A global potential energy surface for H₃⁺

ABSTRACT

A globally correct potential energy surface (PES) for the ${\mathrm{H}}_3^{+}$ molecular ion is presented. The Born-Oppenheimer (BO) ab initio grid points of Pavanello et al. [J. Chem. Phys. 136, 184303 (2012)] are refitted as BOPES75K, which reproduces the energies below dissociation with a root mean square deviation of 0.05 cm⁻¹; points between dissociation and 75,000 cm⁻¹ are reproduced with the average accuracy of a few wavenumbers. The new PES75K+ potential combines BOPES75K with adiabatic, relativistic and quantum electrodynamics (QED) surfaces to provide the most accurate representation of the ${\mathrm{H}}_3^{+}$ global potential to date, overcoming the limitations on previous high accuracy ${\mathrm{H}}_3^{+}$ PESs near and above dissociation. PES75K+ can be used to provide predictions of bound rovibrational energy levels with an accuracy of approaching 0.1 cm⁻¹. Calculation of rovibrational energy levels within PES75K+ suggests that the non-adiabatic correction remains a limiting factor. The PES is also constructed to give the correct asymptotic limit making it suitable for use in studies of the ${\mathrm{H}}^{+}+{\mathrm{H}}_2$ prototypical chemical reaction. An improved dissociation energy for ${\mathrm{H}}_3^{+}$ is derived as $D_0=35,076\pm 2$ cm⁻¹.

GRAPHICAL ABSTRACT

KEYWORDS:

• Ab initio
• potential energy surface
• dissociation
• spectroscopy

Acknowledgments

We thank Eryn Spinlove and Attila Csásár for comments on our potential energy surface.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Irina I. Mizus http://orcid.org/0000-0001-6394-0129

Jonathan Tennyson http://orcid.org/0000-0002-4994-5238

Alexander Alijah http://orcid.org/0000-0002-4915-0558

Additional information

Funding

This work was partially supported by the Russian Fund for Basic Research (RFBR) as part of the research project # 18-02-00705 and by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant through grant number 701962.