Single-Sheeted Double Many-Body Expansion Potential Energy Surface for Ground-State ClO₂

Abstract

A global single-sheeted double many-body expansion potential energy surface is reported for the ground electronic state of ClO2. The potential energy surface is obtained by fitting 3200 energy points that map all atom-diatom dissociation channels as well as all relevant stationary points, including the well-known OClO and ClOO structures. The ab initio calculations are obtained at the multireference configuration interaction level of theory, employing the cc-pVXZ (X = D, T) Dunning basis sets, and then extrapolated to the complete basis set limit with the generalized uniform singlet- and triplet-pair protocol. The topographical features of the novel global potential energy surface are examined in detail.

Accurate Potential Energy Surface for Quartet State HN2 and Interplay of N(4S) + NH(X̃3Σ–) versus H + N2(A3Σu+) Reactions

“…To account for the electronic basis-set incompleteness, we have extrapolated the energies to the complete basis set (CBS) limit using the uniform singlet- and triplet-pair extrapolation (USTE) method, which has been per se or jointly with its generalized version successfully employed in other recent studies of global PESs for a variety of molecular systems. − The extrapolated correlation energy ( E ∞ cor ) is then obtained by fitting to the pair of MRCI+Q/AV T Z and MRCI+Q/AV Q Z calculations for every geometry, thence to the E 3 cor and E 4 cor energies. In the above equation, A 5 (0), c , α, and n are universal parameters, ,− namely, α = −0.375, A 5 (0) = 0.0037685459, c = −1.17847713, and n = 1.25 for the MRCI method.…”

Dynamics of the O + ClO Reaction: Reactive and Vibrational Relaxation Processes

“…In turn, the structure located at (β* = 0.0, γ* = 0.784) corresponds to the C 2 v minimum (MC 2 v ), which lies 34 kJ mol –1 above the C s geometry. In fact, the relative position of the C 2 v and C s minima has been the subject of some debate, , with the most recent predictions following the trend displayed by the current DMBE potential energy surface.…”

The Structure and Cl–O Dissociation Energy of the ClOO Radical: Finally, the Right Answers for the Right Reason

“…The weak bonding and open-shell electronic structure of ClOO result in its notoriously difficult theoretical characterization. A multitude of single reference, − multireference, ,,,− and density functional theory ,− (DFT) studies have been performed on ClOO. For all of these studies, the reported geometries fail to agree with the experimental structure given by Endo and co-workers .…”

“…Finally, Varandas and co-workers computed a global ground state potential energy surface (PES) of the ClO 2 system using a double many-body expansion technique based on energies at MRCISD+Q extrapolated to the CBS limit. A detailed topological analysis of the surface was presented, including 10 stationary points, with ClOO as the global minimum.…”

“…31 Martin's reported geometry (r e (ClO) = 2.032 Å, r e (OO) = 1.208 Å, and θ e (ClOO) = 115.4°using CCSD(T)/cc-pV(Q +d)Z) is notably different from that determined by Endo. 23 Finally, Varandas and co-workers 29 computed a global ground state potential energy surface (PES) of the ClO 2 system using a double many-body expansion technique based on energies at MRCISD+Q extrapolated to the CBS limit. A detailed topological analysis of the surface was presented, including 10 stationary points, with ClOO as the global minimum.…”