Publications

@article{Kender_2025a,

title = {Automatic Determination of Quasicrystalline Patterns from Microscopy Images},

author = {Tano Kim Kender and Marco Corrias and Cesare Franchini},

doi = {10.1002/aidi.202500043},

year  = {2025},

date = {2025-07-09},

journal = {Advanced Intelligent Discovery},

pages = {202500043},

abstract = {Quasicrystals are aperiodically ordered solids that exhibit long-range order without translational periodicity, bridging the gap between crystalline and amorphous materials. Due to their lack of translational periodicity, information on atomic arrangements in quasicrystals cannot be extracted by current crystalline lattice recognition softwares. This work introduces a method to automatically detect quasicrystalline atomic arrangements and tiling using image feature recognition coupled with machine learning, tailored toward quasiperiodic tilings with 8-, 10-, and 12-fold rotational symmetry. Atom positions are identified using clustering of feature descriptors. Subsequent nearest-neighbor analysis and border following on the interatomic connections deliver the tiling. Support vector machines further increase the quality of the results, reaching an accuracy consistent with those reported in the literature. A statistical analysis of the results is performed. The code is now part of the open-source package AiSurf.},

keywords = {P07},

pubstate = {published},

tppubtype = {article}

}

@article{Sringam_2025a,

title = {Direct conversion of methane to value-added hydrocarbons using alkali metal-promoted cobalt catalysts},

author = {Sarannuch Sringam and Punyanut Thansiriphat and Thongthai Witoon and Waleeporn Donphai and Metta Chareonpanich and Chularat Wattanakit and Hiesang Sohn and Nevzat Yigit and Günther Rupprechter and Anusorn Seubsai},

doi = {10.1039/D5RA02408K},

year  = {2025},

date = {2025-07-07},

journal = {RSC Advances},

volume = {15},

issue = {28},

pages = {23103-23114},

abstract = {The oxidative coupling of methane (OCM) is a promising pathway for directly converting methane into higher hydrocarbons (C_{2+}). This research investigated the influence of alkali metal promoters (Li, Na, K, or Rb) on Co/Al_{2}O_{3} catalysts prepared based on incipient wetness impregnation for the OCM reaction. The catalyst investigations demonstrated that the catalysts promoted with K and Rb had superior performance, with the 4.6K–Co/Al_{2}O_{3} catalyst achieving a maximum C_{2+} yield of 8.1%, C_{2+} selectivity of 24.0%, and CH_{4} conversion of 32.1% at 640 °C. Catalyst characterization, based on XRD, HR-TEM, BET, XPS, CO_{2}-TPD, and H_{2}-TPR analyses, revealed the structural and physicochemical properties responsible for the enhanced catalytic activity. Specifically, K and Rb promoters increased surface basicity and enhanced the electron density of active sites, thereby promoting selective methane activation. In-situ DRIFTS and mechanistic studies highlighted the role of reactive oxygen species in promoting C_{2+} hydrocarbon formation. These results should position K–Co/Al_{2}O_{3} as a promising catalyst for OCM and provide valuable guidance for designing more efficient catalytic systems for methane utilization.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Birschitzky_2024b,

title = {Machine Learning Small Polaron Dynamics},

author = {Viktor C. Birschitzky and Luca Leoni and Michele Reticcioli and Cesare Franchini},

url = {https://doi.org/10.1103/PhysRevLett.134.216301},

year  = {2025},

date = {2025-05-27},

urldate = {2024-09-24},

journal = {Physical Review Letters},

volume = {134},

issue = {21},

pages = {216301},

abstract = {Polarons are crucial for charge transport in semiconductors, significantly impacting material properties and device performance. The dynamics of small polarons can be investigated using first-principles molecular dynamics. However, the limited timescale of these simulations presents a challenge for adequately sampling infrequent polaron hopping events. Here, we introduce a message-passing neural network combined with first-principles molecular dynamics within the Born-Oppenheimer approximation that learns the polaronic potential energy surface by encoding the polaronic state, allowing for simulations of polaron hopping dynamics at the nanosecond scale. By leveraging the statistical significance of the long timescale, our framework can accurately estimate polaron (anisotropic) mobilities and activation barriers in prototypical polaronic oxides across different scenarios (hole polarons in rocksalt MgO and electron polarons in pristine and F-doped rutile TiO_{2}) within experimentally measured ranges.},

keywords = {P07},

pubstate = {published},

tppubtype = {article}

}

@article{Sokolovic_2025a,

title = {Duality and degeneracy lifting in two-dimensional electron liquids on SrTiO_{3}(001)},

author = {Igor Sokolović and Eduardo B. Guedes and Thomas P. van Waas and Fei Guo and Samuel Poncé and Craig Polley and Michael Schmid and Ulrike Diebold and Milan Radović and Martin Setvín and J. Hugo Dil},

