N$_3^+$: FullDimensional Potential Energy Surface, Vibrational Energy Levels and Ground State Dynamics
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 3dimensional 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 higherquality 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 HartreeFock as the reference wave function for the coupled cluster calculations. According to this, N$_3^+$ has mainly single reference character in all lowenergy regions of its electronic ground state ($^3$A$''$) 3d PES.
 Publication:

arXiv eprints
 Pub Date:
 April 2020
 arXiv:
 arXiv:2004.12404
 Bibcode:
 2020arXiv200412404K
 Keywords:

 Physics  Chemical Physics
 EPrint:
 J. Chem. Phys. 153, 044302 (2020)