A key challenge in bridging scales from the atomistic to the continuum in electrochemical systems is to handle a variable AND vast number of electronic orbitals and their interactions. Three things are widely agreed. First, most electronic orbitals are not important and can be averaged out on the continuum scale. Second, a few electronic orbitals are vital, especially in electrocatalytic systems. Third, the number of electronic orbitals, determined by the number of atoms in the system, is not a parameter but a dependent variable. Together, these three aspects make density functional approaches inefficient beyond the atomistic scale. In this talk, I will present a hybrid density-potential functional approach as a viable option to address the above challenges[1-3]. The basic idea is that potential should be treated on equal footing with density, rather than being a dependent variable of density, for interfaces and interphases with open boundaries. The theoretical framework, benchmark, and early applications of the hybrid approach will be presented. Disadvantages and future development of the hybrid approach will be discussed.
Acknowledgement
J.H. is supported by the Initiative and Networking Fund of the Helmholtz Association (Grant No. VH-NG-1709) and the European Research Council (ERC) Starting Grant (MESO-CAT, Grant Agreement No. 101163405).
References
[1] Zhang, Mengke, Yanxia Chen, Michael Eikerling, and Jun Huang. "Structured solvent on a split electron tail: A semiclassical theory of electrified metal-solution interfaces." Physical Review Applied 23, no. 2 (2025): 024009.
[2] Huang, Jun, Fabiola Domínguez-Flores, and Marko Melander. "Variants of surface charges and capacitances in electrocatalysis: Insights from density-potential functional theory embedded with an implicit chemisorption model." PRX Energy 3, no. 4 (2024): 043008.
[3] Zhang, Yufan, Tobias Binninger, Jun Huang, and Michael H. Eikerling. "Theory of Electro-Ionic Perturbations at Supported Electrocatalyst Nanoparticles." Physical Review Letters 134, no. 6 (2025): 066201.
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