  We study how the Mott metal-insulator transition (MIT) is affected when we
have to deal with electrons with different angular momentum quantum numbers.
For that purpose we apply ab-initio quantum-chemical methods to lithium rings
in order to investigate the analogue of a MIT. By changing the interatomic
distance we analyse the character of the many-body wavefunction and discuss the
importance of the $s-p$ orbital quasi-degeneracy within the metallic regime.
The charge gap (ionization potential minus electron affinity) shows a minimum
and the static electric dipole polarizability has a pronounced maximum at a
lattice constant where the character of the wavefunction changes from
significant $p$ to essentially $s$-type. In addition, we examine rings with
bond alternation in order to answer the question under which conditions a
Peierls distortion occurs.
