For peptide N-H bonds, N =100 and τ i values were equidistantly spaced in logarithmic scale between 1 ps and 100 ns. For SDS C-H bonds with a substantial amount of dynamics below 1 ps timescales, N =500 and τ i values were equidistantly spaced in logarithmic scale between 1 fs and 1 µs. As a result, the fitting gives the weight, α i , for each timescale that represents the relevance of the given timescale for the rotational relaxation of the bond. Spectral density, J(ω), is then obtained from the analytical Fourier transformation