Exploring the structural stability order and electronic properties of
transition metal M@Ge12 (M = Co, Pd, Tc, and Zr) doped germanium cage
clusters
Abstract
In the present report, the structural stability order and electronic
properties of the transition metal M@Ge12 (M = Co, Pd, Tc, and Zr) doped
germanium cage has been carried out at B3LYP/LANL2DZ ECP level by using
spin polarized density functional theory. Initially, we selected five
lowest energy structure of neutral TM doped Ge12 cluster with high
symmetry point like D6h-symmetric hexagonal prism (HP), the
D6d-symmetric hexagonal anti-prism (HAP), D2d-symmetric bi-capped
pentagonal prism (BPP), perfect icosahedrons (Ih) and Fullerene type
structures. Further, we discussed the electronic origin of stability as
well as electronic properties by calculating binding energy, HOMO-LUMO
gap, charge transfer mechanism and density of states. We indentified
that the Pd, Tc, and Zr encapsulated Ge12 cage with hexagonal prism
[HP] structures are minimum energy structures while Co@Ge12 cage
prefer HAP structure. The magnitudes of binding energy of the clusters
indicate that the doping of 4d transition metal gives most stable
structure rather than 3d transition metal Co atom. The large HOMO-LUMO
gap and natural bond orbital analysis explain the stability of these
clusters using closed shell electronic configuration and the
contribution of π and σ bond. Charge transfer mechanism shows that the
Tc, Pd and Zr atoms play role as an electron donor in the system whereas
Co inclined to accept the electrons. The importances of “d” orbital in
localized electrons near the Fermi level are also explained through
partial density of states.