Hartree-fock ab-initio characterization of ionic crystal surfaces with a slab model. The (0001) face of α-Al2O3

Pisani, Cesare; Causa, Mariella; Dovesi, Roberto; Roetti, C.

doi:10.1016/s0079-6816(87)80009-6

Cited by 44 publications

(21 citation statements)

References 40 publications

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“…Figure shows the electrostatic potential V ( r ) above EDI x S1 and EDI x S2, and at the corresponding regions of the clusters. The presence of a second layer of 4−1 chains does not alter the potential at the surface, to confirm the general finding that very thin films can adequately reproduce the electrostatic potential at low-index surfaces of ionic crystals . On the contrary, the difference between the description of this quantity by periodic and cluster models is striking.…”

Section: Resultssupporting

confidence: 73%

Quantum Mechanical ab Initio Characterization of a Simple Periodic Model of the Silica Surface

et al. 1999

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The electronic, structural, and vibrational properties of a thin silica film are studied by means of periodic ab initio techniques, both Hartree-Fock and density functional. The film is cut from bulk edingtonite, a tetragonal silica structure with five SiO 2 groups per unit cell; the dangling bonds are saturated so as to obtain a fully hydroxylated surface. This model system is proved to possess a number of attractive properties which make it suitable for the study of some properties of silica surfaces: (1) the parent structure is rather stable, its energy per unit SiO 2 being comparable to that of common zeolites such as faujasite; (2) the formation of the surface involves low energy, no reconstruction, and scarce relaxation; (3) the simplest two-dimensional structure contains only five SiO 2 groups in the unit cell and can therefore be treated with limited computational effort; (4) the building block of the two-dimensional periodic structure is easily related to standard cluster models of silica; (5) the density of surface hydroxyls is comparable to that experimentally observed on dehydrated silica; (6) the stretching frequency of the OH group at the surface is very close to that obtained with the best cluster models and to the experimental value for isolated hydroxyls on amorphous silica; (7) a few variants of the fundamental structure are possible, and different low-energy surfaces can be cut from them, which allow the simulation of a number of local situations within the same basic model.

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Section: Resultssupporting

confidence: 73%

Quantum Mechanical ab Initio Characterization of a Simple Periodic Model of the Silica Surface

et al. 1999

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“…The aluminum-terminated surface has the same composition as the bulk. As in the other theoretical calculations [25][26][27][28], one observes a strong negative relaxation of the first interlayer spacing (Table 2), so the aluminum is virtually in the same layer with oxygen atoms. The values of relaxation for both approximations for the exchange-correlation potential used in PP calculations vary within less than 1.5%; the same results were also obtained by the FLAPW-method.…”

Section: Electronic Structure Of the Surface Of α-Al 2 O 3 (0001)supporting

confidence: 80%

Electronic structure of α-Al2O3 in the bulk and on the surface

2005

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“…The properties of both hematite (α-Fe 2 O 3 ) and corundum (α-Al 2 O 3 ) surfaces in vacuo have been studied experimentally [23,19,[24][25][26] and by computer simulations [27][28][29][30][31][32][33]. In this section we consider both ideal vacuum-terminated and hydroxylated (001) and (012) surfaces of hematite.…”

Section: Application To Hematite Surfaces: Background and Previoumentioning

confidence: 99%

Ewald methods for polarizable surfaces with application to hydroxylation and hydrogen bonding on the (012) and (001) surfaces of α-Fe2O3

et al. 1997

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We present a clear and rigorous derivation of the Ewald-like method for calculation of the electrostatic energy of the systems infinitely periodic in two-dimensions and of finite size in the third dimension (slabs). We have generalized this method originally developed by Rhee et al. [Phys. Rev. B 40, 36(1989)] to account for charge-dipole and dipole-dipole interactions and therefore made it suitable for treatment of polarizable systems. This method has the advantage over exact methods of being significantly faster and therefore appropriate for large-scale molecular dynamics simulations. It however involves a Taylor expansion which has to be demonstrated to be of sufficient order. The method was extensively benchmarked against the exact methods by Leckner and Parry. We found it necessary to increase the order of the multipole expansion from 4 (as in original work by Rhee et al.) to 6. In this case the method is adequate for aspect ratios (thickness/shortest side length of the unit cell) ≤ 0.5. Molecular dynamics simulations using the transferable/polarizable model by Rustad et al. were applied to study the surface relaxation of the nonhydroxylated, hydroxylated, and solvated surfaces of α-Fe2O3 (hematite). We find that our nonhydroxylated structures and energies are in good agreement with previous LDA calculations on α-alumina by Manassidis et al. [Surf. Sci. Lett. 285, L517, 1993]. Using the results of molecular dynamics simulations of solvated interfaces, we define end-member hydroxylated-hydrated states for the surfaces which are used in energy minimization calculations. We find that hydration has a small effect on the surface structure, but that hydroxylation has a significant effect. Our calculations, both for gas-phase and solutionphase adsorption, predict a greater amount of hydroxylation for the α-Fe2O3 (012) surface than for the (001) surface. Our simulations also indicate the presence of four-fold coordinated iron ions on the (001) surface.

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Hartree-fock ab-initio characterization of ionic crystal surfaces with a slab model. The (0001) face of α-Al2O3

Cited by 44 publications

References 40 publications

Quantum Mechanical ab Initio Characterization of a Simple Periodic Model of the Silica Surface

Quantum Mechanical ab Initio Characterization of a Simple Periodic Model of the Silica Surface

Electronic structure of α-Al2O3 in the bulk and on the surface

Ewald methods for polarizable surfaces with application to hydroxylation and hydrogen bonding on the (012) and (001) surfaces of α-Fe2O3

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