Characterization of Ag+ Sites in ZSM-5: A combined quantum mechanics/interatomic potential function study

2001 ◽  
Vol 3 (21) ◽  
pp. 4791-4795 ◽  
Author(s):  
Martin Å ilhan ◽  
Dana Nachtigallová ◽  
Petr Nachtigall
Keyword(s):  
Quantum Mechanics ◽  
Potential Function ◽  
Interatomic Potential ◽  
Function Study

Coordination and siting of Cu+ ions in ZSM-5: A combined quantum mechanics/interatomic potential function study

1999 ◽  
Vol 1 (8) ◽  
pp. 2019-2026 ◽  
Author(s):  
Dana Nachtigallová ◽  
Petr Nachtigall ◽  
Marek Sierka ◽  
Joachim Sauer
Keyword(s):  
Quantum Mechanics ◽  
Potential Function ◽  
Interatomic Potential ◽  
Function Study ◽  
Cu Ions

Comparing the Acidities of Microporous Aluminosilicate and Silico-Aluminophosphate Catalysts: A Combined Quantum Mechanics-Interatomic Potential Function Study

1998 ◽  
Vol 63 (9) ◽  
pp. 1394-1408 ◽  
Author(s):  
Joachim Sauer ◽  
Klaus-Peter Schröder ◽  
Volker Termath
Keyword(s):  
Quantum Mechanics ◽  
Potential Function ◽  
Interatomic Potential ◽  
Lattice Energy ◽  
Model Potential ◽  
Acid Sites ◽  
Basis Sets ◽  
Intermolecular Potential ◽  
Average Error ◽  
Maximum Deviation

DFT-B3LYP calculations are performed on 4-ring models of aluminophosphates (AlPOs) and silico-aluminophosphates (SAPOs). The results are used to fit the parameters of ion pair shell model potential functions. The potentials obtained are tested in lattice energy minimizations for berlinite and the microporous materials AlPO-18, AlPO-40, AlPO-52, and VPI-5. Not only does the potential reproduce the observed structures (average error of the cell constants 1.3%), it also predicts vibrational frequencies over the whole frequency range equally well (maximum deviation 50 cm-1). The potential is used to predict the structures and properties of Bronsted acid sites in an aluminosilicate and a SAPO with the chabazite framework structure (HSSZ-13 and HSAPO-34). A new combined quantum mechanics-intermolecular potential function approach (QM-Pot) is used at the DFT level. Comparison is made with full periodic DFT calculations using plane wave basis sets. The deprotonation energies corrected for systematic errors of the methods used are 1 231-1 235 and 1 261-1 280 kJ/mol for HSSZ-13 and HSAPO-34, respectively. The same acid site has a lower acidity in a SAPO than in an aluminosilicate zeolite of the same structure.

A THEOREM OF SOLÉR, THE THEORY OF SYMMETRY AND QUANTUM MECHANICS

2012 ◽  
Vol 09 (02) ◽  
pp. 1260005 ◽  
Author(s):  
GIANNI CASSINELLI ◽  
PEKKA LAHTI
Keyword(s):  
Hilbert Space ◽  
Quantum Mechanics ◽  
Quantum Logic ◽  
Hilbert Spaces ◽  
Classical Problem ◽  
Partial Solution ◽  
Space Realization ◽  
Symmetry Transformations ◽  
Axiomatic Quantum Mechanics

A classical problem in axiomatic quantum mechanics is deducing a Hilbert space realization for a quantum logic that admits a vector space coordinatization of the Piron–McLaren type. Our aim is to show how a theorem of M. Solér [Characterization of Hilbert spaces by orthomodular spaces, Comm. Algebra23 (1995) 219–243.] can be used to get a (partial) solution of this problem. We first derive a generalization of the Wigner theorem on symmetry transformations that holds already in the Piron–McLaren frame. Then we investigate which conditions on the quantum logic allow the use of Solér's theorem in order to obtain a Hilbert space solution for the coordinatization problem.

A Cross-Scale Characterization of Interface Properties between Carbon Nanotubes and Polymer Matrix

2006 ◽  
Vol 312 ◽  
pp. 217-222 ◽  
Author(s):  
Kausala Mylvaganam ◽  
Liang Chi Zhang
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Quantum Mechanics ◽  
High Performance ◽  
Mechanical Deformation ◽  
Polymer Chains ◽  
Interface Properties ◽  
Covalent Bonds ◽  
Scale Characterization

This paper discusses the methods of promoting covalent bonds between polymer and carbon nanotubes to make high performance composites. Such methods involve attachment of chemical moieties (i.e. functional groups) to the sidewalls of carbon nanotubes, introduction of mechanical deformation on nanotubes, or generation of radicals on the polymer chains using free radical generators. The implementation of the latter method is demonstrated at both quantum mechanics and molecular dynamics levels.

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