The nuclear rotational period of the simplest molecule H[subscript]2[superscript]+ is about 550 fs, which is more

than 35 times longer than its vibrational period of 15 fs. The rotational time scale is also

much longer than widely available ultra short laser pulses which have 10 fs or less duration.

The large difference in rotational period and ultra short laser pulse duration raises questions

about the importance of nuclear rotation in theoretical studies of H[subscript]2[superscript]+ dissociation by these

pulses. In most studies, reduced-dimensionality calculations are performed by freezing the

molecular axis in one direction, referred to as the aligned model. We have systematically

compared the aligned model with our full-dimensionality results for total dissociation probability

and field-free dynamics of the dissociating fragments. The agreement between the

two is only qualitative even for ultra short 10 fs pulses. Post-pulse dynamics of the bound

wave function show rotational revivals. Significant alignment of H[subscript]2[superscript]+ occurs at these revivals.

Our theoretical formulation to solve the time-dependent Schrodinger equation is an important

step forward to make quantitative comparison between theory and experiment. We

accurately calculate observables such as kinetic energy, angular, and momentum distributions.

Reduced-dimensionality calculations cannot predict momentum distributions. Our

theoretical approach presents the first momentum distribution of H[subscript]2[superscript]+ dissociation by few cycle

laser pulses. These observables can be directly compared to the experiment. After

taking into account averaging steps over the experimental conditions, we find remarkable

agreement between the theory and experiment. Thus, our theoretical formulation can make

predictions. In H[subscript]2[superscript]+ dissociation by pulses less than 10 fs, an asymmetry in the momentum

distribution occurs by the interference of different pathways contributing to the same energy.

The asymmetry, however, becomes negligible after averaging over experimental conditions.

In a proposed pump-probe scheme, we predict an order of magnitude enhancement in the

asymmetry and are optimistic that it can be observed.