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64 interaction between tetrahydrofuran solvent and zinc oxideFigure 5.4.: Interaction between a THF molecule and the ZnO surface.are indeed explored (with the molecule quasi vertical asshown in Figure 5.5 left and center or, parallel to the surfaceas shown in Figure 5.5 right), desorption is never observed.Figure 5.5.: Some stable configurations of a THF molecule on the ZnOsurface.In order to validate the MPMD result, the minimum energymolecule-surface configuration (inset Figure 5.3 left)is further relaxed at DFT level (Figure 5.3 left) by usingthe Quantum-ESPRESSO [107] code. The method used isdescribed in section A.3.A Zn-O bond of length 2.1 Å due to the electrostaticinteraction between the positively charged Zn and the negativeoxygen of THF and a partial electronic density overlap,can be observed after the relaxation ( Figure 5.3 rightpanel). Both MPMD and DFT calculation show that themolecule prefers the twist geometry with its plane slightlytilted with respect to the vertical (see Figure 5.3 left andinset). The adhesion energy, calculated by including the