  The exact factorization of the time-dependent electron-nuclear wavefunction
has been employed successfully in the field of quantum molecular dynamics
simulations for interpreting and simulating light-induced ultrafast processes.
In this work, we summarize the major developments leading to the formulation of
a trajectory-based approach, derived from the exact factorization equations,
capable of dealing with nonadiabatic electronic processes, and including
spin-orbit coupling and the non-perturbative effect of an external
time-dependent field. This trajectory-based quantum-classical approach has been
dubbed coupled-trajectory mixed quantum-classical (CT-MQC) algorithm, whose
performance is tested here to study the photo-dissociation dynamics of IBr.
