An ab-initio Hartree-Fock study of ?-quartz and stishovite

Nada, R.H.; Catlow, C. Richard A.; Dovesi, Roberto; Pisani, Cesare

doi:10.1007/bf00200131

Cited by 97 publications

(40 citation statements)

References 32 publications

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“…The results are indeed comparable in their accuracy with those reported from periodic boundary condition Hartree-Fock calculations of Nada et al (1990). Our results also show the value of cluster calculations when they are extended to examine the structure of defects such as the hydrogarnet defect where our calculations predict a structure similar to that observed in hydrogarnets.…”

Section: Discussionsupporting

confidence: 87%

LDF pseudopotential calculations of the ?-quartz structure and hydrogarnet defect

et al. 1992

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Section: Discussionsupporting

confidence: 87%

LDF pseudopotential calculations of the ?-quartz structure and hydrogarnet defect

et al. 1992

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“…Note however that these calculations were carried out at the Hartree Fock level of approximation thus ignoring electronic correlation effects hence dispersion interactions. As expected from Pauling's rule for electronegativity, we found that the partial charges of zeolitic species are half their formal values (q oZ = −1.05, q Si = +2.1) in agreement with previous ab initio calculations on quartz (Nada et al 1990). As shown in Fig.…”

Section: Influence Of Water Dipolesupporting

confidence: 87%

Molecular simulations of water in hydrophobic microporous solids

2008

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This work reports Grand Canonical Monte-Carlo molecular simulation (GCMC) results of water adsorption in a priori hydrophobic microporous solids such as silicalite, a purely siliceous zeolite (Ø pore ∼ 5 Å) and C-Y, a pure carbon replica of zeolite Y (Ø pore ∼ 1 nm). At a first step, in both cases, the water-water interactions are described with the SPC model (calibrated for bulk liquid water) while watersubstrate interactions are calculated within the framework of the PN-TrAZ model. This adsorbate-zeolite potential decomposes into short range (repulsive, inductive and dispersive) interaction terms with transferable parameters plus, in the case of silicalite, an electrostatic interaction term based on SPC partial charges for water and ab initio charges for silicalite. With such a standard approach, we found that water fills the microporous volume in both materials at pressure value well below P 0 ; hence does not show a strong hydrophobic behaviour at variance with reference experiments (V. Eroshenko et al. in C. R. Phys. 3:111, 2002). This indicates that common models used to describe confined polar molecules are far from being operative. We show on the basis of periodic ab initio calculations that confined water molecules in silicate have a dipole value ∼10% smaller than that in the 3D liquid phase indicating that the environment felt by a confined water molecule in silicalite pores is not equivalent to that in the bulk liquid. This implies that classical simulations of polar molecules in ultra

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“…28,29 The following all-electron basis sets were employed: 66-21G * for Si, 30 8-411(d1) for O, 31 85-11G * for Al. 32 A full-range hybrid functional 33 was adopted for the treatment of exchange and correlation; the fraction of admixed EXX (α) was evaluated based on the above-mentioned relationship with the macroscopic electronic dielectric constant (ϵ ∞ ), α ≈ 1/ϵ ∞ , 23,24 and obtained selfconsistently for pristine quartz SiO 2 , following the procedure illustrated in Ref.…”

Section: Computational Detailsmentioning

confidence: 99%

Communication: Hole localization in Al-doped quartz SiO2 within ab initio hybrid-functional DFT

Gerosa

Valentin

Bottani

et al. 2015

The Journal of Chemical Physics

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Articles you may be interested inDefect calculations in semiconductors through a dielectric-dependent hybrid DFT functional: The case of oxygen vacancies in metal oxides The Journal of Chemical Physics 143, 134702 (2015) We investigate the long-standing problem of hole localization at the Al impurity in quartz SiO 2 , using a relatively recent DFT hybrid-functional method in which the exchange fraction is obtained ab initio, based on an analogy with the static many-body COHSEX approximation to the electron self-energy. As the amount of the admixed exact exchange in hybrid functionals has been shown to be determinant for properly capturing the hole localization, this problem constitutes a prototypical benchmark for the accuracy of the method, allowing one to assess to what extent self-interaction effects are avoided. We obtain good results in terms of description of the charge localization and structural distortion around the Al center, improving with respect to the more popular B3LYP hybrid-functional approach.We also discuss the accuracy of computed hyperfine parameters, by comparison with previous calculations based on other self-interaction-free methods, as well as experimental values. We discuss and rationalize the limitations of our approach in computing defect-related excitation energies in lowdielectric-constant insulators. C 2015 AIP Publishing LLC.[http://dx

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An ab-initio Hartree-Fock study of ?-quartz and stishovite

Cited by 97 publications

References 32 publications

LDF pseudopotential calculations of the ?-quartz structure and hydrogarnet defect

LDF pseudopotential calculations of the ?-quartz structure and hydrogarnet defect

Molecular simulations of water in hydrophobic microporous solids

Communication: Hole localization in Al-doped quartz SiO2 within ab initio hybrid-functional DFT

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