Dr. John Herbert
Ohio State University
Friday, October 24th, 2025
12:00 Noon
Room 120 – Meyerhoff Chemistry Building
Host: Drs. Joe Bennett, Lisa Kelly, Kamal Seneviratne
“Multiscale Approximations for Quantum Chemistry”
Ab initio quantum chemistry based on correlated wave function models is capable of achieving “the right answer for the right reasons”, albeit at very high cost and mostly in small molecules. In practice, this has led to heavy reliance on semi-empirical density functional theory (and more recently, machine learning models trained on DFT data), where an ever-growing menagerie of functionals affords a diverse set of answers to any chemical problem, meaning that the practicing chemist can always “shop around” for a DFT method that matches their preconceived expectations. I will describe our work on modern “QM/QM” (multiscale) approximations that are intended to extend predictive-quality calculations to large systems and to provide correct, explainable understanding of the relevant molecular physics. Two key areas of interest are:
(1) fully converged enzymatic thermochemistry in active-site models containing 500–1,000 atoms and
(2) understanding short-range intermolecular interactions beyond the (often incorrect) multipolar electrostatics picture that remains pervasive in textbooks.