Logo image
Back
Insights into van der Waals correction effects on Raman vibrational spectra of L-cysteine I
Journal article   Open access   Peer reviewed

Insights into van der Waals correction effects on Raman vibrational spectra of L-cysteine I

Neila Cristina Fonseca Machado, Erika T. Sato, Thamires A. Lima, Julian M. Rayo Alape and Herculano da Silva Martinho
Journal of molecular structure, v 1380, 147447
Aug 2026
DOI: https://doi.org/10.1016/j.molstruc.2026.147447
url
https://doi.org/10.1016/j.molstruc.2026.147447View
Published, Version of Record (VoR) Open

Abstract

Density functional theory Hydration effects L-Cysteine I crystal Raman spectroscopy van der Waal interactions Vibrational modes
•van der Waals corrections improve Raman spectra accuracy of L-cysteine I.•Hydration effects modulate vibrational modes via H-bond networks.•Low-frequency lattice modes strongly depend on dispersion interactions.•Mid-frequency modes show intermolecular coupling induced by hydration.•Combined DFT-vdW and hydration model enhances experiment agreement. •L-Cysteine Raman spectra showing the regions where vdW and vdw + water dimers are relevant the most coupling vibrations. [Display omitted] Understanding the vibrational properties of biologically relevant molecular crystals remains a challenging task, as their spectra arise from the concerted motion of multiple molecular units, analogous to an orchestra in which individual vibrations combine to produce a collective response. In this context, crystalline L-cysteine I represents an ideal model system, since its vibrational behavior arises from the interplay between strong hydrogen-bonding interactions and long-range dispersion (van der Waals) forces, as well as possible hydration effects associated with hydrogen-bonded species. Raman spectroscopy is employed as a sensitive probe of thiol-containing amino acids, while Car-Parrinello molecular dynamics simulations within density functional theory are used to calculate harmonic vibrational frequencies under periodic boundary conditions. Empirical van der Waals corrections are incorporated into the DFT-BLYP framework to improve the description of dispersion interactions and hydrogen-bond networks. By systematically comparing dry and hydrated computational models and providing detailed vibrational assignments, we reveal a pronounced, region-dependent influence of dispersion interactions and hydration effects on the Raman spectra. Low-frequency collective lattice modes and mid-frequency intramolecular vibrations are particularly sensitive to these interactions, leading to improved agreement between simulated and experimental spectra. Overall, this study delivers a comprehensive vibrational characterization of crystalline L-cysteine I and offers molecular-level insight into how intermolecular interactions, including possible hydrogen-bonded water species, influence vibrational signatures in biologically relevant molecular solids.

Metrics

1 Record Views

Details

Logo image