Probing Local Structure in Zeolite Frameworks:  Ultrahigh-Field NMR Measurements and Accurate First-Principles Calculations of Zeolite29Si Magnetic Shielding Tensors

2008 ◽  
Vol 130 (10) ◽  
pp. 3095-3105 ◽  
Author(s):  
Darren H. Brouwer ◽  
Gary D. Enright
Keyword(s):  
First Principles ◽  
Local Structure ◽  
Magnetic Shielding ◽  
First Principles Calculations ◽  
Ultrahigh Field ◽  
Shielding Tensors

First principles calculations on order and disorder in La2Ce2O7 and Nd2Ce2O7

2020 ◽  
Vol 22 (25) ◽  
pp. 13930-13941
Author(s):  
Liv-Elisif Kalland ◽  
Chris E. Mohn
Keyword(s):  
Ion Transport ◽  
First Principles ◽  
Local Structure ◽  
First Principles Calculations ◽  
Order And Disorder

Intimacy between collective ion transport and local structure is a key to understanding poorly understood Ln2Ce2O7 to design future SOFCs.

Experimental and theoretical investigations of selenium nuclear magnetic shielding tensors in Se–N heterocycles

2009 ◽  
Vol 87 (10) ◽  
pp. 1546-1564 ◽  
Author(s):  
Andre Sutrisno ◽  
Andy Y.H. Lo ◽  
Joel A. Tang ◽  
Jason L. Dutton ◽  
Gregg J. Farrar ◽  
...  
Keyword(s):  
Dft Calculations ◽  
First Principles ◽  
Density Functional ◽  
Molecular Geometry ◽  
Molecular Structures ◽  
Magnetic Shielding ◽  
First Principles Calculations ◽  
Theoretical Investigations ◽  
Intermolecular Contacts ◽  
Nuclear Magnetic

A preliminary study involving solid-state 77Se NMR spectroscopy and first principles calculations of 77Se NMR parameters in Se–N heterocycles is reported. 77Se CP/MAS NMR spectra of the ring systems reveal expansive selenium chemical shift (CS) tensors, which are extremely sensitive to molecular geometry, symmetry, ligand substitution, and intermolecular contacts. For systems with known crystal structures, hybrid density functional theory (DFT) calculations of selenium nuclear magnetic shielding (NMS) tensors were carried out, and tensor orientations in the molecular frames examined. Additional DFT calculations of selenium NMS tensors are presented, along with a detailed analysis of pairs of occupied and virtual molecular orbitals that give rise to the Se NMS tensors. A new naturalized local molecular orbital (NLMO) analysis under the same DFT framework is also discussed. Collectively, the NMR data and first principles calculations provide understanding of the influences of electronic structure, bonding, and intermolecular interactions on the selenium NMS tensors, allowing for (i) prediction of unknown molecular structures and (ii) insight into the positions of the stereochemically active selenium lone pairs.

Water adsorption in SAPO-34: elucidating the role of local heterogeneities and defects using dispersion-corrected DFT calculations

2015 ◽  
Vol 17 (38) ◽  
pp. 25260-25271 ◽  
Author(s):  
Michael Fischer
Keyword(s):  
Dft Calculations ◽  
First Principles ◽  
Local Structure ◽  
Water Adsorption ◽  
Adsorption Properties ◽  
First Principles Calculations

The interaction of water with the chabazite-type silicoaluminophosphate SAPO-34 is investigated using first-principles calculations. Models with heterogeneous Si distributions and defects are included, permitting conclusions regarding the influence of variations in the local structure on the water adsorption properties.

Local structure of stoichiometric and oxygen-deficient A2Ti6O13 (A = Li, Na, and K) studied by X-ray absorption spectroscopy and first-principles calculations

2018 ◽  
Vol 124 (15) ◽  
pp. 155101 ◽  
Author(s):  
Jarin Kanchanawarin ◽  
Wanwisa Limphirat ◽  
Pratya Promchana ◽  
Tawan Sooknoi ◽  
Tosapol Maluangnont ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
First Principles ◽  
Local Structure ◽  
First Principles Calculations ◽  
X Ray ◽  
X Ray Absorption

Importance of SiC Stacking to Interlayer States at the SiC/SiO2 Interface

2016 ◽  
Vol 858 ◽  
pp. 457-460
Author(s):  
Christopher James Kirkham ◽  
Tomoya Ono
Keyword(s):  
Electronic Structure ◽  
Conduction Band ◽  
First Principles ◽  
Local Structure ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Conduction Band Edge ◽  
First Principles Calculations

We investigated the effect of SiC stacking on the 4H-SiC/SiO2 interface via first principles calculations. Interlayer states are observed along the SiC conduction band edge, and are affected by the local structure at the interface. The location of these states changes depending on which of two lattice sites, h or k is at the interface. This difference is important for SiC based metal-oxide-semiconductor field-effect transistors which rely on the electronic structure of the conduction band.

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