Broken symmetry in the electronic structure of the ferrocene molecule

Attempts to calculate the metal–ring distance in the ferrocene molecule using a well‐tried minimal basis reveal serious deficiencies in the minimal‐basis SCF model of the electronic structure of organometallics. It is found that the lowest state of the molecule in this approximation is a triplet and that there is a whole manifold of “states” in the ground‐state region that have broken spatial symmetry and high‐spin multiplicity.