Figure 2.

Temperature dependence of fluctuations in density and energy for five archetypal systems. Panel (a) shows the temperature dependence of the density fluctuations quantified as the variance of the density distribution for a given temperature, i.e., ${\sigma }_{\rho }^2=⟨{\rho }^2⟩-{⟨\rho ⟩}^2$. Panel (b) shows the temperature dependence of the specific heat capacity. The specific, constant volume heat capacities were calculated as $C_V=\frac{1}{\mathrm{MW}}{\left(\frac{\partial ⟨E⟩}{\partial T}\right)}_V$, where MW is the molecular weight and ⟨E⟩ is the ensemble-averaged potential energy for simulated ensembles at a given temperature. Typically, one expects sharp transitions for well-defined order-to-disorder transitions and yet, interestingly, the Q₅₆ system shows the sharpest transition. The relatively broad transitions for NTL9 and GB1 highlight the joint contributions of gradual melting and different degrees of residual local structure in their unfolded states.