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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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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Comment on “Additional Insights Between Fermi-Löwdin Orbital SIC and the Localization Equation Constraints in SIC-DFT”

In a recent Letter, Aquino and Wong (AW) analyze the connection between the Fermi-Löwdin orbital self-interaction correction (FLO-SIC) and the traditional Perdew– Zunger self-interaction correction (PZ-SIC) methods. In this work, the authors present a derivation of the conditions required to minimize the SIC density functional theory (DFT) total energy in FLO-SIC. These involve the gradient of the energy with respect to parameters known as Fermi-orbital descriptors (FODs) (called orbital “centroids” in ref 1) that are used together with the total charge density to determine the Fermi- Löwdin orbitals (FLOs). AW state that the conditions, the vanishing of the FOD gradient components, “resemble” the localization equations (LE), the minimum energy conditions in traditional PZ-SIC. The LE involve the equality of certain off-diagonal matrix elements of different orbital-dependent Hamiltonians. While AW are careful to say that their equations do not prove the mathematical equivalence of the two methods, the discussion in the text and the graphical table of contents figure suggest that vanishing FOD gradients imply satisfaction of the LE and vice versa, and hence that the methods are equivalent. We believe this ambiguity clouds an important issue, rather than clarifying it.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

C–H Bond Addition across a Transient Uranium–Nitrido Moiety and Formation of a Parent Uranium Imido Complex

Uranium complexes in the + 3 and + 4 oxidation states were prepared using the anionic PN – (PN – = (N-(2-(diisopropylphosphino)-4-methylphenyl)-2,4,6-trimethylanilide) ligand framework. New complexes include the halide starting materials, (PN) 2 U III I (1) and (PN) 2 U IV Cl 2 (2), which both yield (PN) 2 U IV (N 3 ) 2 (3) by reaction with NaN 3 . Compound 3 was reduced with potassium graphite to produce a putative, transient uranium–nitrido moiety that underwent an intramolecular C–H activation to form a rare example of a parent imido complex, [K(THF) 3 ][(PN)U IV (=NH)[ i Pr 2 P(C 6 H 3 Me)N(C 6 H 2 Me 2 CH 2 )]] (4). Here, calculated reaction energy profiles strongly suggest that a C–H insertion becomes unfavorable when a reductant is present, offering a distinctively different reaction pathway than previously observed for other uranium nitride complexes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Amino-fulleropyrrolidines as electrotropic additives to enhance organic photovoltaics

The synthesis, device fabrication, and electric poling of novel amino-functionalized fulleropyrrolidines in polymer solar cells is reported. Systematically varying the tether lengths between the fullerene cage and tertiary amines provides insight into enhanced device efficiency and stability after poling. DFT calculations in an external electric field result in alignment of molecular dipole moments, which corroborates our hypothesis that electrotropic polarization causes an increased built-in electrostatic potential difference across the device, and results in enhance performance.

solar (photovoltaic), charge transport, materials ↗