where the indices 1-6 refer to the Ni II ions on the ring and 7 the central Ni II ion. This magnetic Hamiltonian divides up 1 into a problem with two exchange constants, 𝐽𝐽 𝑟𝑟𝑟𝑟 and 𝐽𝐽 𝐶𝐶𝑅𝑅 , and two anisotropic terms, 𝐷𝐷 1,2 . Here we have used the result above that the spins on the outer wheel have uniaxial anisotropy while the inner spin has easyplane anisotropy. Note that in the analysis discussed below, we have performed a fit without anisotropy, however this produces exchange constants that are unphysically large (for example 𝐽𝐽 𝐶𝐶𝑅𝑅 ∼ -4 meV = -32 cm -1 ) in comparison to the first principles calculations and experimental fits discussed above. To constrain the parameters used to describe the neutron response, it is important to consider the magnetic susceptibility which is related to the real part of the Green's response function and to the imaginary part via Kramers-Kronig relations.