  The determination of thermal and vibrational relaxation rates of triatomic
systems suitable for application in hypersonic model calculations is discussed.
For this, potential energy surfaces for ground and electronically excited state
species need to be computed and represented with high accuracy and
quasiclassical or quantum nuclear dynamics simulations provide the basis for
determining the relevant rates. These include thermal reaction rates,
state-to-state cross-sections, or vibrational relaxation rates. For exemplary
systems - [NNO], [NOO], and [CNO] - all individual steps are described and a
literature overview for them is provided. Finally, as some of these quantities
involve considerable computational expense, for the example of state-to-state
cross sections the construction of an efficient model based on neural networks
is discussed. All such data is required and being used in more coarse-grained
computational fluid dynamics simulations.
