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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CoAu(BrN)6 by Materials Project

AuBr4Co(NBr)2(N2)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four nitrogen molecules, two AuBr4 clusters, and two Co(NBr)2 clusters. In each AuBr4 cluster, Au5+ is bonded in a square co-planar geometry to four Br1- atoms. There are two shorter (2.48 Å) and two longer (2.52 Å) Au–Br bond lengths. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a single-bond geometry to one Au5+ atom. In the second Br1- site, Br1- is bonded in a distorted single-bond geometry to one Au5+ atom. In each Co(NBr)2 cluster, Co3+ is bonded in a linear geometry to two equivalent N+0.33- atoms. Both Co–N bond lengths are 1.66 Å. N+0.33- is bonded in a distorted single-bond geometry to one Co3+ and one Br1- atom. The N–Br bond length is 1.77 Å. Br1- is bonded in a distorted single-bond geometry to one N+0.33- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

From hard spheres to hard-core spins

A system of hard spheres exhibits physics that is controlled only by their density. This comes about because the interaction energy is either infinite or zero, so all allowed configurations have exactly the same energy. The low-density phase is liquid, while the high-density phase is crystalline, an example of “order by disorder” as it is driven purely by entropic considerations. Here we study a family of hard spin models, which we call hard-core spin models, where we replace the translational degrees of freedom of hard spheres with the orientational degrees of freedom of lattice spins. Their hard-core interaction serves analogously to divide configurations of the many spin system into allowed and disallowed sectors. We present detailed results on the square lattice in d = 2 for a set of models with $\mathbb{Z}_n$ symmetry, which generalize Potts models, and their U(1) limits, for ferromagnetic and antiferromagnetic senses of the interaction, which we refer to as exclusion and inclusion models. As the exclusion and inclusion angles are varied, we find a Kosterlitz-Thouless phase transition between a disordered phase and an ordered phase with quasi-long-ranged order, which is the form order by disorder takes in these systems. These results follow from a set of height representations, an ergodic cluster algorithm, and transfer matrix calculations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on Cu(NCl2)2 by Materials Project

CuCl4N2 crystallizes in the orthorhombic Cmce space group. The structure is zero-dimensional and consists of eight ammonia molecules and four CuCl4 clusters. In each CuCl4 cluster, Cu2+ is bonded in a square co-planar geometry to four Cl1- atoms. All Cu–Cl bond lengths are 2.15 Å. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Cu2+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Cu2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AuNCl4 by Materials Project

(AuCl4)2N2 is Tungsten Carbide-like structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four ammonia molecules and four AuCl4 clusters. In each AuCl4 cluster, Au1- is bonded in a square co-planar geometry to four Cl1- atoms. All Au–Cl bond lengths are 2.30 Å. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Au1- atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Au1- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AuCN3Cl4 by Materials Project

AuCl4CN3 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four guanidine molecules and four AuCl4 clusters. In each AuCl4 cluster, Au1+ is bonded in a square co-planar geometry to four Cl1- atoms. All Au–Cl bond lengths are 2.30 Å. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Au1+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Au1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Molecular structure determination: Equilibrium structure of pyrimidine (m-C 4 H 4 N 2 ) from rotational spectroscopy (reSE) and high-level ab initio calculation (re) agree within the uncertainty of experimental measurement

The pure rotational spectrum of pyrimidine (m-C 4 H 4 N 2 ), the meta-substituted dinitrogen analog of benzene, has been studied in the millimeter-wave region from 235 GHz to 360 GHz. The rotational spectrum of the ground vibrational state has been assigned and fit to yield accurate rotational and distortion constants. Over 1700 distinct transitions were identified for the normal isotopologue in its ground vibrational state and least-squares fit to a partial sextic S-reduced Hamiltonian. Transitions for all four singly substituted 13 C and 15 N isotopologues were observed at natural abundance and were likewise fit. Deuterium-enriched samples of pyrimidine were synthesized, giving access to all eleven possible deuterium-substituted isotopologues, ten of which were previously unreported. Experimental values of rotational constants and computed values of vibration–rotation interaction constants and electron-mass corrections were used to determine semi-experimental equilibrium structures (r e SE ) of pyrimidine. The r e SE structure obtained using coupled-cluster with single, double, and perturbative triple excitations [CCSD(T)] corrections shows exceptional agreement with the re structure computed at the CCSD(T)/cc-pCV5Z level (≤0.0002 Å in bond distance and ≤0.03° in bond angle). Of the various computational methods examined, CCSD(T)/cc-pCV5Z is the only method for which the computed value of each geometric parameter lies within the statistical experimental uncertainty (2σ) of the corresponding semi-experimental coordinate. The exceptionally high accuracy and precision of the structure determination is a consequence of the large number of isotopologues measured, the precision and extent of the experimental frequency measurements, and the sophisticated theoretical treatment of the effects of vibration–rotation coupling and electron mass. Taken together, these demanding experimental and computational studies establish the capabilities of modern structural analysis for a prototypical monocyclic aromatic compound.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Explicitly correlated coupled cluster method for accurate treatment of open-shell molecules with hundreds of atoms

