Effective core potential ab initio calculations on main group heptoxides and large silicate systems

Ribeiro‐Claro, Paulo J. A.; Amado, Ana M.

doi:10.1016/s0166-1280(99)00400-5

Cited by 15 publications

(9 citation statements)

References 53 publications

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“…Although the B3LYP DFT method is one of the most popular methods for calculating the quartz-water interface reaction mechanisms and kinetics (e.g., Becke, 1993;Civalleri et al, 1998;Davis et al, 1988;Ribeiro-Claro and Amado, 2000;Sefcik and Goddard, 2001;Teppen et al, 1994;Wallace et al, 2010;Walsh et al, 2000), recent studies have suggested that the B3LYP method may be deficient in the calculation of the energies of intermolecular interactions (e.g., Zhang et al, 2007;Zhao and Truhlar, 2007). Some new DFT methods (e.g., M05 and M06) have been developed specifically for the calculation of the energies of inter-molecular interactions.…”

Section: Methodsmentioning

confidence: 99%

Molecular-level mechanisms of quartz dissolution under neutral and alkaline conditions in the presence of electrolytes

Zhang

Liu

2014

Geochem. J.

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molecular-level mechanisms for many of these driving forces remain elusive.Quartz is the simplest and an abundant silicate mineral in the earth's crust. The study of its dissolution mechanism was expected to shed light on the dissolution mechanisms of other silicate minerals. However, it has been found that the dissolution mechanism of quartz is very different to that of other silicate minerals in several ways. For instance, the dissolution of most silicate minerals is insensitive in the presence of small amounts of electrolytes (NaCl, CaCl 2 ). However, experimental data show that at near-neutral pH conditions, quartz will dissolve up to 100 times faster in the presence of small amounts of alkali and alkaline earth electrolytes (e.g., Berger et al., 1994;Dove and Crerar, 1990;Dove and Elston, 1992;Dove, 1994Dove, , 1999Dove and Nix, 1997 The mechanisms of quartz dissolution are affected intricately by pH conditions and electrolyte types. Most previous studies have focused on the mechanisms of quartz dissolution under one specific condition (e.g., temperature, pH, saturation or electrolyte type); however, this study investigates molecular-level mechanisms under combinations of electrolyte and pH conditions, which are more complex but closer to the reality. Under neutral and alkaline pH conditions with Ca 2+ , Mg 2+ or Na + aqua ions in the solution, the dissolution of Q1 (Si) and Q2 (Si) sites on the quartz surface, which represents the predominant part of the quartz dissolution story, is investigated by first-principles quantum chemistry calculation methods. Our results confirm that quartz dissolution can be enhanced significantly by the presence of electrolytes under neutral pH conditions. However, under alkaline pH conditions, the surface complexes of aquo ions are different, depending on where and how those electrolytes bond onto the quartz surfaces. The energy barriers of all possible hydrolysis reaction pathways are calculated carefully. The activation energies for the reaction between the negatively charged quartz surface and H 2 O have never been reported before. Our results of activation energy are closer to experimental values than previous calculations have been, suggesting that the cluster models and theoretical levels used here are more reasonable. Such information provides a molecular-level understanding of the differences of quartz dissolution rates between pure water and ion-containing solutions.

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Section: Methodsmentioning

confidence: 99%

Molecular-level mechanisms of quartz dissolution under neutral and alkaline conditions in the presence of electrolytes

Zhang

Liu

2014

Geochem. J.

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“…For siliceous materials, a comprehensive study of 14 density functionals was reported [59], and the M05-2X functional was found to be most accurate for the optimized geometries and energetics. The basis set for these calculations was the all electron 6-31þG(d,p) chosen for the computational affordability for these relatively large silica clusters [60][61][62][63][64][65][66].…”

Section: Reactions and Methodsmentioning

confidence: 99%

Ab initiostudy of dissolution and precipitation reactions from the edge, kink, and terrace sites of quartz as a function of pH

Nangia

Garrison

2009

Molecular Physics

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In this study, the fundamental concept of mineral surface roughness and the role it plays on the dissolution and precipitation processes using ab initio density functional theory calculations, have been investigated. To understand the topological contribution to the dissolution and precipitation rates of quartz, a systematic study was designed to determine the reaction mechanisms and barrier heights of the forward reaction of hydrolysis of -Si(OH) 3 group from underlying edge, kink, and terrace sites. The edge and kink sites are topological features on mineral surfaces that are bound to the bulk with fewer Si-O-Si bridge bonds than a terrace site, a factor that can be significant in the dissolution process. In this work, the local arrangement of atoms on the underlying sites is included by systematically increasing the Si-O-Si bridging to represent the edge, kink, and terrace sites under ambient conditions in the neutral, deprotonated, and protonated states. Nine reaction profiles were studied using the M05-2X density functional with 6-31 þ G(d,p) basis set. The results show that hydrolysis of the -Si(OH) 3 group and the back reactions are not too sensitive to the underlying edge, kink, and terrace site. The barrier height data also explain the experimentally observed dissolution rate over the entire pH range, especially the tremendously high dissolution rate below pH 2.

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“…As shown in Refs. [31,32], such choice of bases leads to good results for systems similar to one under consideration. Standard 3-21G basis was used for hydrogen atoms.…”

Section: Cluster Models and Quantum-chemical Calculationsmentioning

confidence: 99%

Structure of barium chloride-oxide tellurite glasses

Sokolov

Плотниченко

Колташев

2009

Journal of Non-Crystalline Solids

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Effective core potential ab initio calculations on main group heptoxides and large silicate systems

Cited by 15 publications

References 53 publications

Molecular-level mechanisms of quartz dissolution under neutral and alkaline conditions in the presence of electrolytes

Molecular-level mechanisms of quartz dissolution under neutral and alkaline conditions in the presence of electrolytes

Ab initiostudy of dissolution and precipitation reactions from the edge, kink, and terrace sites of quartz as a function of pH

Structure of barium chloride-oxide tellurite glasses

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