(750a) Simple Molecular Reactive Force Field - a Novel Approach to Capturing Bond-Making and-Breaking

A molecular-scale computational study of nucleation and growth mechanisms of materials from solution represents a challenging problem. Early-stage (small scale) nucleation can be tackled using expensive methods such as Density Functional Theory (DFT). This approach has the advantage of allowing the representation of accurate reaction mechanisms but are slow and costly to perform and hence are limited to small system sizes. Methods to accelerate such studies within a semi-empirical Molecular Dynamics (MD) framework do exist using the REAXFF and COMB force fields. However, these force fields are subject to the requirement that a parameter set must already exists for the given system of interest. These two methods are well established and work well, but they are frequently difficult to parameterize. We will discuss a new Simple Molecular Reactive Force Field (SMRFF) which captures the trade-off between atomic accuracy and ease of parameterization by redefining a reactive force field as the smooth transition between a short-range pair potential, and a long-range Lennard-Jones and Coulomb potential. This work elaborates how the implementation of a Tersoff model as a "reactive" short-range pair potential within SMRFF, with a user-friendly parameterization package, can be used to parameterize systems such as PbI2, MAI, and MAPbI3.