Zr@si₂₀: A strongly bound Si endohedral system

We present the results of local density approximation (LDA) calculations for a novel Si endohedral system, Zr@Si₂₀. We compute an LDA endohedral binding energy for this system of 11.2 eV with respect to an isolated Zr atom and the most stable Si₂₀ isomer known. To understand the remarkable binding in this system, we compare the electronic structure of Zr@Si₂₀ with that of the corresponding bare cluster and with other Si₂₀ endohedral systems. We find that the bonding of all the endohedrals can be understood on the basis of a simple model previously used to explain endohedral bonding in small carbon fullerenes. Prospects for producing Zr@Si₂₀ experimentally are discussed.