Time-Dependent Expectation Values from Integral Equations for Quantum Flux and Probability Densities.

We compare the calculation of time-dependent quantum expectation values performed in different ways. In one case, they are obtained from an integral over a function of the probability density, and in the other case, the integral is over a function of the probability flux density. The two kinds of coordinate-dependent integrands are very different in their appearance, but integration yields identical results, if the exact wave function enters into the computation.

Time-dependent momentum expectation values from different quantum probability and flux densities.

Based on the Ehrenfest theorem, the time-dependent expectation value of a momentum operator can be evaluated equivalently in two ways. The integrals appearing in the expressions are taken over two different functions. In one case, the integrand is the quantum mechanical flux density j̲, and in the other, a different quantity j̲̃ appears, which also has the units of a flux density.

Deformation of Atomic p_{±} Orbitals in Strong Elliptically Polarized Laser Fields: Ionization Time Drifts and Spatial Photoelectron Separation.

We theoretically investigate the deformation of atomic p_{±} orbitals driven by strong elliptically polarized (EP) laser fields and the role it plays in tunnel ionization. Our study reveals that different Stark effects induced by orthogonal components of the EP field give rise to subcycle rearrangement of the bound electron density, rendering the initial p_{+} and p_{-} orbitals deformed and polarized along distinctively tilted angles with respect to the polarization ellipse of the EP field. As a consequence, the instantaneous tunneling rates change such that for few-cycle EP laser pulses the bound electron initially counterrotating (corotating) with the electric field is most likely released before (after) the peak of the electric field.

On the parameterization of vibronic Hamiltonians for molecular aggregates using absorption line-shapes as an input.

Absorption line-shapes of molecular aggregates are often calculated using a simple form for a vibronic Hamiltonian. Parameters which enter into the model are usually taken from measured spectra. Here, we address the question in how far different sets of input parameters used to calculate the spectra lead to similar spectral features.

Weak-field, multiple-cycle carrier envelope phase effects in laser excitation.

Although the absolute or carrier envelope phase (CEP) of a laser pulse is usually assumed to be effective for ultrashort and/or ultrastrong pulses only, it is demonstrated that these limitations can eventually be removed. Therefore, the excitation of a model positively charged homonuclear diatomic molecule, in which four electronic states are coupled by the laser field, is studied. In an initial step, nuclear wave packets in two dissociative states are prepared.