@article{RodriguesPelaHsiaoHultmanetal.2024, author = {Rodrigues Pela, Ronaldo and Hsiao, Ching-Lien and Hultman, Lars and Birch, Jens and Gueorguiev, Gueorgui Kostov}, title = {Electronic and optical properties of core-shell InAlN nanorods: a comparative study via LDA, LDA-1/2, mBJ, HSE06, G0W0 and BSE methods}, volume = {26}, journal = {Physical Chemistry Chemical Physics}, publisher = {Royal Society of Chemistry}, arxiv = {http://arxiv.org/abs/https://arxiv.org/abs/2309.14889}, doi = {10.1039/D3CP05295H}, pages = {7504 -- 7514}, year = {2024}, language = {en} } @inproceedings{ChristgauEveringhamMikolajczaketal.2023, author = {Christgau, Steffen and Everingham, Dylan and Mikolajczak, Florian and Schelten, Niklas and Schnor, Bettina and Schroetter, Max and Stabernack, Benno and Steinert, Fritjof}, title = {Enabling Communication with FPGA-based Network-attached Accelerators for HPC Workloads}, booktitle = {Proceedings of the SC'23 Workshops of The International Conference on High Performance Computing, Network, Storage, and Analysis, SC-W 2023, Denver, CO, USA, November 12-17, 2023}, publisher = {ACM}, doi = {10.1145/3624062.3624540}, pages = {530 -- 538}, year = {2023}, abstract = {The use of stand-alone, network-coupled Field Programmable Gate Array (FPGA) accelerators is intended to significantly increase the energy efficiency of HPC applications and thus also of HPC data centers. A loose coupling between the nodes of the HPC data center and the FPGAs is established through the high-speed network of the data center. This allows greater flexibility in combining different nodes and accelerators. Both the resulting energy savings and the increased flexibility through the network connection, enable the economical use of FPGAs. This work presents a communication stack to integrate the so-called Network-attached Accelerator (NAA) into the HPC data center. A low-level Remote Direct Memory Access (RDMA) Application Programming Interface (API) and a high-level Remote Procedure Call (RPC) API is designed on top of the RDMA over Converged Ethernet v2 (RoCEv2) communication stack. The experimental results over 100 Gbps RoCEv2 show that our design and implementation deliver performance close to the theoretical maximum.}, language = {en} } @article{HoeflingDietrich2024, author = {H{\"o}fling, Felix and Dietrich, Siegfried}, title = {Structure of liquid-vapor interfaces: perspectives from liquid state theory, large-scale simulations, and potential grazing-incidence X-ray diffraction}, volume = {160}, journal = {The Journal of Chemical Physics}, arxiv = {http://arxiv.org/abs/2311.06425}, doi = {10.1063/5.0186955}, pages = {104107}, year = {2024}, abstract = {Grazing-incidence X-ray diffraction (GIXRD) is a scattering technique which allows one to characterize the structure of fluid interfaces down to the molecular scale, including the measurement of the surface tension and of the interface roughness. However, the corresponding standard data analysis at non-zero wave numbers has been criticized as to be inconclusive because the scattering intensity is polluted by the unavoidable scattering from the bulk. Here we overcome this ambiguity by proposing a physically consistent model of the bulk contribution which is based on a minimal set of assumptions of experimental relevance. To this end, we derive an explicit integral expression for the background scattering, which can be determined numerically from the static structure factors of the coexisting bulk phases as independent input. Concerning the interpretation of GIXRD data inferred from computer simulations, we account also for the finite sizes of the bulk phases, which are unavoidable in simulations. The corresponding leading-order correction beyond the dominant contribution to the scattered intensity is revealed by asymptotic analysis, which is characterized by the competition between the linear system size and the X-ray penetration depth in the case of simulations. Specifically, we have calculated the expected GIXRD intensity for scattering at the planar liquid--vapor interface of Lennard-Jones fluids with truncated pair interactions via extensive, high-precision simulations. The reported data cover interfacial and bulk properties of fluid states along the whole liquid--vapor coexistence line. A sensitivity analysis demonstrates the robustness of our findings concerning the detailed definition of the mean interface position. We conclude that previous claims of an enhanced surface tension at mesoscopic scales are amenable to unambiguous tests via scattering experiments.