PHONON LOCALIZATION IN QUASI-CRYSTALS

Investigations of phonon localization in a hierarchy of rational appro ximants to icosahedral quasicrystals are presented, based on exact and iterative diagonalizations of the dynamical matrix. Results have been obtained for models of the icosahedral AlZnMg phase with more than 50 000 atoms in the periodically repeated cell. It is shown that localize d or 'confined' modes exist at several well defined frequencies and th at these different groups of modes are associated with distinct topolo gical features of the quasiperiodic lattice.