Lattice dynamics of TTF-CA across the neutral-ionic transition

We present the temperature evolution of polarised Raman and IR reflectivity spectra of Tetrathiafulvalene-Chloranil (TTF-CA) in the lattice phonon region (10-200 cm−1). Quasi Harmonic Lattice Dynamics (QHLD) calculations prove to be essential in discussing the assignment of the phonons and their evolution across the temperature induced neutral-ionic phase transition.