September 2021 Monthly Meeting
Thursday – September 9th, 2021
4:30 – 5:45 – September Board meeting
5:45 – 6:30 – Break for dinner
6:30 – 7:00 – Virtual Networking
- Hosted by Raj (SB) Rajur, NESACS Chair
- Lecture by Steven A. Lopez
“Mechanistic investigations of photochemical reactions with quantum chemical and machine learning photodynamics simulations.”
By Steven A. Lopez
Assistant professor, Department of Chemistry & Chemical Biology, Northeastern University
Photochemical reactions are increasingly important for the construction of value-added, strained organic architectures. Direct excitation and photoredox reactions typically require mild conditions and can access highly strained molecules and new synthetic methodologies. The a priori design of photochemical reactions is challenging because degenerate excited-states often result in competing reaction mechanisms to undesired products. Further, a lack of experimental techniques that provide atomistic structural information on ultrafast timescales (10–15 – 10–12 s) limits our ‘chemical intuition’ about these processes. Computations, however, provide a path forward. I will discuss how my group has leveraged state-of-the-art quantum mechanical calculations, non-adiabatic molecular dynamics, and machine learning (ML) techniques to understand the reactivities and selectivities of a photochemical cascade reaction towards the first stable polyacetylene, fluoropolyacetylene. I will introduce our new open-access machine learning tool, Python Rapid Artificial Intelligence Ab Initio Molecular Dynamics (PyRAI2MD), which enables 1,000-fold longer simulations than are currently possible with multiconfigurational NAMD simulations. PyRAI2MD has enabled nanosecond ML-NAMD simulations on stereoselective electrocyclic reactions with record high degrees of freedom complexities.
Steven Lopez is an assistant professor at Northeastern University in the department of Chemistry & Chemical Biology. His research group focuses on identifying next-generation materials and catalysts to develop new green organic reactions and renewable energy solutions. His open-source database, the Virtual Excited State Reference for the Discovery of Electronic materials DB (VERDE materials DB;www.verdedb.org) is a community hub for automated data-driven discovery through machine learning. His team is developing reactivity and stereoselectivity models for photochemical transformations. He is also the Chair of the Alliance for Diversity in Science and Engineering, a national non-profit organization that he co-founded in 2015.
Steven earned his B.S. in Chemistry at New York University and performed undergraduate research with Prof. Jim Canary. He moved to UCLA for his Ph.D. in computational organic chemistry with Prof. Kendall N. Houk and was a Department of Energy EERE Postdoctoral Researcher at Harvard working alongside Prof. Alan Aspuru-Guzik.