Fay, Thomas

Short Biography

Tom grew up in the UK, where he also studied for his undergraduate Masters in Chemistry (MChem) at the University of Oxford, graduating
in 2016. He continued to obtain an MSc in Theory and Modelling in Chemical Sciences in 2017 and his DPhil (PhD) in Theoretical Chemistry at the University of Oxford in 2021 as a Clarendon Scholar. There he worked in Prof David Manolopoulos’ research group, working in quantum dynamics for spin chemistry. Afterwards he went on to work as a postdoc at UC Berkeley with Prof David Limmer from 2021 to 2024. At UC Berkeley he continued his work on quantum dynamics, devising theories of chirality induced spin selectivity and methods for open quantum system dynamics, and studying electron and energy transfer in biological and artificial photosynthetic systems. Afterwards he spent one year as a postdoc (2024-2025) at Aix-Marseille Université, working with Prof Nicolas Ferré and Dr Miquel Huix-Rotllant. At Aix-Marseille Université he developed a new QM/MM polarizable embedding method for efficiently modeling condensed phase chemistry, as well as a theory for electron transfer rates where strong quantum effects are present. In July 2025 he became an assistant professor in Chemistry at UCLA, starting his own independent research group.

Research Interests

The Fay group research interests span quantum effects in complex chemical systems. We develop theory and computational tools to tackle problems, ranging from magnetic field sensitive chemistry for quantum sensing to developing quantum dynamics methods for exploring complex photochemistry.

Chirality Induced Spin Selectivity (CISS)
Just over 25 years ago a remarkable effect was discovered: electron transport through chiral molecules is spin-selective, so one of the two electron spin states is more likely to be observed after the electron has travelled through a chiral molecule. Many theories of this effect have been proposed, but no single theory has emerged which can quantitatively explain the CISS effect across all experiments. In our group we work to push the boundaries of the theory of the CISS effect and bridge the gap between theory, experiment and application of chirality-dependent spin effects.

Electron and energy transfer
When molecules absorb energy from light a plethora of complex processes can occur, transferring energy and electrons as well as reshaping chemical bonds. In our group we work to develop quantum dynamics methods and tools for describing reactions involving electronic excited states in the condensed phase.

Photosynthesis and photoprotection
Photosynthetic organisms can convert light energy absorbed from the sun into chemical energy with remarkable efficiency, potentially by harnessing quantum effects. In fact these organisms are so good at absorbing light energy that they need to protect themselves from harmful side reactions like the formation of highly reactive oxygen species, which they do through various photoprotective mechanisms. In our group we develop multi-time-scale models and methods to simulate the complex photosynthetic and photoprotective processes in light-harvesting organisms, in order to understand how this process, essential to life on Earth, functions.

Magnetic field effects in chemistry for quantum sensing
Magnetic fields as small as the Earth’s magnetic field (much weaker than that of a fridge magnet) can influence chemical reactions involving unpaired electron spins at room temperature. This is remarkable given that the interaction energy is orders of magnitude smaller than thermal energy. We work with experimental groups to develop models to understand these fascinating effects, and how to harness them for applications in quantum information science and sensing.

Honors & Awards

Clarendon Scholarship, University of Oxford (2017-2021)
DPhil Thesis Commendation, University of Oxford (2021)

Representative Publications

An up-to-date list of publications can be found at
https://scholar.google.co.uk/citations?user=QTfhgdIAAAAJ&hl=en&authuser=1

 

Below is a list of selected publications:

