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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Al(MoS2)4 by Materials Project

Al(MoS2)4 crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mo+3.25+ is bonded to six S2- atoms to form distorted MoS6 octahedra that share corners with three equivalent AlS4 tetrahedra and edges with six equivalent MoS6 octahedra. There are three shorter (2.35 Å) and three longer (2.62 Å) Mo–S bond lengths. Al3+ is bonded to four equivalent S2- atoms to form AlS4 tetrahedra that share corners with twelve equivalent MoS6 octahedra. The corner-sharing octahedral tilt angles are 65°. All Al–S bond lengths are 2.29 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to three equivalent Mo+3.25+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing SAlMo3 tetrahedra. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent Mo+3.25+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(MoS2)4 by Materials Project

Al(MoS2)4 crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are two inequivalent Mo+3.25+ sites. In the first Mo+3.25+ site, Mo+3.25+ is bonded to six S2- atoms to form distorted MoS6 octahedra that share corners with three equivalent AlS4 tetrahedra, edges with four equivalent MoS6 octahedra, and edges with two equivalent MoS6 pentagonal pyramids. There are a spread of Mo–S bond distances ranging from 2.34–2.63 Å. In the second Mo+3.25+ site, Mo+3.25+ is bonded to six S2- atoms to form distorted MoS6 pentagonal pyramids that share corners with three equivalent AlS4 tetrahedra and edges with six equivalent MoS6 octahedra. There are three shorter (2.37 Å) and three longer (2.64 Å) Mo–S bond lengths. Al3+ is bonded to four S2- atoms to form AlS4 tetrahedra that share corners with nine equivalent MoS6 octahedra and corners with three equivalent MoS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 65°. All Al–S bond lengths are 2.29 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent Mo+3.25+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+3.25+ atoms. In the third S2- site, S2- is bonded to three Mo+3.25+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing SAlMo3 tetrahedra. In the fourth S2- site, S2- is bonded to three equivalent Mo+3.25+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing SAlMo3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(MoS2)12 by Materials Project

Al(MoS2)12 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are nine inequivalent Mo+3.75+ sites. In the first Mo+3.75+ site, Mo+3.75+ is bonded to six S2- atoms to form edge-sharing MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.37–2.55 Å. In the second Mo+3.75+ site, Mo+3.75+ is bonded to six S2- atoms to form distorted MoS6 octahedra that share a cornercorner with one AlS4 tetrahedra and edges with six MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.35–2.60 Å. In the third Mo+3.75+ site, Mo+3.75+ is bonded to six S2- atoms to form distorted MoS6 octahedra that share corners with two equivalent AlS4 tetrahedra and edges with six MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.34–2.60 Å. In the fourth Mo+3.75+ site, Mo+3.75+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.36–2.55 Å. In the fifth Mo+3.75+ site, Mo+3.75+ is bonded to six S2- atoms to form distorted MoS6 octahedra that share corners with three equivalent AlS4 tetrahedra and edges with six MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.34–2.60 Å. In the sixth Mo+3.75+ site, Mo+3.75+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.37–2.55 Å. In the seventh Mo+3.75+ site, Mo+3.75+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.37–2.55 Å. In the eighth Mo+3.75+ site, Mo+3.75+ is bonded to six S2- atoms to form distorted MoS6 octahedra that share a cornercorner with one AlS4 tetrahedra and edges with six MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.37–2.62 Å. In the ninth Mo+3.75+ site, Mo+3.75+ is bonded to six S2- atoms to form distorted MoS6 octahedra that share corners with two equivalent AlS4 tetrahedra and edges with six MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.35–2.61 Å. Al3+ is bonded to four S2- atoms to form AlS4 tetrahedra that share corners with twelve MoS6 octahedra. The corner-sharing octahedra tilt angles range from 62–66°. All Al–S bond lengths are 2.26 Å. There are eighteen inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+3.75+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+3.75+ atoms. In the third S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+3.75+ atoms. In the fourth S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+3.75+ atoms. In the fifth S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+3.75+ atoms. In the sixth S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+3.75+ atoms. In the seventh S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+3.75+ atoms. In the eighth S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+3.75+ atoms. In the ninth S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+3.75+ atoms. In the tenth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to three Mo+3.75+ atoms. In the eleventh S2- site, S2- is bonded in a trigonal non-coplanar geometry to three Mo+3.75+ atoms. In the twelfth S2- site, S2- is bonded to three Mo+3.75+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing SAlMo3 tetrahedra. In the thirteenth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to three Mo+3.75+ atoms. In the fourteenth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to three Mo+3.75+ atoms. In the fifteenth S2- site, S2- is bonded to three Mo+3.75+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing SAlMo3 tetrahedra. In the sixteenth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to three Mo+3.75+ atoms. In the seventeenth S2- site, S2- is bonded in a 4-coordinate geometry to three Mo+3.75+ and one Al3+ atom. In the eighteenth S2- site, S2- is bonded in a trigonal non-coplanar geometry to three Mo+3.75+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al3(MoS2)8 by Materials Project

