Once xc approximations are used that depend not only on the electron density, but also on the occupied (and possibly also the virtual) KS orbitals, the first term in Eq. ( ) is not accessible anymore in sDFT because only the KS orbitals of the subsystems are available, and not the KS orbitals of the total system. Therefore, additional approximations need to be introduced for the NAXC (as is already done for the NAKE). If hybrid or meta-GGA functional are used for the subsystems, one commonly applies a GGA for the NAXC and the corresponding potential . We note, however, that these restrictions do no longer apply in the case of projection-based embedding (see Section 6.1).