}, language = {en} } @inproceedings{SkoblinHoeflingChristgau2023, author = {Skoblin, Viktor and H{\"o}fling, Felix and Christgau, Steffen}, title = {Gaining Cross-Platform Parallelism for HAL's Molecular Dynamics Package using SYCL}, volume = {36}, booktitle = {29. PARS-Workshop 2023}, issn = {0177-0454}, arxiv = {http://arxiv.org/abs/2406.04210}, year = {2023}, abstract = {Molecular dynamics simulations are one of the methods in scientific computing that benefit from GPU acceleration. For those devices, SYCL is a promising API for writing portable codes. In this paper, we present the case study of HAL's MD package that has been successfully migrated from CUDA to SYCL. We describe the different strategies that we followed in the process of porting the code. Following these strategies, we achieved code portability across major GPU vendors. Depending on the actual kernels, both significant performance improvements and regressions are observed. As a side effect of the migration process, we obtained impressing speedups also for execution on CPUs.}, language = {en} } @article{RodriguesPelaVonaLubecketal.2024, author = {Rodrigues Pela, Ronaldo and Vona, Cecilia and Lubeck, Sven and Alex, Ben and Gonzalez Oliva, Ignacio and Draxl, Claudia}, title = {Critical assessment of G0W0 calculations for 2D materials: the example of monolayer MoS2}, volume = {10}, journal = {npj Comput. Mater.}, arxiv = {http://arxiv.org/abs/https://arxiv.org/abs/2310.04198}, doi = {10.1038/s41524-024-01253-2}, pages = {77}, year = {2024}, language = {en} } @article{KrishnadasCharronFournier2025, author = {Krishnadas, Anirudh and Charron, Nicolas and Fournier, Rene}, title = {Melting Transitions in Small Aluminum Clusters Simulated with Energies Approaching DFT Accuracy.}, journal = {ACS Publications- Journal of Chemical Theory and Computation}, year = {2025}, abstract = {We describe a computational framework for modelling melting-like transitions in atomic clusters that combines first-principles energy calculations, global optimization, and machine-learned interatomic potentials. A diverse set of configurations is generated by global optimization, and energies are calculated by Density Functional Theory. The energies are fitted to an accuracy of 10 meV/atom or better with an Allegro E(3)-equivariant neural network potential. The model allows efficient parallel tempering Monte Carlo simulations with near DFT-level accuracy. This methodology was validated by simulating Na_20 and comparing it to earlier experimental and computational results. We used it to study melting-like transitions in Al_n+ clusters (n=9 to 16), and Al_n and Al_n^- (n=12, 13,14). The simulated heat capacity of these clusters, in particular Al_16+, are in qualitative agreement with experiments. The melting point of Al_n+ clusters with n=11-16 are well above the bulk melting point (934 K). The closed-shell Al_13- species has an exceptionally high melting point, close to 2100 K.}, language = {en} } @article{KrishnadasMoshiQuintanaetal.2025, author = {Krishnadas, Anirudh and Moshi, Maryam and Quintana, Ramon Alain Miranda and Fournier, Rene}, title = {Geometric Features and a Neural Network Classifier for Detecting Melting-Like Transitions in Clusters.}, journal = {AIP Publications - The Journal of Chemical Physics}, year = {2025}, abstract = {Melting-like transitions in clusters are normally identified by a peak in the heat capacity curve C(T ) at T = Tc. Computing C(T ) requires costly simulations with millions of steps. We discuss four easily calculated functions of temperature that help detect and characterize melting-like transitions. The first, f1 (or WU ), is the width of the potential energy distribution which shows an abrupt increase near Tc. The other three are statistics of the ordered set of N(N - 1)/2 interatomic distances rij: (i) f2 is a measure of dissimilarity to the lowest energy configuration, or global minimum; (ii) f3 is