Ab initio calculation of NH3 spectrum

Polyansky, Oleg

Permalink

https://hdl.handle.net/2142/91484 Copy

Description

Title

Ab initio calculation of NH3 spectrum

Author(s)

Polyansky, Oleg

Contributor(s)

• Zobov, Nikolay Fedorovich
• Yachmenev, Andrey
• Yurchenko, Sergei N.
• Tennyson, Jonathan
• Lodi, Lorenzo
• Kyuberis, Aleksandra
• Ovsyannikov, Roman I.

Issue Date

2016-06-21

Keyword(s)

Theory and Computation

Abstract

An {\it ab initio} potential energy surface (PES) for NH$_3$ is computed using the methodology pioneered for water (Polyansky et al. {\it J. Phys. Chem. A},{\bf 117}, 9633 (2013)). A multireference configuration calclulations are performed at 50000 points using quadruple and 5z basis sets to give a complete basis set (CBS) extrapolation. Relativistic and adiabatic surfaces are also computed. The points are fitted to an analytical PES. The rovibrational energy levels are computed using the program TROVE in both linearized and curvilinear coordinates. Better convergence is obtained for the higher energy levels using curvilinear coordinates: an accuracy of about 1 \wn is achieved for the levels up to 12 000 \wn. The levels up to 18 000 \wn are reproduced with the accuracy of a few \wn. These results are used to assign the visible spectrum of $^{14}$NH$_3$ recorded by Coy and Lehmann ({\it J. Chem. Phys.}, {\bf 84}, 5239 (1988)). Predicted rovibrational levels for NH$_2$D, NHD$_2$, ND$_3$ and $^{15}$NH$_3$ are given.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

En

Permalink

http://hdl.handle.net/2142/91484

Copyright and License Information

Copyright 2016 by the authors

Owning Collections