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All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

X-ray Spectra of the Fe-L Complex II: Atomic Data Constraints from the EBIT Experiment and X-Ray Grating Observations of Capella

The Hitomi results for the Perseus cluster have shown that accurate atomic models are essential to the success of X-ray spectroscopic missions and just as important as the store of knowledge on instrumental calibration and astrophysical modeling. Preparing the models requires a multifaceted approach, including theoretical calculations, laboratory measurements, and calibration using real observations. In a previous paper, we presented a calculation of the electron impact cross sections on the transitions forming the Fe-L complex. In the present work, we systematically tested the calculation against cross-sections of ions measured in an electron beam ion trap experiment. A two-dimensional analysis in the electron beam energies and X-ray photon energies was utilized to disentangle radiative channels following dielectronic recombination, direct electron-impact excitation, and resonant excitation processes in the experimental data. The data calibrated through laboratory measurements were further fed into a global modeling of the Chandra grating spectrum of Capella. We investigated and compared the fit quality, as well as the sensitivity of the derived physical parameters to the underlying atomic data and the astrophysical plasma modeling. We further list the potential areas of disagreement between the observations and the present calculations, which, in turn, calls for renewed efforts with regard to theoretical calculations and targeted laboratory measurements.

Liyi Gu↗
DOE OSTI2020

Materials Data on CuAs2S8N8(OF7)4 by Materials Project

Cu(AsF6)2(NSF2NS(O)F2)4 crystallizes in the tetragonal I4_1/a space group. The structure is zero-dimensional and consists of four copper molecules, eight AsF6 clusters, and sixteen NSF2NS(O)F2 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 1.77–1.79 Å. There are four 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 each NSF2NS(O)F2 cluster, there are two inequivalent N5+ sites. In the first N5+ site, N5+ is bonded in a bent 120 degrees geometry to two S2- atoms. There is one shorter (1.52 Å) and one longer (1.60 Å) N–S bond length. In the second N5+ site, N5+ is bonded in a single-bond geometry to one S2- atom. The N–S bond length is 1.43 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to one N5+, one O2-, and two F1- atoms to form corner-sharing SNOF2 tetrahedra. The S–O bond length is 1.41 Å. Both S–F bond lengths are 1.56 Å. In the second S2- site, S2- is bonded to two N5+ and two F1- atoms to form distorted corner-sharing SN2F2 tetrahedra. Both S–F bond lengths are 1.59 Å. O2- is bonded in a single-bond geometry to one S2- atom. There are four 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.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Observation of halogen-like behavior of gold in fluorinated bimetallic CoAuF 1-2 − and CuAuF 1-2 − clusters: Anion photoelectron spectroscopy and density functional theory

Using size-selected anion photoelectron spectroscopy and density functional theory, we investigated the structures and properties of fluorinated bimetallic clusters CoAuF 1-2 − and CuAuF 1-2 − and their neutrals. Both experimental and theoretical results show that in these cluster anions, Au behaves like a halogen atom. For example, the measured vertical detachment energies (VDEs) of CoAuF − (2.00 ± 0.08 eV) and CuAuF − (3.8 ± 0.1 eV) are close to those of CoF 2 − (2.12 ± 0.08 eV) and CuF 2 − (3.58 ± 0.08 eV), respectively. The theoretical results show that the geometries and electronic structures of CoAuF − and CuAuF − are similar to those of CoF 2 − and CuF 2 − . The natural population analysis and natural electron configuration analyses further confirm that the electronic properties of Au in MAuF − (M = Co, Cu) mimic those of MF 2 − . In addition, the electron localization function analyses show that the M-Au chemical bonds are similar to the corresponding M-F chemical bonds, providing evidence for the ionic nature of the interactions. When a second F atom is attached to the CoAuF − and CuAuF − clusters, the VDEs of the resulting CoAuF 2 − and CuAuF 2 − are 4.38 ± 0.08 eV and 3.71 ± 0.08 eV, respectively, indicating their superhalogen character as these values are higher than those of halogen anions. The results may be useful for understanding the properties of gold at the nanoscale that play an important role in catalysis and nanotechnology.

