Abstract
Notable recent developments in the use of normal mode methods to study protein dynamics include the use of quasiharmonic descriptions in crystallographic and NMR refinement protocols, and the development of techniques that can be applied to disordered systems (such as liquids) that do not oscillate about a single minimum. Harmonic models can also be used to investigate quantum effects and to provide a compact description of correlated motions in biomolecules. This sort of analysis has both prospects and limitations.