[Wien] Magnetic material relaxation, RMT, MAE calculations

[Stefaan Cottenier]

> I am really wondering if we have to "relax" structure everytime when
> calculating magnetic materials.
> When relaxed, the magnetic properties, especially K value, become too
> far from experimental data; K value calculated from not relaxed
> structure is also far from the experimental one.

Hard to give any specific comment. This could have several explanations:

1) either your calculation procedure is not accurate enough (k-points? 
very important for MAE)

2) or there is physics going on that is not described in your model

3) or DFT at the LDA/GGA level is not capable of describing this effect 
for this material.

> And another qeustion is about RMT.
> Is it okay to change RMT to fit experimental data?
> I tried several times to fit experimental one, but still question myself
> if that is okay.

See the FAQ (http://www.wien2k.at/reg_user/faq/rmt.html). And even 
safer: accept the values suggested by setrmt_lapw (take the minimal 
values for the relaxed and unrelaxed cases, then you'r sure you can 
cover 'any' situation).

Stefaan