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Research lectures, seminars and events

The events listed in this area are research seminars, workshops and lectures hosted by Durham University departments and research institutes. If you are not a member of the University, but  wish to enquire about attending one of the events please contact the organiser or host department.



Presented by Dr Basile Curchod, Chemistry, Durham University
14 February 2018 13:00 in OC218

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 frozen Gaussians.[1] In this talk, I intend to survey some recent developments and applications of the AIMS technique.

An important feature of the AIMS formalism is its flexibility, which permits the addition of critical physical processes for a realistic simulation of photochemical processes. We for example recently included in AIMS spin-orbit coupling[2] and the effect of an external electric field,[3] 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.[4]

To study the excited-state dynamics of large molecules, we also recently interfaced AIMS with the GPU-based electronic structure code TeraChem. 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.[5-7]

[1] B. F. E. Curchod and T. J. Martínez, “Ab Initio Nonadiabatic Quantum Molecular Dynamics”, Chem. Rev., in press (2018).

[2] B. F. E. Curchod, C. Rauer, P. Marquetand, L. González, and T. J. Martínez, “GAIMS – Generalized Ab Initio Multiple Spawning for both Internal Conversion and Intersystem Crossing Processes”, J. Chem. Phys., 144, 101102 (2016).

[3] B. Mignolet, B. F. E. Curchod, and T. J. Martínez, “XFAIMS – eXternal Field Ab Initio Multiple Spawning for Electron-Nuclear Dynamics Triggered by Short Laser Pulses”, J. Phys. Chem, 145, 191104 (2016) .
[4] B. F. E. Curchod, W. J. Glover, and T. J. Martínez, “SSAIMS – Stochastic-Selection Ab Initio Multiple Spawning for Efficient Nonadiabatic Molecular Dynamics”, in preparation (2018).
[5] J. W. Snyder Jr., B. F. E. Curchod, and T. J. Martínez, “GPU-Accelerated State-Averaged CASSCF Interfaced with Ab Initio Multiple Spawning Unravels the Photodynamics of Provitamin D3”, J. Phys. Chem. Lett., 7, 2444 (2016).
[6] B. Mignolet, B. F. E. Curchod, and T. J. Martínez, “Rich Athermal Ground-State Chemistry Triggered by Dynamics through a Conical Intersection”, Angew. Chem. Int. Ed., 55, 14993 (2016).
[7] B. F. E. Curchod, A. Sisto, and T. J. Martínez, “Ab Initio Multiple Spawning Photochemical Dynamics of DMABN Using GPUs”, J. Phys. Chem. A, 121, 265 (2017).

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