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Manuscript Title: MOSPLV: a program for simulation of complex Mossbauer spectra in polycrystalline samples.
Authors: R. Chipaux
Program title: MOSPLV
Catalogue identifier: ABTH_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 60(1990)405
Programming language: Fortran.
Computer: IBM PC/AT.
Operating system: MS-DOS.
RAM: 2000K words
Word size: 32
Peripherals: disc.
Keywords: Nuclear physics, State solid, Mossbauer spectroscopy, Non-diagonal hyperfine Hamiltonian.
Classification: 17.3.

Nature of problem:
In some cases, even if only static interactions are involved, Mossbauer spectra are not easy to analyse precisely and rapidly. The classical approximations do not always apply when the hyperfine hamiltonians cannot be expressed in a diagonal form for the standard angular momentum nuclear states. The main problem is to calculate the intensities of transition. Although the mathematical expressions are not very complicated, computing them exactly without approximation needs time and memory size. The increase of computing speeds and the decrease of memory costs allow now to undertake these calculations on micro- computer, with a source code as transparent as possible.

Solution method:
The hyperfine hamiltonian matrix are written in the usual way and diagonalized by EISPACK subroutines. The transition intensities are then integrated over all crystal orientations by means of preliminary analytically calculated rotations coefficients.

Although only a small number of Mossbauer transitions is tabulated in the program the possibility is given to the user of introducing inter- actively his own parameters. The simulation is limited to one site of of one Mossbauer atom at the same time, but no theoretical obstacle exists to increase this number. The main limitation is the amount of memory and computing time required for large spin transitions (say more than 5/2-5/2). Although we present here the full version, a smaller one could be very easily obtained by modifying the parameter NM. Setting NM to 6 instead of 10 allows almost all used Mossbauer transitions, for which spins are less or equal to 5/2.

Unusual features:
The program is fully interactive when used with graphic facilities. Two minimal subroutines are proposed, one uses the GKS standard, the second earlier Tektronix-type subroutines. One should adapt one of them to the available graphic facilities. An extension of the program for least square refinement of spectra, and a smaller version for 237Np transitions only, both commented in French, are also available from the author.

Running time:
Strongly dependent on number of hyperfine nuclear states. For example: 3/2-1/2 transistions: 15s for initialization and 10s for each simulation (total time), (resp. 0.02s and 0.15s on IBM 3090 (CPU time)); 5/2-5/2 transistions: 40s for initalization and 75s for each simulation (0.65s and 2.2s on IBM); 9/2-7/2 transitions: 18s for initalization and 60s for each simulation (CPU time) on IBM.