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 (∼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 σ and π 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.
@article{arxiv.2510.11929,
title = {Bond-resolved STM with density-based methods},
author = {Emiliano Ventura-Macias and Jose Martinez-Castro and Guillermo Haas and Jara Trujillo-Mulero and Pablo Pou and Taner Esat and Markus Ternes and Ruslan Temirov and F. Stefan Tautz and Ruben Perez},
journal= {arXiv preprint arXiv:2510.11929},
year = {2025}
}