  1. Fay, T., Huix-Rotllant, M., & Ferré, N. (2025). Analytic gradients and periodic boundary conditions for direct reaction field polarizable QM/MM. American Chemical Society (ACS). https://doi.org/10.26434/chemrxiv-2025-1jrbx
  2. Lin, N., Tsuji, M., Bruzzese, I., Chen, A., Vrionides, M., Jian, N., Kittur, F., Fay, T. P., & Mani, T. (2025). Molecular Engineering of Emissive Molecular Qubits Based on Spin-Correlated Radical Pairs. Journal of the American Chemical Society, 147(13), 11062–11071. https://doi.org/10.1021/jacs.4c16164
  3. Fay, T. P., Ferré, N., & Huix-Rotllant, M. (2024). Efficient Polarizable QM/MM Using the Direct Reaction Field Hamiltonian with Electrostatic Potential Fitted Multipole Operators. Journal of Chemical Theory and Computation, 21(1), 183–201. https://doi.org/10.1021/acs.jctc.4c01219
  4. Pažėra, G. J., Fay, T. P., Solov’yov, I. A., Hore, P. J., & Gerhards, L. (2024). Spin Dynamics of Radical Pairs Using the Stochastic Schrödinger Equation in MolSpin. Journal of Chemical Theory and Computation, 20(19), 8412–8421. https://doi.org/10.1021/acs.jctc.4c00361
  5. Anderson, M. C., Dodin, A., Fay, T. P., & Limmer, D. T. (2024). Coherent control from quantum commitment probabilities. The Journal of Chemical Physics, 161(2). https://doi.org/10.1063/5.0213444
  6. Fay, T. P. (2024). Extending non-adiabatic rate theory to strong electronic couplings in the Marcus inverted regime. The Journal of Chemical Physics, 161(1). https://doi.org/10.1063/5.0218653
  7. Fay, T. P., & Limmer, D. T. (2024). Unraveling the mechanisms of triplet state formation in a heavy-atom free photosensitizer. Chemical Science, 15(18), 6726–6737. https://doi.org/10.1039/d4sc01369g
  8. Runeson, J. E., Fay, T. P., & Manolopoulos, D. E. (2024). Exciton dynamics from the mapping approach to surface hopping: comparison with Förster and Redfield theories. Physical Chemistry Chemical Physics, 26(6), 4929–4938. https://doi.org/10.1039/d3cp05926j
  9. Anderson, M. C., Woods, E. J., Fay, T. P., Wales, D. J., & Limmer, D. T. (2023). On the Mechanism of Polaritonic Rate Suppression from Quantum Transition Paths. The Journal of Physical Chemistry Letters, 14(30), 6888–6894. https://doi.org/10.1021/acs.jpclett.3c01188
  10. Short, A., Fay, T. P., Crisanto, T., Mangal, R., Niyogi, K. K., Limmer, D. T., & Fleming, G. R. (2023). Kinetics of the xanthophyll cycle and its role in photoprotective memory and response. Nature Communications, 14(1). https://doi.org/10.1038/s41467-023-42281-8
  11. Fay, T. P., & Limmer, D. T. (2023). Spin selective charge recombination in chiral donor–bridge–acceptor triads. The Journal of Chemical Physics, 158(19). https://doi.org/10.1063/5.0150269
  12. Fay, T. P., & Limmer, D. T. (2022). Coupled charge and energy transfer dynamics in light harvesting complexes from a hybrid hierarchical equations of motion approach. The Journal of Chemical Physics, 157(17). https://doi.org/10.1063/5.0117659
  13. Fay, T. P. (2022). A simple improved low temperature correction for the hierarchical equations of motion. The Journal of Chemical Physics, 157(5). https://doi.org/10.1063/5.0100365
  14. Short, A. H., Fay, T. P., Crisanto, T., Hall, J., Steen, C. J., Niyogi, K. K., Limmer, D. T., & Fleming, G. R. (2022). Xanthophyll-cycle based model of the rapid photoprotection of Nannochloropsis in response to regular and irregular light/dark sequences. The Journal of Chemical Physics, 156(20). https://doi.org/10.1063/5.0089335
