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Manuscript Title: Fast computation of close-coupling exchange integrals using polynomials in a tree representation | ||

Authors: Markus Wallerberger, Katharina Igenbergs, Josef Schweinzer, Friedrich Aumayr | ||

Program title: TXINT | ||

Catalogue identifier: AEHS_v1_0Distribution format: tar.gz | ||

Journal reference: Comput. Phys. Commun. 182(2011)775 | ||

Programming language: Fortran 95. | ||

Computer: All with a Fortran 95 compiler. | ||

Operating system: All with a Fortran 95 compiler. | ||

RAM: Depends heavily on input, usually less than 100 MiB | ||

Keywords: Exchange integrals, Symbolic manipulations, Polynomials. | ||

Classification: 16.10. | ||

Nature of problem:Analytical calculation of one- and two-center exchange matrix elements for the close coupling method in the impact parameter model. | ||

Solution method:Similar to the code of Hansen and Dubois [1], we use the Fourier transform method suggested by Shakeshaft [2] to compute the integrals. However, we heavily speed up the calculation using a library for symbolic manipulation of polynomaials. | ||

Restrictions:We restrict ourselves to a defined collision system in the impact parameter model. | ||

Unusual features:A library for symbolic manipulation of polynomials, where polynomials are stored in a space-saving left-child right-sibling binary tree. This provides stable numerical evaluation and fast mutation while maintaining full compatibility with the original code. | ||

Additional comments:This program makes heavy use of the new features provided by the Fortran 90 standard, most prominently pointers, derived types and allocatable structures and a small portion of Fortran 95. Only newer compilers support these features. Following compilers support all features needed by the program. - - GNU Fortran Compiler "gfortran" from version 4.3.0
- - GNU Fortran 95 Compiler "g95" from version 4.2.0
- - Intel Fortran Compiler "ifort" from version 11.0
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Running time:Heavily dependent on input, usually less than one CPU second. | ||

References: | ||

[1] | Hansen, J.-P. and Dubois, A., Comput. Phys. Commun. 67 (1992) 456 . | |

[2] | Shakeshaft, R., J. Phys. B: At. Mol. Opt. Phys. 8 (1975) L134. |

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