Ab-initio methods↗
DOE OSTI2020

Materials Data on NiP4N2O19 by Materials Project

NiO6NiP8(NO13)2(NO)2(O2)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two nitroxyl molecules, two oxygen molecules, one NiO6 cluster, and one NiP8(NO13)2 cluster. In the NiO6 cluster, Ni is bonded in a linear geometry to two equivalent O atoms. Both Ni–O bond lengths are 1.81 Å. There are three inequivalent O sites. In the first O site, O is bonded in a distorted bent 120 degrees geometry to one Ni and one O atom. The O–O bond length is 1.49 Å. In the second O site, O is bonded in a bent 120 degrees geometry to two O atoms. The O–O bond length is 1.24 Å. In the third O site, O is bonded in a single-bond geometry to one O atom. In the NiP8(NO13)2 cluster, Ni is bonded in a square co-planar geometry to four O atoms. There is two shorter (1.92 Å) and two longer (2.00 Å) Ni–O bond length. There are four inequivalent P sites. In the first P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.47–1.63 Å. In the second P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.48–1.63 Å. In the third P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.47–1.61 Å. In the fourth P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.64 Å. N is bonded in a water-like geometry to two O atoms. There is one shorter (1.15 Å) and one longer (1.66 Å) N–O bond length. There are thirteen inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one P atom. In the second O site, O is bonded in a bent 120 degrees geometry to one P and one N atom. In the third O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the fourth O site, O is bonded in a single-bond geometry to one N atom. In the fifth O site, O is bonded in a 2-coordinate geometry to one Ni and one P atom. In the sixth O site, O is bonded in a single-bond geometry to one P atom. In the seventh O site, O is bonded in a bent 150 degrees geometry to two P atoms. In the eighth O site, O is bonded in a distorted bent 150 degrees geometry to one Ni and one P atom. In the ninth O site, O is bonded in a single-bond geometry to one P atom. In the tenth O site, O is bonded in a bent 150 degrees geometry to two P atoms. In the eleventh O site, O is bonded in a single-bond geometry to one P atom. In the twelfth O site, O is bonded in a single-bond geometry to one P atom. In the thirteenth O site, O is bonded in a bent 120 degrees geometry to two P atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuH16PtC4N4O11 by Materials Project

Pt(NH3)4CuC4O9(H2O)2 crystallizes in the monoclinic C2 space group. The structure is zero-dimensional and consists of four water molecules, two CuC4O9 clusters, and two Pt(NH3)4 clusters. In each CuC4O9 cluster, Cu2+ is bonded in a square pyramidal geometry to five O2- atoms. There is one shorter (1.87 Å) and four longer (1.99 Å) Cu–O bond length. There are two inequivalent C+3.50+ sites. In the first C+3.50+ site, C+3.50+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.24 Å) and one longer (1.30 Å) C–O bond length. In the second C+3.50+ site, C+3.50+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.24 Å) and one longer (1.29 Å) C–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one Cu2+ and one C+3.50+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Cu2+ and one C+3.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+3.50+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+3.50+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one Cu2+ atom. In each Pt(NH3)4 cluster, Pt2+ is bonded in a square co-planar geometry to four N3- atoms. All Pt–N bond lengths are 2.06 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted trigonal non-coplanar geometry to one Pt2+ and three H1+ atoms. All N–H bond lengths are 1.03 Å. In the second N3- site, N3- is bonded in a distorted trigonal non-coplanar geometry to one Pt2+ and three H1+ atoms. All N–H bond lengths are 1.03 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AsSXe2(OF3)3 by Materials Project

Xe2S(OF)3AsF6 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four AsF6 clusters and four Xe2S(OF)3 clusters. In each AsF6 cluster, As is bonded in an octahedral geometry to six F atoms. There are a spread of As–F bond distances ranging from 1.77–1.79 Å. There are six inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one As atom. In the second F site, F is bonded in a single-bond geometry to one As atom. In the third F site, F is bonded in a single-bond geometry to one As atom. In the fourth F site, F is bonded in a single-bond geometry to one As atom. In the fifth F site, F is bonded in a single-bond geometry to one As atom. In the sixth F site, F is bonded in a single-bond geometry to one As atom. In each Xe2S(OF)3 cluster, there are two inequivalent Xe sites. In the first Xe site, Xe is bonded in a linear geometry to one O and one F atom. The Xe–O bond length is 2.31 Å. The Xe–F bond length is 2.01 Å. In the second Xe site, Xe is bonded in a linear geometry to one O and one F atom. The Xe–O bond length is 2.29 Å. The Xe–F bond length is 2.02 Å. S is bonded in a tetrahedral geometry to three O and one F atom. There are a spread of S–O bond distances ranging from 1.42–1.50 Å. The S–F bond length is 1.57 Å. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one S atom. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one Xe and one S atom. In the third O site, O is bonded in a distorted bent 120 degrees geometry to one Xe and one S atom. There are three inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Xe atom. In the second F site, F is bonded in a single-bond geometry to one S atom. In the third F site, F is bonded in a single-bond geometry to one Xe atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AsSeS2(NF3)2 by Materials Project

