Transition from exo to endo Cu absorption in CuSi_n clusters: a genetic algorithms density functional theory study

Abstract

The characterisation and prediction of the structures of metal silicon clusters is important for nanotechnology research because these clusters can be used as building blocks for nanodevices, integrated circuits and solar cells. Several authors have postulated that there is a transition between exo and endo absorption of Cu in Si _n clusters and showed that, for n larger than 9, it is possible to find endohedral clusters. Unfortunately, no global searches have confirmed this observation, which is based on local optimisations of plausible structures. Here, we use parallel genetic algorithms (GAs), as implemented in our modified genetic algorithms (MGAC) software, directly coupled with density functional theory energy calculations to show that the global search of CuSi _n cluster structures does not find endohedral clusters for n < 8 but finds them for n ≥ 10.

Keywords:

• copper-silicon clusters
• genetic algorithms
• global optimisation

Acknowledgements

This work has been partially supported by computer time allocations from the NSF TeraGrid PHY080012N and CHPC allocation on the Arches cluster partially funded by the NIH NCRR Grant No. 1S10RR017214-0. The software for this work used the GAlib genetic algorithm package, written by Matthew Wall at the Massachusetts Institute of Technology. MBF greatly acknowledges the financial support from the Universidad de Buenos Aires and the Argentinean CONICET.

Notes

1. Email: [email protected]

2. Email: [email protected]

Additional information

Notes on contributors

Ofelia B. Oña

1

Marta B. Ferraro

2