Susceptibility and Intra-Atomic Exchange in Nickel

We have calculated the generalized susceptibility $\chi (\overrightarrow{\mathrm{K}}, \omega )$ of paramagnetic nickel at $1.6T_c$ using a simple five—$3d$-band model in tight-binding approximation and compared it with neutron-scattering measurements. The only adjustable parameter was the exchange enhancement, considered to arise from an effective Coulomb interaction $I_{\mathrm{eff}}\left(\overrightarrow{\mathrm{r}}\right)$ in the random-phase approximation. Our analysis is consistent with the interaction being dominated by the on-site term at $\mathcal{r}=0\mathrm{}$, the relative contribution from any one nearest-neighbor position coming to less than 10%.