Python package for fitting dielectric/Raman/IR spectral data with an arbitrary number of different lineshape functions
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license PyPI


The spectrumfitter package is an obect-oriented framework for fitting dielectric spectra.

The following lineshapes are supported (bold text refers to the class name):

  • Debye - Debye dielectric relxation
  • DHO - Damped harmonic oscillator
  • Gaussian() - Gaussian function for imaginary part and corresponding real part.
  • Constant() - constant function for real part, 0 imaginary part.
  • ColeCole() - Cole-Cole dielectric relaxation
  • VanVleck() - Van Vleck & Weisskopf lineshape [Rev. Mod. Phys., 17:227 236, (1945)]
  • BrendelDHO - Brendel DHO [Ref: J. Appl. Phys. 71, 1 (1992) ]
  • PowerLawDebye() - Debye lineshape with truncated power law wing. [J. Phys. Chem. B 109 (12), 6031 (2005)]
  • StrExp - Stretched exponential relaxation lineshape (a non-analytic function).

Besides basic fitting it has several advanced features, such as:

  • Use the f-sum rule as a constraint
  • Use the generalized LST (gLST) relation as a constraint
  • Fit and plot the longitudinal dielectric function

Example codes are shown in the examples directory.