I. Rabadán

State-selective electron capture in collisions of ground and metastable O2+ ions with H(1s)

An ab initio calculation of the electron capture cross sections for collisions of ground and metastable states of O2+ with H(1s) is presented. For impact energies between 0.125 and 3.4 keV amu−1, we find good agreement between the cross sections from the ground state ion with the mixed beam experimental data of Phaneuf et al (Phaneuf A, Alvarez I, Meyer F W and Crandall D H 1982 Phys. Rev. A 26 1892).

Classical calculation of ionization and electron-capture total cross sections in H{sup +}+H{sub 2}O collisions

We report total cross sections for single ionization and electron capture in H{sup +} collisions with water molecules at impact energies 25 keV<E<5 MeV. Calculations have been carried out by applying the independent-particle model and the eikonal-classical trajectory Monte Carlo (CTMC) method. We have also estimated fragmentation cross sections by multiplying the partial cross sections by the branching ratios measured in the photoionization experiments of Tan et al. [Chem. Phys. Lett. 29, 299 (1978)].

Molecular treatment of excitation and charge transfer in Be++H collisions

A 28-term molecular expansion is employed to calculate total and partial cross sections for charge exchange and excitation in Be++H collisions in the range of impact energies 0.1-25 keV amu-1, which are of predictive value.

State selective electron capture and excitation in proton collisions with Be

An ab initio study of charge exchange and excitation processes in collisions between protons and beryllium atoms is presented. State selective cross sections are obtained for collision energies between 2.5 × 10−7 and 16 keV/amu, using both quantum and semiclassical treatments. A very large isotopic dependence of the charge exchange cross section is found at energies below 0.6 eV/amu.

A study of conical intersections for the H3(+) system.

A parametrization of the three asymptotic conical intersections between the energies of the H3(+) ground state and the first excited singlet state is presented. The influence of an additional, fourth conical intersection between the first and second excited states at the equilateral geometry on the connection between the three conical regions is studied, for both diatomics-in-molecules and ab initio molecular data.

Ionization and electron capture in ion-molecule collisions: classical (CTMC) and semiclassical calculations.

Total cross-sections for electron capture and electron production in proton collisions with N2, CO and H2O, are evaluated using a classical trajectory Monte Carlo treatment for collision energies between 30 and 3000 keV. A semiclassical close-coupling treatment has been also employed for proton collisions with H2O, to discuss the accuracy of the CTMC treatment. Singly differential cross-sections for electron production have been also evaluated. Total and differential cross are compared with experimental data.

Calculation of total cross sections for ionization and charge transfer in collisions of multicharged ions with water molecules

Classical (CTMC) calculations of single electron capture and single ionization cross sections are carried out for collisions of H+ and C6+ collisions with H2O molecules in the impact energy range 25<E<5000 keV/amu. The calculation employs a multi‐center model potential for the interaction of the active electron with the H2O+ core. The results agree with the experimental data when the independent electron event model is applied to evaluate total electron capture and ionization probabilities from the corresponding one‐electron ones.

Influence of nuclear exchange on nonadiabatic electron processes in H++H2 collisions

H(+)+H(2) collisions are studied by means of a semiclassical approach that explicitly accounts for nuclear rearrangement channels in nonadiabatic electron processes. A set of classical trajectories is used to describe the nuclear motion, while the electronic degrees of freedom are treated quantum mechanically in terms of a three-state expansion of the collision wavefunction. We describe electron capture and vibrational excitation, which can also involve nuclear exchange and dissociation, in the E = 2-1000 eV impact energy range. We compare dynamical results obtained with two parametrizations of the potential energy surface of H(3)(+) ground electronic state. Total cross sections for E > 10 eV agree with previous results using a vibronic close-coupling expansion, and with experimental data for E < 10 eV. Additionally, some prototypical features of both nuclear and electron dynamics at low E are discussed.

Electron capture and nuclear exchange in H+ + H2 collisions at low impact energies

Electron capture, vibrational excitation, dissociation and nuclear exchange in collisions of H+ with H2 are studied at impact energies between 5 eV and 1 keV. Calculations are performed by employing classical trajectories for the nuclear evolution and a three-state expansion of the electronic wavefunction that uses the diatomics in molecules approach. Our results confirm previous vibronic results and show a striking discrepancy in single capture cross sections with experimental data for energies E≤ 200 eV.

Calculation of rate coefficients for electron capture in collisions of O2+ and N2+ ions with H

We present calculations of electron capture cross sections in collisions of O2+ and N2+ with H(1s) for impact energies 0.001 eV < E < 10 keV and the corresponding rate coefficients for temperatures 102 K < T < 105 K. Our molecular close-coupling treatment leads to significant differences from the capture rates usually employed in the modeling of astrophysical plasmas.