Homepage of Petra Ruth Kapralova

Wigner (Quasiclassical) Molecular Dynamics

Past support: grant No. B100550501, 2005-2007

WDYN Program Package

WDYN is a shortcut to our project and program package for molecular modeling focused on calculations of quantum vibrational spectra of large molecular systems; it means "Wigner DYNamics". WDYN is potentionally useful for calculations of quantum mechanical features of extremely large molecules such as proteins and nanosystems.

Principles of Wigner Dynamics

Wigner dynamics does not work with wavefunctions, but rather with density probabilities, which can be understood in terms of the usual world of classical mechanics, i.e., positions and velocities. This method provides us with alternative insights to quantum mechanical phenomena such as quantization and tunnelling, and allows us to reduce computational effort in quantum dynamical calculations, when the so called quasiclassical approximation is introduced.

History of the Wigner molecular dynamics

The quassiclassical Wigner molecular dynamics is a relatively old concept, which was suggested by J. E. Heller and based on an early work by Wigner, one of the pioneers of quantum mechanics, from 1932.

The use for spectroscopic modeling - resolution problem

Our contribution to a development of the quassiclassical method is represented by the fact that we found a way how to calculate vibrationally resolved spectra. How? We found a new way to obtain the so called correct long-time behavior of the autcorrelation function. We disclosed that the original method omitted quantum interference between parts of probability density - for this reason it was not able to obtain correct results.

Progress and development

We are solving fundamental problems - including quantum tunneling. We fight with technical problems arising in problems including coupled motion. We fight with programming problems - we need to include more realistic potentions into our software.