Se(NS)2AsF6 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of eight AsF6 clusters and eight Se(NS)2 clusters. In each AsF6 cluster, As2+ is bonded in an octahedral geometry to six F1- atoms. There are a spread of As–F bond distances ranging from 1.76–1.82 Å. There are six inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one As2+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one As2+ atom. In the third F1- site, F1- is bonded in a distorted single-bond geometry to one As2+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one As2+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one As2+ atom. In the sixth F1- site, F1- is bonded in a single-bond geometry to one As2+ atom. In each Se(NS)2 cluster, there are two inequivalent N5+ sites. In the first N5+ site, N5+ is bonded in a bent 120 degrees geometry to one Se2- and one S2- atom. The N–Se bond length is 1.79 Å. The N–S bond length is 1.57 Å. In the second N5+ site, N5+ is bonded in a bent 120 degrees geometry to two S2- atoms. There is one shorter (1.58 Å) and one longer (1.60 Å) N–S bond length. Se2- is bonded in a 1-coordinate geometry to one N5+ atom. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted single-bond geometry to one N5+ atom. In the second S2- site, S2- is bonded in a distorted water-like geometry to two N5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The reaction between the bromine atom and the water trimer: high level theoretical studies

Three different reaction pathways are found for the reaction of bromine atom (Br) with the lowest-energy structure of the water trimer [uud-(H 2 O) 3 ], initially using the MPW1K-DFT method. The three bromine pathways have closely related geometries and energetics, analogous to those found for the fluorine and chlorine reactions. Here, the lowest-energy pathway of the Br + uud-(H 2 O) 3 reaction was further investigated using the “gold standard” CCSD(T) method and the correlation-consistent basis sets up to cc-pVQZ(-PP). Based on the CCSD(T)/cc-pVQZ(-PP)//CCSD(T)/cc-pVTZ(-PP) results, the Br + (H 2 O) 3 reaction is endothermic by 33.3 kcal mol -1 . The classical barrier height is 29.0 kcal mol -1 between the reactants and the exit complex, and there is no barrier for the reverse reaction. The Br···(H 2 O) 3 entrance complex is found to lie 4.7 kcal mol -1 below the separated reactants, and the HBr···(H 2 O) 2 OH exit complex is bound by 6.4 kcal mol -1 relative to the separated products. This potential energy profile is further corrected by the zero point energies and spin–orbit coupling effects. Structurally, the Br + (H 2 O) 3 stationary points can be derived from those of the simpler Br + (H 2 O) 2 reaction by judiciously appending a H 2 O molecule. The Br + (H 2 O) 3 potential energy profile is compared with the Br + (H 2 O) 2 and Br + H 2 O reactions, as well as to the valence isoelectronic Cl + (H 2 O) 3 and F + (H 2 O) 3 systems. It is reasonable to expect that the reactions between the bromine atom and larger water clusters would be similar to the Br + (H 2 O) 3 reaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1985

Monte Carlo study of reversible growth of clusters on a surface

The effect of binding energy on the growth of clusters on a two-dimensional square lattice was studied by a means of a Monte Carlo simulation. The results indicate that for binding energies higher than 0.5kT, clusters grow relative to the initial random distribution, while for binding energies lower than 0.5 kT, clusters decompose. It was also found that at low binding energies the equilibrium percentage of atoms that are bound in clusters is linearly dependent on the binding energy. The cluster density behaved in a similar manner. This similarity reflects the fact that at low binding energies the growth proceeds mainly by the formation of new clusters rather than by an increase in the size of existing ones.

