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arXiv · 2004.12404

N$_3^+$: Full-Dimensional Potential Energy Surface, Vibrational Energy Levels and Ground State Dynamics

Debasish Koner·Max Schwilk·Sarbani Patra·Evan J. Bieske·Markus Meuwly
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Abstract

The fundamentals and higher vibrationally excited states for the N$_3^+$ ion in its electronic ground state have been determined from quantum bound state calculations on 3-dimensional potential energy surfaces (PESs) at the CCSD(T)-F12 and MRCI+Q levels of theory. The vibrational fundamentals are at 1130 cm$^{-1}$ ($\nu_1$, symmetric stretch), 807 cm$^{-1}$ ($\nu_3$, asymmetric stretch), and 406 cm$^{-1}$ ($\nu_2$, bend) on the higher-quality CCSD(T)-F12 surface. For $\nu_1$, the calculations are close to the estimated frequency from experiment (1170 cm$^{-1}$) and previous calculations\cite{rosmus.n3:1994} which find it at 1190 cm$^{-1}$. Calculations of the vibrational states on the MRCI+Q PES are in qualitative agreement with those using the CCSD(T)-F12 PES. Analysis of the reference CASSCF wave function for the MRCI+Q calculations provides further insight into the shape of the PES and lends support for the reliability of Hartree-Fock as the reference wave function for the coupled cluster calculations. According to this, N$_3^+$ has mainly single reference character in all low-energy regions of its electronic ground state ($^3$A$''$) 3d PES.

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Debasish Koner, Max Schwilk, Sarbani Patra, Evan J. Bieske, Markus Meuwly. 2020-04-26. N$_3^+$: Full-Dimensional Potential Energy Surface, Vibrational Energy Levels and Ground State Dynamics. https://doi.org/10.1063/5.0011957

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