Structural and electronic properties of an [(Al2O3)4]+ cluster

Jaroszyńska-Wolińska, Justyna; Garabato, Brady D.; Alam, Jahangir; Reza, Asmaul; Kozłowski, Pawel M.

doi:10.1007/s00894-015-2711-4

Cited by 8 publications

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References 8 publications

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“…24 Some ambiguity still exists regarding the exact structure of the gas phase cluster, however, on the basis of NBO analysis, the group of P. M. Kozlowski concluded that, both cation [Al 8 O 12 ] + and neutral [Al 8 O 12 ] systems are most appropriately described as molecules, rather than clusters. 25 Industrial production of ethylene by the dehydration of ethanol is mediated by Lewis acid catalysis of γ-Al 2 O 3 . 3,26 It has been reported that the reaction is inhibited by the formation of surface hydroxyl groups that block the C-H bond cleavage which is essentially involved in the rate limiting step.…”

Section: Introductionmentioning

confidence: 99%

Computational studies on the reactivity of alkyl halides over (Al₂O₃)_nnanoclusters: an approach towards room temperature dehydrohalogenation

2016

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The role of alumina nanoclusters as a catalyst on the reactivity of alkyl halides has been explored. The thermochemical data obtained from Density Functional Theory (DFT) calculations and the analyses of the transition structures reveal that, between the two competing reactions, elimination (via E2) versus dissociative addition (via SN2), elimination is the kinetically controlled one and thus at room temperature, olefin is the major product. The results are in excellent agreement with the recent experimental observation where more than 97% of ethylene is formed at room temperature with the reaction of ethyl fluoride over an alumina surface, although the dissociative addition product is being thermodynamically more stable. We have tried to rationalize the fact by using alumina clusters of different sizes as well as different alkyl halides having β-H for elimination. It has been shown that, during the elimination (E2) pathway, the transition structure is oriented in such a way that the eliminating halogen and the β-H are in the interacting position with the three-centered Al and two-centered O atoms, respectively, where the Lewis acid/base interaction is the main guiding factor. We have also shown a possible pathway for regenerating the catalyst. Finally, the possibility of the reactions has been tested in the presence of H2O to mimic the same on the hydrated alumina surface.

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Section: Introductionmentioning

confidence: 99%

Computational studies on the reactivity of alkyl halides over (Al₂O₃)_nnanoclusters: an approach towards room temperature dehydrohalogenation

2016

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“…45 Al 8 O 12 can be treated as a molecule. 46 It can accurately reproduce periodic DFT and experimental values of surface relaxation parameters and energies of the α-Al 2 O 3 surface. 47,48 To this end, we constructed five initial configurations for an α-Al 2 O 3 cluster of α-Al 8 O 12 and the repeat unit of cis-1,4-PB (cis-2-butene) shown in Figure 2.…”

Section: ■ Methodologymentioning

confidence: 85%

“…49 CAM-B3LYP is the bestperforming functional for Al 8 O 12 when compared with experimental values of vibrational IR-MPD data. 46 The basis set superposition error (BSSE) was corrected by the Boys− Bernardi method. 50 For the above computations, Gaussian software 51 was employed.…”

Section: ■ Methodologymentioning

confidence: 99%

“…In this aspect, small cluster models of α-Al 2 O 3 may serve as ideal models for a quick sampling of the structures, the configurations, and the energetics of an interacting alumina surface with a physically or chemically adsorbed molecule, as initially suggested by Hass et al and adopted by a number of researchers. − To be reliable and stable, a bare cluster model must follow the neutrality and stoichiometric principles . Al 8 O 12 can be treated as a molecule . It can accurately reproduce periodic DFT and experimental values of surface relaxation parameters and energies of the α-Al 2 O 3 surface. , To this end, we constructed five initial configurations for an α-Al 2 O 3 cluster of α-Al 8 O 12 and the repeat unit of cis -1,4-PB ( cis -2-butene) shown in Figure .…”

Section: Methodsmentioning

confidence: 99%

“…CAM-B3LYP is a long-range-corrected hybrid functional that uses the Coulomb-attenuating method and comprises 0.19 Hartree–Fock (HF) plus 0.81 Becke 1988 (B88) exchange interaction at a short range, and 0.65 HF plus 0.35 B88 at a long range with the intermediate part being described through the standard error function with parameter 0.33 . CAM-B3LYP is the best-performing functional for Al 8 O 12 when compared with experimental values of vibrational IR-MPD data . The basis set superposition error (BSSE) was corrected by the Boys–Bernardi method .…”