Salik, J.↗
DOE OSTI2020

Materials Data on BH2S3N3F4 by Materials Project

BF4H2(NS)3 is beta-prime cadmium gold structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two BF4 clusters and two H2(NS)3 clusters. In each BF4 cluster, B3+ is bonded in a tetrahedral geometry to four F1- atoms. There are a spread of B–F bond distances ranging from 1.40–1.44 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one B3+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one B3+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one B3+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one B3+ atom. In each H2(NS)3 cluster, there are three inequivalent N+1.67+ sites. In the first N+1.67+ site, N+1.67+ is bonded in a trigonal planar geometry to two H1+ and one S2- atom. Both N–H bond lengths are 1.03 Å. The N–S bond length is 1.60 Å. In the second N+1.67+ site, N+1.67+ is bonded in a bent 120 degrees geometry to two S2- atoms. There is one shorter (1.58 Å) and one longer (1.61 Å) N–S bond length. In the third N+1.67+ site, N+1.67+ is bonded in a bent 120 degrees geometry to two S2- atoms. There is one shorter (1.60 Å) and one longer (1.63 Å) N–S bond length. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N+1.67+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N+1.67+ atom. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 1-coordinate geometry to one N+1.67+ atom. In the second S2- site, S2- is bonded in a water-like geometry to two N+1.67+ atoms. In the third S2- site, S2- is bonded in a distorted water-like geometry to two N+1.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YB3(H6N)4 by Materials Project

YB2(NH5)4BH4 crystallizes in the orthorhombic Pna2_1 space group. The structure is zero-dimensional and consists of four BH4 clusters and four YB2(NH5)4 clusters. In each BH4 cluster, B3- is bonded in a tetrahedral geometry to four H+0.75+ atoms. There are a spread of B–H bond distances ranging from 1.22–1.24 Å. There are four inequivalent H+0.75+ sites. In the first H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one B3- atom. In the second H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one B3- atom. In the third H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one B3- atom. In the fourth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one B3- atom. In each YB2(NH5)4 cluster, Y3+ is bonded in a 10-coordinate geometry to four N3- and six H+0.75+ atoms. There are a spread of Y–N bond distances ranging from 2.45–2.61 Å. There are a spread of Y–H bond distances ranging from 2.29–2.70 Å. There are two inequivalent B3- sites. In the first B3- site, B3- is bonded in a tetrahedral geometry to four H+0.75+ atoms. There are a spread of B–H bond distances ranging from 1.21–1.24 Å. In the second B3- site, B3- is bonded in a tetrahedral geometry to four H+0.75+ atoms. There are a spread of B–H bond distances ranging from 1.20–1.25 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted trigonal non-coplanar geometry to one Y3+ and three H+0.75+ atoms. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. In the second N3- site, N3- is bonded in a trigonal non-coplanar geometry to one Y3+ and three H+0.75+ atoms. There is two shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the third N3- site, N3- is bonded in a distorted trigonal non-coplanar geometry to one Y3+ and three H+0.75+ atoms. There is two shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the fourth N3- site, N3- is bonded in a distorted trigonal non-coplanar geometry to one Y3+ and three H+0.75+ atoms. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. There are twenty inequivalent H+0.75+ sites. In the first H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the second H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the third H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the fourth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the fifth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the sixth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the seventh H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the eighth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the ninth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the tenth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the eleventh H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the twelfth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one N3- atom. In the thirteenth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one B3- atom. In the fourteenth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one Y3+ and one B3- atom. In the fifteenth H+0.75+ site, H+0.75+ is bonded in a distorted single-bond geometry to one Y3+ and one B3- atom. In the sixteenth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one Y3+ and one B3- atom. In the seventeenth H+0.75+ site, H+0.75+ is bonded in a distorted single-bond geometry to one Y3+ and one B3- atom. In the eighteenth H+0.75+ site, H+0.75+ is bonded in a distorted single-bond geometry to one Y3+ and one B3- atom. In the nineteenth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one B3- atom. In the twentieth H+0.75+ site, H+0.75+ is bonded in a single-bond geometry to one Y3+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Constructing a square-like copper cluster to boost C–C coupling for CO 2 electroreduction to ethylene

The CO 2 electroreduction reaction (CO 2 ER) to ethylene (C 2 H 4 ) offers the dual promise of lowering CO 2 emission while storing energy from renewable electricity, for which the development of highly efficient electrocatalysts is of great significance. Herein, by means of density functional theory (DFT) computations, we designed an electrocatalyst for CO 2 -to-C 2 H 4 conversion by anchoring a Cu 5 cluster supported on a MoS 2 monolayer with an S monovacancy (Cu 5 @MoS 2 ). Our results revealed that one Cu atom of the Cu 5 cluster was embedded into the framework of the defective MoS 2 monolayer, while the other four Cu atoms form a square-like island over the substrate surface. Interestingly, the C–C coupling between two *CO species can easily occur on the unique square-like active site with a low kinetic barrier of 0.56 eV to form the key *C 2 O 2 intermediate, which can then be hydrogenated to the C 2 H 4 product with a very low limiting potential (–0.32 eV). Significantly, alkaline conditions (pH = 13) are beneficial to further promote C 2 H 4 synthesis. Finally, our work may offer a new avenue to precisely modulate the structures of Cu clusters for converting CO 2 into high-value target products.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2021

