Comparative Study of Vibrational Raman Optical Activity with Different Time-Dependent Density Functional...

Area of Science:

• Computational Chemistry
• Spectroscopy
• Quantum Chemistry

Background:

• Vibrational Raman Optical Activity (VROA) is a powerful technique for determining molecular structure.
• Accurate theoretical prediction of VROA spectra is crucial for experimental interpretation.
• Assessing computational methods for VROA is essential for advancing chemical research.

Purpose of the Study:

• Introduce the VROA36 database for evaluating computational VROA methods.
• Compare the performance of four density functionals and various basis sets for VROA calculations.
• Identify reliable computational strategies for predicting VROA spectra.

Main Methods:

• Utilized the VROA36 database comprising 36 molecules and 93 conformers with experimental VROA data.
• Computed VROA spectra using B3LYP-D3(BJ)/def2-TZVP normal modes with four functionals: B3LYP-D3(BJ), ωB97X-D, M11, and optimally tuned LC-PBE.
• Employed SimROA indices and frequency scaling factors for spectral comparison.

Main Results:

• All four tested functionals demonstrated comparable performance, independent of the basis set used.
• Calculated VROA spectra generally showed good agreement with experimental data.
• Complex (damped) linear response is vital for accurate VROA intensities under near- or at-resonance conditions.

Conclusions:

• The VROA36 database provides a valuable resource for computational method development.
• B3LYP-D3(BJ), ωB97X-D, M11, and optimally tuned LC-PBE functionals are suitable for VROA studies.
• The def2-SVPD basis set or similar is recommended for efficient and reliable theoretical VROA investigations.