Mechanical Embedding
Advantages
- MM and QM energies are separable
- separate MM relaxation, annealing etc possible
- QM/MM terms can be integrated directly into the forcefield
- No interactions between link atoms and MM centres
- QM energies, gradient, Hessian are the same cost as gas phase
Drawbacks
- No model for polarisation of QM region
- Electrostatic coupling requires atomic charges for QM atoms
- generally these will be dependent on reaction coordinate
Examples
- IMOMM (Morokuma)
- MNDO/MM (Bakowies and Thiel)