How to calculate antiferromagnetic state?

Posted on : April 19, 2017 (Wed) 22:08:04

by 池田敦俊

Dear AkaiKKR users,

In this thread, the administrator says that if ELMD is smaller than Eferro, antiferromagnetic state may be the ground state:
http://kkr.issp.u-tokyo.ac.jp/bbs/thread.php?id=215

I want to calculate the antiferromagnetic state, but I don't know how.
Do I have to extend the unit cell, for example to 2x2x2, and choose an arbitrary antiferromagnetic setting like this?
----------------------------------------------------
c type ncmp rmt field mxl anclr conc
K 1 1 0.0 2 19 100
Mn1 1 1 0.0 2 25 100 #Mn for spin up
Mn2 1 1 0.0 2 25 100 #Mn for spin down
F 1 1 0.0 2 9 100
c atmicx atmtyp
0 0 0 K
0 0 0.5 K
...
0.25 0.25 0.25 Mn1
0.25 0.25 0.75 Mn2
0.25 0.75 0.25 Mn2
0.25 0.75 0.75 Mn1
0.75 0.25 0.25 Mn2
0.75 0.25 0.75 Mn1
0.75 0.75 0.25 Mn1
0.75 0.75 0.75 Mn2
0 0.25 0.25 F
0.25 0 0.25 F
...
-----------------------------------------------------

Or, does Machikaneyama has a special option to find which magnetic setting ("normal" antiferromagnetism, antiferro of ferro chain, etc.) has the lowest energy?

Sincerely,
Ikeda

[Re:02] How to calculate antiferromagnetic state?

Posted on : April 20, 2017 (Thu) 23:52:20

by 池田敦俊

Dear Dr. Gomi,

Thank you for the kind answer.
The fmg program is powerful.

Sicerely,
Ikeda

[Re:01] How to calculate antiferromagnetic state?

Posted on : April 20, 2017 (Thu) 21:58:27

by Hitoshi GOMI

Hello Ikeda,

> Do I have to extend the unit cell, for example to 2x2x2, and choose an arbitrary antiferromagnetic setting like this?

Yes, but an initial potential file is required.

You can prepare the initial potential with up and down spin from ferromagnetic potential file by using the fmg program in the same way as for LMD calculation, as written in the thread.

Hitoshi GOMI