Conclusions
In this present report, we analyzed the stability and electronic properties of M@Ge12 (M = Co, Pd, Tc, and Zr) nanoclusters using the density functional theory. The outcomes are as follows:
1. We can identify that the D6h symmetry hexagonal prism structure is unique for germanium as well as silicon cage as described by José M. Goicoechea in his research [58]. It can be seen by figure 2, the HP, Ih, and HAP structure reach their maximum stability when total valence electron in the system count 52-58 electrons. In this case TM atoms completely fall into the germanium cage.
2. The magnitude of binding energy of the clusters indicate that the doping of 4d transition metal Tc, and Zr gives most stable structure rather than 3d transition metal Co atom.
3. The results show that doping of 4d transition metal like Tc, Zr, and Pd have relatively large gap in compare to 3d transition metal Co. Here we obtain 1.96eV [Tc@Ge12], 1.96eV [Pd@Ge12], 1.86eV [Zr@Ge12], and 0.97eV [Co@Ge12] HOMO-LUMO gap for the most stable clusters. The stability of these clusters can be defined using closed shell electronic configuration and the contribution of π and σ bond.
4. Charge transfer mechanism shows that the Tc, Pd and Zr atoms play role as a electron donor in the system whereas Co inclined to accept the electrons.
5. PDOS calculation provides the information of localized “d” electrons near the Fermi level. The electron density is mainly distributed around the TM atoms. PdGe12 would be a good candidate as the building block with high magnetic moment for cluster assembly system.
So the overall conclusions suggest that the investigations of new hybrid semiconductor clusters doped with different TM atoms are very useful in electronic devices, laser application and sensors. The theoretical modeling also show possibility of designing miniature devices using pure and TM doped hybrid semiconductor clusters.