Potential energy surfaces of quintet and singlet O4

Yuliya Paukku; Ke R Yang; Zoltan Varga; Guoliang Song; Jason D Bender; Donald G Truhlar

doi:10.1063/1.4993624

Potential energy surfaces of quintet and singlet O₄

J Chem Phys. 2017 Jul 21;147(3):034301. doi: 10.1063/1.4993624.

Authors

Yuliya Paukku¹, Ke R Yang¹, Zoltan Varga¹, Guoliang Song¹, Jason D Bender², Donald G Truhlar¹

Affiliations

¹ Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA.
² Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, Minnesota 55455-0153, USA.

PMID: 28734300
DOI: 10.1063/1.4993624

Abstract

We present global ground-state potential energy surfaces for the quintet and singlet spin states of the O₄ system that are suitable for treating high-energy vibrational-rotational energy transfer and collision-induced dissociation in electronically adiabatic, spin-conserving O₂-O₂ collisions. The surfaces are based on MS-CASPT2/maug-cc-pVTZ electronic structure calculations with scaled external correlation. The active space has 16 electrons in 12 orbitals. The calculations cover nine kinds of geometrical arrangements corresponding to dissociative diatom-diatom collisions of O₂, geometries corresponding to O₃-O, geometries identified by running trajectories, and geometries along linear synchronous transit paths. The global ground-state potential energy surfaces were obtained by a many-body approach with an accurate O-O pairwise interaction and a fit of the many-body interaction to 12 684 electronic structure data points for the singlet and 10 543 electronic structure data points for the quintet. The many-body fit is based on permutationally invariant polynomials in terms of bond-order functions of the six interatomic distances; the bond-order functions are mixed exponential-Gaussian functions.