Vibrational circular dichroism spectra for large molecules and molecules with heavy elements

Area of Science:

• Computational Chemistry
• Spectroscopy
• Quantum Chemistry

Background:

• Vibrational Circular Dichroism (VCD) spectroscopy is a powerful technique for determining molecular structure.
• Accurate theoretical prediction of VCD spectra is crucial for experimental interpretation.
• Previous implementations had limitations in handling large systems and relativistic effects.

Purpose of the Study:

• To implement vibrational circular dichroism (VCD) spectra calculations within the TURBOMOLE software package.
• To extend existing modules for magnetic response and vibrational frequency calculations.
• To enable gauge origin invariant calculations and efficient exploitation of molecular symmetry.

Main Methods:

• Followed the methodology proposed by Cheeseman (1996).
• Extended TURBOMOLE modules for magnetic response and vibrational frequencies.
• Implemented gauge origin invariant effective core potentials.
• Incorporated efficient exploitation of molecular symmetry.

Main Results:

• Successfully implemented VCD spectra calculations in TURBOMOLE.
• Demonstrated gauge origin invariant calculations for effective core potentials, including scalar relativistic effects for heavy elements (e.g., Co(ppy)3).
• Showcased the feasibility of calculating VCD spectra for large, symmetric systems, exemplified by icosahedral C6202+.

Conclusions:

• The new TURBOMOLE implementation significantly enhances capabilities for VCD spectral calculations.
• This advancement allows for accurate theoretical studies of complex molecules, including those with heavy elements.
• The efficient use of molecular symmetry makes the computation of large systems practical.