Directing reaction pathways via in situ control of active site geometries in PdAu single-atom alloy catalysts

Abstract The atomic scale structure of the active sites in heterogeneous catalysts is central to their reactivity and selectivity. Therefore, understanding active site stability and evolution under different reaction conditions is key to the design of efficient and robust catalysts. Herein we describe theoretical calculations which predict that carbon monoxide can be used to stabilize different active site geometries in bimetallic alloys and then demonstrate experimentally that the same PdAu bimetallic catalyst can be transitioned between a single-atom alloy and a Pd cluster phase. Each state of the catalyst exhibits distinct selectivity for the dehydrogenation of ethanol reaction with the single-atom alloy phase exhibiting high selectivity to acetaldehyde and hydrogen versus a range of products from Pd clusters. First-principles based Monte Carlo calculations explain the origin of this active site ensemble size tuning effect, and this work serves as a demonstration of what should be a general phenomenon that enables in situ control over catalyst selectivity.

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

Materials Data on HgCN2Cl2O by Materials Project

HgCN2OCl2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of four HgCN2OCl2 clusters. In two of the HgCN2OCl2 clusters, Hg2+ is bonded in a distorted linear geometry to two Cl1- atoms. Both Hg–Cl bond lengths are 2.30 Å. C4+ is bonded in a linear geometry to one N1- and one O2- atom. The C–N bond length is 1.21 Å. The C–O bond length is 1.20 Å. There are two inequivalent N1- sites. In the first N1- site, N1- is bonded in a distorted linear geometry to one C4+ and one N1- atom. The N–N bond length is 1.23 Å. In the second N1- site, N1- is bonded in a distorted single-bond geometry to one N1- and one Cl1- atom. The N–Cl bond length is 3.33 Å. O2- is bonded in a single-bond geometry to one C4+ atom. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Hg2+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Hg2+ and one N1- atom. In two of the HgCN2OCl2 clusters, Hg2+ is bonded in a distorted T-shaped geometry to one O2- and two Cl1- atoms. The Hg–O bond length is 3.06 Å. There are one shorter (2.29 Å) and one longer (2.31 Å) Hg–Cl bond lengths. C4+ is bonded in a 1-coordinate geometry to two N1- and one O2- atom. Both C–N bond lengths are 1.39 Å. The C–O bond length is 1.20 Å. There are two inequivalent N1- sites. In the first N1- site, N1- is bonded in a 1-coordinate geometry to one C4+ and one N1- atom. The N–N bond length is 1.33 Å. In the second N1- site, N1- is bonded in a 1-coordinate geometry to one C4+ and one N1- atom. O2- is bonded in a single-bond geometry to one Hg2+ and one C4+ atom. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Hg2+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Hg2+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS1984

A proposal for the proper use of pseudopotentials in molecular orbital cluster model studies of chemisorption

The interaction of CO with Cu5, Ni5, and Al4 are treated as model systems for molecular adsorption on metal surfaces. The effect of the use of pseudopotentials for the metal atoms is studied by considering three types of clusters. In the first case, all of the metal electrons are explicitly included in the wave function; an all electron (AE) treatment. In the second case, the metal atom which directly interacts with the CO is described by AE but the remaining metal atoms include a pseudopotential for their core electrons. Finally, in the third case, all of the metal atoms in the cluster have a pseudopotential treatment for the core electrons. The AE cluster results are taken as reference values for the two pseudopotential treatments. The mixed cluster results are in excellent agreement with those of the all AE clusters; however, the results for the all pseudopotential cluster of Ni5CO or of Cu5CO are qualitatively different. The pseudopotential treatment for all of the metal atoms often leads to results that contain serious errors and it is not a reliable approach.

