The simulation of metals, oxides,
and hydroxides can
accelerate
the design of therapeutics, alloys, catalysts, cement-based materials,
ceramics, bioinspired composites, and glasses. Here we introduce the
INTERFACE force field (IFF) and surface models for α-Al2O3, α-Cr2O3, α-Fe2O3, NiO, CaO, MgO, β-Ca(OH)2,
β-Mg(OH)2, and β-Ni(OH)2. The force
field parameters are nonbonded, including atomic charges for Coulomb
interactions, Lennard-Jones (LJ) potentials for van der Waals interactions
with 12–6 and 9–6 options, and harmonic bond stretching
for hydroxide ions. The models outperform DFT calculations and earlier
atomistic models (Pedone, ReaxFF, UFF, CLAYFF) up to 2 orders of magnitude
in reliability, compatibility, and interpretability due to a quantitative
representation of chemical bonding consistent with other compounds
across the periodic table and curated experimental data for validation.
The IFF models exhibit average deviations of 0.2% in lattice parameters,
<10% in surface energies (to the extent known), and 6% in bulk
moduli relative to experiments. The parameters and models can be used
with existing parameters for solvents, inorganic compounds, organic
compounds, biomolecules, and polymers in IFF, CHARMM, CVFF, AMBER,
OPLS-AA, PCFF, and COMPASS, to simulate bulk oxides, hydroxides, electrolyte
interfaces, and multiphase, biological, and organic hybrid materials
at length scales from atoms to micrometers. The nonbonded character
of the models also enables the analysis of mixed oxides, glasses,
and certain chemical reactions, and well-performing nonbonded models
for silica phases, SiO2, are introduced. Automated model
building is available in the CHARMM-GUI Nanomaterial Modeler. We illustrate
applications of the models to predict the structure of mixed oxides,
and energy barriers of ion migration, as well as binding energies
of water and organic molecules in outstanding agreement with experimental
data and calculations at the CCSD(T) level. Examples of model building
for hydrated, pH-sensitive oxide surfaces to simulate solid-electrolyte
interfaces are discussed.