Atomic and Molecular Tunneling Processes in Chemistry

Abstract The article presents an overview of atomic and molecular tunneling processes, where tunneling of “heavy” particles (i.e., nuclei, not electrons) is important. After an introductory tour d'horizon including a brief history of the tunnel effect, we discuss some topics of current interest. These include tunneling and parity violation in chiral molecules, tunneling in weakly bound complexes, and tunneling processes in slightly asymmetric potentials with tunneling switching and the development of a molecular quantum switch. We then present a selection of recent results for isomerization reactions, bimolecular reactions, tunneling in ions, radicals and electronically excited states, and of the motions of molecules inside a cage. We conclude with some remarks on certain general problems related to tunneling.