We present a near-linear scaling formulation of the explicitly correlated coupled-cluster singles and doubles with the perturbative triples method [CCSD(T)F12¯] for high-spin states of open-shell species. The approach is based on the conventional open-shell CCSD formalism [M. Saitow et al., J. Chem. Phys. 146, 164105 (2017)] utilizing the domain local pair-natural orbitals (DLPNO) framework. The use of spin-independent set of pair-natural orbitals ensures exact agreement with the closed-shell formalism reported previously, with only marginally impact on the cost (e.g., the open-shell formalism is only 1.5 times slower than the closed-shell counterpart for the C160H322 n-alkane, with the measured size complexity of ≈1.2). Evaluation of coupled-cluster energies near the complete-basis-set (CBS) limit for open-shell systems with more than 550 atoms and 5000 basis functions is feasible on a single multi-core computer in less than 3 days. The aug-cc-pVTZ DLPNO-CCSD(T)F12¯ contribution to the heat of formation for the 50 largest molecules among the 348 core combustion species benchmark set [J. Klippenstein et al., J. Phys. Chem. A 121, 6580–6602 (2017)] had root-mean-square deviation (RMSD) from the extrapolated CBS CCSD(T) reference values of 0.3 kcal/mol. For a more challenging set of 50 reactions involving small closed- and open-shell molecules [G. Knizia et al., J. Chem. Phys. 130, 054104 (2009)], the aug-cc-pVQ(+d)Z DLPNO-CCSD(T)F12¯ yielded a RMSD of ∼0.4 kcal/mol with respect to the CBS CCSD(T) estimate.

Kumar, Ashutosh (ORCID:0000000175896030)↗
DOE OSTI2022

A chiral alkali metal capped Ni 4 cubane complex: Synthesis, structure, magnetic and catalytic bromination studies

A new chiral NaO 2 Ni 4 O 2 N 2 cluster has been developed with a distorted capped cubane-type structure. The structure was determined by single crystal X-ray diffraction. The tetradentate Schiff-base ligand was synthesized by the condensation of o-vanillin and $\textit{D}$-(-)–threo-2-amino-1-(4-nitrophenyl)-1,3-propanediol. X-ray structure reveals that the complex possesses a Ni 4 cubane cluster where sodium ion is anchored on the face of the cubane structure. Continuous shape measurement studies revealed that all the Ni centres are in distorted octahedral geometry and sodium ion adopts the spherical square pyramidal geometry. Further structural exploration reveals that the complex shows local distortions of the coordination geometries at each metal site, and these distortions govern the magnetic anisotropy associated with each Ni II ion. For the present case, an elongation ($d_{str}$ > 0) of the octahedral coordination sphere results in a local easy-plane anisotropy, with a positive $D_{Ni(II)}$ parameter. Temperature dependant magnetization measurements showed a predominant ferromagnetic interaction amongst the four Ni centres. This complex is also catalytically active towards bromination of aromatic phenolic compounds. Initial catalytic activity was verified with the conversion of phenol red to bromophenol blue. Different phenolic substances show good conversion to their corresponding bromo derivatives. The complex showed good catalytic activity towards bromination of aromatic phenolic compounds, offering up to 99% conversion with 100% selectively to their corresponding bromo derivatives.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Abelian SU(N) 1 chiral spin liquids on the square lattice

In the physics of the Fractional Quantum Hall (FQH) effect, a zoo of Abelian topological phases can be obtained by varying the magnetic field. Aiming to reach the same phenomenology in spin-like systems, in this work we propose a family of SU(N)-symmetric models in the fundamental representation, on the square lattice with short-range interactions restricted to triangular units, a natural generalization for arbitrary N of an SU(3) model studied previously where time-reversal symmetry is broken explicitly. Guided by the recent discovery of SU(2) 1 and SU(3) 1 chiral spin liquids (CSL) on similar models we search for topological SU(N) 1 CSL in some range of the Hamiltonian parameters via a combination of complementary numerical methods such as exact diagonaliza- tions (ED), infinite density matrix renormalization group (iDMRG) and infinite Projected Entangled Pair State (iPEPS). Extensive ED on small (periodic and open) clusters up to N = 10 and an innovative SU(N)-symmetric version of iDMRG to compute entanglement spectra on (infinitely-long) cylinders in all topological sectors pro- vide unambiguous signatures of the SU(N) 1 character of the chiral liquids. An SU(4)-symmetric chiral PEPS, constructed in a manner similar to its SU(2) and SU(3) analogs, is shown to give a good variational ansatz of the N = 4 ground state, with chiral edge modes originating from the PEPS holographic bulk-edge correspondence. Finally, we discuss the possible observation of such Abelian CSL in ultracold atom setups where the possibility of varying N provides a tuning parameter similar to the magnetic field in the physics of the FQH effect.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2020

