Installation

Install EPRsim via pip:

$ pip install eprsimgui

Run EPRsimGUI

Call it after installing EPRsimGUI in a virtual Python environment by:

$ EPRsimGUI

Notes

GUI for the simulation of cw-EPR in different motional regimes (isotropic, fast-motion and solid state) All spectra are simulated as field sweep spectra. The GUI program uses the Python package EPRsim.

Isotropic/fast-motion For the fast-motion regime/isotropic limit, the program solves the implicit Breit-Rabi formula [1] in a fixed-point iteration. Anisotropic line-broadening effects in the fast-motion regime are calculated via the Kivelson formula [2]. Currently, Euler angles between tensors are ignored by the algorithm! All tensors (only relevant for fast-motion) need to be in their principal axis system and colinear to each other.

Solid-state In the solid-state regime, the program uses a full matrix diagonalization algorithm. Therefore, only spin systems with a Hilbert space dimension of dim(H) < 512 can be calculated. The powder average is partially generated by interpolation of eigenvalues and transition probabilitites (similar to [1]). The interpolation level is automatically set by the program. The solid state algorithm treats arbitrary spin systems as long as the Hilbert space dimension is within the threshold. Spin-polarization can be defined (withing the electronic sublevels) as zero-field populations. The program constructs (sparse) density matrices out of the zero-field eigenvectors, to efficiently calculate the population transformation from zero field to high field. Per default, the program calculates with thermal equilibrium. Nuclear quadrupolar couplings (for I > 0.5) are currently not implemented.

Properties

EPRsimGUI provides:

• Intuitive GUI for EPR simulations

• Simulation for cw-EPR spectra in the solid-state limit and fast-motion regime

• Flexible simulation options

• Intuitive PSE for choosing nuclear spins

• Basic data processing functions for experimental data

• Optimized performance of the simulation algorithm (uses EPRsim)

• Open-source

Feedback

We are eager to hear about your experiences with GloPel. You can email me at stephan.rein@physchem.uni-freiburg.de.

References

[1] : S. Stoll, A. Schweiger, J. Magn. Reson., 2006, 178, 42-55

[2] : N. M. Atherton, Principles of Electron Spin Resonance, 1993

Acknowledgement

A number of people have helped shaping EPRsim and the ideas behind. First and foremost, Prof. Dr. Stefan Weber and Dr. Sylwia Kacprzak (now Bruker Biospin) were for years the driving force behind EPRsimGUI.