As mentioned above, xTB-driven AIMD in combination with enhanced sampling techniques or metadynamics can be applied for reaction discovery. AIMD simulations with the xTB methods are mainly used in two ways either for direct quantitative analysis of AIMD trajectories, or for qualitative and exploratory AIMD runs before applying more accurate and expensive KS-DFT methods. In the approach termed nanoreactor, potential reaction products from a given set of starting structures are sampled from an enhanced sampling AIMD. Here, the reactants are confined to a limited space and exposed to a recurrent piston-like force that induces reactions among neighboring molecules. Alternatively, a root-mean-square displacement-based metadynamics run, similar to conformer sampling, was shown to perform well in unimolecular rearrangement or fragmentation reactions. The conformational sampling via metadynamics has already been outlined in section 4.1, which is available in the CREST program. Furthermore, specialized applications for AIMD with xTB are available via the QCxMS program for describing molecule fragmentation in high-energy environments like electron ionization mass spectrometry or collisioninduced dissociation. In QCxMS several parallel high-energy AIMD simulations with xTB can automatically explore the energetically accessible phase space regions, yielding fragmentation products without bias.