With this solvent model, the most realistic picture of solute-solvent interaction can be obtained among all solvent models. This model has wide application in molecular dynamics, molecular mechanics, and Monte Carlo simulation. In the field of quantum chemical calculations, this model can be further applied with the use of the molecular cluster as the solvation shell. In general, molecular mechanics (force field) are utilized for the computation of physical and chemical properties including motion of the large molecular system. In the force fields method, the molecules are treated as the mechanically connected system of atoms, which generally consist of empirical and parametrized functions, leading to highly efficient simulation. The force field generally consists of various interaction terms, which describe the respective possible strain in the molecular system . The total strain energy of the molecular system is given as follows;