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

Hello,

the default iscf should be fine

You don't need k-points in the directions perpendicular to the chain,
but need many more along it (almost certainly).

The coupled convergence of tsmear and ngkpt should be in the tutorial
on bulk Al. Correct me if I am wrong.

Matthieu

On Sat, May 9, 2009 at 2:18 AM,  <venomdi2000@yahoo.com> wrote:
> good night abinit user..
>
> For now, I am doing simulation about atom bridge of Fe which has twisted 
> ladder
> structure. I am doing two kinds of simulation: with nsppol=1 and with 
> nsppol=2.
> Later, I intend to compress my structure and see the value of etotal and
> magnetic moments. I provide my code below. My problems are, that I have no 
> idea
> of the value which I will give to iscf parameter. Please give me suggestion
> about the choice of iscf value which I will give..
>
> My another problem is about determining value of tsmear. How to do 
> convergence
> est with tsmear. I ever did convergence test with this parameter with 
> respect
> to etotal, and found that i went divergent...
>
> The following is my input file
>
>
>
> # chain of iron : computation of the total energy
> #
>
> ndtset 2
> #Definition of the unit cell
> acell 2.2 10 10    # The keyword "acell" refers to the
>                  # lengths of the primitive vectors (in Bohr)
>
> spinat2   0.0 0.0 4.0
>         0.0 0.0 4.0
>         0.0 0.0 4.0
>         0.0 0.0 4.0
>  nsppol2   2
> prtdos 1
> occopt 3
> nband 24
>  tsmear 0.12
> prtden 1
>
>
> #Definition of the atom types
> ntypat 1          # There is only one type of atom
> znucl 26          # 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 iron.
>
>
> #Definition of the atoms
> natom 4
> typat 1 1 1 1
> xcart
>   0.0   1.3  0.0
>   0.0  -1.3  0.0
>   2.55  0.0  1.3
>   2.55  0.0 -1.3
>
>
> #Definition of the planewave basis set
>  ecut 24             # Maximal kinetic energy cut-off, in Hartree
>
>
> #Definition of the k-point grid
> kptopt 1          # Option for the automatic generation of k points, taking
>                  # into account the symmetry
> ngkpt  4 4 4     # Definition of the different grids
> nshiftk 1
>
>
> #Definition of the SCF procedure
> nstep 15          # Maximal number of SCF cycles
> toldfe 1.0d-6     # Will stop when, twice in a row, the difference
>                  # between two consecutive evaluations of total energy
>                  # differ by less than toldfe (in Hartree)
> 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.
>



-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Matthieu Verstraete

European Theoretical Spectroscopy Facility (ETSF)
Dpto. Fisica de Materiales,
U. del Pais Vasco,
Centro Joxe Mari Korta, Av. de Tolosa, 72,   Phone: +34-943018393
E-20018 Donostia-San Sebastian, Spain        Fax  : +34-943018390

Mail : matthieu.jean.verstraete@gmail.com
http://www-users.york.ac.uk/~mjv500