Seams of Conical Intersections Relevant to the Quenching
of OH(A<sup>2</sup>Σ<sup>+</sup>) by Collisions with H<sub>2</sub>
Joseph Dillon
David R. Yarkony
10.1021/jp401205c.s001
https://acs.figshare.com/articles/Seams_of_Conical_Intersections_Relevant_to_the_Quenching_of_OH_A_sup_2_sup_sup_sup_by_Collisions_with_H_sub_2_sub_/2386396
Using multireference configuration
interaction wave functions composed
of 17–52 million configuration state functions, 18 points on
the 1<sup>2</sup>A–2<sup>2</sup>A seam and 162 points on the
2<sup>2</sup>A–3<sup>2</sup>A seam of conical intersections
relevant to the collisional quenching of OH(A<sup>2</sup>Σ<sup>+</sup>) by H<sub>2</sub> are determined and analyzed. In the vicinity
of planar nuclear configurations, the former seam corresponds to a
1<sup>2</sup>A′–1<sup>2</sup>A″ seam of intersection
and the latter corresponds to a 1<sup>2</sup>A′–2<sup>2</sup>A′ seam. For the previously studied 2<sup>2</sup>A–3<sup>2</sup>A seam, two regions not previously examined are reported:
(i) an out-of-plane region that connects smoothly to the 1<sup>2</sup>A′–2<sup>2</sup>A′ seam for planar structures
and (ii) a Rydberg region that includes <i>D</i><sub>3<i>h</i></sub>/<i>C</i><sub>3<i>v</i></sub> structures where the 2<sup>2</sup>A–3<sup>2</sup>A seam is
a 2<sup>2</sup>A′–3<sup>2</sup>A′ seam for <i>D</i><sub>3<i>h</i></sub> structures. Some of the
nonplanar points on the 2<sup>2</sup>A–3<sup>2</sup>A seam
of conical intersection are found to have OH and H<sub>2</sub> distances
comparable to those of the reactant molecules and energies below that
of the reactant asymptote. These nonplanar entrance channel conical
intersections suggest new mechanisms for the quenching reaction. The
Rydberg region introduces new connectivity and symmetry issues. For
the 1<sup>2</sup>A–2<sup>2</sup>A [1<sup>2</sup>A′–1<sup>2</sup>A″] seam, which unlike the 2<sup>2</sup>A–3<sup>2</sup>A [1<sup>2</sup>A′–2<sup>2</sup>A′] seam
cannot continuously deform from planar to nonplanar structures except
through confluences, no evidence of nonplanar points on the conical
intersection seam was found. The continuous conical parameters, <i>g</i><sup><i>I,J</i></sup>, <i>h</i><sup><i>I,J</i></sup>, <i>s</i><sub><i>x</i></sub><sup><i>I,J</i></sup>, and <i>s</i><sub><i>y</i></sub><sup><i>I,J</i></sup> and the associated
vectors <b>g</b><sup><i>I,J</i></sup>, <b>h</b><sup><i>I,J</i></sup>, and <b>s</b><sup><i>I,J</i></sup>, are determined and discussed. The conical parameters are
made continuous by a prescribed rotation of the degenerate wave functions.
The continuity of these conical parameters makes it possible to construct
a quasi-diabatic representation of the coupled adiabatic potential
energy surfaces.
2013-08-15 00:00:00
configuration state functions
nonplanar entrance channel conical intersections
nonplanar points
OH
conical intersection seam
H 2Using multireference configuration interaction wave functions
D 3h structures
conical parameters
Rydberg region
H 2 distances