Here, F s,el , is the electronic electric field vector, whereas µ ind s (F tot ) represents the induced dipoles effected by the total electric field at the specific polarizable site. The induced dipoles are determined self-consistently leading to mutual polarization between the QM and MM region. To enable calculations of excited states, as well as general response properties, the PE model has been formulated within the concepts of quantum mechanical response theory. Thus, this extension of PE provides direct access to spectroscopic properties in embedding calculations.