TB2J the choice of cell is impoartant?

[ChenqiangHua]

Dear sir! recently i got this beautiful software. I find taht the use of WFs from DFT codes can be used to generate J parameters. But i have one simple but important question: it is need to get accurate J with primitive cell? even it is not the ground state? for example, a AFM strcuture need supercell. so when i calculate J with TB2j , do i need generate WFs using AFM supercell or primitivecell which must be FM?

thanks!

[mailhexu]

Hi, It is not necessary to use the geometric primitive cell. The AFM supercell is actually the primitive cell considering the magnetism. TB2J works with a perturbation to the reference state(DFT state), so it is more accurate when the reference state is the ground state. Often you can still get reasonable exchange parameters if you use the FM cell, if the structures are very Heisenberg, i.e. the dependency of the J on the spin orientation is weak. Best regards, HeXu

[ChenqiangHua]

Thanks! I get it, the most impoartant thing is the Heisenberg like!

Thanks again for your time!