the effective number of rij's found in a small interval centered around (r1 + r2)/2 where r1, r2 are the positions of the first two peaks in the pair distribution function; and (iii) f4 is a measure of non-uniformity in the distribution of the ri j's. Numerical tests with empirical potentials that model three types of bonding (van der Waals, covalent, and metallic) show that f1, f2, f3, and f4 produce estimates for the middle of the melting region in general agreement with Tc. An Artificial Neural Network (ANN) classifier that takes, as inputs, f2, f3, and many variants of f4, is used to calculate the solid fraction FS(T) and find the solid-liquid coexistence region between freezing and melting temperatures, [Tf , Tm]. Inflection points in f3(T ) and FS(T ) are very sensitive indicators of phase transitions. Estimates of Tc obtained from them converge one to three orders of magnitude faster, in simulation time, than those obtained with C(T ).}, language = {en} } @article{HoelterLemkeWeinzierletal.2025, author = {H{\"o}lter, Arne and Lemke, Mathias and Weinzierl, Stefan and Stein, Lewin}, title = {Non-Reflecting Characteristic Boundary Conditions for Adjoint Time-Domain Acoustic Simulations}, journal = {Journal of Theoretical and Computational Acoustics}, year = {2025}, abstract = {Accurate acoustic simulations in the free field require non-reflective boundary conditions to suppress spurious reflections at the computational domain boundaries. Although several characteristic-based formulations for direct (forward) simulations have been proposed in recent decades, the adjoint formulations of such characteristic-based boundary conditions (CBCs) have received limited atten- tion in the literature and lack a comprehensive analysis. This paper presents the derivation and evaluation of adjoint CBCs complementing the existing direct CBCs. Both the forward and adjoint CBCs are applied to the (nonlinear) Euler equations and linear acoustic equations in time-domain simulations. In this manner, the CBCs are investigated and subsequently compared to assess their respective accuracy and consistency. The CBCs were implemented using both a single-point and a zonal approach, with the former optionally combined with a sponge layer. Both approaches yielded comparable results in direct and adjoint simulations, while the zonal CBC exhibited improved ac- curacy at lower frequencies. Across the evaluated frequency range of approximately 350 - 5600 Hz, spurious reflections were attenuated by up to -70dB in both forward and adjoint cases, demon- strating the effectiveness and consistency of the proposed boundary treatment.}, language = {en} } @article{RodriguesPelaDraxl2024, author = {Rodrigues Pel{\´a}, Ronaldo and Draxl, Claudia}, title = {Speeding up all-electron real-time TDDFT demonstrated by the exciting package}, volume = {304}, journal = {Comput. Phys. Commun.}, arxiv = {http://arxiv.org/abs/https://arxiv.org/abs/2403.04351}, doi = {10.1016/j.cpc.2024.109292}, pages = {109292}, year = {2024}, language = {en} } @article{FritschSchorr2024, author = {Fritsch, Daniel and Schorr, Susan}, title = {Disorder induced band gap lowering in kesterite type Cu2ZnSnSe4 and Ag2ZnSnSe4: a first-principles and special quasirandom structures investigation}, volume = {36}, journal = {Journal of Physics: Condensed Matter}, number = {37}, publisher = {IOP Publishing}, issn = {0953-8984}, doi = {10.1088/1361-648X/ad52de}, year = {2024}, abstract = {Abstract Quaternary chalcogenides, i.e. Cu2ZnSnS4, crystallising in the kesterite crystal structure have already been demonstrated as potential building blocks of thin film solar cells, containing only abundant elements and exhibiting power conversion efficiencies of about 14.9\% so far. However, due to the potential presence of several structurally similar polymorphs, the unequivocal identification of their ground state crystal structures required the application of more elaborate neutron diffraction experiments. One particular complication arose from the later identified Cu-Zn disorder, present in virtually all thin film samples. Subsequently, it has been shown experimentally that this unavoidable Cu-Zn disorder leads to a band gap lowering in the respective samples. Additional