Several FDET-based methods are available in the FDE-Man module of Q-Chem. The FDE-Man job control is accomplished in two sections, $rem and $fde.
The fragments are specified via the fragment descriptors (see Section 12) in the $molecule section, whereas the first fragment corresponds to the embedded species (A), the second fragment represents the environment (B).
Note: The current implementation allows only for closed shell fragments.
Enabling FDE-Man, the specification of the embedding method and other job control parameters (thresholds, max. iterations etc.) should be set in the $rem section.
Other DFT functionals can also be requested with the EXCHANGE and CORRELATION keywords as described in Section 5.4.
Note: The current implementation is restricted to mean-field methods that are solved with the SCFMAN module.
The standard capabilities to use customized basis sets are also possible with the FDE-Man module.
FDE-ADC923 is a density embedding method based on the combination of the Algebraic Diagrammatic Construction scheme for the polarization propagator (ADC, Section 7.11) and Frozen-Density Embedding Theory (FDET). In this particular variant, the subsystem A is represented by a wave function whereas subsystem B is described by a density. The FDE-ADC method uses the linearized FDET approximation.1265
Similar to the other methods, the ADC specifications have to be done inside the $rem section, as shown below.
FDE-ADC also supports the excited state analysis (STATE_ANALYSIS) carried out by the libwfa module.