[Wien] Mailing List

[Gavin Abo]

If your case.struct file has one Mn atom corresponding to one 
inequivalent atomic position that has multiple equivalent atomic 
positions where you want to split the equivalent atomic positions into 
inequivalent ones, then you need to use the "set at least for one 
atom-name a special label" at [1].

There are different approaches that should work to split atoms: 1) Use 
WIEN2k's StructGen, select appropriate general lattice and use split, 2) 
Use WIEN2k's "x supercell", 3) Use WIEN2k's structeditor, or 4) Use 
another crystal maker program compatible with WIEN2k (e.g. Crystal Maker 
imports WIEN2k struct files and outputs cif according to their webpage 
at [2], and WIEN2k's cif2struct can likely be used to convert back to a 
struct file).

Some examples that might help are at [3-5].

If you are displacing Mn atomic position(s) such as to model a crystal 
defect [6], then most likely you need to do the special labels above 
first before doing that.  For the space group that you have for your 
supercell [7], the Mn atom you displace would need to have a free atomic 
position and not a fixed one if you are doing atomic position 
optimization [8,9].  Bilbao Crystallographic Server has tools such as 
Wyckoff Positions [10] that might help you determine in your atomic 
positions are free or fixed.

Displacing one Mn atom is not likely to give a realistic model for an 
experimental sample that probably would have a lot of dislocated Mn 
atoms.  Bigger supercells would be needed for calculations (e.g., refer 
to [11]).


[1] http://susi.theochem.tuwien.ac.at/reg_user/faq/supercells.html
[2] http://crystalmaker.com/crystalmaker/index.html
[3] http://zeus.theochem.tuwien.ac.at/pipermail/wien/2009-April/012454.html
[4] http://susi.theochem.tuwien.ac.at/reg_user/faq/afm.html
[5] Exercise 4:  Creation of supercells (slide 11) 
http://susi.theochem.tuwien.ac.at/events/ws2017/notes/tutorial-Basic-exercises.pdf
[6] 
https://www.substech.com/dokuwiki/doku.php?id=imperfections_of_crystal_structure
[7] 
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg20329.html
[8] Slide 39: 
http://susi.theochem.tuwien.ac.at/events/ws2015/WIEN2k-Blaha-lectures.pdf
[9] http://www.wien2k.at/reg_user/faq/minimization.html
[10] https://www.cryst.ehu.es/cryst/get_wp.html
[11] 
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg06099.html

On 7/23/2020 1:47 PM, djamel slamnia wrote:
> thanks for replay :
> my compound has one Mn atom with one position , i'm trying to split it 
> to get tow atoms of Mn in unit cell but i cant  because Mn has one 
> position can i do for exemple : displace (at least one) atoms
>
> Le jeudi 23 juillet 2020 à 17:49:26 UTC+2, Tran, Fabien 
> <fabien.tran at tuwien.ac.at> a écrit :
>
>
> You need to construct a super cell which contains several Mn atoms (at 
> least one for each orientation of the magnetic moment).
> Then, you need to put labels (1, 2) in case.struct to avoid to 
> reobtain the original cell after init_lapw.
> See for instance discussion here
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg19513.html
>
> From: Wien <wien-bounces at zeus.theochem.tuwien.ac.at 
> <mailto:wien-bounces at zeus.theochem.tuwien.ac.at>> on behalf of djamel 
> slamnia <djamel4009 at yahoo.fr <mailto:djamel4009 at yahoo.fr>>
> Sent: Thursday, July 23, 2020 5:25 PM
> To: A. Mailing List for WIEN2k Users
> Subject: [Wien] Mailing List
>
> Dear wien2k user's
>
> for antiferromagnetic calculation : i have to split the position of Mn 
> atom to get 2 atoms in unit cell but
> in my case.struct the Mn atom has only one position
>
> so what i have to do ???
>
> can i displace Mn atom ??
>
> thanks in advance
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