09:00 - 09:20
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Kang Hun Ahn
(Chungnam Natioanal University)
Physics-inspired denoising AI models
It will describe how the diffusion process is used in generative AI model and a new physics-based AI model.
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09:20 - 09:40
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Liviu Hozoi
(IFW Dresden)
Correlations from quantum chemical perspective: the weak, the strong, the mixed
Wavefunctions can tell everything. The computation of many-electron wavefunctions from first principles in solid-state context is one of the long-term projects set up by Peter Fulde. A few illustrative examples are reviewed in this contribution, ranging from the calculation of quasiparticle bands in either weakly [1] or strongly [2] correlated electronic systems to the nature of ground-state wavefunctions across group-5 mixed-valent 'breathing' pyrochlores [3] and in alkaline-earth hexaborides [4].
[1] L Hozoi, U Birkenheuer, P Fulde, A Mitrushchenkov, and H Stoll, Ab initio wavefunction-based methods for excited states in solids: correlation corrections to the band structure of ionic oxides, Phys. Rev. B 76, 085109 (2007).
[2] L Hozoi, M S Laad, and P Fulde, Fermiology of cuprates from first principles: from small pockets to the Luttinger Fermi surface, Phys. Rev. B 78, 165107 (2008).
[3] T Petersen, P Bhattacharyya, U K Roessler, and L Hozoi, Resonating holes vs molecular spin-orbit coupled states in group-5 lacunar spinels, Nat. Commun. 14, 5218 (2023).
[4] T Petersen, U K Roessler, and L Hozoi, Quantum chemical insights into hexaboride electronic structures: correlations within the boron p-orbital subsystem, Commun. Phys. 5, 214 (2022).
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09:40 - 10:00
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Beate Paulus
(Freie Universität Berlin)
Wavefunction-based methods for extended systems
Peter Fulde's early work on the so-called "local ansatz" for a wavefunction in extended systems provided the basis for the application of correlation methods, developed mainly in Theoretical Chemistry for finite systems, to extended systems namely solids. Within this contributions I will focus on the method of increments and its application to different kind of solids, from insulators to metals, from van der Waals bound rare gas crystals to metallic binding in mercury.
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10:00 - 10:20
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M. Veronica Ganduglia-Pirovano
(Consejo Superior de Investigaciones Científicas, Madrid)
Cerium-Oxide-Bound CO Vibrations: Beyond DFT's Comfort Zone
In cerium oxide-based catalysis, surface structure plays a crucial role in the catalyst's reactivity. The vibrational frequency of surface-adsorbed carbon monoxide (CO) surface serves as a precise marker for identifying active defect sites and determining the exposed crystal facets. To analyze spectroscopic data accurately, reference data for well-characterized single crystal surfaces and a precise theoretical assignment of the vibrations are essential. Significant efforts have been made to gather comprehensive IRRAS (infrared reflection absorption spectroscopy) data for CO adsorption on all three low-index single-crystal ceria surfaces, both in their oxidized and reduced forms, at saturation coverage.$^{1-3}$ However, applying theoretical methods, many of which rely on density functional theory (DFT) with the generalized gradient approximation (GGA) for exchange and correlation, has encountered significant challenges in accurately describing CO adsorption on oxides. Recently, there has been a growing interest in combining machine learning (ML) techniques with DFT calculations for interpreting spectroscopic data. In this study, we demonstrate that by employing DFT with the HSE06 hybrid functional yields excellent agreement with experimental data. Achieving this high level of consistency, requires meticulously adjustment of the model to closely align with experimental conditions. These conditions encompass factors such as surface orientation, the presence of oxygen vacancies, and the extent of CO coverage. Our study reveals that CO is highly sensitive to the precise structure of ceria surfaces. We also explain the limitations of conventional DFT by highlighting its inability to accurately capture facet- and configuration-specific donation and backdonation effects, which control the changes in the C$─$O bond length upon CO adsorption and the CO force constant.$^{4,5}$ Our findings establish a robust theoretical foundation for the accurate interpretation of experimental results. Furthermore, we emphasize the importance of understanding the origin of DFT data before blindly incorporating them into ML models.$^{6}$
[1] C. Yang, X. Yu, S. Heisler, A. Nefedov, S. Colussi, J. Llorca, A. Trovarelli, Y.Wang, C. Wöll, Angew. Chem., Int. Ed. 56 (2017) 375.
[2] C. Yang, L.-L. Yin, F. Bebensee, M. Buchholz, H. Sezen, S. Heissler, J. Chen, A. Nefedov, H. Idriss, X.-Q. Gong, C. Wöll, Phys. Chem. Chem. Phys. 16 (2014) 24165.
