During the past decade, computer simulations based on a quantum-mechanical description of the interactions between electrons and between electrons and atomic nuclei have developed an increasingly important impact on solid-state physics and chemistry and on materials science—promoting not only a deeper understanding, but also the possibility to contribute significantly to materials design for future technologies. This development is based on two important columns: (i) The improved description of electronic many-body effects within density-functional theory (DFT) and the upcoming post-DFT methods. (ii) The implementation of the new functionals and many-body techniques within highly efficient, stable, and versatile computer codes, which allow to exploit the potential of modern computer architectures. In this review, I discuss the implementation of various DFT functionals [local-density approximation (LDA), generalized gradient approximation (GGA), meta-GGA, hybrid functional mixing DFT, and exact (Hartree-Fock) exchange] and post-DFT approaches [DFT + U for strong electronic correlations in narrow bands, many-body perturbation theory (GW) for quasiparticle spectra, dynamical correlation effects via the adiabatic-connection fluctuation-dissipation theorem (AC-FDT)] in the Vienna ab initio simulation package VASP. VASP is a plane-wave all-electron code using the projector-augmented wave method to describe the electron-core interaction. The code uses fast iterative techniques for the diagonalization of the DFT Hamiltonian and allows to perform total-energy calculations and structural optimizations for systems with thousands of atoms and ab initio molecular dynamics simulations for ensembles with a few hundred atoms extending over several tens of ps. Applications in many different areas (structure and phase stability, mechanical and dynamical properties, liquids, glasses and quasicrystals, magnetism and magnetic nanostructures, semiconductors and insulators, surfaces, interfaces and thin films, chemical reactions, and catalysis) are reviewed. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008

Ab-initio simulations of materials using VASP: Density-functional theory and beyond.

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The surface chemistry of amorphous silica. Zhuravlev model

https://www.zora.uzh.ch/id/eprint/44154/1/Rabe1.pdf

Understanding protein adsorption phenomena at solid surfaces

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) generation by silica in inflammation and fibrosis

Molybdenum sulfide materials have been shown as promising non-precious catalysts for hydrogen evolution. This paper describes the study of the promotional effects of certain transition metal ions on the activity of amorphous MoS3 films. Ternary metal sulfide films, M–MoS3 (M = Mn, Fe, Co, Ni, Cu, Zn), have been prepared by cyclic voltammetry of aqueous solutions containing MCl2 and (NH4)2[MoS4]. Whereas the Mn–, Cu–, and Zn–MoS3 films show similar or only slightly higher catalytic activity as the MoS3 film, the Fe–, Co–, and Ni–MoS3 films are significantly more active. The promotional effects of Fe, Co, and Ni ions exist under both acidic and neutral conditions, but the effects are more pronounced under neutral conditions. Up to a 12-fold increase in exchange current density and a 10-fold increase in the current density at an overpotential of 150 mV are observed at pH = 7. It is shown that Fe, Co, and Ni ions promote the growth of the MoS3 films, resulting a high surface area and a higher catalyst loading. These changes are the main contributors to the enhanced activity at pH = 0. However, at pH = 7, Fe, Co, and Ni ions appear to also increase the intrinsic activity of the MoS3 film.

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Fe, Co, and Ni ions promote the catalytic activity of amorphous molybdenum sulfide films for hydrogen evolution

Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments / Albert Rimola;Dominique Costa;Mariona Sodupe;Jean-François Lambert;Piero Ugliengo. In: CHEMICAL REVIEWS. ISSN 0009-2665. STAMPA. 113:6(2013), pp. 4216-4313. Original Citation: Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments

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Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments

A new complete, representative model for the hydroxylated surface of amorphous silica is presented and characterized by means of periodic DFT calculations. This model accounts for the experimentally encountered ring size distribution, Si-O-Si and O-Si-O angles, silanols density, and distribution (isolated, associated, geminals). Properties such as NMR shifts, dehydrogenation energies, OH vibrational frequencies, and the interaction with water are investigated. The results are compared with former experimental and theoretical results. This new representative model for this complex surface would probably help the investigation of its reactivity toward amino acids or other organic molecules, opening new perspectives in the understanding of the chemistry of amorphous materials.

Ab Initio Study of the Hydroxylated Surface of Amorphous Silica: A Representative Model

Surface dehydroxylation of amorphous and crystalline silicas (quartz dust) has been investigated from the standpoint of the development of hydrophobicity upon thermal treatment. Hydrophobicity occurs when only siloxane bridges and isolated silanols (IR band at ca. 3750 cm–1) are present and is monitored by an enthalpy of adsorption of water lower than the latent heat of liquefaction (44 kJ mol–1). This calorimetric method allows the evaluation of the extent of hydrophilic and hydrophobic patches when both are present at the surface. All silicas develop hydrophobicity upon thermal treatment in vacuo, but quartz is much less easily dehydroxylated than amorphous materials. It is still mainly hydrophilic after outgassing at 1073 K, whereas pyrogenic silicas (Aerosil) become hydrophobic upon outgassing at T < 673 K. Quartz is also characterized by a few very reactive sites (q 90 kJ mol–1), absent on the amorphous specimens. Both these facts might be related to the specific quartz pathogenicity. Rehydroxylation at room temperature of dehydroxylated silicas occurs to a very limited extent. Hydrophilic patches exhibit a marked heterogeneity towards water with an enthalpy of adsorption decreasing from 90 to 44 kJ mol–1. The enthalpy of adsorption approaches 44 kJ mol–1 corresponding to the addition of multilayers of adsorbed water.

Hydrophilic and hydrophobic sites on dehydrated crystalline and amorphous silicas

Optimal promoter edge decoration of CoMoS catalysts: A combined theoretical and experimental study

The resistance to pitting of a Fe-17%Cr alloy in Cl[sup [minus]]-containing solution (0.5M H[sub 2]SO[sub 4] + 0.3M NaCl) and its relationship with the chemical composition of the passive film have been studied by electrochemical and x-ray photoelectron spectroscopy analyses. Aging of the passive film in the acid solution without or with Cl[sup [minus]] (at a potential below the pitting potential) improves the resistance to pitting. The passive films formed in 0.5M H[sub 2]SO[sub 4] (at +500 mV/SHE) have a bilayer structure (hydroxide and oxide) already well developed after 5 min of passivation. The thickness of the passive film ([approximately]26 to 28 [angstrom]) remains constant during polarization. The average cation fraction of chromium in the oxide increases with increasing polarization time (from 35% after 5 min of polarization to 80% after 24 h of polarization). The beneficial effect of aging on the resistance to pitting is attributed to the enhancement of the chromium oxide enrichment at the film/alloy interface. The passive films exposed to Cl[sup [minus]] or formed in Cl[sup [minus]]-containing solution (0.3M NaCl) have similar composition and thickness as the films formed in Cl[sup [minus]]-free solution, but they contain Cl[sup [minus]]. The Cl[sup [minus]] ions are located mainly inmore » the hydroxide layer ([approximately]0.016 mol [center dot] cm[sup [minus]3]). A very small amount of Cl[sup [minus]] is found in the inner oxide layer.« less

Dominique Costa

Papers

Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments

Ab Initio Study of the Hydroxylated Surface of Amorphous Silica: A Representative Model

Hydrophilic and hydrophobic sites on dehydrated crystalline and amorphous silicas

Optimal promoter edge decoration of CoMoS catalysts: A combined theoretical and experimental study

Resistance to Pitting and Chemical Composition of Passive Films of a Fe‐17%Cr Alloy in Chloride‐Containing Acid Solution