[Wien] Heusler Alloy Fe2CrSn_Atomic Position

[alpa dashora]

Dear Wien2k Users,

I am trying to calculate the electronic structure of Heusler alloy Fe2CrSn
using Wien2k. It is supposed to exist in L2/1 structure (space group 225)
with following positions:
Fe: 0.25 0.25 0.25
Fe: 0.75 0.75 0.75
Cr:  0.5   0.5   0.5
Sn: 0.0  0.0   0.0

When the positions are changed as follows:
Fe: 0.0  0.0   0.0
Fe:  0.5   0.5   0.5
Cr: 0.25 0.25 0.25 Sn: 0.75 0.75 0.75

then the Wien shows space group 216 and magnetic properties are totally
changed.

Is it right and what is the excact structure for Fe2CrSn?

Please help me.

Thanks in advance,




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Alpa Dashora
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[Wien] Heusler Alloy Fe2CrSn_Atomic Position

[Michael Fischer]

Hello,

the position (1/4, 1/4, 1/4) has eightfold symmetry in space group 225, one of 
the equivalent positions being (3/4, 3/4, 3/4).
Thus, Fe should only be specified once - does this solve the problem?

Best regards
Michael
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[Wien] Heusler Alloy Fe2CrSn_Atomic Position

[Gerhard Fecher]

For the 2 structures below, the result should be the same.
as in space group 216 the change of the atoms in positions 4a, 4b  with those 
on 4c,4d
results in the same symmetry (all positions have Td symmetry)
Occupying 4a,4b or 4c,4d (like you gave below) with the same species will 
always result in a higher symmetry (Oh) for the other two positions,
and thus into space group 225.

If the Fe atoms have an antiparallel coupling then (as this is not possible in 
225) the result of 216 will be different,
otherwise it is identical.

If you exchange in a way that you have for example
Fe: 0.25 0.25 0.25
Cr: 0.75 0.75 0.75
Fe:  0.5   0.5   0.5
Sn: 0.0  0.0   0.0
then this is different from the structures you gave,
and indeed, the magnetic behaviour will be different.

The "exact" structure should be the one with lowest total energy, trivially.

Ciao
Gerhard

EVERYTHING IS SYMMETRY IS EVERYTHING


Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz

Von: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at 
zeus.theochem.tuwien.ac.at] im Auftrag von alpa dashora [dashoralpa at 
gmail.com]
Gesendet: Dienstag, 8. September 2009 05:49
An: wien-request at zeus.theochem.tuwien.ac.at; Wien at 
zeus.theochem.tuwien.ac.at
Betreff: [Wien] Heusler Alloy Fe2CrSn_Atomic Position

Dear Wien2k Users,

I am trying to calculate the electronic structure of Heusler alloy Fe2CrSn 
using Wien2k. It is supposed to exist in L2/1 structure (space group 225) with 
following positions:
Fe: 0.25 0.25 0.25
Fe: 0.75 0.75 0.75
Cr:  0.5   0.5   0.5
Sn: 0.0  0.0   0.0

When the positions are changed as follows:
Fe: 0.0  0.0   0.0
Fe:  0.5   0.5   0.5
Cr: 0.25 0.25 0.25
Sn: 0.75 0.75 0.75

then the Wien shows space group 216 and magnetic properties are totally changed.

Is it right and what is the excact structure for Fe2CrSn?

Please help me.

Thanks in advance,




--
Alpa Dashora