where a X and a C are mixing parameters. In principle, a DHDF calculation follows the same steps as a wave function MP2 calculation: first, the self-consistent field (SCF) problem is solved to generate a set of orbitals and orbital energies which are then used as an input to obtain E MP2 C . In the case of a DHDF, the first three components shown in Eq. 7 are used in the SCF, which is defined as the hybrid portion of the DHDF. That can either have the expression of a global or a range-separated hybrid. For ground-state problems, SCS-and SOS-MP2 have been successfully applied, leading to improved accuracy and robustness, with the pre-factor for E DFT C becoming uncoupled from the SS and OS scale parameters in SCS/SOS-MP2.