The maximum contraction of 3 % observed in these systems has a minor effect on their porosity. However, as reported by previous studies, this contraction has an important effect on the mechanical properties. For example, some MOF materials have shown pressure-induced softening before the point of instability. To investigate the effect that temperature-induced contraction has on the mechanical stability of these materials, cell fluctuations from the molecular dynamics simulations were analyzed to compute the elasticity tensor, C i j . This elastic tensor contains key . The values at 0 K correspond to density functional theory simulations reported previously. quantities that characterize the mechanical behavior of the structures in the elastic regime. For example, the directional Young's modulus is derived from the elasticity tensor. We found that all materials show temperature-induced softening, as illustrated in Figure for MOF-399, which demonstrates considerable softening of the Young's modulus.