The PMF results obtained in the ABF-MD simulations are strongly dependent on the accuracy of the force field describing the interactions between the atoms. To validate the use of OPLS-AA with the explicit modelling of π-electrons through the IFF, we carry out first-principles DFT calculations. As seen in the previous section, the base solvent plays only a minor role in the DCA adsorption process onto a PAH deposit. Therefore, the qualitative trends found in classical MD simulations with explicit modelling of the solvent can be compared with DFT results in vacuum. In particular, the adsorption enthalpy values from the MD simulations shown in Figure provide the most direct comparison to the DFT calculations. Simulations are also performed for iso-octane, which permits to understand how much favourable is the binding of a surfactant polar group in comparison to the solvent tendency to adsorb on circumovalene.