Multidimensional Morse/Long-Range Potential Energy Surface and Predicted Rotational Spectra of the CH4-N2 Complex.
1The Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Yantai University, Yantai 264005, P. R. China.
The Journal of Physical Chemistry. A
|June 30, 2025
Summary
A new five-dimensional potential energy surface was created for the methane-nitrogen (CH4-N2) complex. This computational model accurately predicts the complex's properties and rotational transition frequencies.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- Understanding intermolecular interactions is crucial for predicting molecular behavior.
- The methane-nitrogen (CH4-N2) complex is a relevant system for atmospheric and combustion studies.
Purpose of the Study:
- To develop a high-accuracy five-dimensional intermolecular potential energy surface (PES) for the CH4-N2 complex.
- To compute rovibrational energy levels and rotational transition frequencies for the CH4-N2 complex.
Main Methods:
- Ab initio calculations using the explicitly correlated coupled-cluster [CCSD(T)-F12] method with an aug-cc-pVTZ basis set.
- Fitting a multidimensional Morse/long-range function to 49,385 calculated points.
- Solving the rovibrational Schrödinger equation using discrete variable representation and finite basis representation methods.
Main Results:
- An analytic PES was generated with a root-mean-square deviation of 0.441 cm⁻¹.
- Rovibrational energy levels and wave functions were determined.
- Rotational transition frequencies for the CH4-N2 complex were predicted for the first time.
- The calculated cross second virial coefficient showed good agreement with experimental data.
Conclusions:
- The developed PES provides an accurate description of the CH4-N2 intermolecular potential.
- The predicted spectroscopic properties will aid in the experimental characterization of the CH4-N2 complex.
- The PES is suitable for further theoretical studies of the CH4-N2 system.
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