Tomographic identification of all molecular orbitals in a wide binding energy range
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| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866910778287718400 |
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| author | Haags, Anja Brandstetter, Dominik Yang, Xiaosheng Egger, Larissa Kirschner, Hans Gottwald, Alexander Richter, Mathias Koller, Georg Bocquet, François C. Wagner, Christian Ramsey, Michael G. Soubatch, Serguei Puschnig, Peter Tautz, F. Stefan |
| author_facet | Haags, Anja Brandstetter, Dominik Yang, Xiaosheng Egger, Larissa Kirschner, Hans Gottwald, Alexander Richter, Mathias Koller, Georg Bocquet, François C. Wagner, Christian Ramsey, Michael G. Soubatch, Serguei Puschnig, Peter Tautz, F. Stefan |
| contents | In the past decade, photoemission orbital tomography (POT) has evolved into a powerful tool to investigate the electronic structure of organic molecules adsorbed on surfaces. Here we show that POT allows for the comprehensive experimental identification of all molecular orbitals in a substantial binding energy range, in the present case more than 10 eV. Making use of the angular distribution of photoelectrons as a function of binding energy, we exemplify this by extracting orbital-resolved partial densities of states (pDOS) for 15 $π$ and 23 $σ$ orbitals from the experimental photoemission intensities of the prototypical organic molecule bisanthene (C$_{28}$H$_{14}$) on a Cu(110) surface. In their entirety, these experimentally measured orbital-resolved pDOS for an essentially complete set of orbitals serve as a stringent benchmark for electronic structure methods, which we illustrate by performing density functional theory (DFT) calculations employing four frequently-used exchange-correlation functionals. By computing the respective molecular-orbital-projected densities of states of the bisanthene/Cu(110) interface, a one-to-one comparison with experimental data for an unprecedented number of 38 orbital energies becomes possible. The quantitative analysis of our data reveals that the range-separated hybrid functional HSE performs best for the investigated organic/metal interface. At a more fundamental level, the remarkable agreement between the experimental and the Kohn-Sham orbital energies over a binding energy range larger than 10\,eV suggests that -- perhaps unexpectedly -- Kohn-Sham orbitals approximate Dyson orbitals, which would rigorously account for the electron extraction process in photoemission spectroscopy but are notoriously difficult to compute, in a much better way than previously thought. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2501_05287 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Tomographic identification of all molecular orbitals in a wide binding energy range Haags, Anja Brandstetter, Dominik Yang, Xiaosheng Egger, Larissa Kirschner, Hans Gottwald, Alexander Richter, Mathias Koller, Georg Bocquet, François C. Wagner, Christian Ramsey, Michael G. Soubatch, Serguei Puschnig, Peter Tautz, F. Stefan Chemical Physics Mesoscale and Nanoscale Physics Materials Science In the past decade, photoemission orbital tomography (POT) has evolved into a powerful tool to investigate the electronic structure of organic molecules adsorbed on surfaces. Here we show that POT allows for the comprehensive experimental identification of all molecular orbitals in a substantial binding energy range, in the present case more than 10 eV. Making use of the angular distribution of photoelectrons as a function of binding energy, we exemplify this by extracting orbital-resolved partial densities of states (pDOS) for 15 $π$ and 23 $σ$ orbitals from the experimental photoemission intensities of the prototypical organic molecule bisanthene (C$_{28}$H$_{14}$) on a Cu(110) surface. In their entirety, these experimentally measured orbital-resolved pDOS for an essentially complete set of orbitals serve as a stringent benchmark for electronic structure methods, which we illustrate by performing density functional theory (DFT) calculations employing four frequently-used exchange-correlation functionals. By computing the respective molecular-orbital-projected densities of states of the bisanthene/Cu(110) interface, a one-to-one comparison with experimental data for an unprecedented number of 38 orbital energies becomes possible. The quantitative analysis of our data reveals that the range-separated hybrid functional HSE performs best for the investigated organic/metal interface. At a more fundamental level, the remarkable agreement between the experimental and the Kohn-Sham orbital energies over a binding energy range larger than 10\,eV suggests that -- perhaps unexpectedly -- Kohn-Sham orbitals approximate Dyson orbitals, which would rigorously account for the electron extraction process in photoemission spectroscopy but are notoriously difficult to compute, in a much better way than previously thought. |
| title | Tomographic identification of all molecular orbitals in a wide binding energy range |
| topic | Chemical Physics Mesoscale and Nanoscale Physics Materials Science |
| url | https://arxiv.org/abs/2501.05287 |