A good example of the use of free energy methods is found in the work of Goeminne et al. where the authors obtained the complete thermodynamic landscape of gas adsorption for responsive MOF DUT-49 (more information about this complex and fascinating material will be detailed in subsection 3.1). They used molecular dynamics simulations and thermodynamic integration of the internal pressure in order to reconstruct the 3D profile of osmotic potential as a function of the thermodynamic variables of interest, namely the temperature, the unit cell volume (representing the flexibility of the material) and the gas chemical potential (or external pressure, which is more relevant for experimental comparisons). The different stable states of the system appear as local minima in the thermodynamic potential surface for each value of temperature (see Figure ). In addition to reproducing the experimentally observed structural transitions, traversing the complex landscape of osmotic potential allows the authors to study their temperature dependence, as well as understand the nature of the hysteresis between adsorption and desorption paths, by exploring the metastable states as well.