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Manuscript Title: Numerical evaluation of Kratzer oscillator matrix elements.
Authors: R.E. Tuzun, D. Secrest
Program title: KROSC1
Catalogue identifier: ACHO_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 70(1992)362
Programming language: Fortran.
Computer: VAX 3500.
Operating system: VMS 5.1, UNIX, UNICOS 6.0.
Word size: 32
Keywords: Molecular physics, Vibration, Kratzer oscillator, Variational, Hypergeometric function, Recursion relation, Anharmonic oscillator, Matrix element.
Classification: 16.3.

Nature of problem:
This subroutine calculates a Kratzer oscillator matrix element of products of exponentials and integer powers of position. Matrix elements of this type are used to calculate kinetic energy matrix elements in variational calculations; they can also be used for quite general potential types such as Born-Mayer and Simons-Parr-Finlan.

Solution method:
The matrix element can be written in closed form; the expression includes a terminating F2 hypergeometric function. A quantity related to F2 is calculated by recursion. The rest of the matrix element is easy to calculate.

Running time:
Case-dependent. However, to calculate a table of all possible matrix elements with quantum numbers up to 25 (351 integrals) took .0068 and .0072 seconds in single and double precision, respectively on the VAX 3500 with VMS 5.1.