Employing a SAFT Equation of State to obtain Force Fields for use in Coarse-Grained Molecular Simulations

摘要

The description of fluid systems by either direct molecular simulation or by algebraic equations of state (EoS) is a common practice in chemical engineering, however the two methodologies are rarely used in a coupled fashion. The key for an integrated representation is to employ a well-defined force field and Hamiltonian at the molecular level in both approaches [1]. In developing coarse grained intermolecular potential functions for the fluid state one typically starts with a detailed quantum mechanical or atomic level description and then, in a bottom-up fashion, integrates out the unwanted degrees of freedom using a variety of techniques; an iterative heuristic simulation procedure is then used to refine the parameters of the model. We present here a distinct paradigm; a top-down technique where we use a formulation of the statistical associating fluid theory (SAFT) [2] to estimate the parameters of the Mie force field which can then be used with confidence in direct molecular simulations.