Simplified time-dependent density functional theory (sTD-DFT) for molecular optical rotation.

Area of Science:

• Quantum Chemistry
• Computational Chemistry

Background:

• Accurate calculation of optical rotation is crucial for understanding molecular properties.
• Existing methods like time-dependent density functional theory (TD-DFT) can be computationally expensive for large systems.

Purpose of the Study:

• To extend the simplified time-dependent density functional theory (sTD-DFT) method for calculating optical rotation.
• To provide a computationally efficient alternative for screening large sets of molecular conformers.

Main Methods:

• Implementation of an extended sTD-DFT scheme for optical rotation calculations.
• Benchmarking the new method against experimental data for 42 compounds (OR45 set), 13 helicene derivatives, and one biomolecular system.

Main Results:

• The sTD-DFT method shows good quantitative agreement with experimental optical rotations for valence-dominated responses (e.g., conjugated π-systems).
• Achieved 1-3 orders of magnitude speed-up compared to standard TD-DFT.
• Reasonable agreement for Rydberg state dominated responses in smaller molecules.

Conclusions:

• The extended sTD-DFT method provides an efficient and accurate approach for calculating optical rotation.
• The new implementation enables calculations for systems up to 1000 atoms, facilitating studies of flexible biomolecules.