Simulating Mössbauer Effect Using SHIML

Chad M. Johnston and M. O. Zacate

The stochastic hyperfine interaction modeling library (SHIML) is a collection of computer

routines written in the C programming language [1]. It was created to assist researchers quickly analyze

experimental data that are influenced by fluctuating hyperfine interactions. The original version of

SHIML only supported experimental techniques that measure a single probe spin state. This leaves out

Mössbauer spectroscopy which is an important experimental method used to measure fluctuating

hyperfine interactions.

This summer, we modified the code to include an option for a second spin state. This required

new routines, which we developed using the original single spin state routines as templates, to read and

perform the correct operations on the new spin state. We have also written an example program to

demonstrate how SHIML can now be used to simulate Mössbauer spectroscopy. We did this by

modifying code developed originally to simulate perturbed angular correlation spectra. We had to add

the ability to read Mössbauer-specific parameters and change the spectral function to

GL (ω)=ℜ [∑q (gL)q1

12Γ− λq− i (ω+ωq ) ]. Where (gL)q is a function of eigenvectors of the Blume

Matrix, which is calculated by the new version of SHIML. Gamma (Γ) is the natural linewidth; also λq and

ωq are the real and imaginary parts of the eigenvalues of the Blume Matrix.

Preliminary testing has generated Mössbauer spectra whose behavior mimics

expected/published spectra. However, more rigorous testing is required before the second version of

SHIML is released for public use. The changes that were made this summer have increased the

versatility of the library. Now using SHIML researchers can quickly analyze data gathered from a much

wider range of experimental techniques.

[1] M. O. Zacate, W. E. Evenson, “Stochastic Hyperfine Interactions Modeling Library,” Computer Physics Communications 182, 1061-1077 (2011).