url = {https://doi.org/10.1038/s41467-025-59258-4},

year  = {2025},

date = {2025-05-17},

journal = {Nature Communications},

volume = {16},

issue = {1},

pages = {4594},

abstract = {Two-dimensional electron liquids (2DELs) have increasing technological relevance for ultrafast electronics and spintronics, yet significant gaps in their fundamental understanding are exemplified on the prototypical SrTiO_{3}. We correlate the exact SrTiO_{3}(001) surface structure with distinct 2DELs through combined microscopic angle-resolved photoemission spectroscopy and non-contact atomic force microscopy on truly bulk-terminated surfaces that alleviate structural uncertainties inherent to this long-studied system. The SrO termination is shown to develop a 2DEL following the creation of oxygen vacancies, unlike the intrinsically metallic TiO_{2} termination. Differences in degeneracy of the 2DELs, with nearly the same band filling and identical band bending, are assigned to polar distortions of the Ti atoms in combination with spin order, supported with the extraction of fundamental electron-phonon coupling strength. These results not only resolve the ambiguities regarding 2DELs on SrTiO_{3} thus far, but also pave the way to manipulating band filling and spin order in oxide 2DELs in general.},

keywords = {P02},

pubstate = {published},

tppubtype = {article}

}

@article{Tangpakonsab_2025a,

title = {Mechanistic Insights into CO and H_{2} Oxidation on Cu/CeO_{2} Single Atom Catalysts: A Computational Investigation},

author = {Parinya Tangpakonsab and Alexander Genest and Gareth S. Parkinson and Günther Rupprechter},

url = {https://doi.org/10.1007/s11244-025-02102-2},

doi = {10.1007/s11244-025-02102-2},

year  = {2025},

date = {2025-05-15},

urldate = {2025-05-15},

journal = {Topics in Catalysis},

abstract = {Single atom catalysts (SACs) have attracted significant interest due to their unique properties and potential for enhancing catalytic performance in various chemical reactions. In this study, we atomistically explore adsorption properties and catalytic performance of single Cu atoms anchored at low-index CeO_{2} surfaces, focusing on the oxidation of CO and H_{2}. Utilizing density functional theory (DFT) calculations, we report that Cu adatoms bind favorably on different CeO_{2} surfaces, following a stability order of (100) > (110) > (111). The charge transfer from a single adsorbed Cu atom to Ce leads to the reduction of Ce^{4+} to Ce^{3+} and the oxidation of Cu^{0} to Cu^{+}. This strengthens molecular bonds at Cu sites, particularly for CO, while H_{2} shows a by ~ 1 eV weaker adsorption. CO oxidation is energetically more favorable than H_{2} oxidation on the Cu/CeO_{2}(111) surface. The rate-controlling steps for the Mars–van Krevelen mechanism involve the formation of a bent CO_{2} intermediate for CO and H_{2}O for H_{2}. The lattice oxygen atom at the interface plays a key role for both oxidation processes. Our findings highlight the potential of single atom catalyst, Cu/CeO_{2}, for selective CO adsorption and its subsequent oxidation in heterogeneous catalysis.},

keywords = {P04, P08},

pubstate = {published},

tppubtype = {article}

}

@article{Coretti2022,

title = {Learning Mappings between Equilibrium States of Liquid Systems Using Normalizing Flows},

author = {Alessandro Coretti and Sebastian Falkner and Phillip Geissler and Christoph Dellago},

doi = {10.1063/5.0253034},

year  = {2025},

date = {2025-05-08},

urldate = {2022-08-22},

journal = {The Journal of Chemical Physics},

volume = {162},

issue = {18},

pages = {184102},

abstract = {Generative models and, in particular, normalizing flows are a promising tool in statistical mechanics to address the sampling problem in condensed-matter systems. In this work, we investigate the potential of normalizing flows to learn a transformation to map different liquid systems into each other while allowing at the same time to obtain an unbiased equilibrium distribution. We apply this methodology to the mapping of a small system of fully repulsive disks modeled via the Weeks–Chandler–Andersen potential into a Lennard-Jones system in the liquid phase at different coordinates in the phase diagram. We obtain an improvement in the relative effective sample size of the generated distribution up to a factor of six compared to direct reweighting. We show that this factor can have a strong dependency on the thermodynamic parameters of the source and target system.},

keywords = {P12},

pubstate = {published},

tppubtype = {article}

}

@article{Cao_2025a,

title = {Quantum Delocalization Enables Water Dissociation on Ru(0001)},

author = {Yu Cao and Jiantao Wang and Mingfeng Liu and Yan Liu and Hui Ma and Cesare Franchini and Yan Sun and Georg Kresse and Xing-Qiu Chen and Peitao Liu},

doi = {10.1103/PhysRevLett.134.178001},

year  = {2025},

date = {2025-04-30},

journal = {Physical Review Letters},

volume = {134},

issue = {17},

pages = {178001},

abstract = {We revisit the long-standing question of whether water molecules dissociate on the Ru(0001) surface through nanosecond-scale path-integral molecular dynamics simulations on a sizable supercell. This is made possible through the development of an efficient and reliable machine-learning potential with near first-principles accuracy, overcoming the limitations of previous ab initio studies. We show that the quantum delocalization associated with nuclear quantum effects enables rapid and frequent proton transfers between water molecules, thereby facilitating the water dissociation on Ru(0001). This work provides the direct theoretical evidence of water dissociation on Ru(0001), resolving the enduring issue in surface sciences and offering crucial atomistic insights into water-metal interfaces.},

