Inverted'' porphyrins: a distorted adsorption geometry of free-base porphyrins on Cu(111)

Based on density functional theory calculations combined with experimental results, we report and discuss an extremely distorted, inverted'' adsorption geometry of free-base tetraphenylporphyrin on Cu(111). The current findings yield new insights into a wellstudied system, shedding light on the peculiar molecule-substrate interaction and the resulting intramolecular conformation.