Newton-X CS can simulate surface hopping dynamics and spectra using model potentials and diverse electronic structure methods, as listed in Table . The choice of each one depends on the specific problem, always requiring a trade-off between quality and computational costs. The third-party programs are not distributed with Newton-X. Newton-X operation range. Newton-X CS can simulate the nonadiabatic dynamics of a small system such as cyclohexadiene (left) with a high-level method like CASPT2 (14 atoms, 3 electronic states, 150 trajectories, 0.4 ps/trajectory, 0.5 fs time step). It can also simulate the nonadiabatic dynamics of a large molecule, cycloparaphenylene for example (right), with a low-level method like TD-DFTB (100 atoms, 7 electronic states, 50 trajectories, 3 ps/trajectory, 0.5 fs time step). Thus, Newton-X can be used for a wide variety of simulations (Figure ). On the one hand, it can simulate the short timescale dynamics of a small photoexcited molecule but with a high-level method like the complete active space perturbation theory to the second-order (CASPT2). On the other hand, Newton-X can simulate the dynamics of a large molecule for longer times but using a low-level electronic structure method like the time-dependent density-functional tight-binding (TD-DFTB).