keywords = {P03, P07},

pubstate = {published},

tppubtype = {article}

}

@article{Sokolovic_2024a,

title = {How to cleave cubic perovskite oxides},

author = {Igor Sokolović and Michael Schmid and Ulrike Diebold and Martin Setvín},

doi = {10.1063/5.0233747},

year  = {2025},

date = {2025-03-20},

urldate = {2025-03-20},

journal = {Review of Scientific Instruments},

volume = {96},

issue = {3},

pages = {035113},

abstract = {Surfaces of cubic perovskite oxides attract significant attention for their physical tunability and high potential for technical applications. Bulk-terminated surfaces are desirable for theoretical modeling and experimental reproducibility, yet there is a lack of methods for preparing such well-defined surfaces. We discuss a method for strain-assisted cleaving of perovskite single crystals, using a setup easily transferable between different experimental systems. The details of the cleaving device and the procedure were optimized in a systematic study on the model cubic perovskite oxide SrTiO_{3}. The large-area morphology and typical distribution of surface terminations on cleaved SrTiO_{3}(001) are presented, with specific guidelines on how to distinguish well-cleaved surfaces from conchoidally fractured ones. The cleaving is applicable to other cubic perovskites, as demonstrated on KTaO_{3}(001) and BaTiO_{3}(001). This approach opens up a pathway for obtaining high-quality surfaces of this promising class of materials.},

keywords = {P02},

pubstate = {published},

tppubtype = {article}

}

@article{Wu_2025a,

title = {Green Syngas from Photothermal Catalytic Cellulose Steam Reforming on Ni/SiO_{2} Nanocatalysts: Synergy of La^{3+} Promotion and Ni–O Photoactivation},

author = {Jichun Wu and Chongyang Zhou and Mengqi Zhong and Qing Du and Cong Ji and Qianqian Hu and Lei Ji and Xia Li and Günther Rupprechter and Yuanzhi Li},

doi = {10.1002/smll.202411977},

year  = {2025},

date = {2025-03-03},

journal = {Small},

volume = {21},

issue = {14},

pages = {2411977},

abstract = {Replacing fossil fuels by renewable biomass enables green syngas production in an effort to achieve carbon neutrality and sustainable circular processes. Here, an inexpensive catalyst of Ni nanoparticles supported on SiO_{2} modified by La^{3+} (Ni/La_{0.10}–S) is presented, exhibiting exceptional H_{2} and CO production rates (4051.4 and 2467.8 mmol g_{catalyst}^{−1}h^{−1}, respectively) with 7.7% light-to-fuel efficiency in cellulose steam reforming (SR), merely under focused illumination. Excellent performance is mainly attributed to photothermal catalysis resulting from the strong solar absorption and high photothermal conversion by the Ni nanoparticles. The mitigation of tar and char formation significantly benefits from the H_{2}O involvement in the reaction, which is substantially improved by La^{3+} addition enhancing H_{2}O sorption. Remarkably, the illumination exerts mere photoactivation during reaction, which is primarily attributed to the pronounced activation of Ni─O bonds at the catalyst surface. Particularly, the photoactivation of the Ni–O–La moieties, in combination with O species replenishment by H_{2}O, makes Ni/La_{0.10}–S superior to Ni/SiO_{2}. The synergy of La^{3+} promotion and Ni–O photoactivation poses a promising strategy for efficient photothermal catalytic cellulose SR to green syngas.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Gorfer_2024b,

title = {Mechanism and kinetics of sodium diffusion in Na-feldspar from neural network based atomistic simulations},

author = {Alexander Gorfer and Rainer Abart and Christoph Dellago},

doi = {10.1016/j.actamat.2024.120657},

year  = {2025},

date = {2025-03-01},

urldate = {2024-05-29},

journal = {Acta Materialia},

volume = {286},

pages = {120657},

abstract = {Alkali diffusion is a first-order control for microstructure and compositional evolution of feldspar during cooling from high temperatures of primary magmatic or metamorphic crystallization, and knowledge of the respective diffusion coefficients is crucial for reconstructing thermal histories. Our understanding of alkali diffusion in feldspar is, however, hindered by an insufficient grasp of the underlying diffusion mechanisms. We performed molecular dynamics simulations of sodium feldspar (Albite) containing different point defects using a recently developed neural network potential. A high degree of agreement between the sodium self-diffusion coefficients obtained from model simulations and those determined experimentally in earlier studies motivated a detailed investigation into the interstitial and vacancy mechanisms, corresponding jump rates, correlation factors and anisotropy. We identified a dumbbell shaped double occupancy of an alkali site as an important point defect and a correlation effect originating from the orientation of the dumbbell as a possible cause for the ⊥(001)>⊥(010) diffusion anisotropy, which has been reported in a slew of feldspar cation diffusion experiments.},

note = {Acta Materialia, submitted},

keywords = {P12},

pubstate = {published},

tppubtype = {article}

}