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All sources NASA NTRS DOE OSTI

DOE OSTI2020

Materials Data on MnH(CO)4 by Materials Project

MnH(CO)4 is gamma plutonium structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two MnH(CO)4 clusters. there are three inequivalent Mn3+ sites. In the first Mn3+ site, Mn3+ is bonded to four C1+ and two H1+ atoms to form distorted corner-sharing MnH2C4 octahedra. The corner-sharing octahedra tilt angles range from 38–52°. There are a spread of Mn–C bond distances ranging from 1.82–1.87 Å. There is one shorter (1.68 Å) and one longer (1.70 Å) Mn–H bond length. In the second Mn3+ site, Mn3+ is bonded to four C1+ and two H1+ atoms to form distorted corner-sharing MnH2C4 octahedra. The corner-sharing octahedra tilt angles range from 38–56°. There is two shorter (1.82 Å) and two longer (1.87 Å) Mn–C bond length. There is one shorter (1.69 Å) and one longer (1.73 Å) Mn–H bond length. In the third Mn3+ site, Mn3+ is bonded to four C1+ and two H1+ atoms to form distorted corner-sharing MnH2C4 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Mn–C bond distances ranging from 1.83–1.87 Å. There is one shorter (1.74 Å) and one longer (1.75 Å) Mn–H bond length. There are twelve inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the second C1+ site, C1+ is bonded in a distorted linear geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the third C1+ site, C1+ is bonded in a single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C1+ site, C1+ is bonded in a distorted single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the fifth C1+ site, C1+ is bonded in a single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the sixth C1+ site, C1+ is bonded in a distorted linear geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the seventh C1+ site, C1+ is bonded in a single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the eighth C1+ site, C1+ is bonded in a linear geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the ninth C1+ site, C1+ is bonded in a single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the tenth C1+ site, C1+ is bonded in a distorted single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the eleventh C1+ site, C1+ is bonded in a single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. In the twelfth C1+ site, C1+ is bonded in a distorted single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.16 Å. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a bent 150 degrees geometry to two Mn3+ atoms. In the second H1+ site, H1+ is bonded in a bent 120 degrees geometry to two Mn3+ atoms. In the third H1+ site, H1+ is bonded in a bent 120 degrees geometry to two Mn3+ atoms. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the ninth O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the tenth O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the eleventh O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the twelfth O2- site, O2- is bonded in a single-bond geometry to one C1+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on MnH by Materials Project

MnH is Tungsten Carbide-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mn is bonded to six equivalent H atoms to form a mixture of face, edge, and corner-sharing MnH6 octahedra. The corner-sharing octahedral tilt angles are 45°. All Mn–H bond lengths are 1.97 Å. H is bonded to six equivalent Mn atoms to form a mixture of distorted edge and corner-sharing HMn6 pentagonal pyramids.

36 MATERIALS SCIENCE↗

NASA NTRS1983

CASSCF/CI calculations for first row transition metal hydrides - The TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), FeH(4,6-delta) and NiH(2-delta) states

Calculations are performed for the predicted ground states of TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), Fett(4,6-delta) and NiH(2-delta). For FeH both the 6-delta and 4-delta states are studied, since both are likely candidates for the ground state. The ground state symmetries are predicted based on a combination of atomic coupling arguments and coupling of 4s(2)3d(n) and 4s(1)3d(n+1) terms in the molecular system. Electron correlation is included by a CASSCF/CI (SD) treatment. The CASSCF includes near-degeneracy effects, while correlation of the 3d electrons in included at the CI level.

Walch, S. P.↗

DOE OSTI2022

Encapsulation of hygroscopic liquids via polymer precipitation in non-aqueous emulsions

Here, encapsulation of ionic liquids (ILs) and phase change materials (PCMs) can overcome limitations associated with bulk materials, e.g., slow mass transfer rates, high viscosities, or susceptibility to external environment. Single step soft-templated encapsulation methods commonly use interfacial polymerization for shell formation, with a multifunctional monomer in the continuous phase and another in the discontinuous phase, and thus do not give pristine core material. We posit that polymer precipitation onto emulsion droplets in non-aqueous emulsions could produce a robust shell without contamination of the core, ideal for the encapsulation of water-sensitive or water-miscible materials. Solutions of commodity polymers were added to the continuous phase of non-aqueous Pickering emulsions stabilized by alkylated graphene oxide (GO) nanosheets such that the change in solubility of the polymer led to formation of robust shells and the production of capsules that could be isolated. We demonstrate that a polymer precipitation approach can produce capsules with pristine core of the IL 1-ethyl-3-methylimidazolium hexafluorophosphate [Emim][PF 6 ] or the salt hydrate PCM magnesium nitrate hexahydrate (MNH) and shell of nanosheets and polystyrene, poly(methyl methacrylate), or polyethylene. The capsules are approximately 80 wt% [Emim][PF 6 ] or >90 wt% MNH, and the core can undergo multiple cycles of solidification and melting without leakage or destruction. This novel, single-step methodology provides a distinct advantage to access capsules with pristine core composition and is amenable to different core and shell, paving the way for tailoring capsule composition for desired applications.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Synthesis of U 3 O 8 and UO 2 microspheres using microfluidics

