Benchmarking the quadrupolar coupling tensor for chlorine to probe weak-bonding interactions.

Area of Science:

• Physical Chemistry
• Quantum Chemistry
• Spectroscopy

Background:

• Rotational spectroscopy requires quantum chemical calculations for spectral interpretation.
• Molecules with complex angular momenta coupling to rotation present significant assignment challenges.
• Nuclear quadrupole coupling constants and molecular geometry are critical parameters in spectroscopy.

Purpose of the Study:

• To benchmark computational methods for predicting nuclear quadrupole coupling constants and geometries of chlorine-containing molecules.
• To compare the accuracy of various computational approaches against experimental data.
• To guide the selection of cost-effective methods for rotational spectroscopy applications.

Main Methods:

• Evaluation of commonly used computational methods in rotational spectroscopy.
• Comparison of predicted structural and electronic parameters with experimental values.
• Assessment of computational cost versus prediction accuracy for different methods.

Main Results:

• Ab initio methods demonstrate superior performance in predicting both molecular geometry and chlorine nuclear quadrupole coupling constants.
• Combining ab initio methods with density functional theory (DFT) for structure optimization provides adequate predictions with reduced computational expense.
• The study establishes a benchmark for computational accuracy in this area.

Conclusions:

• Ab initio methods are recommended for high-accuracy predictions of nuclear quadrupole coupling constants and molecular geometry.
• DFT-based structure optimization offers a viable, cost-effective alternative for adequate predictions.
• This research serves as a foundation for expanding computational datasets for molecular clusters.