Physical properties, estimation methods molecular simulations

Physical property estimation methods may be classified into six general areas (1) theory and empirical extension of theory, (2) corresponding states, (3) group contributions, (4) computational chemistry, (5) empirical and quantitative structure property relations (QSPR) correlations, and (6) molecular simulation. A quick overview of each class is given below to provide context for the methods and to define the general assumptions, accuracies, and limitations inherent in each. 

Theoretical approaches to molecular structure design require accurate estimates of physical and transport properties. These are derived commonly iiom the principles of thermodynamics and transport phenomena, and using molecular simulations. Since the literature abounds with estimation methods, reference books and handbooks are particularly useful sources. One of the most widely used. Properties of Gases and Liquids (Poling et al., 2001), provides an excellent collection of estimation methods and data for chemical mixtures in the vapor and liquid phases. For polymers. Properties of Polymers (van Krevelen, 1990) provides a collection of group-contribution methods and data for a host of polymer properties. 

The prediction of physical and chemical properties by computational methods is becoming more and more common in the research area, thanks in part to the computational power available at a low cost. Various computational methods exist to model amorphous materials (e.g., polymers) that are readily available to the modeler molecular dynamics (MD), Monte Carlo, transition state theory (TST), and mesoscale simulations, to name a few. For a complete review of these methods, see Refs. [5] and [6]. Recently, MD simulations of up to 3 ns have been performed to estimate the diffusivity of small gas molecules in amorphous m-l,4-polybutadiene (cis-PBD)J... 

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