From the files you sent, I never get Cm space group.
Anyway, if it is antiferromagnetic, it has only TWO Fe sites, one with
spin-up and one with dn.
So I used your struct file, but the 4 Fe atoms should probably not be
splitted into 1-4, but into two positions, each with multiplicity 2,
such that you get the desired udud spin-pattern.
sgroup gives then P63mc.
PS: You have to distinguish between a hexagonal bravais lattice
(aac,90,90,120) and a hexagonal space group. If you have a hexagonal
lattice, but put atoms in in an arbitrary way, it can easily even go to
P1. So the lattice is still hexagonal, but the SG does not belong to a
hexagonal SG, since the required symm.ops of a hex.SG are gone.
On 08/20/2018 02:54 PM, Enamul Haque wrote:
Dear Wien2k Users and Experts,
We already got sufficient help from Dr. Gavin in this case but we are
not convinced from the space group point of view.
With the original CIF file (attached), we want to check the ground state
energy of the AFM case of "Cs3Fe2Cl9" (conventional standard and
symmetrized taken from MP).
The original structure crystallizes in hexagonal space group (194) with
one Fe atom having multiplicity 4.
So to do AFM calculations, we need four Fe atoms (udud configuration is
reported as a stable structure in AFM case).
We adopted two different ways to make four equivalent Fe atoms (to make
udud AFM configuration) and in both the ways our space group adopts
different geometry (SG) which does not fall within the hexagonal family.
Original SG:
H LATTICE,NONEQUIV.ATOMS: 5 194 P63/mmc
MODE OF CALC=RELA unit=bohr
14.141194 14.141194 34.315650 90.000000 90.000000120.000000
ATOM 1: X=0.66666733 Y=0.33333267 Z=0.41670700
Labeling all Fe (1-4) in the file we get from cif2struct from
conventional standard cif file:
blebleble
CXZ LATTICE,NONEQUIV.ATOMS: *22 8 Cm*
MODE OF CALC=RELA unit=bohr
24.493266 42.160217 14.141194 90.000000 90.000000125.517869
ATOM 1: X=0.26213500 Y=0.92880100 Z=0.00000000
From the supercell approach (from /the symmetrized/ cif file after
rounding off for two positions of Cl, ending with 50 and 800):
/1. initialize (it should be in 194 SG)/
/2. x supercell (1x1x1 with no shift)/
/3. cp case_super.struct case.struct/
/4. open in w2web and split one Fe and save it and it will redirect you
again on w2web/
/5. hit edit structure option and again click on second Fe to split and
split all four Fe atoms/
/6. again click on edit structure and put 1-4 on all four Fe atoms (in
the second column) and remove original Fe atom (you see now five Fe
atoms four that you have split and one will still on original position.
So delete the original one)./
It gave us (attached case.struct)
H LATTICE,NONEQUIV.ATOMS: 16 *156 P3m1*
MODE OF CALC=RELA unit=bohr
14.141194 14.141194 34.315650 90.000000 90.000000120.000000
Now the issue we are facing is:
The pristine structure is having SG 194 and after converting
multiplicity of Fe atom to single atomic positions by two different
approaches, we are getting two different SGs which do not fall within
the hexagonal family.
So, Could someone from the expert list please advice us how to do AFM
calculations of this kind cases and which SG should be appropriate.It
will be a great help.
Best regards.
Enamul Haque
Mawlana Bhashani Science and Technology University
Tangail, Bangladesh.
Email: ena...@mailaps.org <mailto:ena...@mailaps.org>
Cell: +8801831911133
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