A program for optimizing “Lipari-Szabo model free” parameters to heteronuclear relaxation data.

Current version is 4.20

© Copyright 1998, Arthur G. Palmer, III

A. M. Mandel, M. Akke and A. G. Palmer, Backbone dynamics of Escherichia coli ribonuclease HI: Correlations with structure and function in an active enzyme, J. Mol. Biol. 246, 144-163 (1995).

Modelfree4 is now available as compiled executables for Linux and Macintosh OSX operating systems.

If you download ModelFree4 and decide to use it, then please email, so that we can add you to our users list. This way we can reach you with bug reports and updates. If you download the program, please check this site frequently for updates in case of bug fixes (and please send email regarding any bugs you think you find).

If you need access to source code or executables for other computer architectures, please contact Arthur G. Palmer (

Version History

4.00 (04/15/98) Initial version
4.01 (07/15/99) Fixed errors in F-statistic distributions
4.10 (02/4/00) Fixed additional errors in chi2 and F-statistic distributions, added uncertainties to CSA for error analysis, added the relaxation interference rate constant ratio as an optional relaxation parameter.
4.15 (04/10/02) Fixed errors due to type checking. Fixed flush-to-zero flag for SGI R12000 chip
4.16 (07/02/04 Type declarations fixed. Present version can be compiled by GNU g77
4.20 (11/12/06) Ended support for SGI platform. Only linux and mac OSX are supported platforms at present. Fixed termination criteria and simulated distribution of F-statistic error. A bug identified by Edward d’Auvergne that caused the minimization algorithm to terminate inappropriately after an unsuccessful optimization step has been fixed. A bug in the test for whether bounded parameters could be returned to the active set has been fixed. Changed grid search so the exact upper and lower bounds are not grid search points. Maximum number of residues was increased to 300.

Fast ModelFree

A graphical front-end for running the ModelFree program. Originally written by Roger Cole and J. Patrick Loria (Yale University). The current version has been updated by A.G. Palmer and M. Rance.

Current version is 1.3

R. Cole and J.P. Loria, FAST-Modelfree: a program for rapid automated analysis of solution NMR spin-relaxation data, J. Biomol. NMR 26, 203-213 (2003).


A python library and notebook for reading and interpreting the mfout files produced by the ModelFree program. This package replaces the now unsupported STARBASE tools for reading mfout files. mfoutParser is written by Michelle Gill and Arthur Palmer.

Current version is 1.0


ModelFree Manual

ModelFree for Macintosh OSX

ModelFree for Linux64

FastModelFree Manual