  15. Fay, T. P., & Limmer, D. T. (2021). Origin of Chirality Induced Spin Selectivity in Photoinduced Electron Transfer. Nano Letters, 21(15), 6696–6702. https://doi.org/10.1021/acs.nanolett.1c02370
  16. Fay, T. P., Lindoy, L. P., & Manolopoulos, D. E. (2021). Spin relaxation in radical pairs from the stochastic Schrödinger equation. The Journal of Chemical Physics, 154(8). https://doi.org/10.1063/5.0040519
  17. Fay, T. P. (2021). Chirality-Induced Spin Coherence in Electron Transfer Reactions. The Journal of Physical Chemistry Letters, 12(5), 1407–1412. https://doi.org/10.1021/acs.jpclett.1c00009
  18. Lindoy, L. P., Fay, T. P., & Manolopoulos, D. E. (2020). Quantum mechanical spin dynamics of a molecular magnetoreceptor. The Journal of Chemical Physics, 152(16). https://doi.org/10.1063/5.0006411
  19. Alvertis, A. M., Barford, W., Bourne Worster, S., Burghardt, I., Datta, A., Dijkstra, A., Fay, T., Ghosh, S., Grünbaum, T., Habershon, S., Hore, P. J., Hutchinson, D., Iyengar, S., Jones, A. R., Jones, G., Komarova, K., Lawrence, J., Léonard, J., Litman, Y., … Worth, G. (2020). Quantum coherence in complex environments: general discussion. Faraday Discussions, 221, 168–201. https://doi.org/10.1039/c9fd90076d
  20. Fay, T. (2020). Quantum master equations for spin chemistry [PhD thesis]. University of Oxford.
  21. Fay, T. P., Lindoy, L. P., Manolopoulos, D. E., & Hore, P. J. (2020). How quantum is radical pair magnetoreception? Faraday Discussions, 221, 77–91. https://doi.org/10.1039/c9fd00049f
  22. Alvertis, A. M., Barford, W., Bourne Worster, S., Burghardt, I., Chin, A., Datta, A., Dijkstra, A., Fay, T., Fielding, H., Grünbaum, T., Habershon, S., Hammes-Schiffer, S., Iyengar, S., Jones, A. R., Komarova, K., Léonard, J., Litman, Y., Picconi, D., Plant, D., … Worth, G. (2020). Spectroscopic signatures of quantum effects: general discussion. Faraday Discussions, 221, 322–349. https://doi.org/10.1039/c9fd90074h
  23. Fay, T. P., Lindoy, L. P., & Manolopoulos, D. E. (2019). Electron spin relaxation in radical pairs: Beyond the Redfield approximation. The Journal of Chemical Physics, 151(15). https://doi.org/10.1063/1.5125752
  24. Fay, T. P., & Manolopoulos, D. E. (2019). Radical pair intersystem crossing: Quantum dynamics or incoherent kinetics? The Journal of Chemical Physics, 150(15). https://doi.org/10.1063/1.5095204
  25. Fay, T. P., Lindoy, L. P., & Manolopoulos, D. E. (2018). Spin-selective electron transfer reactions of radical pairs: Beyond the Haberkorn master equation. The Journal of Chemical Physics, 149(6). https://doi.org/10.1063/1.5041520
  26. Lewis, A. M., Fay, T. P., Manolopoulos, D. E., Kerpal, C., Richert, S., & Timmel, C. R. (2018). On the low magnetic field effect in radical pair reactions. The Journal of Chemical Physics, 149(3). https://doi.org/10.1063/1.5038558
  27. Fay, T. P., Lewis, A. M., & Manolopoulos, D. E. (2017). Spin-dependent charge recombination along para-phenylene molecular wires. The Journal of Chemical Physics, 147(6). https://doi.org/10.1063/1.4997482
  28. Lewis, A. M., Fay, T. P., & Manolopoulos, D. E. (2016). An efficient quantum mechanical method for radical pair recombination reactions. The Journal of Chemical Physics, 145(24). https://doi.org/10.1063/1.4972277