**Marc Joyeux
**

Canonical Perturbation Theory (CPT) consists of a series of transformations, which are aimed at rewriting the Hamiltonian of a system in a simpler form, that is, in terms of as many good quantum numbers (or classical constants of the motion) as possible, without modifying the geometry of the phase space. Therefore, CPT is particularly well suited for studying energy localization (existence of good quantum numbers) and energy transfer (destruction of good quantum numbers) in molecular systems. Recent results dealing with rigid molecules (e.g. HCP), floppy molecules (e.g. HCN and H2O2) and coupled electronic surfaces (e.g. NO2) will be discussed.

More information, references and reprints can be found at the address

http://www-lsp.ujf-grenoble.fr/link/joyeux.htm