Vibrational (resonance) Raman optical activity with real time time dependent density functional theory

Area of Science:

• Quantum Chemistry
• Spectroscopy
• Computational Chemistry

Background:

• Vibrational Raman optical activity (ROA) spectroscopy is crucial for determining molecular chirality.
• Accurate calculation of ROA spectra, especially under resonance conditions, remains computationally challenging.

Purpose of the Study:

• To introduce a novel, efficient real-time propagation approach for calculating vibrational (resonance) Raman optical activity (ROA) spectra.
• To formulate ROA linear electronic response tensors within a propagator formalism for unified treatment of linear response (LR) and real-time time-dependent density functional theory (RT-TDDFT).

Main Methods:

• Formulation of ROA linear electronic response tensors in a propagator formalism.
• Application of real-time time-dependent density functional theory (RT-TDDFT) for spectral calculations.
• Discussion of length, mixed, and velocity representations and gauge invariance considerations.

Main Results:

• The propagator formalism allows for a straightforward extension to nonlocal potentials while maintaining gauge invariance.
• RT-TDDFT enables efficient calculation of both on- and off-resonance ROA spectra.
• Exemplary calculations for (R)-methyloxirane demonstrate the method's capability to capture resonance effects and excitation profiles.

Conclusions:

• The developed real-time propagation approach offers an innovative and computationally efficient method for calculating ROA spectra.
• This method facilitates the study of molecular chirality through detailed analysis of on- and off-resonance ROA, including resonance effects from excited states.