Title: Mechanical Properties of Metal-Organic Framework-5 from First Principle Speaker: Matthew Shindel, NECIS Student, Johns Hopkins UniversityDate/Time: Tuesday, September 12, 2006, 1:30 – 2:00 pm (PT) Location: Building 980, Room 95 (Sandia-NM), Building 940, Auditorium (Sandia-CA) Brief Abstract: Metal-organic frameworks (MOFs) are an exciting new class of materials that have potential applications in areas such as catalysis, gas storage, and sensing technologies. In order to facilitate the development of devices that incorporate this type of material, it is important to be able to model the material’s interaction with various substrates. This, in part, requires intimate knowledge of the material’s mechanical properties, namely the elastic constants, which relate stress and strain within the system. To date, very little experimental data has been collected on the mechanical properties of MOFs. To circumvent this lack of information, first principle calculations have been made on MOF-5 to determine the system’s elastic constants. Ab initio methods are apowerful set of tools that allow for predictions of a material system’s mechanical properties. In this work, the Vienna Ab-initio Simulation Package (vasp) has been used to calculate the second-order elastic constants of MOF-5. Vasp uses a geometrical input coupled with information about the electronic structure of the atomic species present, to calculate the total energy of a given system. MOF-5’s equilibrium unit cell volume and bulk modulus have been determined by computing the total energy at various cell volumes and then fitting this data to an empirical equation of state. In a similar fashion, the second order elastic constants were found by applying specific geometrical distortions to the shape of the MOF-5 unit cell and then examining the change in energy as a function of strain. The values of these parameters were then used to calculate other material properties of MOF-5, including Young’s modulus, Hill’s shear modulus, and the Poisson ratio.CSRI POC: Mark Allendorf, (925) 294-2895, Roland Stumpf, (925) 294-6114 |