A quantum mechanically guided view of Mg44Rh7

作者：Berger Robert F; Lee Stephen^*; Hoffmann Roald

来源：Chemistry - A European Journal, 2007, 13(28): 7852-7863.

DOI：10.1002/chem.200700930

• intermetallic phases
• magnesium
• rhodium
• semiempirical calculations
• solid-state structures

We present a new geometric description of Mg44Rh7, a compound with 408 atoms in its cubic unit cell. Using both experimental site preferences and LDA-DFT-calibrated extended Huckel (eH) calculations as guides, we highlight the structural units within Mg44Rh7 that reflect the electron-richness or electron-poorness of each crystallographic site. The units that best account for these site preferences and electron populations are 34- and 25-atom fragments of the Ti2Ni structure, rather than the variety of clusters often used to describe complicated intermetallic and ionic structures. These Ti2Ni pieces, located using a systematic search algorithm, fit together in a beautifully intricate network. An examination of this network reveals some surprising geometric features of Mg44Rh7, including a fractal-like arrangement of similar atomic formations on different length scales, geometrically connected to an approximate fivefold symmetry.

• 出版日期2007