Jahn-Teller analysis of the electronic properties of the endohedral clusters M@Al12 (M = B, Al, Ga) and their anions

It is well established that several doped aluminum clusters (M@Al12), with 40 valence electrons and the dopant M at the center of the icosahedral Al12 cage, present a highly stable icosahedral structure with electronic closed-shell and HOMO-LUMO gap comparable to C60 and Au20. It has also been shown that the 39 valence electrons cluster Al13 could be regarded as a superhalogen superatom, with an electron affinity close to the chlorine atom. However, when an electron is detached from an electronic closed-shell icosahedral system, we end up with a degenerated HOMO state, showing a Jahn-Teller instability, undergoing therefore a structural distortion to remove the electron degeneracy by lowering the symmetry. In this work we perform a Jahn-Teller analysis of the electronic properties of the endohedral clusters M@Al12 (M = B, Al, Ga) under the symmetry breaking process, lowering their Ih symmetry to D2h for B and D3d for Al and Ga. We show the necessity of taking into account this symmetry breaking in order t...