# Quantum mechanical calculation of the collision-induced absorption spectra of N{sub 2}–N{sub 2} with anisotropic interactions

## Abstract

We present quantum mechanical calculations of the collision-induced absorption spectra of nitrogen molecules, using ab initio dipole moment and potential energy surfaces. Collision-induced spectra are first calculated using the isotropic interaction approximation. Then, we improve upon these results by considering the full anisotropic interaction potential. We also develop the computationally less expensive coupled-states approximation for calculating collision-induced spectra and validate this approximation by comparing the results to numerically exact close-coupling calculations for low energies. Angular localization of the scattering wave functions due to anisotropic interactions affects the line strength at low energies by two orders of magnitude. The effect of anisotropy decreases at higher energy, which validates the isotropic interaction approximation as a high-temperature approximation for calculating collision-induced spectra. Agreement with experimental data is reasonable in the isotropic interaction approximation, and improves when the full anisotropic potential is considered. Calculated absorption coefficients are tabulated for application in atmospheric modeling.

- Authors:

- Theoretical Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, Nijmegen (Netherlands)
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824 (United States)

- Publication Date:

- OSTI Identifier:
- 22416179

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 8; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ABSORPTION SPECTRA; ANISOTROPY; APPROXIMATIONS; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; COUPLING; DIPOLE MOMENTS; MOLECULE COLLISIONS; MOLECULES; NITROGEN; POTENTIAL ENERGY; POTENTIALS; QUANTUM MECHANICS; SCATTERING; SURFACES; WAVE FUNCTIONS

### Citation Formats

```
Karman, Tijs, Groenenboom, Gerrit C., Avoird, Ad van der, E-mail: avda@theochem.ru.nl, Miliordos, Evangelos, and Hunt, Katharine L. C.
```*Quantum mechanical calculation of the collision-induced absorption spectra of N{sub 2}–N{sub 2} with anisotropic interactions*. United States: N. p., 2015.
Web. doi:10.1063/1.4907917.

```
Karman, Tijs, Groenenboom, Gerrit C., Avoird, Ad van der, E-mail: avda@theochem.ru.nl, Miliordos, Evangelos, & Hunt, Katharine L. C.
```*Quantum mechanical calculation of the collision-induced absorption spectra of N{sub 2}–N{sub 2} with anisotropic interactions*. United States. doi:10.1063/1.4907917.

```
Karman, Tijs, Groenenboom, Gerrit C., Avoird, Ad van der, E-mail: avda@theochem.ru.nl, Miliordos, Evangelos, and Hunt, Katharine L. C. Sat .
"Quantum mechanical calculation of the collision-induced absorption spectra of N{sub 2}–N{sub 2} with anisotropic interactions". United States.
doi:10.1063/1.4907917.
```

```
@article{osti_22416179,
```

title = {Quantum mechanical calculation of the collision-induced absorption spectra of N{sub 2}–N{sub 2} with anisotropic interactions},

author = {Karman, Tijs and Groenenboom, Gerrit C. and Avoird, Ad van der, E-mail: avda@theochem.ru.nl and Miliordos, Evangelos and Hunt, Katharine L. C.},

abstractNote = {We present quantum mechanical calculations of the collision-induced absorption spectra of nitrogen molecules, using ab initio dipole moment and potential energy surfaces. Collision-induced spectra are first calculated using the isotropic interaction approximation. Then, we improve upon these results by considering the full anisotropic interaction potential. We also develop the computationally less expensive coupled-states approximation for calculating collision-induced spectra and validate this approximation by comparing the results to numerically exact close-coupling calculations for low energies. Angular localization of the scattering wave functions due to anisotropic interactions affects the line strength at low energies by two orders of magnitude. The effect of anisotropy decreases at higher energy, which validates the isotropic interaction approximation as a high-temperature approximation for calculating collision-induced spectra. Agreement with experimental data is reasonable in the isotropic interaction approximation, and improves when the full anisotropic potential is considered. Calculated absorption coefficients are tabulated for application in atmospheric modeling.},

doi = {10.1063/1.4907917},

journal = {Journal of Chemical Physics},

number = 8,

volume = 142,

place = {United States},

year = {Sat Feb 28 00:00:00 EST 2015},

month = {Sat Feb 28 00:00:00 EST 2015}

}