[3] C. Yang, M. Capdevila-Cortada, C. Dong, Y. Zhou, J. Wang, X. Yu, A. Nefedov, S. Heissler, N. López, W. Shen, C. Wöll, Y. Wang, J. Phys. Chem. Lett. 11 (2020) 7925.
[4] P. G. Lustemberg, P. N. Plessow, Y. Wang, C. Yang, A. Nefedov, F. Studt, C. Wöll, M. V. Ganduglia-Pirovano, Phys. Rev. Lett. 125 (2020) 256101.
[5] P. G. Lustemberg, C. Yang, Y. Wang, C. Wöll, M. V. Ganduglia-Pirovano, J. Chem. Phys. 159 (2023) 034704.
[6] M. V. Ganduglia-Pirovano, A. Martínez-Arias, S. Chen, Y. Wang, Pablo G. Lustemberg, Mater. Today Sustain. 26 (2024) 100783.
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10:20 - 10:40
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Stefan Blawid
(Federal University of Pernambuco, Recife)
A Hypothetical Route to Computing with Correlated Electrons
Biological sensory systems exhibit remarkable power efficiency, largely due to their capacity to store and recall learned solutions. Emulating this efficiency in artificial sensory systems necessitates adaptability and analog functionality. One promising approach involves computing based on the complex dynamics of interacting oscillators, particularly when these oscillators serve as the building blocks of artificial intelligence. This talk explores how the Coulomb blockade effect in single molecule transistors can form the foundation of the smallest conceivable oscillators. We will discuss a potential pathway from utilizing Coulomb blockade to developing oscillatory neural networks capable of executing complex tasks such as image recognition and tackling computationally intensive problems like vertex coloring.
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10:40 - 11:10
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coffee break
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11:10 - 11:30
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Jochen Wosnitza
(Helmholtz-Zentrum Dresden-Rossendorf)
FFLO States in Organic Superconductors
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11:30 - 11:50
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Sadamichi Maekawa
(RIKEN Center for Emergent Matter Science)
Nonreciprocity in spin transport
“Nonreciprocity” means “not going the same way backward as forward”. The well-known is the rectification by using PN junctions in electronics where electrons flow in one direction but not the other. The spin Hall effect and its inverse are the interconversion mechanism between electron current and spin current. It has been shown that the interconversion is reciprocal and described by the Onsager reciprocal relation [1]. On the contrary, many of the spin transport phenomena are nonreciprocal. Here, the nonreciprocity in spin transport is discussed together with various examples. The key is that the spin current is a flow of spin angular momentum, in contrast to the electric current. A flow of electrons can have the orbital angular momentum , which is called “vorticity”, and may be interconverted with spin current [2]. However, since the vorticity of electron flow is highly nonlinear, the conservation mechanism, i.e., the spin-vorticity coupling, is also nonlinear and, in general, nonreciprocal[1]. As a result, we find a variety of nonreciprocal phenomena in spin transport. The nonreciprocity of surface acoustic waves in magnetic films [3], the magnetic skyrmion generation and annihilation by electric current in magnetic films with notch structure [4], and the spin current generation in the graded materials [5] will be discussed.
[1] T. Kimura, Y. Otani, T. Sato, S. Takahashi and S. Maekawa: Phys. Rev. Lett. 98, 156601 (2007),
[2] M.Matsuo, E.Saitoh and S.Maekawa, Chapter 25 in “Spin Current” ed. S.Maekawa et al.
(Oxford University Press, 2017).
[3] M. Xu, K. Yamamoto, J. Puebla, K. Baungaert, B. Rana, K. Miura, H. Takahashi, D. Grundler, A. Maekawa and Y. Otani: Sci. Adv. 6, eabb1724 (2020),
[4] J.Fujimoto, W.Koshibae, M.Matsuo and S.Maekawa, Phys. Rev. B103, L220404 (2021).
[5] G.Okano, M.Matsuo, Y.Ohnuma, S.Maekawa, and Y.Nozaki, Phys. Rev. Lett. 122, 217701 (2019).
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11:50 - 12:10
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Fu-Chun Zhang
(University of Chinese Academy of Sciences)
Theory for superconductivity in \(La_3Ni_2O_7\)
Recent discovery of high temperature superconductivity La3Ni2O7 under high pressure has attracted a lot of attention. In this talk, I shall present our theory for electronic structure of the compound and address the similarity and difference of this newly discovered bilayer nickelate superconductor in comparison with high temperature superconducting cuprates and with infinite layer nickelate superconductor Nd_(1-x)Sr_xNiO2. I shall propose that La3Ni2O7 is a self-doped molecule Mott insulator, where molecule stands for the strongly coupled nickel ions on the top and bottom layers.
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12:10 - 12:20
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concluding remarks
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12:20 - 14:00
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lunch
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14:00
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free discussions
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