The QM subsystem was defined using a cubic supercell of 18 Å for the plane wave expansion, the BLYP functional, the Martin-Tuckerman Poisson solver, Troullier-Martins 34 pseudopotentials with a 70 Ry kinetic energy cutoff for the expansion of the KS orbitals. The MM subsystem was defined through the AMOEBA force field parameters. The cut-off for non-bonded interactions was set to 9 Å and the real-space cut-off for long-range electrostatic interactions through Ewald method was set to 7 Å. Convergence criteria for induced dipoles The KS-DFT/AMOEBA model is characterized by the nested self-consistent field procedure (SCF) as detailed in the previous sections.