Long-range ab initio potential energy surface for the ground electronic state of the ozone molecule with the accurate dissociation asymptote

•The ab initio potential energies of O3 were computed with the extended CAS(24,15) reference.•The SO coupling between 9 multiplet electronic states approaching De was included.•An excellent agreement was achieved between the empirical and theoretical values of De.•The long-range (RO2-O≥5a0) ab initio PES was developed in the scattering coordinates.