I am not sure I fully understand your problem. You have a few manganese atoms. Wouldn't a translation of half the unit lattice bring them back into corners? Then assign the magnetisation and move back...

Sir,

If suppose i delete atoms at corners and those blue atoms on edges on A and G types, isn't it like... A will turn G ? @Roberto D'Agosta

If I correctly understand your structure, you have some Mn atoms and other atoms that are likely not magnetic (or of whom you don't want to assign an initial magnetisation). So, I take that the empty atoms sites are non-magnetic. Am I right?

I don't believe that with the shift of half a unit lattice in a given direction, A turns into G. Notice that G has a planar symmetry in such a way that any plane has the same magnetisation. A does not have the same symmetry. but rather that of two intercalated ferromagnetic bulks. Also C possesses a planar symmetry where the planes are not parallel to the unit cell.

Exactly sir,you are right about the empty sites as non magnetic.

Turning of A to G upon translation is not what i consider so far.

My Mn atoms are edge centered and face centered.

In the exemplary figure,in A these (edge centered and face centered) are up in lower plane,down in middle plane and up in uppermost plane (in agreement with the definition).Fine it is.

Now,in G, these (edge centered and face centered as represented by blue ones) are down in lower plane,up in middle plane and down in up plane, which again turns to be A type.

In brief, if only face-centered and edge centered atoms are considered in G (as I require as Mn atoms are edge centered and face centered for my case), G turns A?

Kindly, help me in assigning spin orientations to Mn atoms 1,2,3,4 corresponding to A, G and C.

.......For A, it should be Mn1 up,Mn2 up,Mn3 and Mn4 down.....

I had been trying it using pen-paper, Xcrysden, etc.,but still in vain.

Thanks sir

Regards

I would probably proceed in this way -- take your unit cell and double it in any direction. Then shift it by half a unit vector -- you should have displaced some of the Mn atoms back to the corners. Construct your anti-ferromagnetic states and then revert to your unit cell. Does this give you back the same structures for A and G?

On the other hand, it is possible that with your reduced symmetry the two antiferromagnetic configurations are the same.

Regards,

Roberto