Quantum mechanical calculations of dioctahedral 2:1 phyllosilicates: Effect of octahedral cation distributions in pyrophyllite, illite, and smectite

Sainz‐Díaz, C. Ignacio; Timón, Vicente; Botella, V.; Artacho, Emilio; Hernández-Laguna, Alfonso

doi:10.2138/am-2002-0719

Cited by 73 publications

(51 citation statements)

References 37 publications

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“…[14,49] Furthermore, it yields efficient calculations for large systems. In the approach of SIESTA, calculations are performed using a localized basis set that consists of numerical tabulations of the exact solutions to the pseudoatomic problem.…”

Section: Cation-exchange Potential Modelsmentioning

confidence: 99%

“…Note that for layer silicates and other systems, we found that the lattice cell parameters do not change significantly with the cation distribution and thus do not contribute significantly to the resultant ordering energies. [14,28] All configurations of these supercells with different compositions and cation distributions were optimized. The two-species Js (for Al-Mg, Al-Fe and Fe-Mg systems) were then determined using Eq.…”

Section: Case Studiesmentioning

confidence: 99%

“…[12,13] Quantum-mechanical calculations of periodic crystal lattices for a series of dioctahedral 2:1 phyllosilicates in the trans-vacant polymorph (see next section), with tetrahedral and octahedral cation substitutions in different configurations, showed that the most stable configurations had two Fe 31 in two nearest-neighbor octahedra, while Mg 21 and IV Al 31 cations were found to be kept apart and dispersed, respectively. [14][15][16] Dainyak et al [17] studied the redistribution of octahedral cations (Al 31 , Mg 21 , Fe 31 and Fe…”

Section: Introductionmentioning

confidence: 99%

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Computer simulations of cations order‐disorder in 2:1 dioctahedral phyllosilicates using cation‐exchange potentials and monte carlo methods

Palin

Dove

Redfern

et al. 2014

Int J of Quantum Chemistry

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This article reviews the use of Monte Carlo methods with cation-exchange potentials and effective Hamiltonians, based on empirical potentials and quantum-mechanical calculations, for the study of cation ordering in phyllosilicates. The basic methodology is described, and the application of the methods is illustrated with a number of key example case studies. These include Al-Si ordering in muscovite, Al-Fe-Mg ordering (both binary and ternary compositions) in the octahedral illite/smectite sheet, examination of the ordering behavior of phengite, in which the octahedral sites are occupied by Al and Mg and the tetrahedral sites by Al and Si, and Al-Si ordering in the tetrahedral phyllosilicate sheet with variable Al:Si ratio. In several cases, complex ordering processes were found. The essential conclusion from this work is that computer simulation studies of this nature can be a valuable tool in ordering studies of many nanomaterials.

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Section: Cation-exchange Potential Modelsmentioning

confidence: 99%

Section: Case Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Computer simulations of cations order‐disorder in 2:1 dioctahedral phyllosilicates using cation‐exchange potentials and monte carlo methods

Palin

Dove

Redfern

et al. 2014

Int J of Quantum Chemistry

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“…Other studies in this field for which the SIESTA approach has been used include the study of cation distributions in phyllosilicates like pyrophyllite, beidellite and several smectites and illites [149], a study of the (001) surface of galena [150] and the combined theoretical-experimental study of the structure oh the high-pressure monoclinic phase II of cristobalite [151].…”

Section: Minerals and Zeolitesmentioning

confidence: 99%

Computing the Properties of Materials from First Principles with SIESTA

Sánchez‐Portal

Ordejón

Canadell

Structure and Bonding

110

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“…The random assignment of substitutions and the first constraint that prohibits the presence of Mg-(OH) 2 -Mg pairs in the octahedral sheet are based on 1 H magic angle spinning nuclear magnetic resonance (MAS NMR) and FT-IR spectra from MMTs that show no contributions from Mg-(OH) 2 -Mg moieties and QM simulations that demonstrated that Mg 2+ substitutions are randomly distributed within the octahedral layer [35][36][37]. The second constraint, informed by the properties of synthetic MMTs [38][39][40][41], limits the substitution ratio of the edge PBC (i.e., Mg edge substitutions: total number of octahedral edge sites in the PBC) to less than 0.20, which is the maximum substitution ratio for a synthetic MMT with only octahedral substitutions.…”

Section: Molecular Dynamics Simulationsmentioning

confidence: 99%

Na-Montmorillonite Edge Structure and Surface Complexes: An Atomistic Perspective

Newton

Lee

2017

Minerals

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Abstract:The edges of montmorillonite (MMT) react strongly with metals and organic matter, but the atomic structure of the edge and its surface complexes are not unambiguous since the experimental isolation of the edge is challenging. In this study, we introduce an atomistic model of a Na MMT edge that is suitable for classical molecular dynamics (MD) simulations, in particular for the B edge, a representative edge surface of 2:1 phyllosilicates. Our model possesses the surface groups identified through density functional theory (DFT) geometry optimizations performed with variation in the structural charge deficit and Mg substitution sites. The edge structure of the classical MD simulations agreed well with previous DFT-based MD simulation results. Our MD simulations revealed an extensive H-bond network stabilizing the Na-MMT edge surface, which required an extensive simulation trajectory. Some Na counter ions formed inner-sphere complexes at two edge sites. The stronger edge site coincided with the exposed vacancy in the dioctahedral sheet; a weaker site was associated with the cleaved hexagonal cavity of the tetrahedral sheet. The six-coordinate Na complexes were not directly associated with the Mg edge site. Our simulations have demonstrated the heterogeneous surface structures, the distribution of edge surface groups, and the reactivity of the MMT edge.

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Quantum mechanical calculations of dioctahedral 2:1 phyllosilicates: Effect of octahedral cation distributions in pyrophyllite, illite, and smectite

Cited by 73 publications

References 37 publications

Computer simulations of cations order‐disorder in 2:1 dioctahedral phyllosilicates using cation‐exchange potentials and monte carlo methods

Computer simulations of cations order‐disorder in 2:1 dioctahedral phyllosilicates using cation‐exchange potentials and monte carlo methods

Computing the Properties of Materials from First Principles with SIESTA

Na-Montmorillonite Edge Structure and Surface Complexes: An Atomistic Perspective

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