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M. Wallerberger, K. Igenbergs, J. Schweinzer, F. Aumayr:
"Fast computation of close-coupling exchange integrals using polynomials in a tree representation";
Computer Physics Communications, 182 (2011), 775 - 778.

The semi-classical atomic-orbital close-coupling method is a well-known approach for the calculation of
cross sections in ion-atom collisions. It strongly relies on the fast and stable computation of exchange
integrals. We present an upgrade to earlier implementations of the Fourier-transform method.
For this purpose, we implement an extensive library for symbolic storage of polynomials, relying on
sophisticated tree structures to allow fast manipulation and numerically stable evaluation. Using this
library, we considerably speed up creation and computation of exchange integrals. This enables us to
compute cross sections for more complex collision systems.