Hirschfelder Seminar – Prof. Donald G. Truhlar (University of Minnesota)

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1315 Seminar Hall
@ 11:00 am


Professor Donald G. Truhlar

Awardee of the 2023-2024 Joseph O. Hirschfelder Prize in Theoretical Chemistry

Title: Computational Photochemistry


Donald G. Truhlar received a Ph. D. in Chemistry at Caltech in 1970, and since 1969 he has been on the faculty of the University of Minnesota in Minneapolis, where he is currently Regents Professor of Chemistry and Chemical Physics and a member of the Academy of Distinguished Teachers. His research interests are centered on quantum mechanics, chemical dynamics, variational transition state theory, potential energy functions, solvation, and statistical thermochemistry. 

Professor Truhlar is a member of the National Academy of Sciences, American Academy of Arts and Sciences, and International Academy of Quantum Molecular Science. He is an Honorary Fellow of the Chinese Chemical Society and the Chemical Research Society of India and a Fellow of the American Association for the Advancement of Science, American Chemical Society (ACS), American Physical Society (APS) , Royal Society of Chemistry (RSC), and World Association of Theoretical and Computational Chemists (WATOC). He received Doctor Honoris Causa from the Technical University of Lodz, Poland and the Distinguished Alumnus Award from St. Mary’s University of Minnesota, and he was named Honorary Editor of Theoretical Chemistry Accounts

Professor Truhlar’s service includes Associate Editor of the Journal of the American Chemical Society (1984-2016), Secretary of the Theoretical Chemistry Subdivision of the ACS (1981-89), and Chemical Physics Division Chair of the APS (2012-2013).

Prior to his selection for the Joseph O. Hirschfelder Prize in Theoretical Chemistry, he received the ACS Award for Computers in Chemical and Pharmaceutical Research, the ACS Peter Debye Award for Physical Chemistry, the ACS Award in Theoretical Chemistry, the NAS Award for Scientific Reviewing, the Schrödinger Medal of WATOC, the Dudley Herschbach Prize for Molecular Collision Dynamics, the RSC Chemical Dynamics Award, and the APS Earle K. Plyler Prize for Molecular Spectroscopy and Dynamics.

Professor Truhlar has given four previous lectures at the University of Wisconsin, Madison. In 1975 he presented “Approximations for the Exchange Potential in Electron Scattering at the Eighth Midwest Theoretical Chemistry Conference. In 1981 he presented “Resonances in Reactive Scattering” at the International Symposium for New Directions for the Molecular Theory of Gases and Liquids. He was twice selected by the Chemistry graduate students of the University of Wisconsin to deliver the Distinguished McElvain Lecture (1981, 2011); his lecture title in 2011 was “Density Functional Theory: Introduction and Current Status.”

His group Web page is https://truhlar.chem.umn.edu


Theoretical and computational methods for molecular properties and reactivity in the ground electronic state have reached an advanced stage, but the treatment of electronically inelastic processes, such as occur in photochemistry, collisions of electronically excited species, and other laser-driven dynamics, has lagged behind. This lecture will consider recent advances in both electronic structure theory and dynamics that are advancing this area.

Electronically nonadiabatic processes are difficult because

  • One must include coherence and decoherence (affordably) in dynamics.
    – trajectory surface hopping is not good enough
  • Excited states are closely coupled and strongly correlated.
    – need multiple surfaces and couplings
    – need multi-state (“state interaction”), multireference methods
  • Simulations  require ensemble averages and long times.
    – need to keep cost down

This seminar addresses four difficulties and four ways to overcome them.

Problem Solution
Direct dynamics
Multireference dynamic correlation is expensive. CMS-PDFT, L-PDFT [1,2]
Trajectory surface hopping does not balance coherence and decoherence. Coherent switching with decay of mixing [3-5]
Nonadiabatic couplings in a Born-Oppenheimer basis are both expensive and nonphysical. Curvature-driven couplings [6,7]
Dynamics with fitted potentials and couplings
We must include more sampling and longer-time simulations. We must allow quantum dynamics. Direct diabatization by neural network with parametrically managed activation functions [8-10]

[1] C. Zhou, M. R. Hermes, D. Wu, J. J. Bao, R. Pandharkar, D. S. King, D. Zhang, T. R. Scott,  A. O. Lykhin, L. Gagliardi & D. G. Truhlar, Chem. Sci. 13, 7685 (2022).

[2[ M.R. Hennefarth, M. R. Hermes, D. G. Truhlar & L. Gagliardi, JCTC. 19, 3172 (2023).

[3] A. W. Jasper, S. Nangia, C. Zhu & D. G. Truhlar, Acc. Chem. Res. 39, 101 (2006).

[4] Y. Shu & D.G. Truhlar, JCTC 19, 380 (2022).

[5] X. Zhao, Y. Shu, L. Zhang, X. Xu & D.G. Truhlar, JCTC 23, 1672 (2023).

[6] Y. Shu, L. Zhang, X. Chen, S. Sun, Y. Huang & D. G. Truhlar, JCTC 18, 1320 (2022).

[7] L. Zhang, Y. Shu, S. Bhaumik, X. Chen, S. Sun, Y. Huang & D. G. Truhlar, JCTC 18, 7073 (2022).

[8] Y. Shu, Z. Varga, S. Kanchanakungwankul, L. Zhang & D. G. Truhlar, J. Phys. Chem. A 126, 992 (2022).

[9] Y. Shu, Z. Varga, A. G. S. de Oliveira-Filho & D. G. Truhlar, Electronic Structure 4, 047002 (2022).

[10] F. B. Akher, Y. Shu, Z. Varga, S. Bhaumik & D. G. Truhlar, J. Phys. Chem. A 24, 5287 (2023).

Host: Prof. Xuhui Huang

Past Joseph O. Hirschfelder Prize Recipients