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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Surface Modification of Indium–Tin Oxide with Functionalized Perylene Diimides: Characterization of Orientation, Electron-Transfer Kinetics and Electronic Structure
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Transition-Metal-Incorporated Aluminum Oxide Thin Films: Toward Electronic Structure Design in Amorphous Mixed-Metal Oxides
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Phase Stability and Electronic Structure of Tin Sulfide Compounds for Li-ion Batteries
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Using Hyperoptimized Tensor Networks and First-Principles Electronic Structure to Simulate the Experimental Properties of the Giant {Mn 84 } Torus
The single-molecule magnet {Mn 84 } is a challenge to theory because of its high nuclearity. Here, we directly compute two experimentally accessible observables, the field-dependent magnetization up to 75 T and the temperature-dependent heat capacity, using parameter-free theory. In particular, we use first-principles calculations to derive short- and long-range exchange interactions and compute the exact partition function of the resulting classical Potts and Ising spin models for all 84 Mn S = 2 spins to obtain observables. The latter computation is made possible by using hyperoptimized tensor network contractions, a technique developed to simulate quantum supremacy circuits. We also synthesize the magnet and measure its heat capacity and magnetization, observing qualitative agreement between theory and experiment and identifying an unusual bump in the heat capacity and a plateau in the magnetization. Our work also identifies some limitations of current theoretical modeling in large magnets, such as sensitivity to small, long-range exchange couplings.
Physisorption of Water on Graphene: Subchemical Accuracy from Many-Body Electronic Structure Methods
According to the article, wet carbon interfaces are ubiquitous in the natural world and exhibit anomalous properties, which could be exploited by emerging technologies. However, progress is limited by lack of understanding at the molecular level. Remarkably, even for the most fundamental system (a single water molecule interacting with graphene), there is no consensus on the nature of the interaction. We tackle this by performing an extensive set of complementary state-of-the-art computer simulations on some of the world’s largest supercomputers. From this effort a consensus on the water–graphene interaction strength has been obtained. Our results have significant impact for the physical understanding, as they indicate that the interaction is weaker than predicted previously. They also pave the way for more accurate and reliable studies of liquid water at carbon interfaces.
Pentamethylcyclopentadienyl Metalloradical Iron Complexes Containing Redox Noninnocent α-Diimine-Type Ligands: Synthesis, Molecular, and Electronic Structures
The synthesis and characterization of pentamethylcyclopentadienyl iron complexes bearing the redox non-innocent α-diimine (N,N'-dimesitylbutane-2,3-diimine, Mes DI) and α-iminopyridine (N-mesityl(pyridin-2-yl)ethanimine Mes PI) ligands were explored. One-pot reduction and complexation of the cyclopentadienyl ring was accomplished by treatment of (κ 2 -N,N')FeCl 2 (N,N'= Mes DI or Mes PI) pre-cursors with [C 5 Me 5 ]Li. The resulting iron compounds were characterized by paramagnetic 1 H NMR spectroscopy, magnetic susceptibility measurements, zero-field 57 Fe Mössbauer spectroscopy, low-temperature EPR spectroscopy, and cyclic voltammetry. The combined spectroscopic, structural and DFT computational data supported low-spin iron(III) compounds (S Fe = ½) with π-acidic, formally doubly-reduced chelating ligands.