Systems with icosahedral clusters: Direct links between atoms in cluster-recursion methods and DOS spectral fine structure

The origin of narrow pseudogaps close to the Fermi energy is examined in tw o model systems: alpha-AlMn(Si) and i-AlCuFe (1/1). We show that long-range electronic interferences in the Mn/Fe sub-systems give rise to such narrow spectral features which are highly important for the electronic transport. Besides the ASA-LMTO and the TB-LMTO recursion method we employ a cluster- recursion method within the muffin-tin scattered wave concept which reveals interference results on arbitrary length scales. We conclude that certain properties of quasicrystals are due to the physics in chemically defined su b-systems. (C) 2000 Elsevier Science B.V. All rights reserved.