Simulated STM fingerprints for transition-metal porphyrins and phthalocyanines on metallic surfaces

*Luiza Buimaga-Iarinca, Cristian Morari
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca, Romania

Porphyrins and phtalocyanines with transition-metal cores make the ideal building blocks for functional thin films in nanotechnology. Although they were intensively studied in the past decades, some of their characteristics can only be described computationally. In this respect, we investigated the interaction characteristics between some transition-metal phthalocyanines/porphyrins and metallic surfaces i.e. Au(111) and Ag(111), with focus on simulated STM images to be further compared to experimental data. Our approach is based on the vdW-DF-cx exchange–correlation functional of Berland and Hyldgaard as implemented in SIESTA and includes DFT+U corrections. The simulation of the STM images was performed using the Tersoff-Hamman approximation as a "constant current" experiment. We emphasize the role of the transition metals (Cr, Mn, Fe, Co, Ni) as well as that of the organic moiety, and thus provide a powerful tool for discriminating between various experimental STM images.

Acknowledgements: Experimental data is provided by Nanolab team from UniBasel, Switzerland. The computational work was funded by the UEFISCDI, project PN-III-P4-IDPCE-2016-0217.