The ABINIT Users Mailing List ( CLOSED )

[matthieu verstraete <matthieu.jean.verstraete@gmail.com>]

your xred positions are not very precise - abinit needs more digits to
recognize symmetries (this is managed by the tolsym input variable).
It is probably getting a conflict between the highly symmetric Bravais
lattice and the atomic positions. Try replacing with exact fractions
0.5 0.25 etc... for the x and y coordinates.

As mentioned, this is a warning: it just means that no symmetries will
be used in the calculation, but nothing will be wrong.

Matthieu


PS: iscf 5 is not the most efficient - usually the default 7 is better.


On Sun, Oct 4, 2009 at 4:58 PM,  <amir_n_shamkhali@yahoo.com> wrote:
> I faced with a problem in running abinit. I'm trying to opt slab model of
> Ni(111)surface with 5 layers and 15 angstrom vacuum above it. but when I run
> abinis.exe, this
> warning appears:
> symspgr: WARNING
> could not find the space group
> Can anyone help me to solve this problem?
> My input file is as follows:
>
> #Ni(111) surface
>  dilatmx2   1.10    # Maximum scaling allowed for lattice parameters
>  ionmov2   3       # Use BFGS algorithm
>   ntime2   30      # Maximum number of optimization steps
>  optcell2   2       # Fully optimize unit cell geometry, keeping symmetry
>  tolmxf2   1.0e-6  # Convergence limit for forces as above
>  strfact2   100     # Test convergence of stresses (Hartree/bohr^3) by
>                    # multiplying by this factor and applying force
>                    # convergence test
> #Common input data
>
> #Starting approximation for the unit cell
>  acell   3*6.65901691925241
>  rprim   1.41421193 0.00000000 0.00000000
>          0.70710596 1.22474345 0.00000000
>          0.00000000 0.00000000 5.00000000
> chkprim 0
>
> #Definition of the atom types and atoms
>  ntypat   1
>  znucl   28
>  natom   20
>  typat   20*1
>
> xred
>   0.00000000  0.00000000  0.00000000
>   0.49999578  0.00000000  0.00000000
>   0.00002170  0.50002309  0.00000000
>   0.50001749  0.50002309  0.00000000
>   0.16673956  0.16672880  0.11544000
>   0.66673534  0.16672880  0.11544000
>   0.16676127  0.66675188  0.11544000
>   0.66675705  0.66675188  0.11544000
>   0.33347912  0.33345759  0.23088000
>   0.83347490  0.33345759  0.23088000
>   0.33350083  0.83348068  0.23088000
>   0.83349661  0.83348068  0.23088000
>   0.00000000  0.00000000  0.34634000
>   0.49999578  0.00000000  0.34634000
>   0.00002170  0.50002309  0.34634000
>   0.50001749  0.50002309  0.34634000
>   0.16673956  0.16672880  0.46178000
>   0.66673534  0.16672880  0.46178000
>   0.16676127  0.66675188  0.46178000
>   0.66675705  0.66675188  0.46178000
>
> #Gives the number of bands, explicitely (do not take the default)
>  nband   300              # For an insulator (if described correctly as an
>                           # insulator by DFT), conduction bands should not
>                           # be included in response-function calculations
>
> #Definition of the plane wave basis set
>   ecut   12.0             # Maximum kinetic energy cutoff (Hartree)
>   ecutsm   0.5            # Smoothing energy needed for lattice paramete
>                           # optimization.  This will be retained for
>                           # consistency throughout.
>
> #Definition of the k-point grid
>  kptopt  1
>  ngkpt   6 6 1          # 4x4x4 Monkhorst-Pack grid
>                         # Use one copy of grid only (default)
>
>
> #Definition of the self-consistency procedure
>  diemac   9.0            # Model dielectric preconditioner
>   iscf   5              # Use conjugate-gradient SCF cycle
>  nstep   100             # Maxiumum number of SCF iterations
>  tolvrs   1.0d-18        # Strict tolerance on (squared) residual of the
>                         # SCF potential needed for accurate forces and
>                         # stresses in the structural optimization, and
>                         # accurate wave functions in the RF calculations
>



-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. Matthieu Verstraete

Universite de Liège
Institut de Physique, Bat. B5, 3/7
Allée du 6 aout, 17
B- 4000 Sart Tilman, Liège
Belgium

Phone : +32 4 366 90 17
Fax   : +32 4 366 36 29

Mail : matthieu.jean.verstraete@gmail.com