Non-empirical quantum chemical calculation of Henry and separation constants and heats of adsorption for diatomic gases in faujasite

Peirs, J. C.; Proft, Frank De; Baron, Gino V.; Alsenoy, C. Van; Geerlings, Pau̧l

doi:10.1039/a608061h

Cited by 16 publications

(20 citation statements)

References 13 publications

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“…One could conclude that the charges do not change that much with the basis set. 21,31 When comparing the STO-3G Mulliken charges with 3-21G Mulliken charges a correlation coefficient (r 2 = 0.976) is found. Because a good correlation is found in the case of Mulliken charges, this will certainly be found for CHelpG charges, as it is known that CHelpG charges are less basis set dependent than Mulliken charges.…”

Section: Theory and Computational Detailsmentioning

confidence: 96%

“…In the second approach, used in ref. 21, the interaction energy was calculated using the "molecule-in-point-charge environment" or the embedded-cluster approach (Q) as often used in the study of molecular crystals 30 at the HF/6-31G * 29 level (considers only the electrostatic and inductive interactions for the adsorbent). The point charges were obtained with the CHelpG method 31 at the STO-3G 29 level.…”

Section: Theory and Computational Detailsmentioning

confidence: 99%

“…This method was also used in ref. 21, but with less precise grid-point selection. The results obtained for the heat of adsorption were especially good and in agreement with the experiment, and can thus be considered as somewhat fortuitous, again showing the importance of the free-space description inside the cavity.…”

Section: Calculation Of Henry Constantsmentioning

confidence: 99%

“…18 -20 Recently, the first ab initio calculations of Henry constants were performed using a "molecule-inpoint-charge-field" method 21 ; however, this approach proved to be inconvenient and very time consuming. A new method 22 for calculating interaction energies, based on density functional theory, 23 recently presented by our group, may help to cope with this problem.…”

Section: Introductionmentioning

confidence: 99%

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Quantum chemical calculation of Henry constants of diatomic molecules in faujasite-type zeolites

Tielens¹,

Langenaeker²,

Ocakoglu³

et al. 2000

J. Comput. Chem.

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A calculation method for Henry constants of diatomic molecules in zeolite cages is proposed. The method is based on a molecular electrostatic potential approximation formulated within a density functional theory (DFT) context for the evaluation of interaction energies. This approach is compared with ab initio and "molecule-in-point-charge-field" calculations. The effect of wave function versus DFT methods and basis set is discussed. The influence of the integration grid is studied and the partitioning of the cage in different peels, depending on the level of calculation, is considered. An optimal "quality/cost" ratio for the Henry and separation constants for nitrogen, oxygen, and argon (included as reference) in an NaY zeolite α-cage is obtained using the B3LYP/6-31G * method for the evaluation of the interaction energies and a Van der Waals radii-based criterion for determining the integration grid. Including carbon monoxide as a fourth example, for which no experimental results were yet available, confirms the excellent results for the calculation of separation constants. Some further refinement for the evaluation of adsorption energies is necessary.

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Section: Theory and Computational Detailsmentioning

confidence: 96%

Section: Theory and Computational Detailsmentioning

confidence: 99%

Section: Calculation Of Henry Constantsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Quantum chemical calculation of Henry constants of diatomic molecules in faujasite-type zeolites

Tielens¹,

Langenaeker²,

Ocakoglu³

et al. 2000

J. Comput. Chem.

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show abstract

“…The problem we recently addressed [93,94,95] was the selectivity of adsorption of gases [96] for which up to now no parameter free ab initio quantum chemical studies were performed yet [90]. Below we summarize the results for the interaction of small molecules (such as N 2 , O 2 , CO), with a NaY faujasite type zeolite, more specifically with the α cage.…”

Section: Inorganic Chemistry: Zeolitesmentioning

confidence: 99%

Chemical Reactivity as Described by Quantum Chemical Methods

Geerlings¹,

Proft²

2002

IJMS

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159

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Density Functional Theory is situated within the evolution of Quantum Chemistry as a facilitator of computations and a provider of new, chemical insights. The importance of the latter branch of DFT, conceptual DFT is highlighted following Parr's dictum "to calculate a molecule is not to understand it". An overview is given of the most important reactivity descriptors and the principles they are couched in. Examples are given on the evolution of the structure-property-wave function triangle which can be considered as the central paradigm of molecular quantum chemistry to (for many purposes) a structure-property-density triangle. Both kinetic as well as thermodynamic aspects can be included when further linking reactivity to the property vertex. In the field of organic chemistry, the ab initio calculation of functional group properties and their use in studies on acidity and basicity is discussed together with the use of DFT descriptors to study the kinetics of SN2 reactions and the regioselectivity in Diels Alder reactions. Similarity in reactivity is illustrated via a study on peptide isosteres. In the field of inorganic chemistry non empirical studies of adsorption of small molecules in zeolite cages are discussed providing Henry constants and separation constants, the latter in remarkable good agreement with experiments. Possible refinements in a conceptual DFT context are presented. Finally an example from biochemistry is discussed : the influence of point mutations on the catalytic activity of subtilisin

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Thermodynamics of nitrogen adsorption on the zeolite H-FER

Delgado

2007

Applied Surface Science

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Non-empirical quantum chemical calculation of Henry and separation constants and heats of adsorption for diatomic gases in faujasite

Abstract: The Henry and separation constants and heat of adsorption of N 2 and O 2 in faujasite are calculated in a non-empirical way; they show fair agreement with experiment taking into account the extreme sensitivity of the configuration integral to small variations in interaction energy values.

Cited by 16 publications

References 13 publications

Quantum chemical calculation of Henry constants of diatomic molecules in faujasite-type zeolites

Quantum chemical calculation of Henry constants of diatomic molecules in faujasite-type zeolites

Chemical Reactivity as Described by Quantum Chemical Methods

Thermodynamics of nitrogen adsorption on the zeolite H-FER

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