theoretical investigations, mostly based on Monte-Carlo methods, tried to understand the atomistic origin of this disorder induced band gap lowering. Here, we present theoretical results from first-principles calculations based on density functional theory for the disorder induced band gap lowering in kesterite Cu2ZnSnSe4 and Ag2ZnSnSe4, where the Cu-Zn and Ag-Zn disorder is modelled via a supercell approach and special quasirandom structures. Results of subsequent analyses of structural, electronic, and optical properties are discussed with respect to available experimental results, and will provide additional insight and knowledge towards the atomistic origin of the observed disorder induced band gap lowering in kesterite type materials.}, language = {en} } @inproceedings{KramerLaeuter2024, author = {Kramer, Tobias and L{\"a}uter, Matthias}, title = {Benchmarking the rotating jet model of cometary activity with the trajectory of comet 67P/Churyumov-Gerasimenko}, volume = {17}, booktitle = {EPSC Abstracts}, doi = {10.5194/epsc2024-207}, year = {2024}, abstract = {An important tool to assess the composition and the spatial origin of cometary material is the analysis of its trajectory reflecting gravitational acceleration due to solar system bodies complemented by non-gravitational accelerations (NGA).}, language = {en} } @article{AttreeGutierrezGroussinetal.2024, author = {Attree, Nicholas and Guti{\´e}rrez, Pedro and Groussin, Olivier and B{\"u}rger, Johanna and Keller, Horst Uwe and Kramer, Tobias and LASAGNI MANGHI, RICCARDO and L{\"a}uter, Matthias and Lemos, Pablo and Markkanen, Johannes and Marschall, Raphael and Schuckart, Christian}, title = {Varying water activity and momentum transfer on comet 67P/Churyumov-Gerasimenko from its non-gravitational forces and torques}, volume = {690}, journal = {Astronomy and Astrophysics}, arxiv = {http://arxiv.org/abs/2408.10877}, doi = {10.1051/0004-6361/202450728}, pages = {A82}, year = {2024}, abstract = {Aims. We investigate the ability of a simultaneous fitting of comet 67P/Churyumov-Gerasimenko's non-gravitational forces, torques, and total water-outgassing rate, as observed by Rosetta, to constrain complex thermophysical models of cometary material. Methods. We extend the previous work of fitting geographically defined surface outgassing models to the Rosetta observations by testing the effects of a more detailed geomorphological mapping, the resolution of the shape-model used, self-heating by neighbouring facets on the shape-model, thermal inertia in the outgassing solution, and the variation in the momentum coupling between the gas and the nucleus. We also directly compare the non-gravitational acceleration curves available in the literature. Results. We correct an error in the calculation of pole-orientation in the previous paper. We find that, under the assumptions of the model, non-gravitational forces and torques are driven by water sublimation from the nucleus, thermal inertia and self-heating have only minor effects, spatially uniform activity cannot explain 67P's non-gravitational dynamics, spatially uniform momentum transfer cannot explain 67P's non-gravitational dynamics, and different terrain types have different instantaneous responses to insolation. Conclusions. Consolidated terrain facing south on 67P/Churyumov-Gerasimenko has a high outgassing flux, a steep response to insolation, and a large gas momentum transfer coefficient. Instead, that facing north behaves differently, producing little to no water outgassing, and with a lower momentum transfer efficiency. Dusty terrain also has a lower outgassing rate and momentum transfer efficiency, and either depletes its volatile component or is buried in fall-back as the comet approaches the Sun. Momentum transfer appears correlated with insolation, likely due to an increased enhancement in the gas temperature as the dust it flows through is heated.