Zeolite diffusion, simulations energy minimization

Before we can discuss in detail the simulation of adsorption and diffusion in zeolites using atomistic simulation we must ensure that the methods and potentials are appropriate for modelling zeolites. The work of Jackson and Catlow reviewed in the previous section shows the success of this approach. Perhaps the most critical test is to apply lattice dynamics and model the effect of temperature as any instability will cause the calculation to fail. Thus we performed free energy minimization calculations on a range of zeolites to test the methodology and applicability to zeolites. As noted in Section 2.2, the extension of the static lattice simulation technique to include the effects of pressure and temperature leading to the calculations of thermodynamic properties of crystals and the theoretical background to this technique have been outlined by Parker and Price [21], and this forms the basis of the computer code PARAPOCS [92] used for the calculations. 

The adsorption and diffusion properties of benzene are of immense interest in zeolite research aromatics play important roles in a number of zeolite-catalyzed processes. Theoretical simulations of benzene diffusion first began to be published in the late 1980s. The first studies evaluated and minimized the potential energy of a molecule such as benzene within the channels, a method less computationally demanding than the MD simulations that followed. Most recent studies have used the TST formalism. 

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