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The isotopic branching in the reaction He + HD(super +)(v = 0, 1, 2, 3; j=0) --> HeH(D)(super +) + D(H), over a range of translational energy (E(sub trans)) is plotted on two different ab initio potential energy surface. The isotopic branching ratio for the reaction decreases in going from v=0 to v=1 and then becomes nearly v-independent in going from v = 1 to v = 3 in both the surface.

He2H(super +1) and He2D(super +1) are examined to find their bound and quasibound states in three dimensions. This is done by using a time-dependent quantum-mechanical wave packet approach for total angular momentum.

A detailed three-dimensional time-dependent quantum dynamical study of the He+H2+(v=0–3,j=0)→HeH++H reaction is reported for different vibrational v states of H2+ in its ground rotational (j=0) state over a range of translational Etrans energies on an accurate ab initio potential energy surface published by Palmieri et al. Plots of reaction probability as a function of total energy E reveal a large number of oscillations indicating the presence of a number of reactive scattering resonances. When averaged over total angular momentum J, some of the oscillations survive, indicating that they may be amenable to experimental observation. A comparison of our present results with our earlier results on the McLaughlin–Thompson–Joseph–Sathyamurthy surface and the experimental results from different research groups reveal a good deal of agreement as well as some discrepancies between theory and experiment at the level of state-selected gas phase dynamics. © 2005 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A global analytical potential energy surface for the ground state of H3- has been constructed by fitting an analytic function to the ab initio potential energy values computed using coupled cluster singles and doubles with perturbative triples [CCSD(T)] method and Dunning’s augmented correlation consistent polarized valence triple zeta basis set. Using this potential energy surface, time-dependent quantum mechanical wave packet calculations were carried out to calculate the reaction probabilities (PR) for the exchange reaction H-+H2(v,j)→H2+H-, for different initial vibrational (v) and rotational (j) states of H2, for total angular momentum equal to zero. With increase in v, the number of oscillations in the PR(E) plot increases and the oscillations become more pronounced. While PR increases with increase in rotational excitation from j=0 to 1, it decreases with further increase in j to 2 over a wide range of energies. In addition, rotational excitation quenches the oscillations in PR(E) plots. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Vibrational (v) state-selected reaction probabilities (P[sup J, sub vj]) have been calculated for the reaction He+H[sup +, sub 2](v=0,1,2,3)→HeH[sup +] +H, for H[sup +, sub 2] in its ground rotational state (j=0) for a range of total angular momentum (J) values, for total energy (E) in the range 0.94-1.4 eV, using time-dependent quantum mechanical (TDQM) approach and centrifugal sudden approximation. The number of oscillations in P[sup J, sub v0](E) decreases with increase in J. In addition, there is a noticeable increase in the threshold energy (E[sub th]) with increase in J. The magnitude of P[sup J, sub v0] decreases with increase in or resulting in converged cross section values by the time or becomes 35-45, depending upon v and E under investigation. The resulting (converged) reaction cross section values are in excellent agreement with the experimental results at E=1.14 eV, both in terms of the magnitude and in terms of the observed vibrational enhancement. Interestingly, there is a noticeable discrepancy between our TDQM results and earlier time-independent quantum mechanical studies at higher energies, for v=1 and 2. For v=3, the difference between the two theoretical studies is the largest near the threshold. Our results for v=2 and 3 suggest that the oscillations in the vibrational state-selected reaction cross section values are amenable to experimental observation. [ABSTRACT FROM AUTHOR]

A time-dependent quantum mechanical (TDQM) investigation of three-dimensional collisions of (H(super -), H2 (v=0,j=0) and its isotopic variants for a range of total angular momentum values is carried out on an ab initio potential-energy surface (PES), for collision energy in the range 0.3-3.0 eV, and the results obtained are compared with the experimental results.