A systematic investigation of the ground state potential energy surface of \documentclass[12pt]{minimal}\begin{document}${\rm H}_3^+$\end{document}H3+

Abstract

Based on different ab initio electronic structure calculations (CI-R12 and Gaussian Geminals) of the Born-Oppenheimer electronic energy E(BO) of H(3)(+) from high to highest quality, we build up a potential energy surface which represents a highly reliable form of the topology of the whole potential region, locally and globally. We use the CI-R12 method in order to get within reasonable CPU-time a relatively dense grid of energy points. We demonstrate that CI-R12 is good enough to give an accurate surface, i.e., Gaussian Geminals are not absolutely necessary. For different types of potential energy surface fits, we performed variational calculations of all bound vibrational states, including resonances above the dissociation limit, for total angular momentum J = 0. We clarify the differences between different fits of the energy to various functional forms of the potential surface. Small rms-values (<1 cm(-1)) of the fit do not provide precise information about the interpolatory behaviour of the fit functions.

Vibrationally and rotationally nonadiabatic calculations onH3+using coordinate-dependent vibrational and rotational masses

“…+ [1], recent works [2][3][4][5][6][7][8] have focused on its high-lying rovibrational energy states. Especially elusive [9] had been the states lying above the so-called barrier to linearity, i.e., 10 000 cm −1 above the zero-point level or 14 360 cm −1 above the bottom of the potential energy surface (PES).…”

“…These states can access linear H 3 + configurations with non-negligible probability. Theoretical shortcomings had not allowed for a meaningful comparison with the experiment in this high-energy region until the very recent works of Alijah [2], Pavanello et al [3,4,6], and Jaquet et al [7,8].…”

Investigation of Nonadiabatic Effects for the Vibrational Spectrum of a Triatomic Molecule: The Use of a Single Potential Energy Surface with Distance-Dependent Masses for H3+

“…The six different distance-dependent mass corrections μ 2 x , μ 2 y , μ 2 z , μ 3 x , μ 3 y , and μ 3 z have been fitted individually by B-splines, and from them other needed combinations are produced. A polynomial fit (with hyperspherical coordinates) for an extended geometrical region, as performed for the potential or the diagonal adiabatic corrections to guarantee the D 3 h symmetry, had difficulties in reproducing the input data with sufficient accuracy.…”

“…For the MBB-surface we investigate the differences between different constant mass concepts as nuclear, atomic, and vibrational masses based on eq and results based on averaged distance-dependent mass corrections (see eq ). For the PAVA–PES (only electronic contributions: called PAVA-E) based on Gaussian Geminals of Pavanello et al , (similar studies have been performed with our former BO-PES based on Gaussian Geminals, too , ), we compared different distance-dependent mass corrections within eqs and . Similar investigations had been performed by including adiabatic and relativistic corrections (called PAVA-EAR).…”

A global potential energy surface for H$_3^+$

“…A number of global potential energy surfaces (PESs) are available for H + 3 in its electronic ground state [13][14][15][16][17][18][19][20][21][22][23]. Of these we particularly note the GLH3P PES of Pavanello et al [21], which is based on ab initio calculations of spectroscopic accuracy [24,25], and the surface of Velilla et al [18], which is based on less accurate ab initio calculations but whose full treatment of the long-range proton -H 2 interactions is vital for the study of ultra-low energy collisions [12].…”