Time Reversal and Molecular Properties

Chemists regularly exploit point group symmetry in their analyses of molecular structure and properties but they rarely utilize time reversal symmetry. The time reversal operator T reverses the momenta and spins of all particles in a system and distinguishes properties which are even under T, such as the electric dipole moment, from those that are odd, such as the magnetic dipole moment. We review the role of T in quantum mechanics and discuss its application to the properties of molecules in electric and magnetic fields. Among the properties considered are natural and magnetic optical activity, magneto-chiral effects, antisymmetric Raman scattering, optical NMR and ESR, chirality, and absolute enantioselection.