ac conductivity of the transparent states in Fibonacci chains

The electrical transport in quasiperiodic systems at zero temperature is st udied by means of the Kubo-Greenwood formula within a tight-binding model. Their de conductivity is compared,with that obtained from the Landauer form ula. Special attention is paid to the transparent states, whose transmittan ce is unity. The ac conductivity of these states shows a rapid diminution a s a function of the frequency, in comparison with that of periodic systems. Minima in these conduction spectra are observed, which are located at (N-1 )h omega =4n pi /t/ for the periodic case. Finally, the localization of the eigenstates is analyzed by looking at the Lyapunov exponent and the partic ipation ratio. The latter is shown to be an inappropriate quantity to chara cterize the critically localized states.