Atomic and electronic structure of decagonal Al-Pd-Mn alloys and approximant phases

The electronic structure of the decagonal phase Al₇₀{Pd}₁₃Mn₁₇ and related crystalline phases has been calculated using the self-consistent tight-binding linear-muffin-tin-orbital technique. The electronic densities of states and the spectral functions have been calculated via the real-space recursion technique. The structural models are based on the decagon-pentagon-hexagon tiling. Chemical short-range order is optimized using the information about the local densities of states. The pentagonal columnar clusters (identified by Hiraga et al.) exhibit structural stability and play the role of a characteristic structural unit of all the discussed phases. Formation of a pseudogap in the Al-sp band is observed and its origin and role in the stabilization of the decagonal phase is discussed.