Electronic circular dichroism from real-time propagation in state space.

Area of Science:

• Quantum Chemistry
• Spectroscopy
• Computational Chemistry

Background:

• Electronic Circular Dichroism (ECD) spectroscopy is crucial for determining molecular chirality.
• Traditional methods often rely on linear-response theory, limiting analysis to ground-state properties.
• Accurate computation of ECD spectra is essential for understanding molecular structure and interactions.

Purpose of the Study:

• To develop and validate a real-time propagation method for computing ECD spectra.
• To couple the time-dependent Schrödinger equation (TDSE) with electronic structure calculations.
• To explore the capabilities of time-domain ECD beyond ground-state averaged spectra.

Main Methods:

• Real-time propagation of the TDSE in the space of electronic field-free eigenstates.
• Coupling TDSE with electronic structure treatments, specifically time-dependent density functional theory (TD-DFT) eigenstates.
• Calculation of time-dependent induced magnetic moments from electric perturbations.
• Generation of transition magnetic moment matrices from molecular orbital pairs.

Main Results:

• Successfully computed ECD spectra for methyloxirane, L-alanine conformers, and Λ-Co(acac)₃.
• Time-domain ECD spectra accurately reproduced frequency-domain results.
• Quantitative agreement was achieved with available experimental ECD data.
• Demonstrated the ability to compute ECD spectra from electronic excited states.

Conclusions:

• The proposed real-time TDSE propagation method is a robust and accurate approach for ECD spectral computation.
• This time-domain methodology provides a powerful alternative to linear-response methods.
• The approach opens new avenues for investigating excited-state ECD and other complex molecular phenomena.