Zeolite structure and reactivity by combined quantum-chemical-classical calculations
Article Abstract:
Combined quantum-chemical-classical (QM/MM) calculations were used to investigate the proton-energy differences, ammonia adsorption and D/H-exchange barriers for methane at selected isolated Bronsted sites in different zeolites to study the reactivity factors of these sites. The most important factor in determining the intrinsic barrier was found to be the local geometry. Results also demonstrated the potential of combined QM/MM methods for describing the differences in strength between different sites and modeling the effect of geometrical constraints on the transition states.
Publication Name: Journal of Physical Chemistry B
Subject: Chemicals, plastics and rubber industries
ISSN: 1520-6106
Year: 1999
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A new framework for electron-transfer calculations - beyond the Pathways-like models
Article Abstract:
A study was conducted to examine the mechanisms behind the electron-transfer (ET) tunneling matrix element T(sub DA) for proteins. Four factors affecting the ET were addressed, namely, choice of model Hamiltonian approximations, multiple pathway interference, bridge-atom coordinates and bridge dynamics. Effects of pathways mediated by minor long-range interactions were insignificant as shown by the analysis of pathways interference. However, ab initio calculations reveal the sensitivity of the decay to the bridge geometry and to the tunneling energy.
Publication Name: Journal of Physical Chemistry B
Subject: Chemicals, plastics and rubber industries
ISSN: 1520-6106
Year: 1998
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Synthesis and characterization of CuAPO-5 molecular sieves: evidence for the framework incorporation of Cu(II) ions
Article Abstract:
The hydrothermal synthesis of CuAPO-5 molecular sieves was investigated using Cu(II) oxide in combination with tetraethylammonium hydroxide. CuAPO-5 was characterized by X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. In addition, the framework location of octahedral copper in the as-synthesized CuAPO-5 was determined from electron spin resonance and electron spin-echo modulation spectroscopy.
Publication Name: Journal of Physical Chemistry B
Subject: Chemicals, plastics and rubber industries
ISSN: 1520-6106
Year: 1998
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