The Challenge
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.
Our Approach
An automated computational workflow from crystal structure to hydrated NP descriptors in aqueous solution
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.