Towards a gauge invariant method for molecular chiroptical properties in TDDFT

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Spectroscopy

Background:

• Calculating chiroptical response is crucial for understanding molecular properties.
• Existing methods often involve computationally expensive calculations, limiting system size.
• Accurate prediction of chiroptical properties aids in molecular design and analysis.

Purpose of the Study:

• To present an efficient and generalizable computational scheme for chiroptical response.
• To implement and validate the scheme using time-dependent density functional theory (TD-DFT).
• To address limitations in current theoretical methods for predicting excitation energies and spectral features.

Main Methods:

• Employed a real-time propagation or frequency-dependent Sternheimer method within TD-DFT.
• Developed a scheme that avoids the computationally intensive sum over empty orbitals.
• Utilized a real-space pseudo-potential representation with gauge invariance corrections.

Main Results:

• Achieved favorable scaling with system size, enabling larger molecular calculations.
• Demonstrated excellent agreement between calculated and experimental dichroism spectra shapes and signs.
• Identified deficiencies in current exchange-correlation functionals for absolute excitation energy prediction.

Conclusions:

• The presented method offers an efficient and accurate approach to calculating chiroptical responses.
• The scheme's generality and ease of implementation facilitate broader application in computational chemistry.
• This work provides a valuable tool for studying chiral molecules and refining theoretical models.