Recorded 15 September 2025. Kari Laasonen of Aalto University presents "DFT-Based Constrained MD Simulations of Hydrogen Evolution Activities on Pt(111)" at IPAM's Embracing Stochasticity in Electrochemical Modeling Workshop. Abstract: The computational hydrogen evolution activity of Pt(111) remains controversial due to apparent discrepancies with experiments concerning rate-determining activation free energies and equilibrium hydrogen coverages. A fundamental source of error may lie in the static representations of the metal–water interface commonly employed in density functional theory (DFT)-based models neglecting important entropic effects on reaction dynamics. Here, I present a dynamic study of the Volmer–Tafel hydrogen evolution pathway on Pt(111) through DFT-based constrained molecular dynamics simulations and thermodynamic integration [1]. Hydrogen coverage effects are studied at two surface saturations, while the critical potential dependence and constant potential conditions are accounted for using a capacitive model of the electrified interface. The dynamic description of the electrochemical interface promotes a substantial decrease in the Tafel free energy barrier as the coverage is increased to a full monolayer. This follows from a decreased entropic barrier due to suppressed adlayer dynamics compared to the unsaturated surface, a detail easily missed by static calculations predicting notably higher barriers at the same coverage. I will also discuss another work focusing on the difference between the static (NEB) and AIMD simulations of the same reactions [2]. [1] Kronberg and Laasonen, ACS Catal. 2021, 11, 13, 8062–8078 [2] Kronberg, Lappalainen, Laasonen. Phys. Chem. Chem. Phys. 2020, 22, 10536– 10549 Learn more online at: https://www.ipam.ucla.edu/programs/workshops/workshop-i-embracing-stochasticity-in-electrochemical-modeling/?tab=overview