Theoretical treatment of the dielectric response of all-trans-polyacetylene

First-principles electronic-band-structure results for polyacetylene are used to calculate the dielectric function $\epsilon (q,\omega )$ of this material as a function of frequency $\omega$ and wave vector $q$. We find that our theoretical results when compared with the recent experimental results reported by Ritsko describe well many of the dominant features of the electron energy-loss spectra within a self-consistent interband transition linear response model for noninteracting parallel chains. A discussion is provided of other physical effects outside this simple model which may have a measurable effect on the optical and energy-loss spectra of polyacetylene.