Ab initio structure determination of quasicrystals by density modification method

A novel density modification method has been applied to phase reconstruction of X-ray single crystal data of quasicrystals. This is based on the low electron density elimination (LDE) method that is an ab initio structure determination method for crystal in the real space. The location, size and shape of the occupation domains for quasicrystals in the n-dimensional (nD) unit cell are obtained without any model structure. Therefore, the LDE method can be a substitute for the direct method for quasicrystals as nD crystals. The structure solution can easily be found in the trial sets (normally 100 sets) and is confirmed by the subsequent analysis. The result is used as a crude starting model for constructing a detailed structure model of quasicrystals. The solutions of several quasicrystals (i-AlPdMn, i-ZnMgHo and i-CdYb) are exemplified. The reliability and limitations of the algorithm to retrieve the quasicrystalline structures will also be discussed.