Comparison of Siliceous Zeolite Potentials from the Perspective of Infrared Spectroscopy

J Guo and KD Hammond, JOURNAL OF PHYSICAL CHEMISTRY C, 122, 6093-6102 (2018).

DOI: 10.1021/acs.jpcc.7b12491

Zeolites-microporous crystalline aluminosilicate materials-are the basis of many physical and chemical processes. Computational modeling of these processes requires an accurate description of the zeolite structure and the potential energy surface. In this work, two published force fields, the modified Zimmerman, Head-Gordon, and Bell (MZHB) potential Sahoo and Nair, J. Comput. Chem. 2015, 36, 1562-1567 and the core-shell model Schroder and Sauer, J. Phys. Chem. 1996, 100, 11043-11049, are tested in terms of their abilities to predict the structural and dynamical properties, including infrared (IR) spectra, of five silica polymorphs (three siliceous zeolites: zeolite Y, sodalite, and silicalite-1, as well as alpha-quartz and alpha-cristobalite) via classical molecular dynamics simulations. Normal mode analysis at the Gamma point and quantum mechanical cluster calculations are periodic crystals and a finite-size representative cluster model, respectively, to assist in the assignment of IR bands. We observe that the core-shell model predicts a broader distribution of bond angles because of the lack of three-body interactions defined for the Si-O-Si angles. The MZHB potential, in contrast, consistently shifts angle-bending modes to higher wavenumbers relative to experiments.

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