Ab initio potential and rotational spectra of the CO-N₂ complex

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Spectroscopy

Background:

• Understanding intermolecular forces is crucial for predicting molecular behavior in various states.
• The carbon monoxide-nitrogen (CO-N2) complex serves as a model system for studying van der Waals interactions.

Purpose of the Study:

• To compute the intermolecular potential energy surface (PES) of the CO-N2 complex.
• To calculate the bound rovibrational energy levels and dissociation energies.
• To experimentally validate the theoretical PES through millimeter-wave spectroscopy.

Main Methods:

• Ab initio coupled cluster calculations with augmented correlation-consistent quadruple-zeta basis set.
• Calculation of bound rovibrational levels for total angular momenta J = 0-8.
• Millimeter-wave spectroscopy using an intracavity OROTRON jet spectrometer.

Main Results:

• A global minimum on the PES was found for an approximate T-shaped structure.
• Calculated dissociation energies (D0) for ortho-N2 and para-N2 modifications were 75.60 and 76.79 cm-1, respectively.
• New millimeter-wave transitions were observed and assigned, confirming theoretical predictions.

Conclusions:

• The study presents a validated intermolecular PES for the CO-N2 complex.
• Experimental and theoretical results show good agreement, confirming the accuracy of the PES.
• The findings provide a detailed characterization of the rovibrational states for CO-N2 nuclear spin species.