Quantum Dynamical Calculation of Bound Rovibrational States of HO₂ up to Largest Possible Total Angular Momentum, J ≤ 130

Abstract

In a previous article [J. Theor. Comput. Chem. 2010, 9, 435], all rovibrational bound states of HO2 were systematically computed, for all total angular momentum values J = 0-10. In this article, the high-J rovibrational states are computed for every multiple-of-ten J value up to J = 130, which is the point where the centrifugal barrier obliterates the potential well, and bound states no longer exist. The results are used to assess the importance of Coriolis coupling in this floppy system and to evaluate two different J-shifting schemes. Though not effective for multiply vibrationally excited bound states, vibrational-state-dependent J-shifting obtains modestly accurate predictions for the lowest-lying energies [J. Phys. Chem. A 2006, 110, 3246]. However, much better performance is obtained-especially for large J values, and despite substantial Coriolis coupling-using a second, rotational-state-dependent J-shifting scheme [J. Chem. Phys. 1998, 108, 5216], for which the rotational constants themselves depend on J and K. The latter formalism also yields important dynamical insight into the structure of the strongly Coriolis-coupled eigenstate wave functions. The calculations were performed using ScalIT, a suite of codes enabling quantum dynamics calculations on massively parallel computing architectures.

Using <i>ScalIT</i> for Performing Accurate Rovibrational Spectroscopy Calculations for Triatomic Molecules: A Practical Guide

“…In a recent publication [30], the bound states of the hydroperoxl radical, HO 2 , were calculated up to the highest possible total angular momentum value, 130 J = , corroborating and improving upon the studies previously performed by other researchers (up to 50 J = ). Being a notoriously "floppy molecule", HO 2 has remained a relatively difficult molecule to study, due to large coupling between rotational and vibrational degrees of freedom, and a deep potential well on the ground PES.…”

Theoretical methods for the rotation–vibration spectra of triatomic molecules: distributed Gaussian functions compared with hyperspherical coordinates

“…However the approximation can fail for certain molecular systems. HO 2 , for example, is one of those cases in which the comparison [37][38][39] between some of these decoupling schemes and calculations performed with methods such as the ScallT program developed by Poirier and collaborators [40,41] or the Chebyshev filter diagonalization method employed by Zhang and Smith [42][43][44][45] reveals the necessity of a proper account for the Coriolis coupling terms.…”

Rovibrational bound states of SO2 isotopologues. II: Total angular momentum J= 11–20

“…The latter depends on the two rotational constants, A and B, and on the rotational state labels, (J, K). For a highly prolate symmetric rotor such as SO 2 , A B [43,44,45,46,47,48].…”