Non-adiabatic Quantum Dynamics of the Dissociative Charge Transfer He++H2 → He+H+H+

Abstract

We present the non-adiabatic, conical-intersection quantum dynamics of the title collision where reactants and products are in the ground electronic states. Initial-state-resolved reaction probabilities, total integral cross sections, and rate constants of two H 2 vibrational states, v 0 = 0 and 1, in the ground rotational state ( j 0 = 0) are obtained at collision energies E coll ≤ 3 eV. We employ the lowest two excited diabatic electronic states of and their electronic coupling, a coupled-channel time-dependent real wavepacket method, and a flux analysis. Both probabilities and cross sections present a few groups of resonances at low E coll , whose amplitudes decrease with the energy, due to an ion-induced dipole interaction in the entrance channel. At higher E coll , reaction probabilities and cross sections increase monotonically up to 3 eV, remaining however quite small. When H 2 is in the v 0 = 1 state, the reactivity increases by ~2 orders of magnitude at the lowest energies and by ~1 order at the highest ones. Initial-state resolved rate constants at room temperature are equal to 1.74 × 10 −14 and to 1.98 × 10 −12 cm 3 s −1 at v 0 = 0 and 1, respectively. Test calculations for H 2 at j 0 = 1 show that the probabilities can be enhanced by a factor of ~1/3, that is ortho- H 2 seems ~4 times more reactive than para- H 2 .

Study of non‐adiabatic interactions among low‐lying electronic states of HeH2+ with its implication in its dissociation into various species

“…Farther, the plot of variation of Mulliken partial charges on He and H 2 , as presented in the Figure 13A,B, provide us a clear demonstration of a CI‐induced charge transfer at the region close to (2,3) CI point. Such a CI‐induced charge transfer was reported by Fazio et al 26 for collision of He + and H 2 in ground electronic state.…”

“…These ions, atoms and photons are the reactants leading to simple diatoms as H 2 , H 2 + 3 and HeH +. 4,5 The chemical network involving all these neutral atoms, diatoms and corresponding ions have been a focus of experimental 6‐19 and theoretical 19‐31 studies for few decades. The pioneering work by McLaughlin and Thompson 21 was the first study of excited state of the HeH 2 + , which served as a source article for later works 23,27c to get a fit leading to analytical functional form of ground as well as excited‐state potential energy surfaces for HeH 2 + .…”

“…We focus here on the fully quantum mechanical studies accounting the non‐adiabatic interactions. McLaughlin and Thompson, 21 using symmetry argument, gave an analysis of the crossing between low‐lying electronic states and recently Fazio etal 26 have used this fits to obtain the non‐adiabatic couplings. Fazio etal 26 have presented a time‐dependent quantum mechanical study of dissociative charge transfer (DCT), He + + H 2 ( ν = 0, 1) → He + H + H + with all species in the ground electronic state.…”

“…McLaughlin and Thompson, 21 using symmetry argument, gave an analysis of the crossing between low‐lying electronic states and recently Fazio etal 26 have used this fits to obtain the non‐adiabatic couplings. Fazio etal 26 have presented a time‐dependent quantum mechanical study of dissociative charge transfer (DCT), He + + H 2 ( ν = 0, 1) → He + H + H + with all species in the ground electronic state. Gupta et al 31 have investigated the non‐adiabatic effect among three low‐lying electronic states of HeH 2 + in linear and C 2V geometry; they reported a single JT‐CI between the first and second excited electronic states for nearly linear geometry and another JT‐CI between the ground and first excited states of HeH 2 + in C 2V geometry.…”

Molecular-bond breaking induced by interatomic decay processes

“…The surfaces of the decaying and triplet final electronic states have been computed using a fully-correlated method (Full Configuration Interaction method) with an aug-cc-pVDZ basis set [36,37], as implemented in the GAMESS-US ab-initio program [38]. Similar to the lowest states of singly-ionized He-H 2 [39], non-adiabatic couplings between the two singlet final electronic states take place. The corresponding potential energy surfaces and couplings have been determined using the multistate density functional theory (MSDFT) [40][41][42].…”