Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 61: Organic molecules on inorganic substrates: electronic, optical and other properties II

O 61.5: Vortrag

Mittwoch, 11. März 2026, 16:00–16:15, HSZ/0201

Vibrational Spectra of Materials and Molecules with Path Integrals and Machine Learning — •Jorge Castro, Krystof Brezina, and Mariana Rossi — Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany

Vibrational spectroscopy provides fundamental insight into molecular structure and dynamics. Nuclear quantum effects (NQEs) can critically modulate vibrational peak positions, shapes, and intensities. Recently, we showed that the partially adiabatic elevated-temperature centroid molecular dynamics (PA-T_e-CMD) [1] accurately reproduces vibrational spectra across molecular and condensed-phase systems, including low-temperature regimes where NQEs are strongest. This approach enables the simulation of quantum infrared and Raman responses in diverse spectroscopic settings. Tip-Enhanced Raman Spectroscopy (TERS) [2] achieves sub-nanometer spatial resolution and is uniquely sensitive to single-molecule vibrational motion and surface defects. Building on first-principles finite-field formulations of TERS [3], we combine this framework with PA-T_e-CMD to quantify the role of nuclear quantum motion and anharmonicity in near-field Raman observables. As a first application, we investigate hydrogen-bonded chains of 2,5-diamino-1,4-benzoquinonediimine (DABQDI) and discuss how NQEs imprint on vibrational signatures in simulated TERS images.

[1] J. Castro et al., J. Chem. Phys. 163, 204102 (2025). [2] J. Lee et al., Nature 568, 78*82 (2019). [3] K. Brezina et al., arXiv:2509.13075 (2025).

Keywords: nuclear quantum effects; anharmonicity; surface molecular spectroscopy; TERS; vibrational spectroscopy