A non-empirical molecular orbital study on loewenstein's rule and zeolite composition

Haß, Ernst-Christoph; Mezey, Paul G.; Plath, P

doi:10.1016/0166-1280(81)85092-0

Cited by 33 publications

(16 citation statements)

References 23 publications

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“…Finally we consider the aluminium substitution energy. Previous reports (Hass et at. 1981) with cluster calculations gave values of 45 a.u., which seem quite unrealistic.…”

Section: Table 7 Electronic Energy and Net Charge On Various Atoms Of C Lu Ster S W It H E X P E R Im E N T A L G Eomentioning

confidence: 91%

“…Several studies have been undertaken on the electronic structure of zeolites by performing semi-empirical calculations on clusters of different sizes; they were reviewed by Sauer & Zahradnik (1984) as well as by Mezey (1984). Of late, there have also been some attempts to use non-empirical initio methods (Geerlings et al 1984;Sauer 1985 ;Hass et al 1981Hass et al , 1982, but these studies have used a cluster with a normalized geometry (where all T -0 distances and O-T-O angles are equivalent, which does not represent any specific zeolite) and were performed with minimum basis set (STO-3G). The first study to use non-empirical method for clusters with an experimental geometry (where all T -0 distances and O-T-O angles were taken from values reported by crystal structure analysis) was by and their calculations again make use of the STO-3G basis set.…”

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confidence: 99%

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Non-empirical quantum-chemical calculations on ZSM-5 zeolites. I. Brønsted acid sites

Vetrivel

Catlow

Colbourn³

1988

Proc. R. Soc. Lond. A

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This paper describes the study of the -OH group in ZSM-5 zeolite. The importance of zeolite ZSM-5 and the advantages in studying the OH groups by computer simulation techniques are highlighted. The methodology followed in the present study, which is a combination of classical and quantum-chemical calculations, is briefly described. The basis set SV3-21G has been chosen following trial calculations performed with different standard sets of basis functions. Results of geometrical optimizations carried out to determine the position of hydrogen in the ZSM-5 lattice are reported. The size of the point-charge (PC) cluster is varied and its effect on the calculated properties of the hydroxyl group is discussed. Calculations on a larger quantum-chemical (QC) cluster containing the hydroxyl group in both normalized and experimental structures reveal that geometry is an important factor for electronic properties. The procedure for generation of a suitable PC cluster to represent the rest of the lattice is described. Results of a calculation for a cluster model of 82 ions (PC cluster) in which a Si 2 O 7 (QC cluster) entity is explicitly treated by ab initio procedures, are discussed. The reported parameters include the O-H vibrational frequency, the proton binding energy and the aluminium substitution energy and we discuss their implications for the catalytic properties.

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“…Finally we consider the aluminium substitution energy. Previous reports (Hass et at. 1981) with cluster calculations gave values of 45 a.u., which seem quite unrealistic.…”

Section: Table 7 Electronic Energy and Net Charge On Various Atoms Of C Lu Ster S W It H E X P E R Im E N T A L G Eomentioning

confidence: 91%

mentioning

confidence: 99%

Non-empirical quantum-chemical calculations on ZSM-5 zeolites. I. Brønsted acid sites

Vetrivel

Catlow

Colbourn³

1988

Proc. R. Soc. Lond. A

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“…The Si-Al distribution in the tetrahedral sheet has been studied for decades and according to Lowensteins' rule, Al tet -O-Al tet linkages in clay mineral frameworks are forbidden. Indeed, quantum chemical studies have shown that a combination of Al tet -O-Al tet corner sharing tetrahedral linkage and Si-O-Si linkage require higher energy than two Si-O-Al tet linkages [7,8], indicating the instability of Al tet -O-Al tet linkages [9]. However, it has been observed that this Al tet -O-Al tet avoidance principle is not followed in several aluminosilicates, both in layered and framework silicates [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Natural abundance 17O MAS NMR and DFT simulations: New insights into the atomic structure of designed micas

Pavón

Osuna

Alba

et al. 2019

Solid State Nuclear Magnetic Resonance

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Combining 17 O Magic-Angle Spinning (MAS) NMR at natural abundance with DFT calculations is a promising methodology to shed light on the structure and disorder in tetrahedral sheets of designed micas with enhanced properties. Among brittle micas, synthetic mica is an important alternative to natural ones with a swelling sheet-like structure that results in many applications, by exploiting unique characteristics. Lowenstein's rule is one of the main chemical factor that determines the atomic structure of aluminosilicates and furthermore their properties. In the present article, 17 O MAS NMR spectroscopy is used to validate (or not) the agreement of the Lowenstein's rule with the distribution of Si and Al sites in the tetrahedral sheets of synthetic micas. 17 O MAS spectra of synthetic high-charged micas exhibit two regions of signals that revealed two

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“…This charge, in turn, is balanced by an equal and opposite charge on the bonding O atoms. Semi-empirical estimates of the gross atomic charge on surface O atoms in uncharged silicate clusters suggest the range -0.7e to -0.9e (Hass et al 1981, Delville 1992; we have selected the value -0.8e, which has been adopted successfully for MC simulations of the talc-water system (Skipper et al 1989(Skipper et al , 1991. Electroneutrality then dictates a gross atomic charge of + 1.2e for Si in the tetrahedral sheet.…”

Section: Water-water Interactionsmentioning

confidence: 99%

Monte Carlo Simulation of Interlayer Molecular Structure in Swelling Clay Minerals. 1. Methodology

Skipper

Chang

Sposito

1995

Clays and clay miner.

340

342

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Abstract--Monte Carlo (MC) simulations of molecular structure in the interlayers of 2:1 Na-saturated clay minerals were performed to address several important simulation methodological issues. Investigation was focused on monolayer hydrates of the clay minerals because these systems provide a severe test of the quality and sensitivity of MC interlayer simulations. Comparisons were made between two leading models of the water-water interaction in condensed phases, and the sensitivity of the simulations to the size or shape of the periodically-repeated simulation cell was determined. The results indicated that model potential functions permitting significant deviations from the molecular environment in bulk liquid water are superior to those calibrated to mimic the bulk water structure closely. Increasing the simulation cell size or altering its shape from a rectangular 21.12 A x 18.28 ~ x 6.54 ~ cell (about eight clay mineral unit cells) had no significant effect on the calculated interlayer properties.

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A non-empirical molecular orbital study on loewenstein's rule and zeolite composition

Cited by 33 publications

References 23 publications

Non-empirical quantum-chemical calculations on ZSM-5 zeolites. I. Brønsted acid sites

Non-empirical quantum-chemical calculations on ZSM-5 zeolites. I. Brønsted acid sites

Natural abundance 17O MAS NMR and DFT simulations: New insights into the atomic structure of designed micas

Monte Carlo Simulation of Interlayer Molecular Structure in Swelling Clay Minerals. 1. Methodology

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