Apparent Height of the Metal Atom in Phthalocyanine: Co vs Cu

We analyze the influence of the metal center of two metalized phthalocyanines, Cu-phthalocyanine and Co-phthalocyanine, adsorbed on the Ag(100) surface on their imaging characteristics by apparent height spectroscopy performed with a low-temperature scanning tunneling microscope and explain it based on density functional theory calculations. Bias voltages with and without chemical difference in phthalocyanine imaging are identified based on apparent height spectra over a wide range of voltages. These experimental differences are reflected in the varying spatial distributions of the all-atom electron charge density within the phthalocyanines. We thus ascribe the imaging difference of disparate metal centers of metalized phthalocyanine to differing charge transfers induced by the respective metal atoms.