Demos.Main

WavePacket: Demo examples

Many worked-out examples illustrating the use of the WavePacket simulation tools are available here. Along with complete input and output files as well as animated graphics, they serve to introduce new users to the capabilities of the WavePacket program package. All of the demos here are also included in the download. Additional information is also available in our articles describing the WavePacket software package

Quantum dynamics on a single potential energy surface (adiabatic)

The first set of examples serves to illustrate a number of textbook examples where analytical solutions are known for the most part. However, the time-dependent picture of quantum mechanics provides an alternative point of view, and many intriguing features can be found in the animated graphics. Learn more ...

Quantum dynamics on coupled potential energy surfaces (non-adiabatic)

Although the Born-Oppenheimer (adiabatic) approximation provides the most intuitive picture of molecular quantum dynamics in terms of densities/wavepackets moving along uncoupled(!) potential energy surfaces, many chemical reactions, most notably in photochemistry and photobiology are governed by non-adiabatic processes, i. e., they involve nuclear dynamics on (at least!) two different electronic states. This breakdown of the adiabatic approximation occurs most drastically where spectral gaps between electronic eigenstates become sufficiently small or vanish altogether. Prominent examples are (avoided) crossings of potential energy curves (in one dimension) and seams or conical intersections (in two or more dimensions). Learn more ...

Optimal control of quantum dynamics

In optimal control, external electromagnetic fields (e.g. laser pulses) are employed to permanently change the state of quantum systems with which they interact in a specific way. The targets of control can be manifold, e.g. high populations of desired states, high selectivity with respect to other quantum states, or different reaction pathways leading to different products of a chemical reaction. Often, such simulations are subjects to constraints from experiments, e.g. finite intensities, restricted shapes and/or durations of field pulses etc. In the examples below, we demonstrate the use of the rapidly convergent iteration methods introduced by H. Rabitz and coworkers and further developed by Y. Ohtsuki, Y. Maday, G. Turinici and many others (apologies if we forgot to mention someone important). Learn more ...