In other words, all the eigenvalues of the matrix must be non-negatives. However, few of the activated MOFs under study did not satisfy such stability criteria. Moreover, in very few cases the estimated properties using Resus method exceeded that obtained with Voigt method, which is unrealistic. Furthermore, in few cases it resulted into negative mechanical properties, especially the lower bounds. Though, this cannot be surely attributed to instability of the crystal, hence suitability of the employed force field has also some influences. Therefore, in present work, the calculated negative properties for the bulk and shear moduli (mainly with the Reuss method) were rounded to zero, and afterward the young modulus was calculated.