}, language = {en} } @inproceedings{AttreeGutierrezGroussinetal.2024, author = {Attree, Nicholas and Guti{\´e}rrez, Pedro and Groussin, Olivier and B{\"u}rger, Johanna and Keller, Horst Uwe and Kramer, Tobias and Lasagni Manghi, Riccardo and L{\"a}uter, Matthias and Lemos, Pablo and Markkanen, Johannes and Marschall, Raphael and Schuckart, Christian}, title = {The Results of ISSI Team \#547: Understanding the Activity of Comets Through 67P's Dynamics}, volume = {17}, booktitle = {EPSC Abstracts}, doi = {10.5194/epsc2024-82}, year = {2024}, abstract = {Understanding cometary activity gives us an insight into the materials properties, and therefore formation and evolution processes of these relatively pristine protoplanetary objects. We will present the results of an International Space Science Institute project to investigate the phenomenon through the effects of the outgassing activity on the orbit and spin-state of comet 67P/Churymov-Gerasimenko, e.g. its non-gravitational dynamics. This International Team gathered experts in orbital dynamics and trajectory reconstruction together with thermophysical modellers and comet observationalists, in order to compare the available extractions of 67P's non-gravitational acceleration (NGA) from its trajectory. The team then fitted a combination of the NGA, the non-gravitational torque (NGT), and the total water-outgassing rate with a thermophysical activity model. The results of this model will be presented. In particular, it was found that: non-gravitational forces and torques are driven by water sublimation from the nucleus; thermal inertia and self-heating have only minor effects; spatially uniform activity cannot explain 67P's non-gravitational dynamics; spatially uniform momentum transfer cannot explain 67P's non-gravitational dynamics; and different terrain types have different instantaneous responses to insolation. The implications of these findings for the modelling of cometary material and the variety of surface types seen on 67P will be discussed.}, language = {en} } @article{RoyHoefling2024, author = {Roy, Sutapa and H{\"o}fling, Felix}, title = {Critical surface adsorption of confined binary liquids with locally conserved mass and composition}, volume = {122}, journal = {Molecular Physics}, number = {21-22}, doi = {10.1080/00268976.2024.2391998}, pages = {e2391998}, year = {2024}, abstract = {Close to a solid surface, the properties of a fluid deviate significantly from their bulk values. In this context, we study the surface adsorption profiles of a symmetric binary liquid confined to a slit pore by means of molecular dynamics simulations; the latter naturally entails that mass and concentration are locally conserved. Near a bulk consolute point, where the liquid exhibits a demixing transition with the local concentration as the order parameter, we determine the order parameter profiles and characterise the relevant critical scaling behaviour, in the regime of strong surface attraction, for a range of pore widths and temperatures. The obtained order parameter profiles decay monotonically near the surfaces, also in the presence of a pronounced layering in the number density. Overall, our results agree qualitatively with recent theoretical predictions from a mesoscopic field-theoretical approach for the canonical ensemble.}, language = {en} } @article{CarusoSentefAttaccaliteetal.2026, author = {Caruso, Fabio and Sentef, Michael and Attaccalite, Claudio and Bonitz, Michael and Draxl, Claudia and De Giovannini, Umberto and Eckstein, Martin and Ernstorfer, Ralph and Fechner, Michael and Gr{\"u}ning, Myrta and H{\"u}bener, Hannes and Joost, Jan-Philip and Juraschek, Dominik and Karrasch, Christoph and Marvin Kennes, Dante and Latini, Simone and Lu, I-Te and Neufeld, Ofer and Perfetto, Enrico and Rettig, Laurenz and Rodrigues Pel{\´a}, Ronaldo and Rubio, Angel and Rudzinski, Joseph and Ruggenthaler, Michael and Sangalli, Davide and Sch{\"u}ler, Michael and Shallcross, Samuel and Sharma, Sangeeta and Stefanucci, Gianluca and Werner, Philipp}, title = {The 2025 Roadmap to Ultrafast Dynamics: Frontiers of Theoretical and Computational Modelling}, volume = {9}, journal = {J. Phys. Mater.