A two-step quadrature-based variational calculation of ro-vibrational levels and wavefunctions of CO2 using a bisector-x molecule-fixed frame
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Authors
Wang, Xiao-Gang
Carrington, Tucker Jr
Date
2024-04-25
Type
journal article
Language
en
Keyword
Alternative Title
Abstract
In this paper, we propose a new two-step strategy for computing ro-vibrational energy levels and wavefunctions of a triatomic molecule and apply it to CO2. A two-step method [J. Tennyson and B. T. Sutcliffe, Mol. Phys., 1986, 58, 1067] uses a basis whose functions are products of K-dependent “vibrational” functions and symmetric top functions. K is the quantum number for the molecule-fixed z component of the angular momentum. For a linear molecule, a two-step method is efficient because the Hamiltonian used to compute the basis functions includes the largest coupling term. The most important distinguishing feature of the two-step method we propose is that it uses an associated Legendre basis and quadrature rather than a K-dependent discrete variable representation. This reduces the cost of the calculation and simplifies the method. We have computed ro-vibrational energy levels with J up to 100 for CO2, on an accurate available potential energy surface which is known as the AMES-2 PES and present a subset of those levels. We have converged most levels up to 20 000 cm−1 to 0.0001 cm−1.
Description
This is the accepted version version of Wang, X. G.; Carrington, T. A Two-Step Quadrature-Based Variational Calculation of Ro-Vibrational Levels and Wavefunctions of CO2 Using a Bisector-x Molecule-Fixed Frame. Physical chemistry chemical physics : PCCP 2024, 26 (21), 15181–15191. https://doi.org/10.1039/d4cp00655k. The published version of record is available at the publisher's website at https://doi.org/10.1039/d4cp00655k.
Citation
Wang, X. G.; Carrington, T. A Two-Step Quadrature-Based Variational Calculation of Ro-Vibrational Levels and Wavefunctions of CO2 Using a Bisector-x Molecule-Fixed Frame. Physical chemistry chemical physics : PCCP 2024, 26 (21), 15181–15191. https://doi.org/10.1039/d4cp00655k
Publisher
Royal Society of Chemistry