ABSTRACT
This is the “relative” dielectric function (i.e., ε = 1 for vacuum). For convenience, we break the dielectric function into three parts:
(7.4)ε ε χ χ= + +∞ FC L
where ε∞ = 1 + χ∞ is the dielectric constant at high frequencies due to core electrons, χFC is the contribution from free carriers, and χL is from the lattice.
