Magnetic exchange parameter of Nickel Oxide

[Владимир Харитонов]

Hello tb2j users. I am currently trying to calculate J_{ij} for the NiO(AFM) system using VASP + Wannier90 + TB2J.
The input for VASP is taken from here (and want to get a similar value of exchange parameter(20.06 meV)).
However, the value I got is 2 times lower than expected (about 10meV).
The input and output files are attached

[Xu He]

Hello, 

Could you check if the convention of the literature and in TB2J are the same?

From Eq. 1 of Hutchings M. T., Samuelsen E. J., Phys. Rev. B 6, 9, 1972, 3447, the summation runs over distinct ij pairs, whereas in TB2J , it runs over both ij and ji (so counted twice). 

Therefore, the J in TB2J should be 1/2 of that in the reference paper. 

See https://tb2j.readthedocs.io/en/latest/src/convention.html for the details of the different conventions. 

Best regards, 

HeXu