Description
Chirality is essential in biochemical processes and drug design [1]. While traditionally studied in the optical regime, X-ray sources allow extending chiroptical techniques to core-level excitations, offering element-specific information and enhanced sensitivity due to shorter wavelengths [2]. However, theoretical support is vital to interpret these spectra [3]. In this work, we present a method implemented in the WaveT code [4] based on solving the time-dependent electronic Schrödinger equation with explicit pulse propagation to compute X-ray absorption and X-ray natural circular dichroism. The wavefunction is expanded using time-dependent density functional theory field-free eigenstates. We demonstrate this using the Carbon K-edge of methyloxirane, providing a clear assignment of core transitions for ground and excited states [5] compared to experimental and other theoretical data [6]. We also compute spectra from valence excited states. This framework provides a practical route for interpreting X-ray chiroptical spectra and simulating time-resolved pump-probe experiments.
References
[1] Majed Chergui. “Time-resolved X-ray spectroscopies of chemical systems: New perspectives”. In: Structural Dynamics 3.3 (2016), p. 031001.
[2] Masahito Tanaka, Kazumichi Nakagawa, Akane Agui, Kentaro Fujii, and Akinari Yokoya. “First observation of natural circular dichroism for biomolecules in soft x-ray region studied with a polarizing undulator”. In: Physica Scripta 2005.T115 (2005), p. 873.
[3] Yeonsig Nam, Majed Chergui, Linda Young, and Jérémy R. Rouxel. “Linear and Nonlinear X-ray Spectra of Chiral Molecules: X-ray Circular Dichroism, Sum- and Difference-Frequency Generation of Fenchone and Cysteine”. In: The Journal of Physical Chemistry Letters 16.19 (2025), pp. 4652–4661.
[4] M. Monti, M. Stener, and E. Coccia. “Electronic circular dichroism from real-time propagation in state space”. In: The Journal of Chemical Physics 158.8 (2023), p. 084102.
[5] M. F. Sánchez, E. Coccia, and M. Chergui. In preparation.
[6] Josefine H. Andersen, Kaushik D. Nanda, Anna I. Krylov, and Sonia Coriani. “Probing Molecular Chirality of Ground and Electronically Excited States in the UV-vis and X-ray Regimes: An EOM-CCSD Study”. In: Journal of Chemical Theory and Computation 18.3 (2022), pp. 1748–1764.
