A recently developed molecular three-continuum approximation is employed to compute differential cross sections for the ionization of hydrogen molecules by electron impact. Within the framework of this approximation, the chosen final electronic wavefunction takes into account the molecular character of the target as well as the correlate motion between the aggregates in the final channel of the reaction. Fivefold-differential cross sections as a function of both the electron momenta in the final state and the molecular orientation are studied for different kinematical arrangements. Interference structures coming from the two-centre geometry of the molecule are predicted in this case. Integrated cross sections over all molecular orientations are also calculated. It is shown that interference patterns remain, even for this case.During the last decades, a large number of theoretical and experimental studies have treated the (e, 2e) reactions with atomic targets, providing a general understanding of these processes (see, for example, [1]). In contrast, the research on ionization of molecules has advanced in a slower way due to some extra complications appearing in this case. For instance, on the experimental side, it has not been possible yet to prepare the molecular target in a particular rovibrational state. Another difficulty is imposed by the finite resolution of the electron beam. On the theoretical side, the molecular structure must be fully included in any realistic description of the process.The main purpose of the present investigation is the study of interference effects which appear as a consequence of the two-centre character of the target, and may be related to the Young's two-slit experiment. This effect was theoretically predicted for ionization by photon impact on H 2 [2] (see also Walter and Briggs [3]), and recently measured for electron emission by fast multicharged ion impact on the same target [4,5]. Different theoretical
The early stages of the Coulomb explosion of a doubly ionized water molecule immersed in liquid water are investigated with time-dependent density functional theory molecular dynamics (TD-DFT MD) simulations. Our aim is to verify that the double ionization of one target water molecule leads to the formation of atomic oxygen as a direct consequence of the Coulomb explosion of the molecule. To that end, we used TD-DFT MD simulations in which effective molecular orbitals are propagated in time. These molecular orbitals are constructed as a unitary transformation of maximally localized Wannier orbitals, and the ionization process was obtained by removing two electrons from the molecular orbitals with symmetry 1B(1), 3A(1), 1B(2) and 2A(1) in turn. We show that the doubly charged H(2)O(2+) molecule explodes into its three atomic fragments in less than 4 fs, which leads to the formation of one isolated oxygen atom whatever the ionized molecular orbital. This process is followed by the ultrafast transfer of an electron to the ionized molecule in the first femtosecond. A faster dissociation pattern can be observed when the electrons are removed from the molecular orbitals of the innermost shell. A Bader analysis of the charges carried by the molecules during the dissociation trajectories is also reported.
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