Solving the nuclear Schrödinger equation for complex molecules is computationally demanding. The computational work grows exponentially in the number of involved nuclei. With the algorithms and hardware currently available, problems with more than, say, four nuclei would be intractable using standard methods.

One can construct approximate methods which circumvent this limitation by taking the asymptotic behaviour of heavy nuclei into account. Such methods are called semiclassical. We study methods based on Hagedorn wave packets in collaboration with Vasile Gradinaru at ETH Zürich, and methods based on Gaussian beams in collaboration with Olof Runborg at KTH.

1. Coupling of Gaussian beam and finite difference solvers for semiclassical Schrödinger equations. Emil Kieri, Gunilla Kreiss, and Olof Runborg. Technical report / Department of Information Technology, Uppsala University nr 2013-019, 2013. (External link).
2. An adaptive pseudospectral method for wave packet dynamics. Emil Kieri, Sverker Holmgren, and Hans O. Karlsson. In Journal of Chemical Physics, volume 137, pp 044111:1-12, 2012. (DOI, fulltext:print).

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