Chiral vibrational modes and vibrational circular dichroism
Abstract
The recent interest in chiral phonons in a variety of physical phenomena and their hypothesized role in the chiral-induced spin selectivity effect [Phys. Rev. Research, 5, L022039 (2023)] call for further investigation into the chirality of molecular vibrations. Although molecular chirality has conventionally been quantified using structural properties, recent work has highlighted the role of dynamical response properties as chirality metrics. In this work, we examine an inter-atom helicity pseudoscalar as a complementary measure of vibrational chirality, associated with the vibrational circular dichroism (VCD) intensity in the fixed partial charge (FPC) approximation. This pseudoscalar is translationally and rotationally invariant, can distinguish between opposite enantiomers, and unlike an atomic pseudoscalar measure considered in our earlier work [Phys. Rev. Lett., 133, 268001 (2024)] does not rely on a predefined symmetry axis. For a twisted ethane model as well as several small molecules, this pseudoscalar correlates well with structural descriptors based on the continuous chirality measure. Overall, our results support response-based metrics as a physically meaningful and practically useful characterization of vibrational chirality. Importantly, while the FPC-based VCD estimate provides a useful quantifier of vibrational chirality, we show that it is a rather poor predictor of the actual molecular VCD response because the latter is strongly influenced by the (vibrational configuration-dependent) molecular electronic response.
Versions
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BibTeX
@misc{tao2026chiral,
title = {{Chiral vibrational modes and vibrational circular dichroism}},
author = {Xuecheng Tao and Clàudia Climent and Ethan Abraham and Jichen Feng and Abraham Nitzan},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.22257},
eprint = {2607.22257},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.22257},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Chiral vibrational modes and vibrational circular dichroism
AU - Xuecheng Tao
AU - Clàudia Climent
AU - Ethan Abraham
AU - Jichen Feng
AU - Abraham Nitzan
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2607.22257
UR - https://arxiv.org/abs/2607.22257
AB - The recent interest in chiral phonons in a variety of physical phenomena and their hypothesized role in the chiral-induced spin selectivity effect [Phys. Rev. Research, 5, L022039 (2023)] call for further investigation into the chirality of molecular vibrations. Although molecular chirality has conventionally been quantified using structural properties, recent work has highlighted the role of dynamical response properties as chirality metrics. In this work, we examine an inter-atom helicity pseudoscalar as a complementary measure of vibrational chirality, associated with the vibrational circular dichroism (VCD) intensity in the fixed partial charge (FPC) approximation. This pseudoscalar is translationally and rotationally invariant, can distinguish between opposite enantiomers, and unlike an atomic pseudoscalar measure considered in our earlier work [Phys. Rev. Lett., 133, 268001 (2024)] does not rely on a predefined symmetry axis. For a twisted ethane model as well as several small molecules, this pseudoscalar correlates well with structural descriptors based on the continuous chirality measure. Overall, our results support response-based metrics as a physically meaningful and practically useful characterization of vibrational chirality. Importantly, while the FPC-based VCD estimate provides a useful quantifier of vibrational chirality, we show that it is a rather poor predictor of the actual molecular VCD response because the latter is strongly influenced by the (vibrational configuration-dependent) molecular electronic response.
ER -