#1 spin spiral calculations of two or more magnetic atoms by xdzhou 25.01.2022 15:36

Dear Fleur developers,

I want to do a spin spiral calculation involving two magnetic atoms (fleur, v26 version).
I have reproduced the result of fcc Fe (one magnetic atom), but I do not know if there is any difference between one magnetic atom and more magnetic atoms.
The following are my material system (two magnetic Pd atoms) and my calculation progress.

This is my input generator.
#################################################################
PdF3

&input film=f cartesian=f cal_symm=t /

! primitive:
2.4387895018949948 1.4080357754159085 4.7429872621175369
-2.4387895018949948 1.4080357754159085 4.7429872621175369
0.0000000000000000 -2.8160715508318170 4.7429872621175369
1.889726125
1 1 1

8
46 0.5000000000000002 0.5000000000000001 0.5000000000000001
46 0.0000000000000002 0.0000000000000001 0.0000000000000000
9 0.5922679954685097 0.2500000000000003 0.9077320045314906
9 0.2500000000000003 0.9077320045314906 0.5922679954685096
9 0.0922679954685095 0.4077320045314906 0.7500000000000000
9 0.7500000000000000 0.0922679954685095 0.4077320045314906
9 0.4077320045314907 0.7500000000000000 0.0922679954685095
9 0.9077320045314908 0.5922679954685096 0.2500000000000002

&qss 0.0000000000 -0.8469595000 1.4264960700 /

&atom element="Pd" id=46 bmu=4.0/
&atom element="F" id=9 bmu=0.0/

&kpt div1=12 div2=12 div3=12 /

&end /
#################################################################



Here are the bravais matrices of real and reciprocal lattices from "out" file,
##################################################################
4.608644 -4.608644 0.000000 0.681674 0.393565 0.233673
2.660802 2.660802 -5.321604 -0.681674 0.393565 0.233673
8.962947 8.962947 8.962947 0.000000 -0.787129 0.233673
##################################################################



Then I define the q vector = (0.0, -0.8469595, 1.42649607), which will describe a spin spiral in z-direction [reciprocal lattice * q = (0,0,1)].
The following is the nocoinp file.
############################################################3
atom-type 1,l_relax=F
alpha = 0.0000000000,b_cons_x = 0.0000000000
beta = 1.5707963268,b_cons_y = 0.0000000000
0.0000000000
atom-type 2,l_relax=F
alpha = 0.0000000000,b_cons_x = 0.0000000000
beta = 1.5707963268,b_cons_y = 0.0000000000
0.0000000000
-- logical parameters --
l_ss=T,l_mperp=F,l_constr=F
mix_b= 0.500
qss=( 0.0000000000, -0.8469595000, 1.4264960700)
#############################################################3



Finally, I will change the qss from (0.0,0,0,0,0) to ( 0.0000000000, -0.8469595000, 1.4264960700).

Is there a problem with the above calculation process ?
Besides, without SOC, I wonder whether there is any difference when q vector is along different axis (e.g. x, y, z axes).

Look forward to your kind reply and thank you very much.

xdzhou

#2 RE: spin spiral calculations of two or more magnetic atoms by gbihl 25.01.2022 17:54

Dear xdzhou,

as an introduction to this topic I recommend reading this paper:
https://journals.aps.org/prb/abstract/10...sRevB.88.134403
where it is described how to deal with different magnetic sublattices.
We have some switches in the nocoinp-file, that help you with the calculations,
https://www.flapw.de/Fleur-v26/v26/files/#nocoinp
but I'm not sure whether I have a documentation of those described in the lower panel.

Whether the exchange in x,y,z direction is different does not depend on SOC,
but on the crystal structure.

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