<p>Despite the continuous development of
theoretical methodologies for describing nonadiabatic dynamics of molecular
systems, there is a lack of approaches for processes where the norm of the wave
function is not conserved, i.e., when an imaginary potential accounts for some
irreversible decaying mechanism. Current approaches rely on building potential
energy surfaces of reduced dimensionality, which is not optimal for more involving
and realistic multidimensional problems. Here, we present a novel methodology for
describing the dynamics of complex-valued molecular Hamiltonians, which is a
generalisation of the trajectory surface hopping method. As a first
application, the complex surface fewest switches surface hopping (CS-FSSH)
method was employed to survey the relaxation mechanisms of the shape resonant
anions of iodoethene. We have provided the first detailed and dynamical picture
of the p*/s* mechanism of dissociative electron attachment in halogenated
unsaturated compounds, which is believed to underlie electron-induced reactions
of several molecules of interest. Electron capture into the p* orbital
promotes C=C stretching and out-of-plane vibrations, followed by charge
transfer from the double bond into the s* orbital at the C-I bond, and, finally, release of
the iodine ion, all within only 15 fs. On-the-fly dynamics simulations of a vast
class of processes can be envisioned with the CS-FSSH methodology, including autoionisation
from transient anions, core-ionised and superexcited states, Auger and interatomic
Coulombic decay, and time-dependent luminescence.</p>
Investigating Tunneling Controlled Chemical Reactions Through Ab-Initio Ring Polymer Molecular Dynamics
