Formation and migration of H3O+ and OH− ions at the water/silica and water/vapor interfaces under the influence of a static electric field: a molecular dynamics study

Water ‘layers’ 1 and 2 in pink; ‘layer’ 3 in blue and green over portion of glass surface (grey). +90° field causes water migration and clustering.

An effective partial charge model for bulk and surface properties of cubic ZrO2, Y2O3 and yttrium-stabilised zirconia

In this work a newly parametrised Coulomb plus Buckingham potential formulation for cubic ZrO₂, Y₂O₃ and yttrium-stabilised zirconia (YSZ) is presented. The density and pair distributions obtained for neat ZrO₂ and Y₂O₃ under ambient conditions are in excellent agreement with experimental data, while the vibrational power spectra are highly similar compared to those obtained via ab initio molecular dynamics simulations at the PBEsol level. In addition, it is shown that the use of effective partial charges has several advantages compared to interaction potentials employing the oxidation states in the evaluation of the coulombic interactions: (i) the diffusion coefficient and the associated activation energy of oxygen ions evaluated for YSZn (n = 4 to 12) display the best agreement with experimental data; (ii) no unphysical reorganisation of the interface and the bulk are observed in simulations of the (110) and (111) surfaces of cubic ZrO₂ and Y₂O₃, while due to the strong coulombic contributions in the case of the tested full-charge models a pronounced restructuring of the interface and the bulk is observed in the ZrO₂ case, and (iii) the use of effective partial charges ensures compatibility with existing solvent models and force-fields for the treatment of molecular compounds.

Towards a dissociative SPC-like water model II. The impact of Lennard-Jones and Buckingham non-coulombic forces

The dissociative water potential by Garofalini and coworkers has been re-formulated in the framework of the widely employed Lennard-Jones and Buckingham potentials, enhancing the transferability of the model to third party simulation programs.

Towards a dissociative SPC-like water model – probing the impact of intramolecular Coulombic contributions

A modification of the dissociative Garofalini water model towards an SPC-like Coulombic formulation proved to enhance accuracy and transferability of this successful force field approach.