Abstract
We present Born-Oppenheimer (BO) and Renner-Teller (RT) time dependent quantum dynamics studies of the reactions O((3)P) + H2(+)(X(2)Σg(+)) → OH(+)(X(3)Σ(-)) + H((2)S) and OH(X(2)Π) + H(+). We consider the OH2(+) X[combining tilde](2)A'' and Ã(2)A' electronic states that correlate with a linear (2)Π species. The electronic angular momenta operators L[combining circumflex] and L[combining circumflex](2) are considered in nonadiabatic coupled-channel calculations, where the associated RT effects are due to diagonal V(RT) potentials that add up to the PESs and to off-diagonal C(RT) couplings between the potential energy surfaces (PESs). Initial-state-resolved reaction probabilities PI, integral cross sections σI, and rate constants kI are obtained using recent ab initio PESs and couplings and the real wavepacket formalism. Because the PESs are strongly attractive, PI have no threshold energy and are large, σI decrease with collision energy, and kI depend little on the temperature. The X[combining tilde](2)A'' PES is up to three times more reactive than the Ã(2)A' PES and H2(+) rotational effects (j0 = 0, 1) are negligible. The diagonal V(RT) potentials are strongly repulsive at the collinearity and nearly halve all low-energy observables with respect to the BO ones. The off-diagonal C(RT) couplings are important at low partial waves, where they mix the X[combining tilde](2)A'' and Ã(2)A' states up to ∼20%. However, V(RT) effects predominate over the C(RT) ones that change at most by ∼19% the BO values of σI and kI. The reaction O((3)P) + H2(+)(X(2)Σg(+)) → OH(+)(X(3)Σ(-)) + H((2)S) is probably one of the most reactive atom + diatom collisions because its RT rate constant at room temperature is equal to 2.26 × 10(-10) cm(3) s(-1). Within the BO approximation, the present results agree rather well with recent quasiclassical and centrifugal-sudden data using the same PESs.
Highlights
The atom–molecular ion reactionsO(3P) + H2+(X2Sg+) - OH+(X3SÀ) + H(2S), DD0 = À2.44 eV proton transfer, H channel, (1.1)- OH(X2P) + H+, DD0 = À1.74 eV hydrogen transfer, H+ channel, (1.2)are important in the astrochemical context, it should be noted that the importance of reactions (1.1) and (1.2) in astrochemistry is still unclear.[4]
(MEP) connecting reactants and OH+ + H products; while the first excited potential energy surfaces (PESs) (A2A0) includes the first excited electronic state of the water cation, H2O+(A2A1), in the MEP involving reactants and OH + H+ products. These two electronic states of H2O+ correspond to the degenerate components of a 2Pu species, when the molecule is in a linear arrangement, and the associated nonadiabatic (NA) Renner–Teller (RT) effects can remarkably influence the dynamics of these collisions, as they occur for the X2B1 À A2A1 optical spectrum[12] of H2+O
We report initial-state-resolved integral cross sections and rate constants in Section IV, discussing the influence of the RT effects on both product channels and comparing our BO results with previous QCT8,9 and real wavepacket (RWP) CS9 calculations and we, present in Section V the main conclusions
Summary
(MEP) connecting reactants and OH+ + H products; while the first excited PES (A2A0) includes the first excited electronic state of the water cation, H2O+(A2A1), in the MEP involving reactants and OH + H+ products These two electronic states of H2O+ correspond to the degenerate components of a 2Pu species, when the molecule is in a linear arrangement, and the associated nonadiabatic (NA) Renner–Teller (RT) effects can remarkably influence the dynamics of these collisions, as they occur for the X2B1 À A2A1 optical spectrum[12] of H2+O. We report initial-state-resolved integral cross sections and rate constants, discussing the influence of the RT effects on both product channels and comparing our BO results with previous QCT8,9 and RWP CS9 calculations and we, present in Section V the main conclusions We report initial-state-resolved integral cross sections and rate constants in Section IV, discussing the influence of the RT effects on both product channels and comparing our BO results with previous QCT8,9 and RWP CS9 calculations and we, present in Section V the main conclusions
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