CHIFIT 2.0
Maximum Likelihood Analysis of Multidimensional NMR Spectra
Roger A. Chylla National Magnetic Resonance Facility at Madison
Maintained by the NMRFAM Software Development Group

CHIFIT 2.0 is an application which extracts NMR parameters (frequency, amplitude, phase, decay rate, etc.) from n-dimensional NMR data by fitting the absorption spectrum of the data to the absorption spectrum of an analytical time-domain model of the data. The model fitting process is done simultaneously along all n-dimensions of the data thus taking advantage of the entire information content of the spectrum. This approach provides a completely automated pathway for signal recognition and parameter estimation of large n-dimensional experiments.

CHIFIT version 2.0 is in a beta test phase.

CHIFIT 2.0 is currently undergoing testing and reprogramming for a version that can be distributed to outside NMRFAM users. CHIFIT 1.0 is still available, but it is not being serviced in any way at this time.

Main Features of Chifit 2.0a
Main Function
  • Extracts parameters (e.g. frequency, amplitude, phase, decay rates, etc.) from large n-dimensional NMR matrixes by fitting the fourier transform of the acquired data to the fourier transform of a n-dimensional NMR matrix.
  • Fitting process is done simultaneously along all dimensions thus taking advantage of the entire information content of the spectrum.
  • Can provide a completely automated pathway for signal recognition and parameter estimation of large multidimensional experiments.
Signal Models
  • Models can be constructed for any dimensionality (e.g. 1D,2D,3D,4D, etc.)
  • Flexible models allow the spectroscopist to tailor a signal type or series of type(s) to model the specific features of the acquired data
  • Constraints can be placed on any parameter
  • Parameters can be held static.
Applicaton Programming Interface (API)
  • The Chifit 2.0a API is implemented as an extension module of Python.
  • The Chifit/Python API provides an object-oriented environment that allows full control of the graphical user interface (GUI), database, signal creation, signal optimization, output formatting, etc. from the dynamic execution of macros.
  • Jobs may be performed in foreground or background
  • Control can be established from standard input either locally or remotely
Graphical User Interface (GUI)
  • Menus, dialog boxes, and other standard GUI elements are implemented using XWindows (Motif) and can be run remotely from a X-Windows client.
  • The absorption spectrum, model, residual, and components of the signal model can be viewed graphically as 2D contour plots or as 1D slices through any dimension.
  • Display of the signal parameters via dialog boxes is linked with graphical visualization of the results.
  • The Chifit 2.0a graphical interface is built upon wxPython and thus can be completely controlled from dynamically executed scripts.
Exporting Results
  • Data can be exported to an ASCII file in any arbitrary format