Molecular dynamics simulations of real systems: application to chloro-fluoro-hydrocarbons and polymers

The present paper reports the results obtained from MD calculations on the following systems: (1) chloro-fluoro-hydrocarbons (CFHs) of widespread use in the refrigerant industry (e.g., R22, R32, R123, etc.) and (2) selected polymers of industrial applications. In the case of CFHs, force field and quantum-mechanical techniques were employed in molecular modeling and for the calculation of geometrical and chemico-physical parameters. The Connolly surface algorithm, corrected for quantum-mechanical effects, was used in the evaluation of molecular surfaces and volumes. From these data, the parameters of the perturbed hard sphere chain equation of state, V* and A*, were obtained. The third parameter, E*, was calculated from extensive MD simulations under NPT conditions. For polymers, a more complicated preliminary procedure was necessary to model realistic amorphous polymeric chains. The Lattice Fluid equation parameters were then calculated from thorough MD simulations both under NVT and NPT conditions. The predicted thermophysical properties of both classes of substances are then discussed and compared with the relevant experimental data, were available.