Calculation of optical properties of trans-polyacetylene by the linear muffin-tin-orbital method

The basic optical properties of trans-(CH${)}_{\mathrm{x}}$ in the P$2_1$/n and the P$2_1$/a space groups are derived from first principles. The relevant optical matrix elements are calculated within the self-consistent linear muffin-tin-orbital band-structure method. The derived optical response functions are compared with the results from a variety of optical as well as electron-energy-loss experimental studies. It is shown that the measured optical constants are consistent with the P$2_1$/n structure.