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A Quantum Mechanically Guided View of Mg 44 Rh 7
Author(s) -
Berger Robert F.,
Lee Stephen,
Hoffmann Roald
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200700930
Subject(s) - ionic bonding , intermetallic , crystallography , atom (system on chip) , variety (cybernetics) , symmetry (geometry) , quasicrystal , physics , geometry , materials science , molecular physics , chemistry , theoretical physics , computer science , mathematics , ion , quantum mechanics , artificial intelligence , alloy , composite material , embedded system
We present a new geometric description of Mg 44 Rh 7 , a compound with 408 atoms in its cubic unit cell. Using both experimental site preferences and LDA‐DFT‐calibrated extended Hückel (eH) calculations as guides, we highlight the structural units within Mg 44 Rh 7 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 Ti 2 Ni structure, rather than the variety of clusters often used to describe complicated intermetallic and ionic structures. These Ti 2 Ni 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 Mg 44 Rh 7 , including a fractal‐like arrangement of similar atomic formations on different length scales, geometrically connected to an approximate fivefold symmetry.