Alkaline earth metal substitutional doped C ₂₀ : a density functional study

Exploring the structure and electronic properties has become a very interesting subject for nanomaterial application in many fields. This study presents a comprehensive density functional theory exploration of structure and electronic properties of alkaline earth metal (Be, Mg, and Ca) substitutional doped C20 fullerene. The study shows that MC19 (M = Be, Mg, and Ca) cage has elongated M–C bond lengths and expanded C–M–C bond angles. The Be in BeC19 gains a modest charge, while Mg in MgC19 and Ca in CaC19 donate charge. The most amazing result is that MC19 has very large energy gap, which indicates their higher stabilities than C60, and further proved by the larger hardness of MC19 than that of C20. Importantly, the physical interaction mechanism between M and the cage are different for three MC19 structures, which can be proved by the frontier orbital wavefunction and total density of states. The chemical potential values of C20 are larger than that of MC19, indicating their weaker ability to contain electrons and higher activity. Our research will provide the groundwork for rational design and application of such materials in electronic devices and nanotechnology fields.