 In its original formulation, the Renner–Teller effect was a vibronic coupling between the motions of the electrons and the nuclear vibrations in triatomic linear molecules.The 1934 article by Rudolf Renner was the first that considered dynamic effects that go beyond the Born–Oppenheimer approximation, in which the nuclear and electronic motions in a molecule are uncoupled.This is a good approximation when the electronic energies are well separated.