Quantum, classical, and multi-scale simulation of silica–water interaction: molecules, clusters, and extended systems

National Renewable Energy Research Laboratory, 1617 Cole Blvd., Golden, CO 80401-3393, USA; Deptartment of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, IL 61801, USA
Journal of Computer-Aided Materials Design (Impact Factor: 1.3). 10/2006; 13(1):161-183. DOI: 10.1007/s10820-006-9009-x

ABSTRACT Over the past 6years, we have engaged in a multi-faceted computational investigation of water–silica interactions at the fundamental physical and chemical level. This effort has necessitated development and implementation of simulation methods including high-accuracy quantum mechanical approaches, classical molecular dynamics, finite element techniques, and multi-scale modeling. We have found that water and silica can interact via either hydration or hydroxylation. Depending on physical conditions, the former process can be weak (<0.2eV) or strong (near 1.0eV). Compared to hydration, the latter process yields much larger energy gains (2–3eV/water). Some hydroxylated silica systems can accept more water molecules and undergo further hydroxylation. We have also studied the role of external stress, effects of finite silica system size, different numbers of water molecules, and temperature dependences.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Explicit molecular dynamics simulations were applied to two pairs of amorphous silica nanoparticles in aqueous solution (2.0 and 4.4 nm in diameter) and four different background electrolyte concentrations, to extract the potential of mean force acting between the two pairs of silica nanoparticles. Dependences of the interparticle potential of mean forces with separation and the background electrolyte concentration for the two sizes of particle radius were demonstrated. Radial distribution functions and derived quantities were used to probe the surface environment of the nanoparticles. Direct evidence of the solvation forces is presented in terms of changes of the water ordering at the surfaces of the isolated and double nanoparticles. The nature of the interaction of the counterions with charged silica surface sites (deprotonated silanols) was investigated in terms of quantifying the effects of the number of water molecules separately inside the each of the pair of nanoparticles by defining an impermeability measure. Differences in the impermeability between the pairs of nanoparticles are attributed to differences in the calculated dipole moment. A direct correlation was found between impermeability (related to the silica surface 'hairiness') and the disruption of water ordering.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This article describes the genesis of amorphous silica under high-heat conditions from SiO2 molecules through protoparticles, primary particles, and aggregates to agglomerates using vibrational spectra and quantum chemical simulations data. The impact of small molecules (water, HCl, CO2) is also discussed. The article also explains the nature of the pyrogenic silica amorphism.
    Critical Reviews in Solid State and Material Sciences 04/2011; 36:47-65. · 5.95 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, a few problems based on my work at QTP are selected and organized with a focus on physical systems and processes that involve interaction between extended states in solids and localized states in molecules. Such interactions are ubiquitous in interfacial processes that stir an intense interest in the science community.
    Molecular Physics 01/2010; 108:3235-3248. · 1.67 Impact Factor

Full-text (2 Sources)

Available from
May 30, 2014