  Nonadiabatic ab initio molecular dynamics (MD) including spin-orbit coupling
(SOC) and laser fields is investigated as a general tool for studies of
excited-state processes. Up to now, SOCs are not included in standard ab initio
MD packages. Therefore, transitions to triplet states cannot be treated in a
straightforward way. Nevertheless, triplet states play an important role in a
large variety of systems and can now be treated within the given framework. The
laser interaction is treated on a non-perturbative level that allows nonlinear
effects like strong Stark shifts to be considered. As MD allows for the
handling of many atoms, the interplay between triplet and singlet states of
large molecular systems will be accessible. In order to test the method, IBr is
taken as a model system, where SOC plays a crucial role for the shape of the
potential curves and thus the dynamics. Moreover, the influence of the
nonresonant dynamic Stark effect is considered. The latter is capable of
controlling reaction barriers by electric fields in timereversible conditions,
and thus a control laser using this effect acts like a photonic catalyst. In
the IBr molecule, the branching ratio at an avoided crossing, which arises from
SOC, can be influenced.
