Force Field Development and Nanoreactor Chemistry

The application of theory and computation to understand reactivity at high pressures is beset by several challenges: (1) the nontrivial changes in electronic structure that take place during the reaction, (2) the many possible initial configurations of reacting species, and (3) the simulation timescales needed for reaction events to occur. In this chapter, we will discuss two methods for meeting these challenges. The development of accurate molecular mechanics force fields is needed to sample initial configurations of reactants. This chapter provides a perspective on the functional forms and parameterization strategies of modern force fields. In particular, we highlight the ForceBalance parameterization method for optimizing force fields systematically and reproducibly using a free and open-source code. The ab initio nanoreactor is a new simulation method for rapidly discovering new reaction pathways from first-principles molecular dynamics. The main components of the nanoreactor approach include an external time-dependent potential that induces high-velocity molecular collisions, a trajectory analysis and visualization tool for identifying and extracting individual reaction events, and a reaction path optimization workflow for estimating the reaction energies and barrier heights from a reaction event.