Analytic Route to Tunneling Splittings Using Semiclassical Perturbation Theory
Timothy A. H. Burd, David C. Clary
Abstract
We present an efficient, analytical, and simple route to approximating tunneling splittings in multidimensional chemical systems, directly from ab initio computations. The method is based on the Wentzel–Kramers–Brillouin (WKB) approximation combined with the vibrational perturbation theory. Anharmonicity and corner-cutting effects are implicitly accounted for without requiring a full potential energy surface. We test this method on the following three systems: a model one-dimensional double-well potential, the isomerization of malonaldehyde, and the isomerization of tropolone. The method is shown to be efficient and reliable.
Topics & Concepts
WKB approximationSemiclassical physicsAnharmonicityIsomerizationAb initioTropoloneQuantum tunnellingPotential energy surfacePerturbation theory (quantum mechanics)ComputationPerturbation (astronomy)Computational chemistryQuantum mechanicsPhysicsChemistryMathematicsAlgorithmOrganic chemistryQuantumBiochemistryCatalysisAdvanced Chemical Physics StudiesSpectroscopy and Quantum Chemical StudiesMolecular Junctions and Nanostructures