Density functional calculations of the 29Si and 27 Al MAS NMR spectra of the zeolite mazzite: analysis of geometrical and electronic effects

Article Abstract:

Research was conducted to examine the 29Si and 27Al NMR chemical shifts of the two crystallographic sites of the zeolite mazzite from the NMR shielding tensors by the SOS-DFPT approach. The NMR shielding constants of the Si sites and models, wherein each T site in turn was substituted by aluminum, were measured. Results reveal that a good description of the relative position of the NMR peaks is derived using clusters including two coordination shells around each site.

Nuclear magnetic resonance spectroscopy, Aluminum, Aluminum (Metal), Zeolites, Silicon

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Origin of the lone pair of alpha-PbO from density functional theory calculations

Article Abstract:

A study was conducted to analyze ab initio computations utilizing density functional theory within the local density approximation on PbO during the alpha-phase and idealized CsCl structure. An interactive matrix diagonalization technique was utilized to solve Kohn-Sham equations. Results indicated that the stabilization of the alpha-PbO structure over the CsCl structure correlated with the mixing of lead 6p states into the filled antibonding O 2p and Pb 6s states.

Cesium, Lead compounds

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