The tests with T (n) mod with 0.31 and 0.73 Å corresponding to actual covalent radii of hydrogen and oxygen, as presented in Fig. , which are more representative of the true charge density distributions as defined through covalent radii. These favorable properties of the modified interaction tensor T (n) mod encourage us to apply it to several test case systems to see how the different covalent radii affect the QM/MM energy contributions in a fully-polarizable KS-DFT/AMOEBA model with PWs.