This OPTESIM toobox enables automated numerical simulation of powder ESEEM for arbitrary number (N) and type (I, gN) of coupled nuclei, and arbitrary mutual orientations of the hyperfine tensor principal axis systems for N>1.
The toolbox is based in the Matlab environment, and includes the following features:

  1. a fast algorithm for the computation of spin Hamiltonian into ESEEM,
  2. variety of optimization methods that can be hybridized to achieve an efficient coarse-to-fine grained search of the parameter space and convergence to a global minimum,
  3. statistical analysis of the simulation parameters, which allows the identification of simultaneous confidence regions at specific confident levels.

The toolbox includes a geometry preserving spherical averaging algorithm as default for N>1, and global optimization over multiple experimental conditions, such as the dephasing time (τ) for three-pulse ESEEM, and external magnetic field values.
In addition, a Java-RMI based distributed computational framework is included in OPTESIM. This framework allows users to build a distributed system of ESEEM simulation on their own PC computer hardware resources.

Example of a Screenshot
Example of an Automatically Generated Report

ESEEM Simulation Theory

Electron spin echo envelope modulation (ESEEM) is a technique of pulsed-electron paramagnetic resonance (EPR) spectroscopy. The analysis of ESEEM data to extract information about the nuclear and electronic structure of a disordered (powder) paramagnetic system requires accurate and efficient numerical simulations. Please refer to the following topics:

Download & Install

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The installation notes can be found at here.
To install the distributed computation framework for OPTESIM.
To adapt OPTESIM to your data acquisition format.


The OPTESIM toolbox consists of 26 Matlab functions and 8 Java classes that can be divided into the following four categories: experimental data filtering, numerical simulation, simulation parameter optimization, and distributed computation framework.  These categories are incorporated into four stand-alone modules that are integrated in OPTESIM, as described in the user's guide.  The modules may be individually substituted by the routines of users', if desired.


MATLAB function references
Javadoc for the distributed computation framework


Running simulation on a local PC
Managing Node servers
Running simulation on a distributed computation framework
Using diferent optimization algorithms

Literature References

[ 1] A. Schweiger, and G. Jeschke, Principles of pulse electron paramagnetic resonance, Oxford University Press, Oxford, UK ; New York, 2001.
[ 2] S.A. Dikanov, and Y.D. Tsvetkov, Electron spin echo envelope modulation (ESEEM) spectroscopy, CRC Press, Boca Raton, 1992.
[ 3] J.M. Canfield, and K. Warncke, Geometry of reactant centers in the Co-II-substrate radical pair state of coenzyme B-12-dependent ethanolamine deaminase determined by using orientation-selection-ESEEM spectroscopy. Journal of Physical Chemistry B 106 (2002) 8831-8841.
[ 4] J.E. Wertz, and J.R. Bolton, Electron spin resonance; elementary theory and practical applications, McGraw-Hill, New York, 1972.
[ 5] S. Stoll, and A. Schweiger, Rapid construction of solid-state magnetic resonance powder spectra from frequencies and amplitudes as applied to ESEEM. Journal of Magnetic Resonance 163 (2003) 248-256.
[ 6] G.R. Hanson, K.E. Gates, C.J. Noble, M. Griffin, A. Mitchell, and S. Benson, XSophe-Sophe-XeprView (R). A computer simulation software suite (v. 1.1.3) for the analysis of continuous wave EPR spectra. Journal of Inorganic Biochemistry 98 (2004) 903-916.
[ 7] S. Stoll, and A. Schweiger, EasySpin, a comprehensive software package for spectral simulation and analysis in EPR. Journal of Magnetic Resonance 178 (2006) 42-55.
[ 8] L.G. Rowan, E.L. Hahn, and W.B. Mims, Electron-Spin-Echo Envelope Modulation. Physical Review 137 (1965) A61-A71.
[ 9] S.A. Dikanov, A.A. Shubin, and V.N. Parmon, Modulation effects in the electron spin echo resulting from hyperfine interaction with a nucleus of an arbitrary spin. J. Magn. Reson. 42 (1981) 474-487.
[10] J.M. Canfield, and K. Warncke, Active site reactant center geometry in the Co-II-product radical pair state of coenzyme B-12-dependent ethanolamine deaminase determined by using orientation-selection electron spin-echo envelope modulation spectroscopy. Journal of Physical Chemistry B 109 (2005) 3053-3064.
[11] L. Sun, O.A. Groover, J.M. Canfield, and K. Warncke, Critical role of arginine 160 of the EutB protein subunit for active site structure and radical catalysis in coenzyme B-12-dependent ethanolamine ammonia-lyase. Biochemistry 47 (2008) 5523-5535.
[12] K. Warncke, Characterization of the product radical structure in the Co-II-product radical pair state of coenzyme B-12-dependent ethanolamine deaminase by using three-pulse H-2 ESEEM spectroscopy. Biochemistry 44 (2005) 3184-3193.
[13] Y.S. Zhu, Probability and Statistics in Experimental Physics, Science Press, Beijing, 2006.
[14] K. Warncke, and J. McCracken, Analysis of static distributions in hydrogen hyperfine interactions in randomly oriented radicals in the solid state by using 2H electron spin echo envelope modulation spectroscopy: conformational dispersion of b-2H coupling in the model tyrosyl radical. J. Chem. Phys. 103 (1995) 6829-40.