Section: Methodsmentioning

confidence: 99%

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Understanding the Interaction between Polybutadiene and Alumina via Density Functional Theory Calculations and Machine-Learned Atomistic Simulations

et al. 2022

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We provide a fundamental understanding of the interaction between cis-1,4-polybtadiene (PB) and the alumina (001) surface via a computational multi-stage methodology involving density functional theory (DFT) calculations and atomistic simulations. The latter were performed via newly derived, computationally efficient, pairwise-additive, parametric atomistic models using machine learning (ML) algorithms. First, DFT calculations that include van der Waals (vdW) interactions were performed to investigate the adsorption of cis-2-butene (i.e., the repeat unit of cis-1,4-PB) on the alumina surface. To obtain an accurate sampling of the complex cis-2-butene/alumina configurational space at the DFT level, we studied several systems in which alumina is modeled as (a) a small cluster, to quickly find the stable configurations of the system, and be used as a guide in (b) realistic periodic surface models. We found similar optimal (stable) structures in both models. We also performed a series of constrained DFT simulations to enhance the configurational space sampling between cis-2-butene and alumina for the periodic alumina (001). The atomistic model for the cis-2-butene/alumina interaction was developed using ML algorithms that find, using a specific functional representation, the optimum classical model parameters, which reproduce at the atomistic level the DFT-calculated adsorption energy. To examine the whole procedure, we developed atomistic models, using Lennard–Jones or Morse potential functions, in both all-atom and united-atom representations. Moreover, we provide a detailed statistical estimation of parametric uncertainty of the derived atomistic models by applying the Bootstrap method. We were able to fit the data with a mean absolute error below 1 kcal/mol, for all the models considered. As a last part of the proposed methodology, we performed molecular dynamics simulations, using the newly developed models, of a representative system of 30mer cis-1,4-PB chains confined between an infinite (periodic) alumina slab of thickness ≈1.114 nm at a temperature of 413 K and a pressure of 1 atm. We studied the molecular packing in the vicinity of the interface. The results demonstrate that the new atomistic models can accurately reproduce the structure of PB chains in the vicinity of the alumina substrate. In addition, we compared our results with atomistic simulations describing the PB/alumina interaction via standard mixing (Lorentz–Berthelot combination) rules. We demonstrate that the latter are inadequate in describing the complex interfacial polymer/solid interaction.

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Characterizing Ni(II) hydration in aqueous solution using DFT and EXAFS

Liu

Fang

et al. 2015

J Mol Model

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In the present work, a detailed investigation of Ni(II) hydration in water solutions was carried out using density functional theory (DFT) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The hydrated characteristics of [Ni(H2O)n](2+) clusters, such as energy parameters, atomic charge distributions, and bond parameters, were explored using DFT with Becke's three-parameter exchange potential and the Lee-Yang-Parr correlation functional (B3LYP). DFT calculations indicated that the preferred structure of the first hydration shell of Ni(II) generally has a coordination number of six and is almost unaffected by the water molecules in the outer solvation shell, whereas the structure of the second solvation shell varies as the hydration proceeds. EXAFS measurements are reported for aqueous NiSO4 and Ni(NO3)2 solutions and the Ni(NO3)2·6H2O crystal. Analysis of the EXAFS spectra of these three systems using a multiparameter fitting procedure showed that, in each case, the first coordination shell consists of six water molecules with a Ni-O coordination distance of 2.04 Å, and that there is no Ni-S or Ni-N coordination in the first shell. There was no evidence of outer-shell SO4(2-) or NO3(-) ions substituting inner-sphere water molecules in NiSO4 and Ni(NO3)2. The characteristics of Ni(II) hydration obtained from DFT calculations agreed well with those obtained experimentally using EXAFS.

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Structural and electronic properties of an [(Al2O3)4]+ cluster

Cited by 8 publications

References 8 publications

Computational studies on the reactivity of alkyl halides over (Al₂O₃)_nnanoclusters: an approach towards room temperature dehydrohalogenation

Computational studies on the reactivity of alkyl halides over (Al₂O₃)_nnanoclusters: an approach towards room temperature dehydrohalogenation

Understanding the Interaction between Polybutadiene and Alumina via Density Functional Theory Calculations and Machine-Learned Atomistic Simulations

Characterizing Ni(II) hydration in aqueous solution using DFT and EXAFS

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Structural and electronic properties of an [(Al2O3)4]+ cluster

Cited by 8 publications

References 8 publications

Computational studies on the reactivity of alkyl halides over (Al2O3)nnanoclusters: an approach towards room temperature dehydrohalogenation

Computational studies on the reactivity of alkyl halides over (Al2O3)nnanoclusters: an approach towards room temperature dehydrohalogenation

Understanding the Interaction between Polybutadiene and Alumina via Density Functional Theory Calculations and Machine-Learned Atomistic Simulations

Characterizing Ni(II) hydration in aqueous solution using DFT and EXAFS

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Computational studies on the reactivity of alkyl halides over (Al₂O₃)_nnanoclusters: an approach towards room temperature dehydrohalogenation

Computational studies on the reactivity of alkyl halides over (Al₂O₃)_nnanoclusters: an approach towards room temperature dehydrohalogenation