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Six new potential energy surfaces of four singlet states and two triplet states for the title oxygen molecule reaction along with the spin-orbit coupling among them have been constructed from the complete active space second-order perturbation theory with a 6-311+G(d) basis. Accurate integral cross sections are calculated with a full six-dimensional nonadiabatic time-dependent quantum wave packet method. The thermal rate constant based on the integral cross sections agrees well with the result of the experimental measurements, and the intersystem crossing effects are also discussed in this electronic energy-transfer process.

Five-dimensional nonadiabatic quantum dynamics studies have been carried out on two new potential energy surfaces of S(2)((1)A(')) and T(7)((3)A(")) states for the title oxygen molecules collision with coplanar configurations, along with the spin-orbit coupling between them. The ab initio calculations are based on complete active state second-order perturbation theory with the 6-31+G(d) basis set. The calculated spin-orbit induced transition probability as a function of collision energy is found to be very small for this energy pooling reaction. The rate constant obtained from a uniform J-shifting approach is compared with the existing theoretical and experimental data, and the spin-orbit effect is also discussed in this electronic energy-transfer process.

We present for the first time an exact quantum study of spin-orbit-induced intersystem crossing effects in the title reaction. The time-dependent wave-packet method, combined with an extended split operator scheme, is used to calculate the fine-structure resolved cross section. The calculation involves four electronic potential-energy surfaces of the 1A' state [J. Dobbyn and P. J. Knowles, Faraday Discuss. 110, 247 (1998)], the 3A' and the two degenerate 3A" states [S. Rogers, D. Wang, A. Kuppermann, and S. Wald, J. Phys. Chem. A 104, 2308 (2000)], and the spin-orbit couplings between them [B. Maiti, and G. C. Schatz, J. Chem. Phys. 119, 12360 (2003)]. Our quantum dynamics calculations clearly demonstrate that the spin-orbit coupling between the triplet states of different symmetries has the greatest contribution to the intersystem crossing, whereas the singlet-triplet coupling is not an important effect. A branch ratio of the spin state Pi32 to Pi12 of the product OH was calculated to be approximately 2.75, with collision energy higher than 0.6 eV, when the wave packet was initially on the triplet surfaces. The quantum calculation agrees quantitatively with the previous quasiclassical trajectory surface hopping study.

The seams of conical intersection exist between the ground (1 (2)A') and the first-excited (2 (2)A') electronic potential energy surfaces (PESs) of OH(A (2)Sigma(+), X (2)Pi) + H-2 system. This intersection induces the nonadiabatic quenching of OH(A (2)Sigma(+)) by D-2. We present nonadiabatic quantum dynamics study for OH(A (2)Sigma(+)) + D-2 on new five-dimensional coplanar PESs. The ab initio calculations of PESs are based on multireference configuration interaction (MRCI)/aug-cc-pVQZ level. A back-propagation neural network is utilized to fit the PESs and nonadiabatic coupling. High degrees of rotational excitation of quenched OH(X (2)Pi) products are found in nonreactive quenching channel, and the quenched D-2 products are vibrationally excited up to quantum number v(2)' = 8. The theoretical results of nonadiabatic time-dependent wave-packet calculation are in good agreement with the existing experimental data. (C) 2010 American Institute of Physics. [doi:10.1063/1.3502468]

By applying the semirigid vibrating rotor target (SVRT) model to the title reaction, five-dimensional wave packet quantum dynamics calculations have been carried out on the new potential energy surface PES-2006 [Espinosa-Garcia et al., J. Phys. Chem. A 111, 2761 (2007)]. The reaction probabilities have been calculated for total angular momentum J up to 105 to obtain the converged integral cross sections over a collision energy range of 0.01-0.345 eV. With the polyatomic system initially in its ground rovibrational state |000, no obvious resonance signature has been observed in the integral cross sections although it appears in the reaction probabilities for Jor = 40. However, when the umbrella mode of the collision system is initially excited to nu(alpha0) = 1 level, |001state, there is resonance signature in both the reaction probabilities with Jor = 55 and the integral cross sections. In addition, rate constants are calculated by Boltzmann averaging of the |000integral cross sections over collision energy and compared with both the previous kinetic calculations and the experimental measurements. A reasonable agreement has been achieved over the investigated temperature range of 180-400 K.

