https://doi.org/10.1140/epjd/e2015-50607-9
Regular Article
Wade’s rules and the stability of AunGem clusters*
1
Department of Physics, Wabash College, Crawfordsville, IN
47933,
USA
2
Department of Physics, University of Notre Dame,
Notre Dame, IN
46556,
USA
a e-mail: mcdermod@wabash.edu
b e-mail: newman@nd.edu
Received:
19
August
2014
Received in final form:
4
January
2015
Published online:
24
March
2015
The properties of clusters formed from two connected Gem cage-like clusters, such as experimentally synthesized Au3Ge185-, are examined using first-principles DFT methods. We focus particularly on AunGe12q- formed from a Wade-rules stable Ge6 cluster, where n = 0–3 and q = 0,2. The geometries, electronic structure, and thermal excitations of these clusters are examined using the SIESTA code. Cluster stability is tested using short molecular dynamics simulations. We find that intercluster bridges between Gem cages, formed of either Ge-Ge or Au-Ge bonds, can either bind a cluster together or tear it apart depending on the orientation of the bridging atoms with respect to the cages. The properties of neutrally charged AuGe12 and Au2Ge12 are characterized, and we observe that radially directed molecular orbitals stabilize AuGe12 while a geometric asymmetry stabilizes Au2Ge12 and Au3Ge18. A two-dimensional 2∞[ Au2Ge6 ] structure is examined and found to be more stable than other periodic [ AunGe6 ] subunits. While no stable neutral isomers of Au3Ge12 are observed in our calculations, our work suggests additional charge stabilizes isomers of both Au2Ge12 and Au3Ge12.
Key words: Molecular Physics and Chemical Physics
Supplementary material in the form of one pdf file available from the Journal web page at: http://dx.doi.org/10.1140/epjd/e2015-50607-9
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2015