  A method is presented for calculating the frequencies of non-retarded surface
plasmons propagating on a semi-inifinite medium with a surface profile
described by a one-dimension quasiperiodic function. The profiles are
generated, in analogy with previous work on quasiperiodic superlattices, by
repeating unitary cells constructed according to an inflation rule. Dispersion
relations are obtained for a semi-infinite free-electron metal as the active
medium, with surface profiles obeying the Fibonacci and Thue-Morse sequences.
