Computational study of one-step polar Diels–Alder reactions using the NEB method for the minimum energy paths search

The Nudged Elastic Band (NEB) method is an algorithm to search the minimum energy path (MEP), which has been successfully applied for studying several processes that involve solid-state models; however, it has not been widely tested in discrete molecular systems. Performing density functional theory calculations, this method was employed in NWChem to find the MEP of reactions between cyclopentadiene and cyano-substituted ethylenes. Results suggest that the reaction mechanism is concerted in all systems. Also, kinetics and thermodynamics analysis were done: With respect to experimental data, energetic parameters are computed better at the M06-2X/6-31++G** level; entropy and frequency factors were poorly predicted. This is a simple methodology, where the NEB method is evaluated to find the MEP in some prototypical Diels–Alder reactions.