Thermodynamic Properties for Applications in Chemical Industry via Classical Force Fields - Multiscale Molecular Methods in Applied Chemistry - page 201

Thermodynamic Properties for Applications
in Chemical Industry via Classical Force Fields

Gabriela Guevara-Carrion, Hans Hasse, and Jadran Vrabec

Abstract Thermodynamic properties of fluids are of key importance for the chemical
industry. Presently, the fluid property models used in process design and optimization
are mostly equations of state or G E models, which are parameterized using experimen-
tal data. Molecular modeling and simulation based on classical force fields is a
promising alternative route, which in many cases reasonably complements the well
established methods. This chapter gives an introduction to the state-of-the-art in this
field regarding molecular models, simulation methods, and tools. Attention is given to
the way modeling and simulation on the scale of molecular force fields interact with
other scales, which is mainly by parameter inheritance. Parameters for molecular force
fields are determined both bottom-up from quantum chemistry and top-down from
experimental data. Commonly used functional forms for describing the intra- and
intermolecular interactions are presented. Several approaches for ab initio to empirical
force field parameterization are discussed. Some transferable force field families, which
are frequently used in chemical engineering applications, are described. Furthermore,
some examples of force fields that were parameterized for specific molecules are given.
Molecular dynamics and Monte Carlo methods for the calculation of transport proper-
ties and vapor-liquid equilibria are introduced. Two case studies are presented. First,
using liquid ammonia as an example, the capabilities of semi-empirical force fields,
parameterized on the basis of quantum chemical information and experimental data, are
discussed with respect to thermodynamic properties that are relevant for the chemical
industry. Second, the ability of molecular simulation methods to describe accurately
vapor-liquid equilibrium properties of binary mixtures containing CO 2 is shown.

Keywords Force field Molecular dynamics Monte Carlo Thermodynamics