Research Topic
Can electrochemical simulations reveal the atomic-level mechanisms behind PFAS degradation — and point the way toward breaking down forever chemicals?
Project Summary
Wong's team used large-scale ab initio molecular dynamics simulations to observe PFAS degradation in real time at the atomic scale. The research required tracking molecular behavior under applied electrical fields—a computationally intensive process that demanded quantum-mechanical calculations for thousands of electrons simultaneously.
The project utilized a strategic multi-cluster approach, beginning on SDSC's Expanse for initial development and on PSC's Bridges-2 for production simulations. The team used Open OnDemand to manage and monitor these complex, long-running VASP simulations across both systems. Open OnDemand was used to coordinate the workflow between Expanse and Bridges-2, enabling Wong’s team to explore different initial conditions for the calculations. Globus data management was used to ensure consistent data/settings among the quantum calculations.
The computational pipeline primarily utilized VASP for ab initio molecular dynamics calculations, supplemented by proprietary quantum chemistry software. The team found that simpler computational approaches that did not account for charged surfaces failed to show any bond breaking, validating the necessity of their full-scale electrochemical simulations. Specifically, a constant-electrode potential approach was used to introduce varying numbers of electrons into the entire chemical system to simulate the applied potential.
The simulations revealed that PFAS degradation occurs only when metal surfaces reach sufficiently negative electrical potentials, with electrons flowing into PFAS molecules, weakening carbon-fluorine bonds until they break. This provided direct evidence for stepwise degradation mechanisms that laboratory experiments had suggested but never directly observed.
