Resolving Photoinduced Femtosecond Three-Dimensional Solute-Solvent Dynamics through Surface Hopping Simulations

Author(s)

Severin Polonius, David Lehrner, Leticia González, Sebastian Mai

Abstract

Photoinduced dynamics in solution is governed by mutual solute-solvent interactions, which give rise to phenomena like solvatochromism, the Stokes shift, dual fluorescence, or charge transfer. Understanding these phenomena requires simulating the solute’s photoinduced dynamics and simultaneously resolving the three-dimensional solvent distribution dynamics. If using trajectory surface hopping (TSH) to this aim, thousands of trajectories are required to adequately sample the time-dependent three-dimensional solvent distribution functions, and thus resolve the solvent dynamics with sub-Ångstrom and femtosecond accuracy and sufficiently low noise levels. Unfortunately, simulating thousands of trajectories with TSH in the framework of hybrid quantum mechanical/molecular mechanical (QM/MM) can be prohibitively expensive when employing ab initio electronic structure methods. To tackle this challenge, we recently introduced a computationally efficient approach that combines efficient linear vibronic coupling models with molecular mechanics (LVC/MM) via electrostatic embedding [Polonius et al., JCTC 2023, 19, 7171-7186]. This method provides solvent-embedded, nonadiabatically coupled potential energy surfaces while scaling similarly to MM force fields. Here, we employ TSH with LVC/MM to unravel the photoinduced dynamics of two small thiocarbonyl compounds solvated in water. We describe how to estimate the number of trajectories required to produce nearly noise-free three-dimensional solvent distribution functions and present an analysis based on approximately 10,000 trajectories propagated for 3 ps. In the electronic ground state, both molecules exhibit in-plane hydrogen bonds to the sulfur atom. Shortly after excitation, these bonds are broken and reform perpendicular to the molecular plane on timescales that differ by an order of magnitude due to steric effects. We also show that the solvent relaxation dynamics is coupled to the electronic dynamics, including intersystem crossing. These findings are relevant to advance the understanding of the coupled solute-solvent dynamics of solvated photoexcited molecules, e.g., biologically relevant thio-nucleobases.

Organisation(s)

Department of Theoretical Chemistry, Research Platform Accelerating Photoreaction Discovery

External organisation(s)

Vienna Doctoral School in Chemistry (DoSChem)

Journal

Journal of Chemical Theory and Computation

Volume

20

Pages

4738-4750

No. of pages

13

ISSN

1549-9618

DOI

https://doi.org/10.1021/acs.jctc.4c00169

Publication date

2024

Peer reviewed

Yes

Austrian Fields of Science 2012

104027 Computational chemistry, 104022 Theoretical chemistry

ASJC Scopus subject areas

Computer Science Applications, Physical and Theoretical Chemistry

Portal url

https://ucrisportal.univie.ac.at/en/publications/resolving-photoinduced-femtosecond-threedimensional-solutesolvent-dynamics-through-surface-hopping-simulations(3891d5b6-14e1-451e-8e40-c3a5639dc539).html