| Summary |
The study of confined fields in plasmonic nanocavities and their interaction with molecules and nanostructures is an area of research with vast applications, including enhanced spectroscopy techniques as well as photoinduced/photocatalytic non-equilibrium phenomena. From the theoretical perspective, either classical electromagnetic models or atomistic/quantum descriptions are usually considered. However, in many cases these models ignore the electronic and nuclear quantum effects arising from the chemical nature and dynamics of a junction, such as tunneling, adsorption geometry, structure of the interface, vibrations, etc., or include them only approximately. Hence, a full quantum dynamical description is sometimes inescapable.
In this seminar I will present insights on ab-initio, light-driven, real-time dynamics at the atomistic level in scanning tunneling microscopes (STM) cavities by means of simulations within time-dependent density functional theory (TD-DFT) using the Octopus code [1] and time-dependent density functional tight-binding (TD-DFTB) using the DFTB+ code [2]. Results on the tip-enhanced Raman scattering from single-atom vibrations in a picocavity [3], as well as simulations of time-resolved spectra showing signatures of molecular vibrations, will be presented. These findings highlight the role of the electron dynamics (e.g. tunneling) and structural relaxation on the plasmon-induced phenomena. Finally, preliminary results that account for the back-reaction of the induced currents onto the electromagnetic fields by a full ab-initio treatment of electrons, nuclei and photons in the mean field, known as the coupled Ehrenfest-Maxwell-Pauli-Kohn-Sham equations [4], will be discussed.
[1] N. Tancogne-Dejean, M. J. T. Oliveira, et al. J. Chem. Phys. 152 124119 (2020)
[2] B. Hourahine, B. Aradi, et al. J. Chem. Phys. 152, 124101 (2020)
[3] S. Liu, F. Bonafé, H. Appel, A. Rubio, M. Wolf, and T. Kumagai. Submitted (2022)
[4] R. Jestädt, M. Ruggenthaler, M.J.T. Oliveira, A. Rubio, and H. Appel. Advances in Physics 68:4, 225-333 (2019)
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