Speaker: Aderonke Simi Folorunso, Louisiana State University
Program Description:
Aderonke S. Folorunso1, François Mauger2, Kyle A. Hamer2, Denawakage D. Jayasinghe1, Robert R. Jones3, Louis F. DiMauro4, Mette B. Gaarde2, Kenneth J. Schafer2, and Kenneth Lopata1,5
1 Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803.
2 Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803.
3 Department of Physics, University of Virginia, Charlottesville, VA 22904.
4 Department of Physics, The Ohio State University, Columbus, OH 43210.
5 Center for Computation and Technology, Louisiana State University, Baton Rouge, LA 70803.
Attosecond charge migration (CM) is a coherent process that involves the particle-like movement of a localized hole across a molecule. Despite the numerous experimental and theoretical studies, there are still some unanswered questions regarding how systematically changing the chemical environment such as the effect of the structure of the molecule on the mechanisms and charge migration dynamics. In this work, we report systematic real-time time dependent density functional theory (RT-TDDFT) simulations of hole dynamics in linear and ring-shaped halogenated molecules following sudden ionization at the halogen. In the linear molecules, we studied the effects of halogenation and bonding on charge migration dynamics [1]. Furthermore, the effects of dependence of CM dynamics on the electron donating strength of different functional groups for para-functionalized bromobenzene derivatives was studied[2]. Our results show that conjugation is required for CM and strong electron donors (such R = N(CH3)2, -NH2) have greater hole contrast, whereas electron acceptors exhibit reduced contrast (e.g., -CF3). The Hammett sigma value of the group, a metric used to describe the chemical reactivity of benzene derivatives, provides a quantitative description of the trend. Overall, our findings show that CM may be predicted and understood using basic attochemistry principles and a density-based model without the need for an ambiguous interpretation in terms of a complicated beating of many states.
[1] A. S. Folorunso, A. Bruner, F. Mauger, K. A. Hamer, S. Hernandez, Robert R. Jones, L. F. DiMauro, M. B. Gaarde, K. J. Schafer, K. Lopata, “Molecular Modes of Attosecond Charge Migration”, Phys. Rev. Lett. 126, 133002 (2021).
[2] A. S. Folorunso, F. Mauger, K. A. Hamer, D. D. Jayasinghe, I. S. Wahyutama, J. R. Ragains, R. R. Jones, L. F. DiMauro, M. B. Gaarde, K. J. Schafer, K. Lopata, “Attochemistry Regulation of Charge Migration”, J. Phys. Chem. A, accepted (2023).
