The volumetric thermal expansion coefficient was calculated at different temperatures within the range investigated, and we found a relatively constant rate of contraction, Figure . However, there was a noticeable change in contraction rate observed at approximately 300 K for DUT-49, which is discussed in Section 3.3. Given that NTE in MOF materials is considered a phonon-mediated phenomenon it is unsurprising that NTE persists over this entire temperature range. Notably, this has also been experimentally observed for MOF-5, which shows NTE from 80-500 K. The associated volumetric thermal expansion coefficients were also calculated over the entire temperature range, presented in Table , which provides a metric for these materials. We find that a majority of the investigated MOFs show NTE coefficients > 50 MK -1 , and MOF-399 has an amazingly high coefficient of 87.6 MK -1 . There are very few materials with "colossal" thermal expansion, such as Ag 3 [Co(CN) 6 ], which is defined by Similarly, the linear thermal expansion coefficient (α L ), defined in Equation , can be computed to provide a measure of the expansion rate with respect to each cell length.