2 research outputs found
Effect of dispersion interactions on the properties of LiF in condensed phases
Classical molecular dynamics simulations are performed on LiF in the
framework of the polarizable ion model. The overlap-repulsion and polarization
terms of the interaction potential are derived on a purely non empirical,
first-principles basis. For the dispersion, three cases are considered: a first
one in which the dispersion parameters are set to zero and two others in which
they are included, with different parameterizations. Various thermodynamic,
structural and dynamic properties are calculated for the solid and liquid
phases. The melting temperature is also obtained by direct coexistence
simulations of the liquid and solid phases. Dispersion interactions appear to
have an important effect on the density of both phases and on the melting
point, although the liquid properties are not affected when simulations are
performed in the NVT ensemble at the experimental density.Comment: 8 pages, 5 figure
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Computational Investigation of Nanoporous Materials for Clean Energy Applications
Nanoporous materials such as metal-organic frameworks (MOFs) are promising for applications in clean energy thanks to their diverse and extraordinary gas adsorption properties. Additionally, these materials' high degree of tunability means that nearly infinite distinct materials can be envisioned with different combinations of compositions, topologies, and surface properties. Each combination could yield a material with its own unique gas adsorption phenomena and resulting real-world applications. While many materials with outstanding properties have been studied, it remains a challenge to find or design an optimal material for a given application and to understand the complex molecular-level interactions that give rise to macroscopic behavior.In this dissertation, we take three different computational approaches towards advancing the discovery and understanding of nanoporous materials for various clean energy applications.In Chapters 2 and 3, we screen large databases of materials for carbon capture and hydrogen storage, using molecular simulations. We develop accurate atomistic models for the relevant adsorption phenomena and identify appropriate criteria for predicting performance. In this way, we identify optimal materials for carbon capture and hydrogen storage, as well as characteristics common among top performers. Ultimately, such findings can help guide the design of optimal materials for these applications.In Chapter 4, we study in depth a novel biporous MOF for natural gas processing, using molecular simulations in conjunction with experiments. This MOF's rare feature of biporosity, or coexistence of two chemically distinct pores within the same MOF, gives rise to unique stepwise activation that can be controlled to consequently tune the MOF's CO2/CH4 separation performance. This phenomenon is explained in terms of CO2's and CH4's differing interactions with the pore surfaces. In this way, we contribute to the understanding of complex behavior in biporous materials that affects their gas separation performance.Finally, in Chapter 5, we investigate the assembly process of MOFs using a statistical mechanical lattice model. In particular, we map out the thermodynamic assembly pathway of MOF-74 and explore the effect of surface tension energies on the shapes of nucleating clusters. With this study we work towards understanding the assembly pathway of MOFs with the ultimate goal of being able to control the synthesis process and obtain crystals of the desired morphology