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

Abstract

Using the core-mass approach, we have generated a vibrational-mass surface for the triatomic H 3 +. The coordinate-dependent masses account for the off-resonance nonadiabatic coupling and permit a very accurate determination of the rovibrational states using a single potential energy surface. The new, high-precision measurements of 12 rovibrational transitions in the ν 2 bending fundamental of H 3 + by Wu et al. [Phys. Rev. A 88, 032507 (2013)] are used to scale this surface empirically and to derive state-dependent vibrational and rotational masses that reproduce the experimental transition energies to 10 −3 cm −1. Rotational term values for J 10 are presented for the two lowest vibrational states and equivalent transitions in D 3 + considered.

ExoMol molecular line lists – XX. A comprehensive line list for H3+

“…Unlike NMT, the model used here is essentially ab initio. H + 3 is a two-electron system and is a benchmark for developments in high accuracy ab initio quantum chemical methods (Röhse et al 1994;Cencek et al 1998;Polyansky & Tennyson 1999;Schiffels et al 2003a,c;Kutzelnigg & Jaquet 2006;Pavanello et al 2009Pavanello et al , 2012bDiniz et al 2013). Of particular note here is the nonadiabatic model developed by Polyansky & Tennyson (1999) and the ultra-high accuracy ab initio PES of Pavanello et al (2012b).…”

Uncertainty estimates for theoretical atomic and molecular data

“…As a consequence of the BO approximation, electronic structure theory and nuclear motion theory emerge as the two main subfields of molecular quantum chemistry. These two fields are linked by potential energy surfaces (PESs), plus any beyond-BO corrections that may deemed appropriate for a given problem [46][47][48][49]. Given that for all but a few simple problems the converged absolute energy of a molecular system cannot be obtained, it is important to note that molecular structure computations are always concerned with relative rather than total energies, and the same must be the case for the uncertainty estimates.…”

Perspective: Accurate ro-vibrational calculations on small molecules

“…76 The subsequent focus in these studies has been on including QED effects 77 and improving the treatment of non-adiabatic effects. [78][79][80] The recent high-precision spectra recorded for H + 3 and its isotopologues 81,82 will in due course serve as benchmarks against which improved ab initio procedures can be tested.…”