Development of the ReaxFF Methodology for Electrolyte–Water Systems

Abstract

A new ReaxFF reactive force field has been developed for water− electrolyte systems including cations Li + , Na + , K + , and Cs + and anions F − , Cl − , and I − . The reactive force field parameters have been trained against quantum mechanical (QM) calculations related to water binding energies, hydration energies and energies of proton transfer. The new force field has been validated by applying it to molecular dynamics (MD) simulations of the ionization of different electrolytes in water and comparison of the results with experimental observations and thermodynamics. Radial distribution functions (RDF) determined for most of the atom pairs (cation or anion with oxygen and hydrogen of water) show a good agreement with the RDF values obtained from DFT calculations. On the basis of the applied force field, the ReaxFF simulations have described the diffusion constants for water and electrolyte ions in alkali metal hydroxide and chloride salt solutions as a function of composition and electrolyte concentration. The obtained results open opportunities to advance ReaxFF methodology to a wide range of applications involving electrolyte ions and solutions.

Development and application of ReaxFF methodology for understanding the chemical dynamics of metal carbonates in aqueous solutions

“…We used the general C/O/H parameters which were derived from the ReaxFF protein force field 29 where the atomic C parameters were derived from the combustion force field 30 and the H/O atomic parameters came from the first generation water force field. 31 The Ca–O parameters were taken from the Pitman force field, 32 Mg–O parameters from the Protein force field 29 and Na–O parameters from the recently developed Fedkin et al 33 force field. The general description of the total interaction energy in ReaxFF is as follows: E sys = E bond + E val + E tor + E over + E under + E lp + E vdWaals + E coulomb In eqn (1), E bond (bond energy), E val (valence angle energy), E tor (torsion angle energy), E over (over-coordination penalty energy), E under (under-coordination penalty energy), and E lp (lone-pair energy) are bond-order-dependent terms, meaning that the contribution of these energies disappears upon bond dissociation, leaving only the nonbonded interactions.…”

Atomistic Insights Into the Degradation of Inorganic Halide Perovskite CsPbI3: A Reactive Force Field Molecular Dynamics Study

“…The parameter optimization was done with a Monte Carlo-based force field optimizer 39 as implemented in AMS 2020. 40 As a starting point for the parameter optimization, we used the Cs and I ReaxFF parameters from the electrolyte-water parameter set by Fedkin et al 41 Without any ReaxFF parameters for Pb in the literature, we used the atomic parameters from the parametrically similar element platinum by Fantauzzi et al, 42 which we appropriately adjusted to account for the valency and atomic mass of lead.…”

Hydrolytic Degradation of Polylactic Acid Fibers as a Function of pH and Exposure Time

“…Three systems were built for each composition for statistical analysis. Each molecular model system was equilibrated to minimize energy and optimize density, and the MD simulations were performed with the canonical ensemble which maintains a constant number of particles, volume, and temperature (NVT), using the Nose-Hoover thermostat at 37 • C using ReaxFF for aqueous systems [36]. (A.C.T.…”