Materials Data on SbN2F5 by Materials Project

N2SbF5 crystallizes in the orthorhombic Cmcm space group. The structure is zero-dimensional and consists of eight ammonia molecules and four SbF5 clusters. In each SbF5 cluster, Sb3+ is bonded in a distorted square pyramidal geometry to five F1- atoms. There is one shorter (1.87 Å) and four longer (1.90 Å) Sb–F bond length. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Sb3+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Sb3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuC2(NCl2)2 by Materials Project

CuCl4(CN)2 is Cubane-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four hydrogen cyanide molecules and two CuCl4 clusters. In each CuCl4 cluster, Cu2+ is bonded in a square co-planar geometry to four Cl1- atoms. There are two shorter (2.12 Å) and two longer (2.14 Å) Cu–Cl bond lengths. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Cu2+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Cu2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Co2CN9(Cl2O3)2 by Materials Project

(CoN2Cl)4(N2)3(CO2)2(NO2Cl)4 crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four carbon dioxide molecules, four triazane molecules, eight CoN2Cl clusters, and four NO2Cl clusters. In each CoN2Cl cluster, Co+3.50+ is bonded in a 1-coordinate geometry to two N+0.56+ atoms. There is one shorter (1.55 Å) and one longer (1.71 Å) Co–N bond length. There are two inequivalent N+0.56+ sites. In the first N+0.56+ site, N+0.56+ is bonded in a single-bond geometry to one Co+3.50+ atom. In the second N+0.56+ site, N+0.56+ is bonded in a distorted bent 120 degrees geometry to one Co+3.50+ and one Cl1- atom. The N–Cl bond length is 1.61 Å. Cl1- is bonded in a single-bond geometry to one N+0.56+ atom. In each NO2Cl cluster, N+0.56+ is bonded in a 1-coordinate geometry to two Cl1- atoms. There are one shorter (1.70 Å) and one longer (2.63 Å) N–Cl bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one O2- and one Cl1- atom. The O–O bond length is 1.23 Å. The O–Cl bond length is 3.41 Å. In the second O2- site, O2- is bonded in a single-bond geometry to one O2- atom. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted square co-planar geometry to two equivalent N+0.56+ and two equivalent O2- atoms. In the second Cl1- site, Cl1- is bonded in a bent 120 degrees geometry to two equivalent N+0.56+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pt(S3N)2 by Materials Project

PtS6N2 crystallizes in the monoclinic C2/m space group. The structure is zero-dimensional and consists of four ammonia molecules and two PtS6 clusters. In each PtS6 cluster, Pt2+ is bonded in a square co-planar geometry to four equivalent S2- atoms. All Pt–S bond lengths are 2.30 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in an L-shaped geometry to two equivalent S2- atoms. Both S–S bond lengths are 2.03 Å. In the second S2- site, S2- is bonded in an L-shaped geometry to one Pt2+ and one S2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Redshift evolution and covariances for joint lensing and clustering studies with DESI Y1

ABSTRACT Galaxy–galaxy lensing (GGL) and clustering measurements from the Dark Energy Spectroscopic Instrument Year 1 (DESI Y1) data set promise to yield unprecedented combined-probe tests of cosmology and the galaxy–halo connection. In such analyses, it is essential to identify and characterize all relevant statistical and systematic errors. We forecast the covariances of DESI Y1 GGL + clustering measurements and the systematic bias due to redshift evolution in the lens samples. Focusing on the projected clustering and GGL correlations, we compute a Gaussian analytical covariance, using a suite of N-body and lognormal simulations to characterize the effect of the survey footprint. Using the DESI one percent survey data, we measure the evolution of galaxy bias parameters for the DESI luminous red galaxy (LRG) and bright galaxy survey (BGS) samples. We find mild evolution in the LRGs in $0.4 < z < 0.8$, subdominant to the expected statistical errors. For BGS, we find less evolution for brighter absolute magnitude cuts, at the cost of reduced sample size. We find that for a redshift bin width $\Delta z = 0.1$, evolution effects on DESI Y1 GGL is negligible across all scales, all fiducial selection cuts, all fiducial redshift bins. Galaxy clustering is more sensitive to evolution due to the bias squared scaling. Nevertheless the redshift evolution effect is insignificant for clustering above the 1-halo scale of $0.1h^{-1}$ Mpc. For studies that wish to reliably access smaller scales, additional treatment of redshift evolution is likely needed. This study serves as a reference for GGL and clustering studies using the DESI Y1 sample.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Finite-Temperature Structures of Supported Subnanometer Catalysts Inferred via Statistical Learning and Genetic Algorithm-Based Optimization

