Optimisation of the model-free models

This is the simplest category as it involves solely the optimisation of the model-free parameters of an individual residue while the diffusion tensor parameters are held constant. The model-free parameters belong to the set $\mathfrak{F}_i$ of the residue i. The models include m0 to m9 and the dimensionality is low with

$$\mathfrak{F}_i = k \leqslant 5$$ (15.1)

for the most complex model m8 = {S², τ_f, S²_f, τ_s, R_ex}. The relaxation data of a single residue is used to build the chi-squared value, gradient, and Hessian.