Table 1.

Parameters used to fit magnetic and INS data and calculated by DFT

	3		4
	Best fit parameters	DFT calculation	Best fit parameters	DFT calculation
J12/meV	−0.409 (1)	−0.621 (10)	−0.71163 (4)	−0.91 (10)
J19/meV	−0.0037 (5)	−0.197 (10)	−0.2715 (1)	−0.346 (10)
J23/meV	−0.726*	−0.914 (10)	−0.726*	−0.930 (10)
DCr/meV	−0.029	Not applicable	−0.038	Not applicable
Spin ground state	3/2	1/2	1/2	1/2

Numbers in parentheses are estimated error on last digit.

*Fixed based on previous studies (e.g., ref. 17).