4. CONCLUSIONS
High-level quantum calculations were performed to study ground and
excited states of endohedral M@C20H20 (M
= Li, Na, Mg+). Ground state of each
Li@C20H20,
Na@C20H20, and
Mg@C20H20+ has an
electron in a pseudo spherical s-type orbital positioned around
Li@C20H20+,
Na@C20H20+, and
Mg@C20H202+ skeletons.
In excited states they populate higher angular momentum p-, d-, f-,
g-type superatomic orbitals. Excited states of
Li@C20H20 were investigated under
several basis sets. M:cc-pVTZ, C:cc-pVTZ, H:d-aug-cc-pVTZ combination
accurately represent ground and excited electronic structures of these
superatoms. The proposed shell model of
Li@C20H20 and
Na@C20H20 is 1s, 1p, 1d, 2s, 1f, 2p, 2d,
1g, 2f. The series of
Mg@C20H20+ is 1s, 1p,
1d, 2s, 1f, 2p, 2d, 1g, 3s, 2f, 2g, 3p. Excitation energies of
Li@C20H20 are bigger than
Na@C20H20 but lower compared to the
Mg@C20H20+. We believe
these findings will be useful for future studies on similar superatomic
systems.