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Manuscript Title: Stochastic Hyperfine Interactions Modeling Library
Authors: Matthew O. Zacate, William E. Evenson
Program title: SHIML
Catalogue identifier: AEIF_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 182(2011)1061
Programming language: C.
Computer: Any.
Operating system: LINUX, OS X.
RAM: Varies
Keywords: Perturbed angular correlation spectroscopy, TDPAC, stochastic models, hyperfine methods.
PACS: 76.80.+y, 76.60.-k, 76.75.+i.
Classification: 7.4.

External routines: TAPP [1], BLAS [2], a C-interface to BLAS [3], and LAPACK [4]

Nature of problem:
In condensed matter systems, hyperfine methods such as nuclear magnetic resonance (NMR), Mössbauer effect (ME), muon spin rotation (μSR), and perturbed angular correlation spectroscopy (PAC) measure electronic and magnetic structure within Angstroms of nuclear probes through the hyperfine interaction. When interactions fluctuate at rates comparable to the time scale of a hyperfine method, there is a loss in signal coherence, and spectra are damped. The degree of damping can be used to determine fluctuation rates, provided that theoretical expressions for spectra can be derived for relevant physical models of the fluctuations. SHIML provides routines to help researchers quickly develop code to incorporate stochastic models of fluctuating hyperfine interactions in calculations of hyperfine spectra.

Solution method:
Calculations are based on the method for modeling stochastic hyperfine interactions for PAC by Winkler and Gerdau [5]. The method is extended to include other hyperfine methods following the work of Dattagupta [6]. The code provides routines for reading model information from text files, allowing researchers to develop new models quickly without the need to modify computer code for each new model to be considered.

In the present version of the code, only methods that measure the hyperfine interaction on one probe spin state, such as PAC, μSR, and NMR, are supported.

Running time:

[1] M. O. Zacate, The Adjustable Parameter Package, Technical Report 2, CINSAM Grant 2006-R7 (unpublished); available for download at http://tapp.nku.edu/ .
[2] L. S. Blackford et al., ACM Trans. Math. Soft., vol. 22, no. 2, pp. 135-151 (2002); J. Dongarra, International Journal of High Performance Applications and Supercomputing, vol. 16, nos. 1-2, pp. 1-199 (2002); http://www.netlib.org/blas/ .
[3] M. Galassi et al., GNU Scientific Library Reference Manual, third edition (2009); available for download at http://www.gnu.org/software/gsl/.
[4] E. Anderson et al., LAPACK Users' Guide (third ed.), Society for Industrial and Applied Mathematics: Philadelphia, 1999; http://www.netlib.org/lapack/ .
[5] H. Winkler and E. Gerdau, Z. Phys., vol. 262, pp. 363-376 (1973).
[6] S. Dattagupta, Hyperfine Interactions, vol. 11, pp. 77-126 (1981).