  The alkali hyperoxide KO$_2$ is a molecular analog of strongly-correlated
systems, comprising of orbitally degenerate magnetic O$_2^-$ ions. Using
first-principles electronic structure calculations, we set up an effective
spin-orbital model for the low-energy \textit{molecular} orbitals and argue
that many anomalous properties of KO$_2$ replicate the status of its orbital
system in various temperature regimes.
