Electrostatic interaction energy, SCRF calculations

Reaction field methods model solutions by placing the solute in a cavity of a polarizable medium. The electrostatic potential due to the solute molecule polarizes the surrounding medium which in turn changes the charge distribution of the solute. Hence, the electrostatic interaction has to be evaluated self-consistently (self-consistent reaction field, SCRF). A term for creating the cavity (calculated from the surface of the cavity) has a be added to the solvation energy. Explicit treatment of solvent molecules can be combined with a reaction field method. 

Continuum models are the most efficient way to include condensed-phase effects into quantum-mechanical calculations, and this is typically accomplished by using the self-consistent reaction field (SCRF) approach for the electrostatic component. Therefore it is very common to replace the quantal problem by a classical one in which the electronic energy plus the coulombic interactions of the nuclei, taken together, are modeled by a classical force field—this approach usually called molecular mechanics (MM) (Cramer and Truhlar, 1996). 

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