Theoretical spectroscopy of the N2HAr+ complex

Area of Science:

• Theoretical Chemistry
• Computational Chemistry
• Spectroscopy

Background:

• The study of molecular ions like N2HAr+ provides insights into chemical bonding and reaction dynamics.
• Accurate potential energy surfaces are crucial for predicting molecular properties and spectra.

Purpose of the Study:

• To determine the six-dimensional potential energy surface (PES) for the electronic ground state of the N2HAr+ cation.
• To compute and analyze the rovibrational spectra of N2HAr+ and its deuterated isotopomer (N2DAr+).

Main Methods:

• Ab initio computations utilizing the coupled cluster with singles, doubles, and perturbative triples (CCSD(T)) level of theory.
• Second-order perturbation theory for deriving spectroscopic data.
• Full six-dimensional (6-D) rotation-vibration computations using an analytical PES representation.

Main Results:

• A high-accuracy six-dimensional PES for N2HAr+ was successfully determined.
• Calculated anharmonic wavenumbers show excellent agreement with experimental data (within 15 cm(-1)).
• Strong anharmonic resonances were identified between rovibrational energy levels of N2HAr+ and N2DAr+ at low energies.

Conclusions:

• The computed PES accurately reproduces experimental spectroscopic data for N2HAr+ and N2DAr+.
• The findings highlight the importance of anharmonic effects in the rovibrational spectra of these molecular ions.
• This work provides a valuable theoretical benchmark for future studies of similar systems.