where 𝐸 𝑠𝑡𝑎𝑡𝑖𝑐 is the electrostatic interaction energy between MM point charges and the unpolarized (gas phase) electronic density of the QM part, 𝐸 𝑖𝑛𝑑 is the interaction between MM and the "induced electrostatic potential" (generated by the changes in the QM electronic density due to the presence of point charges) and 𝐸 𝑝𝑜𝑙 is the polarization cost.