Radial induced-charge screening kernel ($g(q)=q[1-ϵ(q{)}^{-1}]/(2{\pi }^2)$)

For a point source $Ze$ and the Fourier transform convention $\rho (\mathbf{q})=\int e^{-i\mathbf{q}\cdot \mathbf{r}}\rho (\mathbf{r})d^{3}r$, self-consistent screening gives ${\rho }_{\mathrm{ind}}(q)=Ze[ϵ(q{)}^{-1}-1]$. Angular inversion yields ${\rho }_{\mathrm{ind}}(r)=-(Ze/r){\int }_0^{\infty }g(q)\sin (qr)dq$. The factor $1/(2{\pi }^2)$ includes the inverse-transform normalization and spherical angular integral. Perfect long-wavelength screening implies total induced charge $-Ze$.