5. Hybrid methods

Hybrid methods, which should not be confused with "hybrid" DFT functions in the above sense, are approaches that combine classical force-field processing and quantum processing (at Hartree-Fock, post-Hartree-Fock or DFT level). The general aim of such an approach is to process large atomistic models while finding the best possible compromise between accuracy and computational effort. Quantum processing is reserved for a "core", a set of atoms constituting, for example, a reactive site, while force-field processing applies to the core's environment. The abbreviation QM/MM (Quantum Mechanics/Molecular Mechanics) is often used.

Hybrid methods also include continuum treatments of the environment. In this category, we find models derived from Onsager's model, which consider a surrounding medium characterized by a dielectric constant ε, whose polarization near the boundary...