To parameterize the results, we have combined the first principles DFT results with the thermodynamic magnetic susceptibility to constrain excitonic calculations for the neutron spectroscopy results. The methodology we have used involves first fitting the high temperature magnetic susceptibility to obtain a Curie-Weiss constant thereby fixing the sum of the two exchange constants 𝐽𝐽 𝑟𝑟𝑟𝑟 and 𝐽𝐽 𝐶𝐶𝑅𝑅 with the signs of these exchange constants fixed through the DFT first principles calculations described above. Applying the results from neutron spectroscopy and our excitonic calculations described above, we then parameterize the two excitations observed through varying the anisotropy parameters, also guided by first principles calculations. This parameterization was done by performing a least squares fit to the Ei = 12 meV data illustrated in Fig. . The results of this are shown in Fig. . This fit produces a weak high energy peak as found in the data, however it fails to capture the significant intensity present at lowenergies found in the Ei = 3 meV data in Fig. . The parameters were then varied to bring the spectra down to lower energies while preserving a weak peak at ∼6 meV and keeping the values consistent with DFT estimates and within the constraints set by the high temperature Curie Weiss temperature (Θ 𝐶𝐶𝐶𝐶 ).