Dissociation error of a doubly occupied bonding orbital
= Dissociation error of a doubly occupied bonding orbital
A normalized product of two identical bonding orbitals built from separated orthogonal centers has finite weight in configurations with both <electrons> on one center. Repulsion penalizes that ionic weight even when hopping disappears. Mixing configurations can instead approach one <electron> per center while preserving the required <spin> and exchange symmetries.