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Whether a molecular or crystal surface is chemically active plays a crucial role in evaluating both the selectivity of molecular adsorption and the interatomic forces observed in atomic force microscopy (AFM). In this study, we propose a local regional chemical potential (RCP) analysis method based on an energy window scheme [1] to quantitatively estimate the selectivity of atomic and molecular adsorption on surfaces, as well as the strength of chemical bonding forces between a probe tip and a surface in AFM measurements [2,3].

In particular, focusing on the local picture of covalent bonding, we use a simple H2 molecular model to demonstrate a clear relationship between chemical bonding forces and the local RCP. Moreover, for molecular systems and diamond C(001) surfaces, we perform density functional theory calculations and reveal that the local RCP at the surfaces successfully visualizes electron-donating regions such as dangling bonds and double bonds. These results suggest that the local RCP can serve as an effective measure to analyze high-resolution non-contact or near-contact AFM images enhanced by chemical bonding forces.

[1] M. Fukuda, M. Senami, Y. Sugimoto, and T. Ozaki, arXiv:2505.04053.
[2] R. Zhang, Y. Yasui, M. Fukuda, T. Ozaki, M. Ogura, T. Makino, D. Takeuchi, and Y. Sugimoto, Nano Letters 25, 1101 (2025).
[3] R. Zhang, Y. Yasui, M. Fukuda, M. Ogura, T. Makino, D. Takeuchi, T. Ozaki, and Y. Sugimoto, Phys. Rev. Res. 7, 023036 (2025).

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