[Wien] why Fe spin at [A] site is not showing negative value than that in [B] site in a ferrimagnetic calculation?

[shamik chakrabarti]

Dear Stefan Cottenier Sir,

Yes, you are right, I have flipped the spin after lstart and hence (as you
said) it has no effect. It is indeed an user problem as the material is
itself ferrimagnetic. Sir, I will flip the spin *after instgen_lapw* and
rerun the calculation again.
Sir, thank you very much for your kind help.

with best regards,

On Fri, Aug 12, 2011 at 9:11 PM, Stefaan Cottenier <
Stefaan.Cottenier at ugent.be> wrote:

>
>        I am doing a ferrimagnetic calculation for [A][B]O4 type material
>> in which I have flipped the spin of Fe atoms at [A] site. I have
>> modified case.inst file after input file generation (just before giving
>> the number of K points) and flipped the spin of Fe atoms. Then as usual
>> I go for dstart -up/dn and then run a spin polarize calculation. But
>> after 24 cycles (it is still running) when I checked Fe moments at [A]
>> site, *the moments are positive !! (although different from that in [B]
>> sites)*. I have checked again the case.inst file and see that it has
>> sticked to the modified form, i.e., Fe spins are opposite in [A] site
>> than it is in [B] site. *Then why it is giving positive moments instead
>> of negative?*..whether I have done something wrong in the steps?
>> **Any response in this regard will be very helpful for us.
>>
>
> This might either be physics or a user problem.
>
> Check how your moments evolved throughout the scf-cycle, and especially how
> they were in the first iteration. Did the sign originally correspond to what
> you have put in case.inst, and did it later gradually flip to the undesired
> sign? In that case, it is physics: your material does not 'like' a
> ferrimagnetic solution. In case your moment had already the undesired sign
> in the very first iteration, you probably did something wrong. From your
> description, you seem to have changed case.inst *after* lstart had run, and
> therefore your changes had no effect. In recent wien2k versions, you can
> specify the moment (and its sign) atom by atom during init_lapw, before
> lstart is run.
>
> Stefaan
>
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-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA
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