Large-amplitude quantum mechanics in polyatomic hydrides II A particle-on-a-sphere model for XHn (n=4,5)

Deskevich, Michael P.; Mccoy, Anne B.; Hutson, Jeremy M.; Nesbitt, David J.

Abstract

This paper describes the application of a relatively simple, but computationally tractable, “particle-on-a-sphere” (POS) model for quantum-mechanical calculation of large-amplitude, H atom dynamics in polyatomic hydrides (XHn), based on radially relaxed, two-dimensional angular motion of H atoms on the surface of a sphere. This work focuses on systems with many degrees of freedom, i.e., XH4 (eight dimensional) and XH5 (ten dimensional), with corresponding molecular analogs of CH4 and CH5+ and is applicable to rovibrationally excited states with J ≥ 0. A pairwise-additive potential fit for CH5+, which yields remarkable agreement with geometries, energies, and barrier heights on the full-dimensional surface of Brown et al. [J. Chem. Phys. 121, 4105 (2004)] is presented. Comparisons with experimental data and diffusion quantum Monte Carlo (DMC) methods test convergence for the POS model and provide insight into multidimensional quantum rovibrational dynamics. In particular, POS energy-level patterns for a series of scaled CH5+ potentials indicate an absence of strong tunneling behavior, consistent with the highly delocalized wave functions, large zero-point energies, and small interconversion barriers noted in previous DMC studies of Brown et al.

Citation

Deskevich, M. P., Mccoy, A. B., Hutson, J. M., & Nesbitt, D. J. (2008). Large-amplitude quantum mechanics in polyatomic hydrides II A particle-on-a-sphere model for XHn (n=4,5). The Journal of Chemical Physics, 128(9), Article 094306. https://doi.org/10.1063/1.2828478

• Journal Article Type: Article
• Publication Date: Jan 1, 2008
• Deposit Date: Jun 19, 2013
• Publicly Available Date: Apr 17, 2015
• Journal: Journal of Chemical Physics
• Print ISSN: 0021-9606
• Electronic ISSN: 1089-7690
• Publisher: American Institute of Physics
• Peer Reviewed: Peer Reviewed
• Volume: 128
• Issue: 9
• Article Number: 094306
• DOI: https://doi.org/10.1063/1.2828478