Hierarchical multiscale modeling of materials: an application to microporous systems

Computer modeling techniques have now established as a standard method for the study of chemical and physical phenomena in complex systems. The origin of their success is twofold: from one side, the continuous increase in the computational power, along with the spread of parallel architectures, has made accessible to a wide audience the most accurate methodologies, while, on the other side, the refinement of the techniques themselves has improved the reliability of the results. Nevertheless, when dealing with multiscale systems it is not possible to effectively use just one single simulation technique. This problem is largely due to inherent limitations of the methods, and it depends only slightly on the finite nature of computing resources. The extension of space and time scales can be achieved through two different approaches: one consists in connecting different levels in the hierarchy by a coarse-graining of the information coming from highly detailed levels, and the other consists in overcoming the intrinsic limitations of the single techniques.In this thesis, the possibility of using both approaches for large scale simulations has been investigated. The methods here developed have been applied to the study of microporous systems, being particularly well suited for a multiscale approach. Nonetheless, such methods are completely general, and can be employed for the simulation of a wide class of materials without too much effort.