ABC: a quantum reactive scattering program

1. Unconventional Conditions at Ultracold Temperatures 4949 1.

Ultracold molecules under control

We give a snapshot of the rapidly developing field of ultracold polar molecules and walk the reader through the papers appearing in this Topical Issue.

https://link.springer.com/content/pdf/10.1140%2Fepjd%2Fe2004-00151-x.pdf

Editorial: Quo vadis, cold molecules?

A three dimensional potential energy surface for the F+H2→HF+H reaction has been computed using the internally contracted multireference configuration interaction (MRCI) method with complete active space self‐consistent field (CASSCF) reference functions and a very large basis set. Calibration calculations have been performed using the triple‐zeta plus polarization basis set employed in previous nine‐electron full CI (FCI) calculations of Knowles, Stark, and Werner [Chem. Phys. Lett. 185, 555 (1991)]. While all variational MRCI wave functions yield considerably larger barrier heights than the FCI, excellent agreement with the FCI barrier height and the exothermicity was obtained when the Davidson correction was applied (MRCI+Q). The convergence of the barrier height and exothermicity, spectroscopic constants of the HF and H2 fragments, and the electron affinity of the fluorine atom with respect to the basis set has been carefully tested. Using the largest basis sets, which included 5d, 4f, 3g, and 2h func...

An accurate multireference configuration interaction calculation of the potential energy surface for the F+H2→HF+H reaction

This review discusses recent quantum scattering calculations on bimolecular chemical reactions in the gas phase. This theory provides detailed and accurate predictions on the dynamics and kinetics of reactions containing three atoms. In addition, the method can now be applied to reactions involving polyatomic molecules. Results obtained with both time-independent and time-dependent quantum dynamical methods are described. The review emphasises the recent development in time-dependent wave packet theories and the applications of reduced dimensionality approaches for treating polyatomic reactions. Calculations on over 40 different reactions are described.

Quantum scattering calculations on chemical reactions.

Hyperspherical close-coupling calculation of integral cross sections for the reaction H+H2→H2+H

Quantum-mechanical calculation of integral cross sections for the reaction F+H2(v=0, j=0)→FH(v′ j′)+H by the hyperspherical method

The hyperspherical close-coupling formalism is applied to the study of triatomic collinear chemical reactions involving electronically non-adiabatic transitions. We propose the use of hyperspherical coordinates in the complex zone and of locally adapted Jacobi coordinates in the fragmentation zones. Matching procedures, allowing the switch from one representation to the other, are described. The possibility of long-range electrovibrational couplings is considered. Possible simplifications in the practical implementation of the formalism are examined.

Quantum study of electronically non-adiabatic collinear reactions. I. Hyperspherical description of the electronuclear dynamics

Electronic transitions in the collinear reactive FHH system are investigated using two models of electronic potentials with different spin-orbit coupling strengths. One is based on the DIM method and the other one uses the Muckerman's MV reactive surface and a modified Blais-Truhlar repulsive potential. The hyperspherical electronuclear potential diagram permits to predict two kinds of spin-orbit transitions: (1) vibrationally adiabatic spin transitions are induced in the reactant valley where the two electronic surfaces are nearly degenerate; (2) electrovibrational transitions are induced in the complex zone at the crossings between hyperspherical potentials. A close-coupling procedure based on hyperspherical coordinates allows one to compute inelastic and reactive probabilities up to 1.8 eV. The first mechanism induces reactive or inelastic probabilities from the electronically excited state by multi-step processes. The second mechanism is responsible for local enhancement of the reactivity on several probabilities involving vibrationally excited products. Resonances are found at the same total energies as in the single-surface calculation, but their intensities are partly controlled by the second mechanism.

M. Le Dourneuf

Papers

Hyperspherical close-coupling calculation of integral cross sections for the reaction H+H2→H2+H

Quantum-mechanical calculation of integral cross sections for the reaction F+H2(v=0, j=0)→FH(v′ j′)+H by the hyperspherical method

Quantum study of electronically non-adiabatic collinear reactions. I. Hyperspherical description of the electronuclear dynamics

Quantum study of electronically non-adiabatic collinear reactions. II. Influence of spin-orbit transitions on the F + HH reaction

Quantum dynamics of the collinear CsHH system