Model Hamiltonians in the Macroscopic Approximation

A considerable shortcoming of Eq. (3.2) consists in the assumption of invariability of the electron structure of the solute molecule when it passes from free space into solution, i.e., in the assumption of constancy of Eq. However, Eq can change significantly, particularly for the systems of high polarizability. This limitation of the calculational scheme may be overcome by constructing a model Hamiltonian of the solute molecule. The general form of this Hamiltonian H is  

Strictly speaking, when constructing the operator U it is necessary to take into account all types of the intermolecular forces. However, such a scheme that would actually represent the supermolecular approach (see below) requires unjustifiably excessive expenditure of computer time. For this reason, when 

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