Al3(MoS2)8 crystallizes in the tetragonal P-4m2 space group. The structure is three-dimensional. there are two inequivalent Mo+2.88+ sites. In the first Mo+2.88+ site, Mo+2.88+ is bonded to six S2- atoms to form distorted MoS6 octahedra that share corners with four AlS4 tetrahedra and edges with six MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.31–2.68 Å. In the second Mo+2.88+ site, Mo+2.88+ is bonded to six S2- atoms to form distorted MoS6 octahedra that share corners with five AlS4 tetrahedra and edges with six MoS6 octahedra. There are a spread of Mo–S bond distances ranging from 2.31–2.70 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four equivalent S2- atoms to form AlS4 tetrahedra that share corners with twelve MoS6 octahedra. The corner-sharing octahedra tilt angles range from 45–47°. All Al–S bond lengths are 2.17 Å. In the second Al3+ site, Al3+ is bonded to four S2- atoms to form AlS4 tetrahedra that share corners with twelve MoS6 octahedra. The corner-sharing octahedra tilt angles range from 63–66°. There are two shorter (2.31 Å) and two longer (2.33 Å) Al–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to three Mo+2.88+ and one Al3+ atom. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Mo+2.88+ atoms. In the third S2- site, S2- is bonded to three equivalent Mo+2.88+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing SAlMo3 tetrahedra. In the fourth S2- site, S2- is bonded to three equivalent Mo+2.88+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing SAlMo3 tetrahedra.

36 MATERIALS SCIENCE↗
NASA NTRS2003

Search for X-Ray Emission in the Nearest Known Brown Dwarf

The XMM observation were obtained on 2001 January 07-08 for 51767 s. The Optical Monitor (OM) was used with the V filter for 4 exposures of 5000 s each in imaging mode. We used the data given by the OM to confirm the presence of the source in the field of view. The European Photon Imaging Camera (EPIC) MOS 1 and MOS2 were used 48724 s each in prime full window mode with 2.5 s time resolution. The EPIC PN was used 46618 s in prime full window mode with 73.4 ms time resolution. The X-ray source closest to the expected position of our target is offset by delta R.A=2.5 arcsec and delta Dec=-28.37 arcsec. This offset is high in comparison with the 0.4 arcsec observed with the optical data. So at this point we already knew that the target was not detected. To confirm that conclusion, we performed the identification of all X-ray sources in the field of view by comparing source to source our image with the one obtained by Rutledge et al. with Chandra. This allowed us to identify all the X-ray sources in our field of view in an area of 20 arcsec times 10 arcsec centered on the expected coordinates of LP944-20. We were then able to conclude that the target was not detected during this observation. This result allowed us to determine a new and better 3 sigma upper limit of X-Ray emission for this object. We have also derived duty cycles for X-ray flares as a function of X-ray luminosity by comparing the XMM data with Chandra and ROSAT data. One student has been supported with the grant during four months (Herve Bouy). A Sun workstation was purchased for him.

