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[cszakacs@mun.ca]

Dear users,

I am testing some zero-dimensional calculations with Abinit. I am following 
the
example given in Lesson 1 (with the hydrogen).
I want to optimize a ZnO cluster containing 12 atoms in a supercell (I am
considering it to be neutral). Here is my input:

acell 30 30 30
ecut 80
#optimization
natom 12
ionmov 3             # Use the modified Broyden algorithm
ntime 10            # Maximum number of Broyden "timesteps"
tolmxf 5.0d-4        # Stopping criterion for the geometry optimization : when
                         # the residual forces are less than tolmxf, the
Broyden
                         # algorithm can stop
xangst           1.69555300   -0.71202600   -1.53300200
                 -0.23112400    1.82435000   -1.53300200
                 -1.46439400   -1.11236700   -1.53302300
                  0.23532700   -1.75354400   -0.85437000
                  0.23971200   -1.71537200    1.06255400
                 -1.63626200    0.67295000   -0.85436900
                 -1.60538200    0.65003600    1.06257500
                  1.40092400    1.08057300   -0.85436500
                  1.36569300    1.06523600    1.06259300
                  1.76646300   -0.70453700    1.71357600
                 -1.49337800   -1.17754600    1.71354300
                 -0.27303100    1.88202800    1.71359200



toldff 5.0d-5        # Will stop the SCF cycle when, twice in a row,
                         # the difference between two consecutive evaluations
of
                         # forces differ by less than toldff (in Hartree/Bohr)
nband  108            #  band for energy calc
#Definition of the atom types
ntypat 2          # There is only one type of atom
znucl 8 30           # 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.


#Definition of the atoms
typat 1 1 1 2 1 2 1 2 1 2 2 2        # For the first dataset, both numbers 
will
be read,
                  # while for the second dataset, only one number will be read

#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
iprcel 45
nstep 10          # Maximal number of SCF cycles
#toldfe is no more defined, as toldff is used above...
diemac 2.0        # 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 prescriptions for molecules
                  # in a big box

The main problem I am encountering is the huge memory needed and the length of
the computation (about 8GB memory and the calculation is runnning now for a 
few
days and it didn't finished yet.)

Is this normal? Or I am using a too large ecut? 
I have done before some calculation on the bulk ZnO and using 80 as the value
for the ecut I've got good convergence, so I considered that this would be ok.
Or are there other things that I've missed?
Or the acell parameters are to high?

Could you give me some advice about this?

Thank you,

Csaba Szakacs