Experimental THz spectra and long-range correlated fluctuations. (a) Experimental THz spectrum of the LHS (blue solid line) and the HHS (red dotted-dashed-dotted line) of crambin in the 100 – 165 cm−1 spectral region at 303 K. (b) The network representation of the LHS of crambin depicting long-range correlated fluctuations in the protein detected in the MD simulations (using Equation 3). The nodes represent amino acids and the sizes of the nodes reflect the amplitude of the fluctuation. The edges between the nodes reflect correlated fluctuations and the thickness of the edges depict the extent of the correlation. The nodes labeled in white represent amino acids involved in disulfide bridges. (c) The Fourier Transform of the rotational autocorrelation function of the vector between the Cα atoms of residues Cys 16 and Cys 40 and (d) the spectrum of the velocity autocorrelation function of the correlated fluctuation involving Cys 16 and Cys 40 from the MD simulations.