Vibrations of Molecules and Solids

MasterVibrations in molecules and in condensed matter are described and discussed. Forces between neighboring atoms are considered classically as radial or angular meaning that vibrational potential energy is due either to length change in bonding distance (two-body effect) or angle change (bending) of bonding configuration (three-body effect). After describing the historical (Diamond case) and later the general theory of vibrations in condensed matter, we apply it to the 1D diatomic chain to explain the notions of acoustic and optic phonons from their dispersion and density of states points of view. Application to Graphene is later described as a general methodology for phonon dispersion and density of states determination