}, number = {1}, arxiv = {http://arxiv.org/abs/2501.06752}, doi = {10.1088/2515-7639/ae1165}, year = {2026}, language = {en} } @article{LaeuterKramer2025, author = {L{\"a}uter, Matthias and Kramer, Tobias}, title = {Rotation dynamics and torque efficiency of cometary nuclei}, volume = {699}, journal = {Astronomy \& Astrophysics}, arxiv = {http://arxiv.org/abs/2507.06036}, doi = {10.1051/0004-6361/202553845}, pages = {A75}, year = {2025}, abstract = {The dynamics of a rigid cometary nucleus is described by the evolutions of its center-of-mass and of its rotation state. Solar irradiation that reaches the surface of a cometary nucleus causes the sublimation of volatiles that form the coma around the nucleus. The sublimation process transfers linear momentum and rotational angular momentum from the nucleus to the surrounding space, and thus affects the dynamics via nongravitational forces and nongravitational torques. With the exception of close approaches to planets, these torques exert the dominant influence on the rotation states of cometary nuclei. The Rosetta mission 2014-2016 accompanying comet 67P/Churyumov-Gerasimenko provides the longest continuous observational data to track its rotation state. In particular, the data set encompasses the direction of the angular velocity, denoted by ω, and the angular frequency |ω|over a time period of approximately 700 days. The observed change of the rotation state is not explained by a low heat conductivity thermophysical model in combination with a homogeneous surface ice coverage of comet 67P. Spatially and/or temporally varying weights for effective active fraction with respect to a prescribed set of surface regions provide a potential solution to this problem. Here, we present a methodology for classifying the surface based on vectorial efficiency of the torque. On any cometary surface without geometric symmetry, the methodology highlights the decomposition into eight characteristic regions that encode the signs of torque efficiency with respect to all vector components. This decomposition is divided into two subsets of four regions each of which is located in one of both hemispheric regions. We analyze in detail rotation states close to lowest energy and different thermophysical models, and we discuss how the uncertainties of observations affect the model parameters. We study the occurrence of these regions for an oblate ellipsoid, a nearprolate ellipsoid, a bilobed shape, and a shape model analogous to that of comet 67P. The sensitivity analysis for comet 67P indicates that the observations constrain only one of the eight weights uniquely. The other directions are poorly constrained and show the limitation of the rotational data to determine the regional activity on comet 67P.}, language = {en} } @article{RossiQiaoDykstraetal.2025, author = {Rossi, Thomas and Qiao, Lu and Dykstra, Conner P. and Rodrigues Pel{\´a}, Ronaldo and Gnewkow, Richard and Wallick, Rachel F. and Burke, John H. and Nicholas, Erin and March, Anne-Marie and Doumy, Gilles and Buchholz, D. Bruce and Deparis, Christiane and Zu{\~n}iga-P{\´e}rez, Jesus and Weise, Michael and Ellmer, Klaus and Fondell, Mattis and Draxl, Claudia and van der Veen, Renske}, title = {Dynamic control of X-ray core-exciton resonances by Coulomb screening in photoexcited semiconductors}, volume = {6}, journal = {Communications Materials}, arxiv = {http://arxiv.org/abs/2412.01945}, doi = {10.1038/s43246-025-00909-w}, pages = {191}, year = {2025}, language = {en} } @article{HawthorneRaulinoRodriguesPelaetal.2025, author = {Hawthorne, Felipe and Raulino, Paulo R. E. and Rodrigues Pel{\´a}, Ronaldo and Woellner, Cristiano F.}, title = {Efficient and Accurate Machine Learning Interatomic Potential for Graphene: Capturing Stress-Strain and Vibrational Properties}, volume = {129}, journal = {The Journal of Physical Chemistry C}, arxiv = {http://arxiv.org/abs/2505.12140}, doi = {10.1021/acs.jpcc.5c03470}, pages = {16319 -- 16326}, year = {2025}, language = {en} } @article{GroussinJordaAttreeetal.2025, author = {Groussin, Olivier and Jorda, L. and Attree, N. and Birch, S.P.D. and B{\"u}rger, Johanna and Guti{\´e}rrez, Pedro and Jindal, Abhinav S. and Keller, H.U. and Kramer, Tobias and Lasagni Manghi, Riccardo and L{\"a}uter, Matthias and Markkanen, J. and Marschall, R. and Schuckart, C.