Crystalline porous materials have various industrial applications; in that sense Zeolites Imidazolate Frameworks (ZIF) are a subclass of organometallic structures which may be technologically feasible for storage of chemicals, chemical detector, chemical stripper, including separations based membrane [1]. Identification of materials suitable for a given application can be done by screening of an enumerated database of materials. Such screening requires high performance automated tools that analyze and calculate the topological and geometrical parameters to describe the pores. The structure descriptors can be used to compare, select, and classify a group of materials. The project objective is to develop and apply such tools to characterize pore geometries in materials such as zeolites and Metal Organic Frameworks (MOF) to identify materials with adsorption properties relevant to a number of gas storage and separation applications. A molecular simulation study is reported for ZIF. The effects of the force fields with standard and extended parameters are systematically examined and compared with experimental data. Among three force fields (UFF [2], CHARMM [3], and DREIDING [4]), DREIDING has the best agreement with experiment. Other important aspect of the structural analysis of these materials is the investigation of the geometrical parameters describing pores. Our methods are based on the Voronoi decomposition according the algorithm implemented with free software, Zeo ++ [5], the resulting is analyzed to obtain the diameter of the largest included sphere and the largest free sphere, which are two geometrical parameters that are frequently used to describe pore geometry. Accessibility Surface Area is also determined with Monte Carlo Sampling and reported in this work.