What are the atomic positions of the antiferromagnetic structure of the NiS comopund

[Wien] What are the atomic positions of the antiferromagnetic structure of the NiS compund

ABDERRAHMANE REGGAD Sun, 06 Mar 2016 12:38:57 -0800

Dear wien2k's users

I'm going to do the antiferromagnetic calculation of the NiS compound which
has the NiAs structure in the non magnetic state (space group: 195 ;atomic
positions : Ni    2a     0, 0, 0         S   2c     1/3, 2/3, 1/4)

The antiferromagnetic structure , as i found in the literature, has the
space group number of 164 which a subgroup of the first one .

I need to know how to get the atomic poistions of the antoferromagnetic
strucure.

Best wishes
-- 
Mr: A.Reggad
Laboratoire de Génie Physique
Université Ibn Khaldoun - Tiaret
Algerie

Reply:

Gavin Abo Sun, 06 Mar 2016 16:10:08 -0800

The short answer: contact the corresponding author(s) of the literature and ask them if they can provide that data.

**********The long answer: ***************

You could try the following to see if you can get what you want.

1. Start with the NiAs structure [https://chemistry.osu.edu/~woodward/ch754/struct/NiAs.htm ]:

username@computername:~/wiendata/NiS$ ls
NiS.struct
username@computername:~/wiendata/NiS$ sed -n '2p' NiS.struct

H LATTICE,NONEQUIV.ATOMS: 2 194_P63/mmc <= Shows that NiS structure file with NiAs parameters has space group 194.

2. Split the Ni equivalent positions into non-equivalent ones.

Use the structeditor (refer to section "9.26 structeditor" in the WIEN2k usersguide) to split all the positions:

username@computername:~/wiendata/NiS$ octave
GNU Octave, version 3.8.1
...

octave:1> s=loadstruct('NiS.struct');
octave:2> p=makeprimitive(s);
octave:3> savestruct(p,'NiS.struct_prim');
octave:4> exit

Use a text editor (like gedit) to label the positions that you want to be non-equivalent (similar to constructing a supercell [http://www.wien2k.at/reg_user/faq/supercells.html ]):

username@computername:~/wiendata/NiS$ sed -n '7p' NiS.struct_prim

Ni NPT= 781 R0=.000050000 RMT= 2.31000 Z: 28.00000 <= Without special label

username@computername:~/wiendata/NiS$ sed -n '13p' NiS.struct_prim
Ni         NPT=  781  R0=.000050000 RMT= 2.31000   Z:  28.00000
username@computername:~/wiendata/NiS$ gedit NiS.struct_prim
username@computername:~/wiendata/NiS$ sed -n '7p' NiS.struct_prim

Ni1 NPT= 781 R0=.000050000 RMT= 2.31000 Z: 28.00000 <= With special label. WARNING: make sure you maintain the formatting (e.g., file spacing), else use StructGen.

username@computername:~/wiendata/NiS$ sed -n '13p' NiS.struct_prim

Ni2 NPT= 781 R0=.000050000 RMT= 2.31000 Z: 28.00000 <= Shows that one blank space was removed and 2 was added after Ni.

username@computername:~/wiendata/NiS$ mv NiS.struct NiS.struct_orig
 username@computername:~/wiendata/NiS$ cp NiS.struct_prim NiS.struct  

 

or an alternative method is to:  open NiS.struct in StructGen of w2web

select 'H' for the Lattice
click 'Save Structure'
click 'continue editing'
click 'split' next to Pos2 for the Ni atom (Atom 1)

enter 1 in the special label box (second box) for Atom 1 (Ni atom with position 0, 0, 0) enter 2 in the special label box after Atom 2 (Ni atom with the position 0, 0, 0.5)
3. Use the sgroup program to find and generate a structure file with the new space group:

username@computername:~/wiendata/NiS$ x sgroup
0.0u 0.0s 0:00.00 0.0% 0+0k 0+8io 0pf+0w
username@computername:~/wiendata/NiS$ cp NiS.struct_sgroup NiSafm.struct
username@computername:~/wiendata/NiS$ sed -n '2p' NiSafm.struct

H LATTICE,NONEQUIV.ATOMS: 3 164 P-3m1<= sgroup found and generated a structure file with space group 164, which seems to be what you are looking for.
You would still need to take NiSafm.struct, adjust it for your lattice constants (as you did not provide them), run init_lapw to make sure it passes all the checks, and look at it in XCrySDen to verify that it is still the same structure that is being used in the literature.

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