Force field multipole analysis

On the basis of a sound analysis of intermolecular interactions, performed by means of a quantum perturbational approach, Claverie derived a force field that could suitably represent intermolecular interactions. The electrostatic interactions are described by means of a distributed multipole analysis, and induction effects are taken into account. The force field sum of interactions between fragments completed ab initio (SIBFA) originated from this study and was subsequently applied successfully to many biophysical problems. 

It is has been known that the atomic multipole moments for atoms in AMOEBA model can be calculated through quantum mechanics method and Stone s distributed multipole analysis [61]. Thus, it is straightforward to obtain the parameters of electric multipole potentials based on the distributed multipole analysis after the EMP sites of Gay-Berne particles are decided or directly from AMOEBA force field. However, the EMP parameters of Gay-Berne particles need to be optimized because they are derived based on the gas-phase ab initio quantum mechanics. One possible solution would be to match GBEMP and AMOEBA results for the electrostatic energies between CG particles and water molecules, or between CG particle dimers, at various separations and/or in different orientations. 

The dispersion forces can be depicted as a coupling between polarijtation of the solute and solvent molecules, so the electron correlation between solvent and solute is the important quantitative effect on the solvation free energy. In the first treatment of this phenomenon London [38] introduced some appropriate approximations that enabled him to relate the dispersion energy of a pair of molecules to their polarizabilities. A more detailed analysis of the dispersion interaction in the reaction field formalism was performed by Linder in the case of a spherical cavity for purely dipolar interactions. In [39] the theory has been generalized to the case of non-spherical cavity and extended to higher order multipole polarizabilities as... 

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