Direct versus resonances mediated F+OH collisions on a new A″3 potential energy surface

Abstract

A theoretical study of the F(2P) + OH(2Pi) --> HF(1Sigma+) + O(3P) reactive collisions is carried out on a new global potential energy surface (PES) of the ground 3A" adiabatic electronic state. The ab initio calculations are based on multireference configuration interaction calculations, using the aug-cc-pVTZ extended basis sets of Dunning et al. A functional representation of the PES shows no nominal barrier to reaction, contrary to previous results by others. Wave packet and quasiclassical trajectory calculations have been performed for this PES to study the F + OH(v = 0,j) reactive collision. The comparison was performed at fixed and constant values of the total angular momentum from 0 to 110 and relative translational energy up to 0.8 eV. The reaction presents a dynamical barrier, essentially due to the zero-point energy for the bending vibration near the saddle point. This determines two different reaction mechanisms. At energies higher than approximately 0.125 eV the reaction is direct, while below that value it is indirect and mediated by heavy-light-heavy resonances. Such resonances, also found in the simulations of the photodetachment spectrum of the triatomic anion, manifest themselves in the quasiclassical simulations, too, where they are associated to periodic orbits.

Quantum and quasi-classical calculations for the S+ + H2(v,j) → SH+(v′,j′) + H reactive collisions

“…If the roaming regions are dense enough in the phase space, resonances may appear classicaly as reported in ref. [31], where classical resonances mimicking the quantum ones have been observed for J=0 at collision energy near the threshold. …”

Full dimensional potential energy surface for the ground state of $\mathbf {H_4^+}$H4+ system based on triatomic-in-molecules formalism

“…48-51, and applied to a wide variety of triatomic systems. [52][53][54] In this case, to account for the permutation invariance, the four-body terms are expressed as linear combinations of symmetry adapted functions as 42,50,51 …”

Time‐dependent quantum study of H(2S) + FO(2Π) → OH(2Π) + F(2P) reaction on the 13A′ and 13A″ states

“…Gómez-Carrasco et al 5 performed high-level MRCI electronic structure calculations for 8069 energy points to calibrate the fitted potential energy surface (PES) of the ground adiabatic 1 3 A triplet electronic state. Quasi-classical trajectory (QCT) and wave packet studies [5][6][7] of F( 2 P) + OH( 2 ) → O( 3 P) + HF( 1 + ) reaction have been performed on this high-quality triplet PES and a subsequent improved version. 6 Quantum state-to-state calculation 8 of the same reaction were repeated by using a newly proposed coordinate transformation method in conjunction with the Coriolis-coupled (CC) method.…”

“…Quasi-classical trajectory (QCT) and wave packet studies [5][6][7] of F( 2 P) + OH( 2 ) → O( 3 P) + HF( 1 + ) reaction have been performed on this high-quality triplet PES and a subsequent improved version. 6 Quantum state-to-state calculation 8 of the same reaction were repeated by using a newly proposed coordinate transformation method in conjunction with the Coriolis-coupled (CC) method. Recently, the reverse reaction, H( 2 S) + FO( 2 ) → OH( 2 ) + F( 2 P) has been subject to many studies.…”