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Graphical abstract Abstract Boron oxide (B 2 O 3) is investigated by a combination of ab initio (DFT-based) molecular dynamics (MD) simulations and classical MD simulations. From the trajectories of the ab initio MD simulation, we derive a three-body interaction potential which is used in classical MD simulations to study various structural and dynamic properties on larger time and length scales than possible in the ab initio simulations. Differences and similarities to the structure and dynamics of other network glass formers such as SiO 2 and GeO 2 are discussed. Moreover, various properties as obtained from the simulations are compared to those from experiments of B 2 O 3. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The anisotropic nature of water and ions dynamics is quantified. • The deceleration effects of confinement on electrolyte dynamics are computed. • Ion concentration affects the electrolyte dynamics on an ion specific way. • Collisions of particles on HAP walls are crucial to determine out-of-plane diffusion. Abstract Hydroxyapatite (HAP) is the principal phase of bones, where the presence of ions in the fluids within HAP pores is critical to important phenomena such as bone remodeling, mineralization and fossilization. Classical molecular dynamics simulations of HAP pores ranging from 2 to 120 nm, containing pure water and aqueous solutions of CaCl 2 and of CaF 2 , were conducted to quantify the effect of confinement and solution composition on the dynamic properties of water and ions. Diffusion coefficients were obtained from formulations adapted to diffusion processes parallel and perpendicular to the HAP walls. A change in diffusion mechanism is observed in the direction perpendicular to the HAP walls: after a transition period proportional to the pore size, the mean squared displacement scales with the square-root of the time instead of being linear. The presence of CaCl 2 and CaF 2 decelerates water and ion dynamics, and changes in ion concentration modify the in-plane dynamics more strongly than the out-plane dynamics of ions in HAP pores. [ABSTRACT FROM AUTHOR]

Polycrystalline structure plays an important role in the macroscopic properties of a solid material. In this paper we propose a new code to generate a polycrystalline material at the atomic scale. Our polycrystalline systems are based on the random generation from initial germs. From a mechanical point of view, it brings new features as for example ductility of 3D polycrystalline aluminium. By using molecular dynamics simulations, we also show the effect of temperature on a geological material, olivine, one of the most abundant silicate mineral of the Earth upper mantle. The importance of porous media is also considered (e.g. metals). [ABSTRACT FROM AUTHOR]

[Display omitted] • Machine learning interatomic potential is developed for superionic phase of Ag 2 S. • Crystalline behavior of S subsystem and liquid-like behavior of Ag subsystem is found. • Performance of model is 4 orders of magnitude higher than for ab initio simulation. • Direct simulation of phase transitions in Ag 2 S by proposed model will be possible. Artificial neural networks are used for describing potential energy surface of β -Ag 2 S silver sulfide. It has allowed performing accurate and fast atomistic simulations for describing behavior of investigated system. We develop neural network potential for high temperature ionic conductor β -Ag 2 S using DeePMD approach. Reference ab initio dataset was generated using active learning technique implemented in DP-GEN package. Classical molecular simulations with developed neural network potential were performed. Partial radial distribution function for S-S pair and bond-angle distribution function for S-S-S triplet demonstrate crystalline behavior, while the same functions for Ag-Ag pair and Ag-Ag-Ag triplet demonstrate liquid-like behavior. Mean squared displacement of S atoms indicates absence of diffusion for sulfur atoms, while the same function for Ag atoms has linear form at large times that indicates presence of diffusion for this sort of atoms. Velocity autocorrelation functions for S atoms have oscillatory behavior, while for Ag atoms no oscillations are observed. Comparison of mean squared displacement for S atoms and diffusivity for Ag atoms is performed to other ab initio and classical simulations as well as experimental data and demonstrates good agreement in all the cases. Obtained by active learning technique dataset could be expanded to other Ag 2 S phases for describing Ag 2 S in wider range of temperatures. Thus accurate, productive, almost free of parameters and promising for future use model for β -Ag 2 S was created. [ABSTRACT FROM AUTHOR]

• Simulation of ZnS deposition on Ag 2 S is performed by classical molecular dynamics. • Main interactions in Ag 2 S + ZnS + H 2 O system are pair interactions Ag-S, Zn-S, and Ag-Zn. • Initially sulfur ions are adsorbed from the solution on [0 0 1] plane of the Ag 2 S. • Zn atoms penetrate under this S layer more close to a surface of silver sulfide. Classical molecular dynamics (CMD) simulation has been performed to study the ZnS deposition from aqueous solution on a surface of crystalline Ag 2 S. The initial configuration of the Ag 2 S + ZnS + H 2 O simulated system includes the surface of crystalline Ag 2 S silver sulfide with H 2 O molecules above this surface and Zn2+ and S2- ions located between water molecules. In Ag 2 S + ZnS + H 2 O system, sulfur ions are adsorbed originally from a solution on Ag 2 S surface. The part of deposited Zn atoms Zn is under the first deposited layer of S atoms S, and other Zn atoms Zn are located approximately level with surface S atoms. Performed CMD calculation has shown that the dependences of relative number of the deposited sulfur and zinc atoms on the deposition time are symbate, and formation of first surface ZnS layer occurs during deposition about 10 ns. In addition, the analytical model of ZnS deposition on Ag 2 S surface is proposed. The CMD simulation confirmed the adequacy of this analytical model. [ABSTRACT FROM AUTHOR]