Strong-field ionization dynamics of a model H 2 molecule

We investigate the dynamics of a one-dimensional ${\mathrm{H}}_{2}$ model molecule in strong laser fields by numerical integration of the time-dependent Schr\"odinger equation without the use of the Born\char21{}Oppenheimer approximation. Ionization typically occurs at internuclear separations close to the ground-state equilibrium distance. This is contrary to the case of ${\mathrm{H}}_{2}^{+},$ which ionizes at larger internuclear distances where charge-resonance-enhanced ionization is possible. Similar to the case of atoms, we find considerable nonsequential double ionization.