Addressing challenges of identifying geometrically diverse sets of crystalline porous materials

Crystalline porous materials have a variety of uses, such as for catalysis and separations. Identifying suitable materials for a given application can, in principle, be done by screening material databases. Such a screening requires automated high-throughput analysis tools that calculate topological and geometrical parameters describing pores. These descriptors can be used to compare, select, group, and classify materials. Here, we present a descriptor that captures shape and geometry characteristics of pores. Together with proposed similarity measures, it can be used to perform diversity selection on a set of porous materials. Our representations are histogram encodings of the probe-accessible fragment of the Voronoi network representing the void space of a material. We discuss and demonstrate the application of our approach on the International Zeolite Association (IZA) database of zeolite frameworks and the Deem database of hypothetical zeolites, as well as zeolitic imidazolate frameworks constructed from IZA zeolite structures. The diverse structures retrieved by our method are complementary to those expected by emphasizing diversity in existing one-dimensional descriptors, e.g., surface area, and similar to those obtainable by a (subjective) manual selection based on materials' visual representations. Our technique allows for reduction of large sets of structures and thus enables the material researcher to focus efforts on maximally dissimilar structures.