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arXiv · 2510.11929

Bond-resolved STM with density-based methods

Emiliano Ventura-Macias·Jose Martinez-Castro·Guillermo Haas·Jara Trujillo-Mulero·Pablo Pou·Taner Esat·Markus Ternes·Ruslan Temirov·F. Stefan Tautz·Ruben Perez
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Abstract

Bond-resolved STM (BRSTM) is a recent technique that combines the advantages of scanning tunneling microscopy (STM) with the outstanding intramolecular resolution provided by non-contact atomic force microscopy (ncAFM) using a CO-functionalized tips, offering unique insights into molecular interactions at surfaces. In this work, we present a novel and easily implementable approach for simulating BRSTM images, which we have applied to reproduce new experimental BRSTM data of Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) on Ag(111), obtained with unprecedented control of tip-sample separation ($\sim$10~pm). Our method integrates the Full-Density-Based Model (FDBM) developed for High-Resolution Atomic Force Microscopy (HRAFM) with Chen's derivative approximation for tunneling channels, effectively capturing the contributions of both $\sigma$ and $\pi$ channels, while accounting for the CO-tip deflection induced by probe-sample interactions. This approach accurately reproduces the experimental results for both PTCDA/Ag(111) and 1,5,9-trioxo-13-azatriangulene (TOAT)/Cu(111) systems, including intricate tip-sample distance-dependent features. Furthermore, we also demonstrate the important role of substrate-induced effects, which can modify molecular orbital occupation and the relaxation of the CO probe, resulting in distinct BRSTM image characteristics.

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Emiliano Ventura-Macias, Jose Martinez-Castro, Guillermo Haas, Jara Trujillo-Mulero, Pablo Pou, Taner Esat, Markus Ternes, Ruslan Temirov, F. Stefan Tautz, Ruben Perez. 2025-10-13. Bond-resolved STM with density-based methods. https://arxiv.org/abs/2510.11929

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