We note that the resulting set of screened polarizabilities { ᾱ j (iν)} are not isotropic due to the effect of self-consistent screening. Finally, the screened resonant frequencies used in the zero-point energy E 0 , are defined similarly to Eq.( ): this time instead, screened quantities are used and the screened dispersion coefficients must be explicitly computed via the Casimir-Polder integral, Eq. (14).