}, title = {Thermal environment and erosion of comet 67P/Churyumov-Gerasimenko}, volume = {694}, journal = {Astronomy and Astrophysics}, doi = {10.1051/0004-6361/202452260}, pages = {A21}, year = {2025}, abstract = {Aims. This paper focuses on how insolation affects the nucleus of comet 67P/Churyumov-Gerasimenko over its current orbit. We aim to better understand the thermal environment of the nucleus, in particular its surface temperature variations, erosion, relationship with topography, and how insolation affects the interior temperature for the location of volatile species (H2O and CO2). Methods. We have developed two thermal models to calculate the surface and subsurface temperatures of 67P over its 6.45-year orbit. The first model, with high resolution (300 000 facets), calculates surface temperatures, taking shadows and self-heating into account but ignoring thermal conductivity. The second model, with lower resolution (10 000 facets), includes thermal conductivity to estimate temperatures down to ∼3 m below the surface. Results. The thermal environment of 67P is strongly influenced by its large obliquity (52◦), which causes significant seasonal effects and polar nights. The northern hemisphere is the coldest region, with temperatures of 210-300 K. H2O is found in the first few centimetres, while CO2 is found deeper (∼2 m) except during polar night around perihelion, when CO2 accumulates near the surface. Cliffs erode 3-5 times faster than plains, forming terraces. The equatorial region receives maximum solar energy (8.5×109 J m-2 per orbit), with maximum surface temperatures of 300-350 K. On the plains, H2O is found in the first few centimetres, while CO2 is found deeper (∼2 m) and never accumulates near the surface. In the southern hemisphere, a brief intense perihelion heating raises temperatures to 350-400 K, which is followed by a 5-year polar night when surface temperatures drop to 55 K. Here H2O remains in the first few centimetres, while CO2 accumulates shallowly during polar night, enriching the region. Erosion is maximal in the southern hemisphere and concentrated on the plains, which explains the observed overall flatness of this hemisphere compared to the northern one. Over one orbit, the total energy from self-heating is 17\% of the total energy budget, and 34\% for thermal conduction. Our study contributes to a better understanding of the surface changes observed on 67P.}, language = {en} } @article{BuergerHayneGundlachetal.2024, author = {B{\"u}rger, Johanna and Hayne, Paul and Gundlach, Bastian and L{\"a}uter, Matthias and Kramer, Tobias and Blum, J{\"u}rgen}, title = {A Microphysical Thermal Model for the Lunar Regolith: Investigating the Latitudinal Dependence of Regolith Properties}, volume = {129}, journal = {Journal of Geophysical Research: Planets}, number = {3}, doi = {10.1029/2023JE008152}, year = {2024}, abstract = {The microphysical structure of the lunar regolith provides information on the geologic history of the Moon. We used remote sensing measurements of thermal emission and a thermophysical model to determine the microphysical properties of the lunar regolith. We expand upon previous investigations by developing a microphysical thermal model, which more directly simulates regolith properties, such as grain size and volume filling factor. The modeled temperatures are matched with surface temperatures measured by the Diviner Lunar Radiometer Experiment on board the Lunar Reconnaissance Orbiter. The maria and highlands are investigated separately and characterized in the model by a difference in albedo and grain density. We find similar regolith temperatures for both terrains, which can be well described by similar volume filling factor profiles and mean grain sizes obtained from returned Apollo samples. We also investigate a significantly lower thermal conductivity for highlands, which formally also gives a very good solution, but in a parameter range that is well outside the Apollo data. We then study the latitudinal dependence of regolith properties up to ±80° latitude. When assuming constant regolith properties, we find that a variation of the solar incidence-dependent albedo can reduce the initially observed latitudinal gradient between model and Diviner measurements significantly. A better match between measurements and model can be achieved by a variation in intrinsic regolith properties with a decrease in bulk density with increasing latitude. We find that a variation in grain size alone cannot explain the Diviner measurements at higher latitudes.}, language = {en} }