Uranium-bearing microspheres below 50µm with a narrow size distribution allows for a wider variety of fuel forms. To accommodate the smaller size, gel microspheres with a composition of UO 3 ∙nH 2 O∙mNH 3 were synthesized using microfluidics and subsequently converted to U 3 O 8 and UO 2 . To accommodate the slower flow rates required by microfluidics, a more stable broth was established. Additionally, the gelation studies resulted in a broth that was stable for more than two days at 0°C and for close to 3 h at room temperature while still gelling within 25 s. Synthesis of gel microspheres with a narrow size distribution lasted for 5 h and produced ~0.5 g of air-dried material. The gelled microspheres were converted to U 3 O 8 and UO 2 and with sizes of 50 and 40 µm in diameter, respectively.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2024

Prediction of ambient pressure superconductivity in cubic ternary hydrides with MH 6 octahedra

Exploring high-temperature superconducting (high-T c ) material at ambient pressure holds immense significance for physics, chemistry, and materials science. In this study, we perform a high-throughput screening of strong electron-phonon interactions in X 2 MH 6 compounds (X = Li, Na, Mg, Al, K, Ca, Ga, Rb, Sr, and In; M are 3d, 4d, and 5d transition metals). These compounds have a cubic structure featuring an MH 6 octahedron motif. Our screening calculations suggest that 26 compounds exhibit dynamic stability and strong electron-phonon coupling. Among them, Mg 2 RhH 6 , Mg 2 IrH 6 , Al 2 MnH 6 , and Li 2 CuH 6 show promising energetic stability and T c of more than 50 K at ambient pressure. This study underscores promising high-T c compounds at ambient pressure with distinctive MH 6 motifs.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Extending GPU-accelerated Gaussian integrals in the TeraChem software package to f type orbitals: Implementation and applications

Here, the increasing availability of graphics processing units (GPUs) for scientific computing has prompted interest in accelerating quantum chemical calculations through their use. However, the complexity of integral kernels for high angular momentum basis functions often limits the utility of GPU implementations with large basis sets or for metal containing systems. In this work, we report the implementation of f function support in the GPU-accelerated TeraChem software package through the development of efficient kernels for the evaluation of Hamiltonian integrals. The high efficiency of the resulting code is demonstrated through density functional theory (DFT) calculations on increasingly large organic molecules and transition metal complexes, as well as coupled cluster singles and doubles calculations on water clusters. Preliminary investigations into Ni(I) catalysis with DFT and the photochemistry of MnH(CH 3 ) with complete active space self-consistent field are also carried out. Overall, our GPU-accelerated software appears to be well-suited for fast simulation of large transition metal containing systems, as well as organic molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

ReMU: regional minimal updating for model-based derivative-free optimization

Derivative-free optimization (DFO) problems are optimization problems where derivative information is unavailable or extremely difficult to obtain. Model-based DFO solvers have been applied extensively in scientific computing. Powell's NEWUOA (2004) [Powell, The NEWUOA software for unconstrained optimization without derivatives, in Large-Scale Nonlinear Optimization, Nonconvex Optimization and its Applications Vol. 83, G. Di Pillo and M. Roma, eds., Springer, 2006, pp. 255–297] and Wild's POUNDerS (2014) [Wild, Solving derivative-free nonlinear least squares problems with POUNDERS, in Advances and Trends in Optimization with Engineering Applications, T. Terlaky, M.F. Anjos, and S. Ahmed, eds., SIAM, 2017, pp. 529–540] explore the numerical power of the minimal norm Hessian (MNH) model for DFO and contributed to the open discussion on building better models with fewer data to achieve faster numerical convergence. Another decade later, we propose the regional minimal updating (ReMU) models, and extend the previous models into a broader class, including the H 2 norm models [Xie and Yuan, Least H 2 norm updating of quadratic interpolation models for derivative-free trust-region algorithms, IMA J. Numer. Anal. 46 (2025), pp. 21–50]. This paper shows motivation behind ReMU models, computational details, theoretical and numerical results on particular extreme points and the barycentre of ReMU's weight coefficient region, and the associated KKT matrix error and distance. Novel metrics, such as the truncated Newton step error, are proposed to numerically understand the new models' properties. A new algorithmic strategy, based on iteratively adjusting the ReMU model type, is also proposed, and shows numerical advantages by combining and switching between the barycentric model and the classic least Frobenius norm model in an online fashion.

derivative-free trust-region methods↗