The total energy of the system is split into three contributions (as usual for additive QM/MM schemes): the energy of the QM subsystem, the energy of the MM subsystem, and the QM/MM interaction energy. The QM subsystem is described according to planewave/pseudopotential-based KS-DFT while the MM subsystem is represented by an MM force field. As mentioned before, the QM and MM contributions are computed by CPMD and GROMACS, respectively. Here, we will focus on the QM/MM part, which includes all interactions between the electrons and nuclei in the QM subsystem and the atoms in the MM subsystem.