The ABINIT Users Mailing List ( CLOSED )

[Masayoshi Mikami <mmikami@rc.m-kagaku.co.jp>]

Cher Francois,

It would have been much better to put the complete input
for us to clearly understand what you did ... (Netiquette !)

If you have all the internal coordinates of Y2O3 cell
(80 atoms), you just put the coordinates in "xred"
with no "spgroup" parameters, then ABINIT will
recognize the symmetry group (#206) automatically.

Otherwise ... there are two possibilities:
(Y2O3: http://dx.doi.org/10.1107/S0567740880011351)

Case-1) conventional cell
acell 3*10.6073  angstrom
ecut 30         # it depend on your pseudopotential ...
chkprim 0
ntypat  2
spgroup 206
spgaxor 1
spgorig 1
brvltt 2     # N.B. "brvltt 1" produces the same output
natom 80     # number of atoms in the conventional cell
natrd 3
typat  1 1 2
xred      # Reduced coordinates of atoms
  1/4         1/4        1/4     # Y  8(b)
-0.0323      0.0        1/4     # Y 24(d)
  0.3912      0.1515     0.3800  # O 48(c)
znucl 39.0 8.0
# put "tol*" parameters as you like ...

Case-2) primitive cell
acell 3*10.6073  angstrom
ecut 30         # it depend on your pseudopotential ...
ntypat  2
spgroup 206
brvltt -1    # primitive cell
natom 40     # number of atoms in the primitive cell
natrd 3
typat  1 1 2
xred      # Reduced coordinates of atoms
  1/4         1/4        1/4     # Y  8(b)
-0.0323      0.0        1/4     # Y 24(d)
  0.3912      0.1515     0.3800  # O 48(c)
znucl 39.0 8.0
# put "tol*" parameters as you like ...

You might want to check Y pseudopotential;
it may need semi-core states as valence.
(so, +11 ionic charge may be necessary)

Hope this helps,
Masayoshi "Netiquette man" ...

On 2007/06/04, at 23:03, francois.lallet@umontreal.ca wrote:

> Dear users,
>
> I try to optimize the structure of Y2O3 bixbyite.
> In the input file, I wrote the ionic positions using the reduced  
> coordinates. I simply followed the coordinates given in Wyckoff  
> "Crystal Structures". However, Abinit doesn't recognize the space  
> group (Ia-3)...
> Any idea?
> Thank you all.
>
> Francois