Six new potential energy surfaces of four singlet states and two triplet states for the title oxygen molecule reaction along with the spin-orbit coupling among them have been constructed from the complete active space second-order perturbation theory with a 6-311+G(d) basis. Accurate integral cross sections are calculated with a full six-dimensional nonadiabatic time-dependent quantum wave packet method. The thermal rate constant based on the integral cross sections agrees well with the result of the experimental measurements, and the intersystem crossing effects are also discussed in this electronic energy-transfer process.

Time-dependent wave packet quantum scattering (TWQS) calculations are presented for HD(+) (v = 0 - 3;j(0)=1) + He collisions in the center-of-mass collision energy (E(T)) range of 0.0-2.0 eV. The present TWQS approach accounts for Coriolis coupling and uses the ab initio potential energy surface of Palmieri et al. [Mol. Phys. 98, 1839 (2000)]. For a fixed total angular momentum J, the energy dependence of reaction probabilities exhibits quantum resonance structure. The resonances are more pronounced for low J values and for the HeH(+) + D channel than for the HeD(+) + H channel and are particularly prominent near threshold. The quantum effects are no longer discernable in the integral cross sections, which compare closely to quasiclassical trajectory calculations conducted on the same potential energy surface. The integral cross sections also compare well to recent state-selected experimental values over the same reactant and translational energy range. Classical impulsive dynamics and steric arguments can account for the significant isotope effect in favor of the deuteron transfer channel observed for HD(+)(v

Five-dimensional nonadiabatic quantum dynamics studies have been carried out on two new potential energy surfaces of S2(A′1) and T7(A″3) states for the title oxygen molecules collision with coplanar configurations, along with the spin-orbit coupling between them. The ab initio calculations are based on complete active state second-order perturbation theory with the 6‐31+G(d) basis set. The calculated spin-orbit induced transition probability as a function of collision energy is found to be very small for this energy pooling reaction. The rate constant obtained from a uniform J-shifting approach is compared with the existing theoretical and experimental data, and the spin-orbit effect is also discussed in this electronic energy-transfer process.

The state-to-state dynamics of the H+D2 reaction is studied by the reactant-product decoupling method using the double many-body expansion potential energy surface. Two approaches are compared: one uses only the lowest adiabatic sheet while the other employs both coupled diabatic sheets. Rotational distributions for the reaction H+D2 (upsilon = 0, j = 0)--HD(upsilon' = 3, j')+D are obtained at eight different collision energies between 1.49 and 1.85 eV; no significant difference are found between the two approaches. Initial state-selected total reaction probabilities and integral cross sections are also given for energies ranging from 0.25 up to 2.0 eV with extremely small differences being observed between the two sets of results, thus showing that the nonadiabatic effects in the title reaction are negligible at least for small energies below 2.0 eV.

We present for the first time an exact quantum study of spin-orbit-induced intersystem crossing effects in the title reaction. The time-dependent wave-packet method, combined with an extended split operator scheme, is used to calculate the fine-structure resolved cross section. The calculation involves four electronic potential-energy surfaces of the (1)A' state [J. Dobbyn and P. J. Knowles, Faraday Discuss. 110, 247 (1998)], the (3)A' and the two degenerate (3)A" states [S. Rogers, D. Wang, A. Kuppermann, and S. Wald, J. Phys. Chem. A 104, 2308 (2000)], and the spin-orbit couplings between them [B. Maiti, and G. C. Schatz, J. Chem. Phys. 119, 12360 (2003)]. Our quantum dynamics calculations clearly demonstrate that the spin-orbit coupling between the triplet states of different symmetries has the greatest contribution to the intersystem crossing, whereas the singlet-triplet coupling is not an important effect. A branch ratio of the spin state Pi(3/2) to Pi(1/2) of the product OH was calculated to be similar to 2.75, with collision energy higher than 0.6 eV, when the wave packet was initially on the triplet surfaces. The quantum calculation agrees quantitatively with the previous quasiclassical trajectory surface hopping study. (c) 2005 American Institute of Physics.