Six-dimensional model of an i-Al–Pd–Mn quasicrystal compatible with its 2/1 approximant

A six-dimensional (6D) model of the icosahedral Al–Pd–Mn quasicrystal is given, which is obtained from our old model with slight modification and leads to the 2/1 approximant structure by the introduction of an appropriate phason strain. In the old model, two clusters are situated at even- and odd-parity vertices of the 3D Penrose pattern with an edge length of about 20 Å. One of them is quite similar to that of the 2/1 approximant but the third and ninth shells of the cluster in the approximant cannot be derived. After adding small occupation domains in the 6D model, we could reproduce all atom sites in the approximant structure by the introduction of appropriate cubic phason strain.