Electrostatic Embedding
(i) Assign MM Charges for pure MM system
- Derived from empirical schemes (e.g. as part of forcefield)
- Fitted to electrostatic potentials
- Formal charges (e.g. shell model potentials)
- Electronegativity equalisation (e.g. QEq)
(ii) Delete MM charges on atoms in inner region
- Attempt to ensure that MM “defect” + terminated QM region has
- correct total charge
- approximately correct dipole moment
(iii) Insert charges on MM centres into QM Hamiltonian
- Explicit point charges
- Smeared point charges
- Semi-empirical core interaction terms
- Make adjustments to closest charges (deletion, shift etc)
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