Ab initio studies of strong-field ionization of arbitrarily oriented H2+ molecules

We calculate ionization probabilities for the H-2(+) molecule subject to a linearly polarized infrared laser field. The time-dependent Schrodinger equation is solved numerically for all electronic degrees of freedom while the nuclei are fixed at arbitrary separations and orientations with respect to the direction of the field. The ionization signal displays a strong dependence on the degree of alignment between the laser polarization and the internuclear vector. At perpendicularly aligned geometry the signal is suppressed due to a symmetry selection rule that excludes an important intermediate resonance.