An automated web tool for constructing hydrated metal oxide nanoparticles in aqueous environments and calculating their atomistic descriptors — extending nanostructure design to realistic water-based conditions. Modelling Metal Oxide Nanoparticles in Their Real-World Environment Metal oxide nanoparticles (MO NPs) are widely used in pharmaceuticals, cosmetics, environmental remediation, and advanced materials. However, most existing computational NP construction tools model these materials in vacuum only, ignoring the fact that many real-world applications involve aqueous environments. When metal oxide NPs interact with water, their surface atoms undergo significant structural and chemical changes: hydroxyl groups attach to metal/metalloid atoms, hydrogen ions interact with oxygen atoms, and water molecules penetrate the surface. No comprehensive tool existed to digitally construct hydrated metal oxide nanoparticles with realistic surface chemistry and calculate their properties in water. A solution was needed that could bridge in silico design with Safe and Sustainable by Design principles for water-based applications. Any MO Metal oxide via CIF — fully customizable crystal structures In Water Aqueous environment support — realistic hydrated NP modelling Fe₃O₄ Magnetite case study — fully validated and demonstrated Load metal oxide CIF and visualize structure Import crystallographic information files (CIF) from the Crystallography Open Database for any metal/metalloid oxide. The tool displays the unit cell and provides optional element substitution with same-group neighbors, allowing users to explore compositional variants while preserving crystal structure. Define NP geometry and surface hydration Set nanoparticle geometry (ellipsoidal axes), charge, metal-oxygen bond length reference, and water penetration depth. The tool geometrically constructs the hydrated NP by attaching surface hydroxyl anions, hydrogen cations, and water molecules while preserving bulk material coordination numbers for all metal and metalloid atoms. Energy minimization in vacuum Apply molecular dynamics energy minimization using LAMMPS with force fields from the OPENKIM database (REAXFF, COMB, and others). Reactive force fields enable realistic bond breaking and formation at hydrated NP surfaces, creating energetically favorable structures. Embed in water and MD-minimization cycles Place the minimized NP in a water box with surrounding water molecules and run multiple molecular dynamics minimization cycles. This simulates realistic interactions between the hydrated NP surface and the aqueous environment, enabling calculation of surface tension in water and investigation of crystal growth in hydrated conditions. Calculate atomistic descriptors Automatically compute comprehensive descriptors including surface tension (in vacuum and in water), coordination numbers, structural parameters, and crystal growth investigation metrics — enabling detailed characterization of hydrated NP properties for materials design and safety assessment. Hydrated Realistic Aqueous NPs Metal oxide NPs modelled with hydroxyl groups, hydrogen cations, and water molecules on surfaces Surface Tension Vacuum & Water Calculated Comprehensive surface property characterization in both environments Crystal Growth Investigation Enabled Study structural evolution of hydrated NPs through multiple MD cycles MD Cycles Multiple Minimization Realistic structures through iterative minimization in aqueous environments DFT Validated SiO₂ & Fe₃O₄ Computational results validated against density functional theory calculations Free Web Access Freely available on the EosCloud Platform
