The upper and lower polariton potential energy surfaces with a large number of atoms N ≳ 10 coupled to the cavity. For a small number of atoms, N ≲ 10, the stability of the molecule may be enhanced. The authors report constructive and destructive interference at the avoided crossings which prevent molecular dissociation and leads to molecular stability. It is worth mentioning, as this analysis indicates, that collective cavity coupling can only affect a molecular excited state potential energy surface to a limited extent.