Abstract
H 3 + is a key player in molecular astrophysics, appearing in the interstellar medium and in the atmospheres of gas giants. It also plays an important role in star formation, and it has also been detected in supernova remnants. In theoretical chemistry, H3+ has long been a benchmark polyatomic system for high-level electronic-structure computations, as well as for quantum dynamics studies. In this work, exact quantum dynamical calculations are carried out for H3+, using the ScalIT suite of parallel codes, applied to two spectroscopically accurate potential energy surfaces. Specifically, rovibrational energy levels and wavefunctions are computed and labeled. Sixty vibrational states (for J = 0) are first determined, and then, rotational excitations for each of these “vibrational parent” states are computed up to total angular momentum J = 46, which is the highest value for which bound states of this molecule exist (D0 ∼ 35 000 cm−1). For these calculations, a very tight basis set convergence of a few 10−4 cm−1 (or less) has been achieved for almost all the computed energy levels. Where comparisons can be made, our results are found to agree well with earlier calculations and experimental data.
Highlights
H+3 1–33 is a key player in molecular astrophysics, appearing in the interstellar medium and in the atmospheres of gas giants and other planets, even exoplanets.3,18,30 It plays an important role in star formation, and it has been detected in supernova remnants.12,30 Reference 30 provides an excellent and timely review of H+3 in its many and varied astrophysical contexts
For PES1 and earlier potential energy surface (PES), a variety of rovibrational bound state calculations have been performed.2,7–9,15–20,22–27,81. These can be characterized by the extent to which they pushed the envelope with respect to the (a) highest vibrational excitation, v1, v2, |l|, (b) highest rotational excitation, J, and (c) highest convergence accuracy
The H+3 ion-molecule system has long served as an important benchmark system, appearing in nature in a variety of contexts
Summary
H+3 1–33 is a key player in molecular astrophysics, appearing in the interstellar medium and in the atmospheres of gas giants and other planets, even exoplanets. It plays an important role in star formation, and it has been detected in supernova remnants. Reference 30 provides an excellent and timely review of H+3 in its many and varied astrophysical contexts. Were basis sizes varied independently in all vibrational and rotational directions but many combinations of different coordinate ranges were considered Such a high level of numerical convergence has not been achieved previously, to our knowledge, but is important for PES characterization (e.g., for making progress on characterizing small effects and non-Born–Oppenheimer corrections) and for assessing various vibrational mass modifications, as have recently often been employed with H+3. Given the target accuracy of the present study, and the extent of light-atom tunneling in H+3 , these spurious wells can have an impact on spectral calculations even well below the dissociation threshold They strongly argue for a new benchmark rovibrational calculation using a more accurate PES, which has no such spurious features, i.e., PES2. For J ≥ 20, meaningful assignments of this kind become unfeasible, at least using the tools at our disposal
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