In order to have a successful theoretical model or simulation, one needs to adopt a physically correct inter-particle potential energy model. The majority of the interatomic and intermolecular potential energy models, e.g., Lennard-Jones, (r)=4 ? [( ? /r) ¹² -( ? /r) ⁶ ], are designed to give a statistically-averaged (effective) representation of such forces for macroscopic systems consisting of many particles. Even the ranges of accuracy of the available interparticle potential energy parameters and constants are limited and are aimed at the prediction of certain macroscopic properties. That is probably why the application of the existing interatomic and intermolecular force models for prediction of nano-crystalline structures, fullerene, nanotube, diamondoids, aggregation of amphiphilic molecules into micelles and coacervates, biological macromolecules interactions, such as between DNA and other molecules, are not quantitatively accurate. The interatomic and intermolecular potential energy database for rather simple fluids and solids in macroscale are rather complete. Parameters of interaction energies between atoms and simple molecules have been calculated through such measurements as x-ray crystallography, light scattering, nuclear magnetic resonance spectroscopy, gas viscosity, thermal conductivity, diffusivity and the virial coefficients data. Most of the present phenomenological models for interparticle forces are tuned specifically for statistical mechanical treatment of macroscopic systems. However, such information may not be sufficiently accurate in treatment of nanosystems where the number of particles is finite and validity of the existing statistical averaging techniques fail [4-11].

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