Bagus, P. S.↗
DOE OSTI2020

Materials Data on ScH16C3S3O17F9 by Materials Project

Sc(H2O)7Sc(H2O)9(CF3)6(SO3)6 crystallizes in the monoclinic Pm space group. The structure is zero-dimensional and consists of six fluoroform molecules, six sulfur trioxide molecules, one Sc(H2O)7 cluster, and one Sc(H2O)9 cluster. In the Sc(H2O)7 cluster, Sc3+ is bonded in a distorted pentagonal bipyramidal geometry to seven O2- atoms. There are a spread of Sc–O bond distances ranging from 2.15–2.31 Å. There are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one Sc3+ and two H1+ atoms. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Sc3+ and two H1+ atoms. In the third O2- site, O2- is bonded in a distorted water-like geometry to one Sc3+ and two equivalent H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one Sc3+ and two H1+ atoms. In the Sc(H2O)9 cluster, Sc3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Sc–O bond distances ranging from 2.21–2.60 Å. There are nine inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one Sc3+ and two H1+ atoms. In the second O2- site, O2- is bonded in a water-like geometry to one Sc3+ and two equivalent H1+ atoms. In the third O2- site, O2- is bonded in a water-like geometry to one Sc3+ and two equivalent H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one Sc3+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted water-like geometry to one Sc3+ and two H1+ atoms. In the sixth O2- site, O2- is bonded in a water-like geometry to one Sc3+ and two equivalent H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

WALLABY pilot survey: H i gas disc truncation and star formation of galaxies falling into the Hydra I cluster

ABSTRACT We present results from our analysis of the Hydra I cluster observed in neutral atomic hydrogen (H i) as part of the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY). These WALLABY observations cover a 60-square-degree field of view with uniform sensitivity and a spatial resolution of 30 arcsec. We use these wide-field observations to investigate the effect of galaxy environment on H i gas removal and star formation quenching by comparing the properties of cluster, infall, and field galaxies extending up to ∼5R200 from the cluster centre. We find a sharp decrease in the H i-detected fraction of infalling galaxies at a projected distance of ∼1.5R200 from the cluster centre from $\sim 85{{\ \rm per\ cent}}$ to $\sim 35{{\ \rm per\ cent}}$. We see evidence for the environment removing gas from the outskirts of H i-detected cluster and infall galaxies through the decrease in the H i to r-band optical disc diameter ratio. These galaxies lie on the star-forming main sequence, indicating that gas removal is not yet affecting the inner star-forming discs and is limited to the galaxy outskirts. Although we do not detect galaxies undergoing galaxy-wide quenching, we do observe a reduction in recent star formation in the outer disc of cluster galaxies, which is likely due to the smaller gas reservoirs present beyond the optical radius in these galaxies. Stacking of H i non-detections with H i masses below $M_{\rm {HI}}\lesssim 10^{8.4}\, \rm {M}_{\odot }$ will be required to probe the H i of galaxies undergoing quenching at distances ≳60 Mpc with WALLABY.

Reynolds, T. N. (ORCID:0000000266065953)↗
DOE OSTI2020

Materials Data on AlFe3(SO7)6 by Materials Project

(Fe(SO5)2)3AlO6(O2)3 crystallizes in the trigonal P-31c space group. The structure is zero-dimensional and consists of six oxygen molecules, two AlO6 clusters, and two Fe(SO5)2 clusters. In each AlO6 cluster, Al is bonded in an octahedral geometry to six equivalent O atoms. All Al–O bond lengths are 1.84 Å. O is bonded in a single-bond geometry to one Al atom. In each Fe(SO5)2 cluster, there are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with three equivalent SO4 tetrahedra. There is three shorter (1.79 Å) and three longer (1.95 Å) Fe–O bond length. In the second Fe site, Fe is bonded to six equivalent O atoms to form FeO6 octahedra that share corners with six equivalent SO4 tetrahedra. All Fe–O bond lengths are 2.01 Å. S is bonded to four O atoms to form SO4 tetrahedra that share corners with two FeO6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are a spread of S–O bond distances ranging from 1.45–1.53 Å. There are five inequivalent O sites. In the first O site, O is bonded in a distorted bent 150 degrees geometry to one Fe and one S atom. In the second O site, O is bonded in a single-bond geometry to one S atom. In the third O site, O is bonded in a single-bond geometry to one S atom. In the fourth O site, O is bonded in a distorted bent 150 degrees geometry to one Fe and one S atom. In the fifth O site, O is bonded in a single-bond geometry to one Fe atom.

36 MATERIALS SCIENCE↗