Multicritical phenomena for the hydrogen molecule at the large-dimension limit

We show that symmetry breaking of the electronic structure configurations for the Hartree-Fock hydrogen molecule at the large-dimension limit can be described as standard phase transitions. The phase diagram in the internuclear distance-nuclear charge plane shows three different stable phases corresponding to different electronic structure configurations. This phase diagram is characterized by a bicritical point where the two continuous phase transition lines join a first order transition line.