PNNL

Abstract

Steady improvements in the efficiency of reactive forcefields are helping bridge the gap in computational expense and accuracy between classical and ab initio molecular dynamics simulations for reactions entailing bond making / breaking steps. We present an efficient reactive force field using a small set of parameters based on Lennard-Jones, the Stillinger-Weber nonbonded angle term, and additional two-body terms using Gaussian functions. The parameter set is aimed at modeling aluminate reactivity in alkaline solutions, and is based on a global minimization of the error in forces and energies with respect to ab initio molecular dynamics simulations including aluminate monomers and oligomers in sodium hydroxide solutions. It was validated by comparing solution radial distribution functions to experiment, dimerization free energy profile to a previously parameterized DFTB Hamiltonian, and formation energies of various oligomers to DLPNO-CCSD(T), thus enabling the simulation of the early stages of Al(OH)3 nucleation. Its computational cost is reduced by one order of magnitude relative to a widely used bond order-based reactive force field.