Martin, Eduardo↗
DOE OSTI2026

matsim-agents v1.0

matsim-agents is a multi-agent AI framework for atomistic materials simulation and discovery. It orchestrates large language models (LLMs), machine-learned interatomic potentials (MLIPs), and DFT codes into a single agentic loop running on laptops and DOE leadership-class supercomputers. MULTI-AGENT ORCHESTRATION A LangGraph state machine with three nodes: a Planner that converts a natural-language research objective into structured tasks; an Executor that dispatches atomistic tools and loops until the queue is empty; and an Analyst that summarizes results into a human-readable report. State is checkpointed after every step and human-in-the-loop gates can be inserted at any edge. HYPOTHESIS-DRIVEN DISCOVERY CHAT An interactive REPL (matsim-agents chat) that couples LLM dialogue with atomistic simulation. Chemical formulas are automatically detected in conversation turns and trigger a full crystal-phase exploration: structure generation → relaxation → stability scoring → result injection back into the conversation, creating a closed hypothesis-refinement loop. CRYSTAL PHASE ENUMERATION Given a composition, the phase explorer enumerates prototypes by stoichiometry: elemental (fcc/bcc/hcp/sc/diamond), binary 1:1 (rocksalt/CsCl/zincblende/ wurtzite/fluorite/rutile), ternary 1:1:3 (cubic perovskite), ternary 1:2:4 (perovskite + spinel), quaternary 1:1:2:6 (Fm-3m double perovskite). 2-D prototypes (graphene, h-BN, MoS2 2H/1T) and multilayer stacking are also supported via --include-2d and --num-layers. SUPERCELL GENERATION AND SITE DECORATION Auto-tiling to a minimum atom count (--min-atoms), explicit NxNxN tiling (--supercell), symmetry-distinct site decorations (--n-orderings), and isotropic lattice-scale sweeps (--lattice-scales) for volume bracketing. MLFF RELAXATION AND STABILITY SCORING HydraGNN (multi-headed GNN) drives structure relaxation via ASE with FIRE, BFGS, or BFGSLineSearch. Stability output: delta-E/atom ranking across phases and a max-residual-force dynamical-stability proxy. Other MLIPs (MACE, NequIP, Orb) can be plugged in through the same interface. DFT BACKENDS Quantum ESPRESSO pw.x and VASP 6.6 are first-class labellers. Both have validated GPU builds and SLURM/PBS launchers for three DOE platforms: Frontier (AMD MI250X, ROCm), Aurora (Intel PVC, oneAPI), Perlmutter (NVIDIA A100, CUDA). QE produces ~100 binaries (pw.x, ph.x, epw.x, ...). VASP supports scf, relax, vc-relax, and vc-relax-shape run types. ACTIVE-LEARNING LOOP matsim-agents al run CONFIG.yaml drives an iterative HydraGNN-DFT loop: MD generates candidates → ensemble/MC-dropout uncertainty selects the most informative → DFT labels them in parallel inside one allocation → dataset grows → HydraGNN retrains → repeat. DFT backend is a single YAML toggle (dft.backend: vasp | qe). LLM-generated seed structures are supported (no curated POSCAR library needed). Config uses ${VAR}, ${VAR:-default}, ${VAR:?msg} shell-style substitution for cross-user/cross-site portability. LLM BACKENDS Ollama (local, default), vLLM (HPC multi-GPU serving), OpenAI, Anthropic, HuggingFace Transformers+Accelerate. Selected at runtime via flag or env var with no code changes. HPC PORTABILITY Same Python entry points run on Frontier (ROCm 7.2), Aurora (oneAPI), and Perlmutter (CUDA 12). DFT and ML stacks are never co-loaded in the same shell; they couple through the scheduler and filesystem. Advanced multi-node launchers (serve, discovery-chat, single-relaxation, active-learning, QE warm-start) are provided for all three platforms. CODABENCH COMPETITION BUNDLE A self-contained benchmark: 159 atomistic test structures across 11 material classes, 5 tasks (formation energy, forces, ML relaxation, AI-DFT relaxation, phase stability ranking), public/private leaderboard split (30/70), and four ready-to-run baselines: MACE-MP-0, HydraGNN, UMA, AllScAIP.

Lupo Pasini, Massimiliano [Oak Ridge National Labo↗
DOE OSTI2020

Uncovering the Effects of Metal Contacts on Monolayer MoS 2

Metal contacts are a key limiter to the electronic performance of two-dimensional (2D) semiconductor devices. In this work, we present a comprehensive study of contact interfaces between seven metals (Y, Sc, Ag, Al, Ti, Au, Ni, with work functions from 3.1 to 5.2 eV) and monolayer MoS 2 grown by chemical vapor deposition. We evaporate thin metal films onto MoS 2 and study the interfaces by Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, and electrical characterization. We uncover that (1) ultrathin oxidized Al dopes MoS 2 n-type (>2 × 1012 cm –2 ) without degrading its mobility, (2) Ag, Au, and Ni deposition causes varying levels of damage to MoS 2 (e.g. broadening Raman E' peak from <3 to >6 cm –1 ), and (3) Ti, Sc, and Y react with MoS 2 . Reactive metals must be avoided in contacts to monolayer MoS 2 , but control studies reveal the reaction is mostly limited to the top layer of multilayer films. Finally, we find that (4) thin metals do not significantly strain MoS 2 , as confirmed by X-ray diffraction. These are important findings for metal contacts to MoS 2 and broadly applicable to many other 2D semiconductors.

2D materials↗
DOE OSTI2025

Origin of Large Effective Phonon Magnetic Moments in Monolayer MoS 2

Recent helicity-resolved magneto-Raman spectroscopy measurement demonstrates large effective phonon magnetic moments of ~2.5 μ B in monolayer MoS 2 , highlighting resonant excitation of bright excitons as a feasible route to activate Γ-point circularly polarized phonons in transition metal dichalcogenides. However, a microscopic picture of this intriguing phenomenon remains lacking. In this work, we show that an orbital transition between the split conduction bands (Δ 0 = 4 meV) of MoS 2 couples to the doubly degenerate E" phonon mode (Ω 0 = 33 meV), forming two hybridized states. Our phononic and electronic Raman scattering measurements capture these two states: (i) one with predominantly phonon contribution in the helicity-switched channels and (ii) one with primarily orbital contribution in the helicity-conserved channels. An orbital-phonon coupling model successfully reproduces the large effective magnetic moments of the circularly polarized phonons and explains their thermodynamic properties. Strikingly, the Raman mode from the orbital transition is superimposed on a strong quasi-elastic scattering background, indicating the presence of spin fluctuations. As a result, the electrons excited to the conduction bands through the exciton exhibit paramagnetic behavior although MoS 2 is generally considered as a nonmagnetic material. By depositing nanometer-thickness nickel thin films on monolayer MoS 2 , we tune the electronic structure so that the A exciton perfectly overlaps with the 633 nm laser. The optimization of resonance excitation leads to pronounced tunability of the orbital-phonon hybridized states. Our results generalize the orbital-phonon coupling model of effective phonon magnetic moments to material systems beyond the paramagnets and magnets.

2D transition metal dichalcogenide↗