(488c) Free Energy Surface of Nitrogen Dissociation on Ru(0001) from First Principles Molecular Dynamics with Enhanced Sampling Methods
AIChE Annual Meeting
Wednesday, November 18, 2020 - 8:30am to 8:45am
In this work, we study a chemical reaction catalyzed by a metal surface by coupling state-of-the art enhanced sampling methods, including adaptive biasing force and recently developed machine-learning-based approach  to Density Functional Theory (DFT)-based molecular dynamics. The dissociation/association of nitrogen on the close packed ruthenium is chosen as prototypical example due to its relevance as a critical step in ammonia synthesis and the large body of previous theoretical and experimental studies. We compare free energy surfaces from these enhanced sampling methods to those predicted using harmonic TST. We find that the free energy surfaces obtained from enhanced sampling methods and harmonic TST differ. We discuss the origins of their differences and implications on predicting the most probable reaction pathway. This work is a step toward the application of free energy enhanced sampling to predict chemical reactions in increasingly complex systems.
 E. Sevgen, A. Z. Guo, H. Sidky, J. K. Whitmer, J. J. de Pablo. âCombined Force-Frequency Sampling for Simulation of Systems Having Rugged Free Energy Landscapesâ. J. Chem. Theory Comput. 2020, 16, 3, 1448-1455; https://github.com/MICCoM/SSAGES-public