In this short review, we provide an update of recent developments in Kramers' theory of
reaction rates. After a brief introduction stressing the importance of this theory initially …

Quantum tunneling can have a dramatic effect on chemical reaction rates. In nonadiabatic
reactions such as electron transfers or spin crossovers, nuclear tunneling effects can be …

Thermally activated chemical reactions are typically understood in terms of overcoming
potential-energy barriers. However, standard rate theories break down in the presence of a …

It is well-known that fewest-switches surface hopping (FSSH) fails to correctly capture the
quadratic scaling of rate constants with diabatic coupling in the weak-coupling limit, as …

We introduce an approach for calculating perturbative corrections to the ring-polymer
instanton approximation to tunneling splittings (RPI+ PC) by computing higher-order terms in …

We simulate two recent matrix‐isolation experiments at cryogenic temperatures, in which a
nitrene undergoes spin crossover from its triplet state to a singlet state via quantum …

This Perspective offers an overview of the applications of the exact factorization of the
electronnuclear wavefunction to the domain of theoretical photochemistry, where the aim is …

Instanton theory relates the rate constant for tunneling through a barrier to the periodic
classical trajectory on the upturned potential energy surface, whose period is τ= ℏ/(k BT) …

Canonical (thermal) instanton theory is now routinely applicable to complex gas-phase
reactions and allows for the accurate description of tunnelling in highly non-separable …

Triplet excited state generation plays a pivotal role in photosensitizers, however the reliance
on transition metals and heavy atoms can limit the utility of these systems. In this study, we …