Accurate global potential energy surface for the H + OH+ collision

Dynamics of the O + H2+ → OH+ + H, OH + H+ proton and hydrogen atom transfer reactions on the two lowest potential energy surfaces

The dynamics of the title reaction was studied using mainly the quasiclassical trajectory (QCT) method on the ground 1²A'' (OH⁺ channel) and first excited 1²A' (OH channel) potential energy surfaces (PESs) employing ab initio analytical representations of the PESs developed by us. Both PESs correspond to exoergic reactions, are barrierless and present a deep minimum along the minimum energy path (MEP). Some extra calculations (cross sections) were also performed with the time dependent quantum real wave packet method at the centrifugal sudden level (RWP-CS method). A broad set of properties as a function of collision energy (E_col ≤ 0.5 eV) was considered using the QCT method: cross sections, average fractions of energy, product rovibrational distributions, two- and three-vector properties, and the microscopic mechanisms analyzing their influence on the dynamics. The proton transfer channel dominates the reactivity of the system and significant differences between the two reaction channels are found for the vibrational distributions and microscopic mechanisms. The results were interpreted according to the properties of the ground and excited PESs. Moreover, the QCT and RWP-CS cross sections are in rather good agreement for both reaction channels. We hope that this study will encourage the experimentalists to investigate the dynamics of this interesting but scarcely studied system, whose two lowest PESs include the ground and first excited electronic states of the H₂O⁺ cation.

Rotational Excitation of the OH(+) Radical by Collision with H at Low Temperature

A ro-vibrationally inelastic close coupling study of the rotational excitation of OH(+)(X(3)Σ(-)) by collisions with H((2)S) is presented. The two lowest potential energy surfaces of doublet and quadruplet spin multiplicity are involved. The former is the one we developed recently, and the latter is a modified version of the quadruplet surface of Martinez et al. to include the long-range charge-induced-dipole potential. The details of the modification of this surface are presented as well as the comparison of the rotational excitation resulting from collisions with hydrogen on these two surfaces. The effect of the coupling between vibration and rotation on the rotational excitation rate is also discussed, as the potential well depth of the doublet surface is quite large and allows the coupling between many vibrational channels of OH(+). As the hydrogen exchange reaction can occur for both potential energy surfaces, we discuss the reliability of the approximation made by the calculation of the cross sections with a quantum dynamics limited to the inelastic process. The relative importance of the collisions on the doublet or quadruplet surface within a given rotational transition is also discussed.

Born–Oppenheimer and Renner–Teller coupled-channel quantum reaction dynamics of O(3P) + H2+(X2Σg+) collisions

We present Born–Oppenheimer (BO) and Renner–Teller (RT) time dependent quantum dynamics studies of the reactions O(³P) + H₂⁺(X²Σ_g⁺) → OH⁺(X³Σ⁻) + H(²S) and OH(X²Π) + H⁺.