Quantum effects in chemistry: seven sample situations

Significant quantum effects in chemistry range from static structure (electronic and geometrical) through dynamical behavior, including optical properties, conductance, relaxation, decoherence, and thermalization. We outline seven situations in which molecular systems exhibit ineluctably quantum behavior. These range from situations in which the community can understand the problem quantitatively and conceptually (for example for dilute sets of spins in NMR) to femtosecond/attosecond situations, which the community understands only primitively. In condensed phase, the dynamics will always evolve in a system/bath environment, and we discuss here how to pose, and to start understanding, problems of that sort.