The formation of a transient anion, generated from the capture of a low-energy electron by a molecule, triggers off a nuclear dynamics that may lead to its dissociation, in a process called dissociative electron attachment (DEA). Despite of its recognized importance in astrophysics, biology and in several technological applications, and the abundant experimental data, theoretical descriptions of the phenomenon are still very scarce. In this project we propose a new theoretical framework to describe the DEA process, which is founded on semiclassical dynamics calculations of the anion states that initiate dissociation. The nuclei will be propagated classically along potential energy curves computed on-the-fly, while non-adiabatic effects will be incorporated with the surface-hopping technique. The main difficulty in adapting this approach to the dynamics of transient anions lies in properly describing the probability of electron autodetachment. We propose to account for autoionization through a strategy that combines scattering and bound state calculations. The former method, more computationally demanding, will supply the lifetime model, whereas the latter, faster method, will be used to compute the lifetimes throughout the dynamics simulation. The proposed methodology will be applied to investigate DEA of chloroethane and chloroethene, which can be regarded as prototypes for the direct and indirect mechanisms of DEA. Once the methodology is developed, it will consist in a new and robust tool for probing electron induced processes in molecules, providing a mechanistic view on the relaxing mechanism of transient anions.
News published in Agência FAPESP Newsletter about the scholarship: