The ABINIT Users Mailing List ( CLOSED )

[Gian-Marco Rignanese <rignanese@pcpm.ucl.ac.be>]

Dear Aldo,

I do not quite see what is the problem that you encounter with zircon, 
which has already been studied with ABINIT [see details in Phys. Rev. B 
63, pp 104305-7 (2001).]
You can work with the primitive unit cell which is given at the URL 
that you sent. In this case, the input file for abinit should look like 
the following:

# -- STRUCTURE PARAMETERS 
----------------------------------------------------
#
#  the lattice vectors
acell
    1.00000000000000    1.00000000000000    1.00000000000000
rprim
   12.48542056681771    0.00000000000000    0.00000000000000
    0.00000000000000   12.48542056681771    0.00000000000000
    6.24271028340886    6.24271028340886    5.65217086655846
# the coordinates of the atoms:
xred
 -0.12500000 -0.37500000  0.25000000
  0.12500000  0.37500000 -0.25000000
 -0.37500000 -0.12500000 -0.25000000
  0.37500000  0.12500000  0.25000000
 -0.19530000 -0.12920000  0.39060000
 -0.19530000  0.23860000  0.39060000
 -0.26140000  0.30470000 -0.10940000
  0.37080000  0.30470000 -0.10940000
  0.19530000  0.12920000 -0.39060000
  0.19530000 -0.23860000 -0.39060000
  0.26140000 -0.30470000  0.10940000
 -0.37080000 -0.30470000  0.10940000
natom  12
nsppol 1
zatnum 40.00  14.00  8.000
amu    91.2200  28.0860  15.9994
ntype  3
type   2*1 2*2 8*3

In this case, you cannot use "spgroup" to specify the space group 
directly in the input file (this should be fixed in the future).
But you can also work with the tetragonal unit cell (4 times bigger). 
In this case, you can directly specify the space group in the input 
file, like the following:

#
# -- STRUCTURE PARAMETERS 
----------------------------------------------------
#
#  the lattice vectors
acell
    1.00000000000000    1.00000000000000    1.00000000000000
rprim
   12.48542056681771    0.00000000000000    0.00000000000000
    0.00000000000000   12.48542056681771    0.00000000000000
    6.24271028340886    6.24271028340886    5.65217086655846
    0.00000000000000    0.00000000000000   11.30434173311692
chkprim  0
# the coordinates of the atoms:
xred
    0.12500000000000    0.37500000000000    0.75000000000000
    0.37500000000000    0.12500000000000    0.25000000000000
    0.19530000000000    0.12920000000000    0.60940000000000
spgroup 141
natrd  3
natom  48
nsppol 1
zatnum 40.00  14.00  8.000
amu    91.2200  28.0860  15.9994
ntype  3
type   1 2 3

Best regards,

Gian-Marco.