Can CF<sub>3</sub>-Functionalized La@C<sub>60</sub> Be Isolated Experimentally and Become Superconducting?

Guan, Jie; Tománek, David · Nano Lett · 2017

basic_science · Level V

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Abstract

Superconducting behavior even under harsh ambient conditions is expected to occur in La@C<sub>60</sub> if it could be isolated from the primary metallofullerene soot when functionalized by CF<sub>3</sub> radicals. We use ab initio density functional theory calculations to compare the stability and electronic structure of C<sub>60</sub> and the La@C<sub>60</sub> endohedral metallofullerene to their counterparts functionalized by CF<sub>3</sub>. We found that CF<sub>3</sub> radicals favor binding to C<sub>60</sub> and La@C<sub>60</sub> and have identified the most stable isomers. Structures with an even number m of radicals are energetically preferred for C<sub>60</sub> and structures with odd m for La@C<sub>60</sub> due to the extra charge on the fullerene. This is consistent with a wide HOMO-LUMO gap in La@C<sub>60</sub>(CF<sub>3</sub>)<sub>m</sub> with odd m, causing extra stabilization in the closed-shell electronic configuration. CF<sub>3</sub> radicals are both stabilizing agents and molecular separators in a metallic crystal, which could increase the critical temperature for superconductivity.