A Correlated Flat-bottom Elastic Network Model for Improved Bond Rearrangement in Reaction Paths

This study introduces correlated flat-bottom elastic network model (CFB-ENM), an extension of our recently developed flat-bottom elastic network model (FB-ENM) for generating plausible reaction paths. While FB-ENM improved upon the widely used image-dependent pair potential (IDPP) by addressing unintended structural distortion and bond breaking, it still struggled with regulating the timing of series of bond breaking and formation. CFB-ENM overcomes this limitation by incorporating structure-based correlation terms. These terms impose constraints on pairs of atom pairs, ensuring immediate formation of new bonds after breaking of existing bonds. We optimized paths for 121 reactions using the direct MaxFlux method to find that CFB-ENM significantly improves reaction paths. Compared to FB-ENM, CFB-ENM paths exhibited lower maximum DFT energies along the paths in 82\% of reactions, with an average decrease of 30.0 kcal/mol. In cases where CFB-ENM produced higher energies, most increases were below 10 kcal/mol and often involved quasi-four-membered ring formation, which can be omitted beforehand. CFB-ENM generates collision-free paths that preserve non-reactive structural elements and regulate bond rearrangements, potentially reducing computational costs in subsequent precise reaction path or transition state searches. An implementation of CFB-ENM based on the Atomic Simulation Environment is available on GitHub, facilitating its use in computational chemistry research.