Zeolites and Related Microporous Materials

In comparison of lattice energy minimized structures with experimental data, one often finds that the X-ray diffraction experiment cannot distinguish 

The best agreement between observed and computed unit cells for a-quartz is obtained using the molecular mechanics force field of de Vos Bur-chart et The ext best agreement was achieved with the density func- 

Structure Unit Cell Axis Experiment de Man (Ref. 188) Vessal (Ref. 174) van Beest (Ref. 120) Gale (Ref. 189) de Vos Burchart (Ref. 190) 

From these tabulations, we see the deviations between calculated and observed unit cell parameters to be somewhat larger for the dense silica modifications considered here compared to a-quartz. The force field of van Beest and coworkers is the most satisfactory of those considered for dense silica modification structures. This force field is the best for coesite and stishovite and the 

It is instructive to compare the performance of empirically derived force fields with those potentials derived from quantum mechanical calculations. Sierka and Sauer compared results from Jackson and Catlow s empirical shell model potential with Schroder and Sauer s Hartree-Fock based and their own density functional based shell model potentials. The mean deviation between computed and observed unit cell parameters was found to be 0.7%, 1.9%, and 1.4%, respectively, for the three potentials. This means that the empirical shell model potential is twice as accurate as the best quantum chemically derived force field for unit cell predictions. However, the calculated vibrational spectra of silicalite are in good agreement with experiment for both of the quantum chemically derived potentials,whereas agreement is not as satisfactory for the empirical force field.  

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Volume 84 Zeolites and Related Microporous Materials State of the Art 1994. 

Hoppe, R., Schulz-Ekloff, G., Wohrle, D., Kirschhock, C., Fuess, H. (1994). Location and photostability of faujasite-incorporated methylene blue. In Zeolites and Related Microporous Materials State of the Art 1994, Weitkamp, J., Karge, H.G., Pfeifer, H. and Holderich, W. (eds), Vol. 84, pp. 821-827. Elsevier Science BV, Amsterdam... 

W. Reschetilowski, U. Bohmer, J. Wiehl, in Zeolites and Related Microporous Materials State of the Art, J. Weitkamp, H.G. Karge, H. Pfeifer, W. Holderich (Eds.), Stud. Surf. Sci. Catal. Elsevier Science BV, Amsterdam, The Netherlands. 84 (1994) 2021. 

Zeolites and Related Microporous Materials State of the Art 1994 Weitkamp, J. Karge, H. G. Pfeifer, H. Holderich, W., Eds. Studies in Surface Science and Catalysis Elsevier Amsterdam, 1994 Vol.84. 

V. I. Smirnitsky, V. A. Plakhotnik, I. I. Lishchiner and E. S. Mortikov, Zeolites and related microporous materials State of the Art 1994, Part C, Proced. of the 10th International Zeolite Conference. Garmish-partenkirchen, Germany, July 17-22, 1994, pp. 1813-1820. 

F Schuth, D Demuth, S Kallus in Zeolites and Related Microporous Materials State of the Art 1994, (Eds J Weitkamp, H G Karge, H Pfeifer, W Holdench), Elsevier, Amsterdam 1994, part B, p 1223... 

Inelastic and quasielastic neutron scattering have special advantages for studying certain of the motional properties of protonated or organic species within zeolites and related microporous materials. These advantages and various experimental methods are outlined, and illustrated by measurements of torsional vibrations and rotational diffusion of tetramethylammonium (TMA) cations occluded within zeolites TMA-sodalite, omega, ZK-4 and S APO-20. 

J.P. Boom, D. Bargeman, and H. Strathmann, Zeolite filled membranes for gas separation and pervaporation. Zeolites and related microporous materials State of the art 1994 Part B, Proc. 10th Int. Zeol. Conf., Garmisch-Panenkirchen (J. Weitkamp, H.G. Kaige, H. Pfeifer, and W. Holderich, eds.), Elsevier, Amsterdam, 1994, p. 1167. 

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