Hannover 2013 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 4: Quantum Chemistry and Molecular Dynamics I

MO 4.7: Vortrag

Montag, 18. März 2013, 15:45–16:00, F 102

Quantum dynamics on flexible space grids — •Julius Zauleck and Regina de Vivie-Riedle — Department Chemie, Ludwig-Maximilians-Universität München

An increasing number of successful ultrafast experiments are reported in the field of complex chemical reactions. For their interpretation quantum dynamical simulations are helpful. Most of them use constant equidistant space or momentum grids. This works well because many efficient algorithms -- like the fast Fourier transform -- have been developed for such conditions. However, as a result the whole grid that is used during the propagation is needed at each time step. This means that most of the time large parts of the grid carry very little information while they still require the full computing time.

Alternatives are given by flexible grids. One of several approaches uses the de-Broglie-Bohm formulation of quantum mechanics in a quantum trajectory method. This leads to a split of the Schrödinger equation into an imaginary and a real part. The resulting quantum hydrodynamical equations of motion can now be handled in analogy to classical fluid dynamics. A useful tool is the Lagrangian frame of reference. It describes the movement of the space grid along with the fluid elements that represent the wave packet. As a result the space grid is moving with it and can be chosen much smaller than constant grids.

In addition to the general structure of the methods, problems with the maintenance of the grid will be discussed and different procedures will be shown by means of examples.