HN₂(²A‘) Electronic Manifold. I. A Global ab Initio Study of First Two States

Abstract

A detailed ab initio multireference configuration interaction calculation with a standard aug-cc-pVTZ basis set is reported for the 1(2)A' and 2(2)A' states of the title system. The aim is to establish the dissociation scheme of all channels, while revealing the 2(2)A'/3(2)A' seam of conical intersections consistent with the crossings in the diatomic fragments. An ab initio mapping of linear NNH and T-shaped and linear NHN loci of conical intersections is also reported, jointly with a discussion of the topological features associated to a newly reported 2(2)A'/3(2)A' crossing seam.

HN2(2A‘) Electronic Manifold. II. Ab Initio Based Double-Sheeted DMBE Potential Energy Surface via a Global Diabatization Angle

“…All crossing seams were described to their full extent, with the ground state PES showing good agreement with the previously reported single-sheeted DMBE PES 2 except for regions close to the crossing seams where the present PES should obviously be preferred. For the excited state, a transition state connecting the T-shaped and NNH linear crossing seams as well as a linear barrier due to the avoiding 2 2 A′/3 2 A′ crossing seams 5 are reported. For this state, two local minima, one for C 2V and the other for D ∞h arrangements have been also reported.…”

“…5 Note that we have chosen y T -(r 1 ) such as to assume very small values for r 1 j 1.5a 0 , where no data is available. For y nnh , we have considered where ∆r nnh,i ) r 1 -r nnh,i , which has been designed to reproduce simultaneously the shape of NH as a function of r 1 in the interval 1.5 j r 1 /a 0 j 3.6 as well as the rapid decay for both small (r 1 j 1.5a 0 ) and large (r 1 J 3.6a 0 ) values of this coordinate.…”

“…1,3 This conjecture is supported by the disagreement observed in trajectory calculations 3 for the N + NH f N 2 + H reaction, despite the fact that the reported single-sheeted potential energy surface 2,3 (PES) reveals a high-degree of accuracy. The unavailability of a multisheeted PES 5 then forbids any evaluation of such nonadiabatic effects. Our main goal in this paper is therefore to model a global double-sheeted PES, a natural step to follow our recent ab initio study of the title system in ref 5.…”

“…The unavailability of a multisheeted PES 5 then forbids any evaluation of such nonadiabatic effects. Our main goal in this paper is therefore to model a global double-sheeted PES, a natural step to follow our recent ab initio study of the title system in ref 5.…”

Toward the modeling of the NO2(2A″) manifold

“…Following other work [59,60], the presence of several conical intersections led us to include up to six 2 A states in the average state calculations. The first four 2 A triatomic states as well as the corresponding states in C 2v symmetry are shown.…”