Fig. 10. Optimized adsorption heights (a) and corresponding adsorption energies (b) for PTCDA/Ag(111) with different methods. Results for different functional/vdW-correction scheme combinations. The different functionals (LDA, PW91, PBE, revPBE), were combined with the Grimme-D3 scheme and the Tkatchenko–Scheffler correction method in their original (TS), surface (vdW^surf) and MBD variant. The vdW-DF and the SCAN+rVV10 functional were used as representatives for non-local functionals (right column in a and b). (c) shows the energy difference between the two stable adsorption sites of the molecule. Calculations details are given in Hörmann et al.²⁸² The experimental values are reproduced from literature:^161,284,285 For the adsorption height, they were obtained by X-ray standing wave experiments,^284,285 the adsorption energy was extrapolated based on the chemically related NTCDA molecule.¹⁶¹.