TYC Soiree: Excited States Dynamics

Dr Basile Churchod

University of Durham

Dr Tom Penfold

University of Newcastle

Thursday 14th June 2018
Time: 5pm
Venue: David Sizer LT, Bancroft building, Queen Mary University of London, Mile End
Contact: Rachel Crespo-Otero
Tel: +44 (0)20 7882 8404
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    Basile Churchod

    Towards in Silico Photochemistry using Ab Initio Nonadiabatic Molecular Dynamics

    What happens to a molecule once it has absorbed UV or visible light? How does the molecule release or convert the extra-energy it just received? Answering these questions clearly goes beyond a pure theoretical curiosity, as photochemical and photophysical processes are central for numerous domains like energy conversion and storage, radiation damages in DNA, or atmospheric chemistry, to name a few. Ab initio multiple spawning (AIMS) is a theoretical tool that aims at an accurate yet efficient in silico description of photochemical and photophysical processes in molecules. AIMS describes the excited-state dynamics of nuclear wavepackets using adaptive linear combinations of traveling frozen Gaussians [1].

    In this talk, I intend to survey some recent developments and applications of the AIMS technique. A significant feature of the AIMS framework – besides its controlled approximations [2] – is its adaptability, which permits the addition of critical physical processes for a realistic simulation of photochemical processes. For example, we recently included spin-orbit coupling in AIMS [3] and the effect of an external electric field [4], leading to two new schemes called Generalized AIMS (GAIMS) and eXternal Field AIMS (XFAIMS). We also proposed a simple yet rational approximation to AIMS termed Stochastic-Selection AIMS (SSAIMS), which allows decreasing the computational cost of an AIMS dynamics substantially [5].

    Also, we also interfaced AIMS with the GPU-based electronic structure code TeraChem to study the excited-state dynamics of large molecular systems. Combining the accuracy of AIMS with the efficiency of GPU-accelerated electronic structure calculations (LR-TDDFT or SA-CASSCF) allows indeed for a significant step forward in the simulation of nonadiabatic events, as it pushes the boundaries of the well-known compromise between efficiency and accuracy imposed by the computational cost of such dynamics. Thanks to this new interface, we could investigate the nonadiabatic dynamics of different medium-size organic molecules important in biological chemistry, organic electronics, and atmospheric chemistry [6-8].

    [1] B. F. E. Curchod and T. J. Martínez, Chem. Rev. 2018, 118, 3305.
    [2] B. Mignolet and B. F. E. Curchod, J. Chem. Phys. 2018, 148, 134110.
    [3] B. F. E. Curchod, C. Rauer, P. Marquetand, L. González, and T. J. Martínez, J. Chem. Phys. 2016, 144, 101102.
    [4] B. Mignolet, B. F. E. Curchod, and T. J. Martínez, J. Phys. Chem. 2016, 145, 191104.
    [5] B. F. E. Curchod, W. J. Glover, and T. J. Martínez, in preparation 2018.
    [6] J. W. Snyder Jr., B. F. E. Curchod, and T. J. Martínez, J. Phys. Chem. Lett. 2016, 7, 2444.
    [7] B. Mignolet, B. F. E. Curchod, and T. J. Martínez, Angew. Chem. Int. Ed. 2016, 55, 14993.
    [8] B. F. E. Curchod, A. Sisto, and T. J. Martínez, J. Phys. Chem. A 2017, 121, 265.


    Basile F. E. Curchod obtained his PhD in theoretical chemistry in 2013 at EPFL (Lausanne, Switzerland), under the direction of Dr. Ivano Tavernelli and co-direction of Prof. Ursula Röthlisberger. He was then invited for a short stay in the laboratory of Prof. Clémence Corminboeuf (EPFL, Lausanne).
    In early 2014, he was awarded an Early.PostDoc grant from the Swiss National Science Foundation to join the group of Prof. Todd J. Martínez at Stanford University (USA).
    In December 2015, he initiated a short postdoctoral stay in the Theory Group directed by Prof. Eberhard K. U. Gross, at the Max Planck Institute in Halle (Germany).
    He has then been awarded a Marie Curie Research Fellowship to join, in May 2016, the Centre for Computational Chemistry at the University of Bristol (UK), working with Dr. David R. Glowacki.
    Since November 2017, he is Assistant Professor in Theoretical Chemistry at Durham University (UK).

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    Tom Penfold

    Simulating and understanding dynamical effects on X-ray Spectra

    Advances in experimental methodology aligned with technological developments, such as 3rd generation light sources, X-ray Free Electron Lasers (X-FELs) and High Harmonic Generation (HHG), has led to a paradigm shift in the capability of X-ray Spectroscopy to deliver simultaneously high temporal and spectral resolution on an extremely broad range of samples in a wide array of different environments. Importantly, the complex nature and high information content of this class of techniques means that detailed theoretical studies are often essential to provide a firm link between the spectroscopic observables and the underlying molecular structure and dynamics.

    In this talk, I will present some of my recent work in simulating and understanding dynamical effects on X-ray Spectra. This will include exploiting high-level quantum chemistry, molecular and quantum dynamics methods to understand and predict time-resolved X-ray spectroscopy possible at 3rd generation light sources and X-ray Free Electron Lasers (X-FELs).


    Tom Penfold completed his Ph.D at the University of Birmingham under the supervision of Prof. Graham Worth where he studied the excited state dynamics of Benzene. He subsequently moved to the group of Prof. Majed Chergui at the École Polytechnique Fédérale de Lausanne developing the theory for time-resolved X-ray spectroscopy. He then work for 2-years as a Research Scientist within the SwissFEL project at the Paul Scherrer Institute, Switzerland. Tom joined Newcastle University as Lecturer in Computational and Theoretical Chemistry in September 2015. His research upon developing and exploiting methods for simulating and understanding excited state dynamics and time-resolved spectroscopy. Two strong focuses of his present research are femtosecond X-ray spectroscopy  and Thermally Activated Delayed Fluorescence.


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