Single-atom catalysts (SACs) minimize noble metal utilization and can alter the activity and selectivity of supported metal nanoparticles. However, the morphology of active centers, including single atoms and subnanometer clusters of a few atoms, remains elusive due to experimental challenges. The computational cost to describe numerous cluster shapes and sizes makes direct first-principles calculations impractical. We present a computational framework to enable structure determination for single-atom and subnanometer cluster catalysts. As a case study, we obtained the low energy structures of Pd n (n = 1-21) clusters supported on CeO 2 (111), which are critical components of automobile three-way catalysts. Trained on density functional theory data, a three-dimensional cluster expansion is established using statistical learning to describe the Hamiltonian and predict energies of supported Pdn clusters of any structure. Low energy stable and metastable structures are identified using a Metropolis Monte Carlo-based genetic algorithm in the canonical ensemble at 300 K. We observe that supported single atoms sinter to form bilayer clusters and large cluster isomers share similarities in both shape and energy, and elucidate the significance of the support and microstructure on cluster stability. We discovered a simple surrogate structure-energy model, where the energy per atom scales with the square root of the average first coordination number, which can be used to estimate energies and compare the stability of clusters. Our framework, applicable to any metal/support system, fills an important methodological gap to predict the stability of supported metal catalysts in the subnanometer regime.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

The Atacama Cosmology Telescope: DR6 Sunyaev-Zel'dovich Selected Galaxy Clusters Catalog

We present the results of a search for galaxy clusters in the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) microwave sky maps covering 16293 square degrees in three frequency bands, using data obtained over the lifetime of the project (2008-2022). We report redshifts and mass estimates for 10040 clusters detected via their Sunyaev-Zel'dovich (SZ) effect with signal-to-noise greater than 4 at a 2.4 arcminute filter scale. The catalog includes 1180 clusters at redshifts greater than 1, and 124 clusters at redshifts greater than 1.5. Using a relation between cluster SZ signal and mass that is consistent with recent weak-lensing measurements, we estimate that clusters detected with signal-to-noise greater than 5 form a sample which is 90% complete for clusters with masses greater than $5 \times 10^{14}$ MSun (measured within a spherical volume with mean density 500 times the critical density). El Gordo, a cluster found in an initial ACT survey of 755 square degrees, remains the most extreme cluster in mass and redshift; we find no cluster with a mass and redshift combination high enough to falsify the standard LCDM cosmology with Gaussian initial perturbations. We make public a variety of data products, including the full cluster candidate list, noise maps, and sky masks, along with our software for cluster detection and instructions for reproducing our cluster catalogs from the public ACT maps.

Aguena, M. [Trieste Observ.; LIneA, Rio de Janeiro↗
DOE OSTI2020

Materials Data on AsCS3N2F11 by Materials Project

CN2S3F5AsF6 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two AsF6 clusters and two CN2S3F5 clusters. In each AsF6 cluster, As5+ is bonded in an octahedral geometry to six F1- atoms. There are a spread of As–F bond distances ranging from 1.76–1.79 Å. There are six inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the sixth F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In each CN2S3F5 cluster, C4+ is bonded in a distorted trigonal planar geometry to one N4+ and two S2- atoms. The C–N bond length is 1.30 Å. There is one shorter (1.74 Å) and one longer (1.85 Å) C–S bond length. There are two inequivalent N4+ sites. In the first N4+ site, N4+ is bonded in a bent 120 degrees geometry to two S2- atoms. There is one shorter (1.59 Å) and one longer (1.60 Å) N–S bond length. In the second N4+ site, N4+ is bonded in a bent 120 degrees geometry to one C4+ and one S2- atom. The N–S bond length is 1.62 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a square pyramidal geometry to one C4+ and five F1- atoms. There are a spread of S–F bond distances ranging from 1.59–1.62 Å. In the second S2- site, S2- is bonded in a distorted water-like geometry to two N4+ atoms. In the third S2- site, S2- is bonded in a 1-coordinate geometry to one C4+ and one N4+ atom. There are five inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one S2- atom. In the second F1- site, F1- is bonded in a single-bond geometry to one S2- atom. In the third F1- site, F1- is bonded in a single-bond geometry to one S2- atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one S2- atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one S2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SbN2Cl5 by Materials Project

N2SbCl5 crystallizes in the monoclinic C2/m space group. The structure is zero-dimensional and consists of eight ammonia molecules and four SbCl5 clusters. In each SbCl5 cluster, Sb3+ is bonded in a distorted square pyramidal geometry to five Cl1- atoms. There are a spread of Sb–Cl bond distances ranging from 2.33–2.37 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Sb3+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Sb3+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Sb3+ atom.

36 MATERIALS SCIENCE↗