Time Domain Simulations of Single Molecule Raman Scattering

Journal Article · Thu Sep 20 04:00:00 EDT 2018 · Journal of Physical Chemistry A

DOI:https://doi.org/10.1021/acs.jpca.8b05912· OSTI ID:1773365

Apra, Edoardo ^[1]; Bhattarai, Ashish ^[1]; Crampton, Kevin T. ^[1]; Bylaska, Eric J. ^[1]; Govind, Niranjan ^[1]; Hess, Wayne P. ^[1]; El-Khoury, Patrick Z. ^[1]

---

1. BATTELLE (PACIFIC NW LAB)

Non-equilibrium chemical phenomena are known to play an important role in single molecule microscopy and spectroscopy. Herein, we explore these effects through ab initio molecular dynamics (AIMD)-based Raman spectral simulations. We target an isolated aromatic thiol (thiobenzonitrile, TBN) as a prototypical molecular system. We first show that the essential features contained in the ensemble-averaged Raman spectrum of TBN can be reproduced by averaging over 18 short AIMD trajectories spanning a total simulation time of ~60 ps. This involved more than 90,000 polarizability calculations at the B3LYP/def2-TZVP level of theory. We then illustrate that the short trajectories (~3.3 ps total simulation time), where the accessible phase space is not fully sampled, provide a basis set for understanding key features that are often observed in measurements targeting single molecules. Our results suggest that a complete understanding of single molecule Raman scattering needs to account for molecular conformational flexibility and non-equilibrium chemical phenomena. These effects are well-captured using the described AIMD-based single molecule Raman spectral simulations.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1773365
• Report Number(s): PNNL-SA-135554
• Journal Information: Journal of Physical Chemistry A, Journal Name: Journal of Physical Chemistry A Journal Issue: 37 Vol. 122
• Country of Publication: United States
• Language: English