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[Pascal Boulet <pascal.boulet@univ-provence.fr>]

Dear Prasun Sharma Chowdhury,

I think there are 2 major problems in your input file:
First the rprim matrix is not precise enough, especially -0.866 and 0.866 which need at least 10 digits. Alternatively you can use "angdeg 90. 90. 120." instead of rprim.
Second, I think you need to provide 2 positions for Zr. From this site
http://cst-www.nrl.navy.mil/lattice/struk/a3.html
it is said that the positions are:
1/3 2/3 1/4
2/3 1/3 3/4
You can try these positions using fractions as I did here.

Last point, which is not responsible for your problem though, is the shifted grid you use. it is not relevant to an hexagonal structure. Hence your grid of k-points will not be optimal. You should use
nshiftk 1
shiftk 0.0 0.0 0.5

I hope this will solve your problem for the symmetry.

But your job will still crash (I guess)...
It seems that you want to optimize the cell parameters, but you did not set any convergence criteria for that. You should have a look at the tolmxf and strfact variables.

Finally, your ecut value is very low! I guess this is for tests purposes and not production work... Same for the k-point grid you use: 2x2x2 is very small for metals...


Hope this help,

Pascal


Prasun Sharma Chowdhury wrote:

c6f464140905020121r24d43376hdae710f566ecbcc@mail.gmail.com" type="cite">Dear all,
              The .in file i constructed for Zr(P63/mmc space group) is given below... but running this gives me a space group of Cm m m. Can anyone tell where the problem is? again, is the rprime data we put is correct? the angles for Zr structure are 90 90 and 120 deg. where and how can i put tem? Thanking you all in advance,
prasun sharma chowdhury
VECC,Kolkata
WB, India

=====================================
# Zr

#Definition of occupation numbers
occopt 4
tsmear 0.01

#Definition of the unit cell
acell 2*6.0966   9.7126       
rprim  0.5  -0.866  0.0 
       0.5  0.866  0.0
       0.0  0.0  1.0

#Optimization of the lattice parameters
optcell 1
ionmov  3
ntime  10
dilatmx 1.05
ecutsm  0.5

#Definition of the atom types
ntypat 1          # There is only one type of atom
znucl 40        
                        

#Definition of the atoms
natom 1           # There is only one atom per cell
typat 1           # This atom is of type 1
xred             

   0.0  0.0  0.0     # Triplet giving the REDUCED coordinate of atom 1.

#Definition of the planewave basis set
ecut  6.0         # Maximal kinetic energy cut-off, in Hartree

#Exchange-correlation functional
ixc 1             # LDA Teter Pade parametrization

#Definition of the k-point grid
kptopt 1          #
ngkpt 2 2 2       #
nshiftk 4         # of the reciprocal space. For a FCC real space lattice,
                  # like the present one, it actually corresponds to the
                  # so-called 4x4x4 Monkhorst-Pack grid, if the following shifts
                  # are used :
shiftk 0.5 0.5 0.5
       0.5 0.0 0.0
       0.0 0.5 0.0
       0.0 0.0 0.5

#Definition of the SCF procedure
nstep 10          # 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)
=====================================

-- 
Dr. Pascal Boulet, Computational Chemist
University Aix-Marseille I
Laboratoire Chimie Provence, UMR6264
Centre Saint-Jerome, Bat. MADIREL
F-13397 MARSEILLE Cedex 20, France
Tel. +33 (0) 491 63 71 17 Fax. +33 (0) 491 63 71 11
courriel: pascal.boulet@univ-provence.fr
http://www.lc-provence.fr
http://allos.up.univ-mrs.fr/boulet