Hydrogen molecules in nanoscale confinement: A combined eigenstate-resolved/path integral study of the quantum translation-rotation dynamics, spectroscopy, and diffusion

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Zlatko Bacic (PI) and Mark E. Tuckerman (co-PI) of New York University are supported by an award from the Chemical Structures, Dynamics and Mechanisms program of the Chemistry Division for a computational study aimed at achieving a fundamental understanding and a comprehensive theoretical description of the quantum dynamics, spectroscopy, and diffusion of hydrogen molecules inside the nanoscale cavities of diverse host materials, such as clathrate hydrates, fullerenes and carbon nanotubes, and metal-organic frameworks (MOFs). This will provide a broad theoretical framework, as well as quantitative predictions, indispensable for the planning, analysis, and interpretation of various types of spectroscopic measurements of these systems presently carried out by groups around the world. An array of robust theoretical approaches, ranging from high-dimensional quantum bound state and scattering methods to diffusion Monte Carlo and path integral simulations, will be brought to bear on these objectives. Another goal of this proposal is the accurate determination of multidimensional, anisotropic and anharmonic interaction potentials of the nanoconfined hydrogen, and in certain cases H2O, with the host materials. Accomplishing this will involve the combination of sophisticated quantum dynamics and ab initio electronic structure calculations. The eigenstate-resolved calculations will be complemented by path integral simulations directed at elucidating the temperature and concentration dependence of the energetics, free-energetics, spatial distributions, and diffusion of molecular hydrogen, especially in bulk clathrate hydrates and MOFs. A major hurdle for the large-scale use of hydrogen as a clean and efficient energy carrier is developing ways to store it safely and economically. One possibility currently under intense investigation worldwide absorption in nanoporous materials. Quantitative understanding of the properties of molecular hydrogen under such conditions, and characterization of the interactions of hydrogen with various host environments is essential in joint experimental and theoretical efforts aimed at rational design of new media for hydrogen storage. If met, the challenge of developing efficient hydrogen-storage materials will have an enormous impact on emerging energy technologies. This research will be carried out by graduate and undergraduate students at NYU, including those from traditionally underrepresented groups. In addition, one of our experimental collaborators, Prof. Stephen FitzGerald, is at an undergraduate institution (Oberlin), and his students will be directly involved in the project.