A very first draft of the lecture notes of the course “Small vibrations: introductory course on phonons in solids” are available online:

https://www.attaccalite.com/lecture_notes/main.pdf

In this course we present: introduction to phonons; the Born–Oppenheimer Approximation; polar materials and LO-TO splitting; infrared and Raman spectroscopy; electron-phonon coupling; an-harmonic effects.