get what's wrong. 
I construct this structure in Castep. And in the abinit, I used the rprim, the acell, atomic positions from Castep output file. I don't know how the rprim, or angdeg 
should be to find the symmetry correctly. Should I plus the variable angdeg? Whether there is a certain form for the rprim matrix?

The following is my input file.
kptopt1  1            # Option for the automatic generation of k points,
nkpt1    432
ngkpt1   12 6 12
nshiftk1 1
shiftk1  0.5 0.5 0.5  # These shifts will be the same for all grids
# Definition of the SCF procedure
toldfe1  1.0d-6    # Will stop when this tolerance is achieved on total 
 energy
prtden1  1         # Print out density

# Dataset2: calculation of kss file
# Definition of k-points
kptopt2  0              # K-points will be provided
nkpt2    1              # Take only 1 k-point:
kpt2     0.0  0.0  0.0  # the Gamma point
istwfk2  1              # Option needed for special k-points like Gamma
# Definition of the SCF procedure
iscf2    -2             # Non self-consistent calculation
getden2  -1             # Read previous density file
tolwfr2  
 1.0d-10        # Still get it converged
nband2   13

# Definition of parameters for the calculation of the kss file
nbandkss2 -1        # Number of bands in KSS file (the maximum possible)
# Dataset3: Calculation of the screening (epsilon^-1 matrix)
optdriver3  3
getkss3     -1
nband3      37
ecutwfn3    3.6
ecuteps3    6.0
ppmfrq3    16.7 eV

# Definition of the unit cell: fcc
acell  4.827496 8.976202 5.427863        # This is equivalent to   10.217 10.217 10.217
rprim   0.500000  0.929695  0.000000   # FCC primitive vectors (to be scaled by
 acell)
       -0.500000  0.929695  0.000000
         0.000000  0.000000  1.000000

# Definition of the atom types
ntypat  1         # There is only one type of atom
znucl 1           # 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 Silicon.

# Definition of the atoms
natom
 12           # There are two atoms
typat  1 1 1 1 1 1 1 1 1 1 1 1         # They both are of type 1, that is, Silicon.
xred              # Reduced coordinate of atoms
     0.50359   0.50359   0.63530
     0.63171   0.63171   0.95315
     0.76831   0.76831   0.81692
     0.99641   0.99641   0.13530
     0.86829   0.86829   0.45315
     0.73169   0.73169   0.31692
     0.00359   0.00359   0.86470
     0.13171   0.13171   0.54685
     0.26831  
 0.26831   0.68308
     0.49641   0.49641   0.36470
     0.36829    0.36829   0.04685
     0.23169   0.23169   0.18308

# Definition of the planewave basis set (at convergence 16 Rydberg 8 Hartree)
ecut 8.0          # Maximal kinetic energy cut-off, in Hartree

# Use only symmorphic operations
symmorphi 0

# Definition of the SCF procedure
nstep   20        # 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.

timopt -1
# This line added when defaults were changed (v5.3) to keep the previous, old behaviour
  iscf 5

There is no ERR or WARN message in the output file, except that the wrong space group (monoclinic).

If anyone has such experience, please do me a favor. Thanks very much.

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