Molecular-level modelling

However, one should keep in mind that simplified models of the actual physical systems are routinely used and that molecular-level modeling techniques involve various levels of approximations. In principle, computational chemistry can only disprove, and never prove, a particular reaction mechanism. In practice, however, a computational investigation may still, in many cases, be a useful guide as to the likeliness of a given reaction pathway. Comparison to experimental information and to computational studies of alternative reaction mechanisms will help establish the kind of trust (or lack thereof) that should be put into a particular reaction mechanism obtained by computational chemistry. 

Classical molecular simulation methods such as MC and MD represent atomistic/molecular-level modeling, which discards the electronic degrees of freedom while utilizing parameters transferred from quantum level simulation as force field information. A molecule in the simulation is composed of beads representing atoms, where the interactions are described by classical potential functions. Each bead has a dispersive pair-wise interaction as described by the Lennard-Jones (LJ) potential, ULj(Ly) ... 

This section deals with multi-scale models for the PEFC and consists of three subsections, 4.1,4.2, and 4.3, that relate to molecular-level models, bridging models between scales and device/process level models, respectively. The objectives of these subsections are to survey the development and application of these models. 

A predictive molecular thermodynamics approach is developed for microemulsions, to determine their structural and compositional characteristics [3.7]. The theory is built upon a molecular level model for the free energy change. For illustrative purposes, numerical calculations are performed for the system water, cyclohexane, sodium dodecyl sulfate as surfactant, pentanol as cosurfactant and NaCl as electrolyte. The droplet radius, the thickness of the surfactant layer at the interface, the number of molecules of various species in the droplets, and the distribution of the components between droplets and the continuous phase are calculated. The theory also predicts the transition from a mi-... 

Molecular-Level Modeling of the Structure and Proton Transport within the Membrane Electrode Assembly of Hydrogen Proton Exchange Membrane Fuel Cells... 

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