It has been recently shown, using ab-initio methods, that bulk diamond is characterized
by a large band-gap renormalization (~0.6 eV) induced by the electron-phonon
interaction. In this work we show that in polymers, compared to bulk materials, the larger
amplitude of the atomic vibrations makes the real excitations of the system be composed by
entangled electron-phonon states. We prove that these states carry only a fraction of the
electronic charge, thus leading, inevitably, to the failure of the electronic picture. The
present results cast doubts on the accuracy of purely electronic calculations. They also
lead to a critical revision of the state-of-the-art description of carbon-based
nanostructures, opening a wealth of potential implications