Time-dependent variational approach to molecules in strong laser fields

We study the dynamics of the electronic and nuclear degrees of freedom for molecules in strong laser fields using an ansatz for the wavefunction that explicitly incorporates the electron–nuclear correlation. Equations of motion for this wavefunction are derived on the basis of the stationary action principle. The method is tested on a one-dimensional model of the H2+ molecule that can be solved essentially exactly by numerical integration of the time-dependent Schrödinger equation. By comparison with this exact solution we find that the correlated approach improves significantly on a mean-field treatment, especially for laser fields strong enough to cause substantial dissociation. These results are very promising since our method still has a simple orbital structure and can hence be applied to realistic many-electron molecules.