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All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

The Effect of Aqueous Alteration in Antarctic Carbonaceous Chondrites from Comparative ICP-MS Bulk Chemistry

Terrestrial ages of Antarctic carbonaceous chondrites (CC) indicate that these meteorites have been preserved in or on ice for, at least, tens of thousands of years. Due to the porous structure of these chondrites formed by the aggregation of silicate-rich chondrules, refractory inclusions, metal grains, and fine-grained matrix materials, the effect of pervasive terrestrial water is relevant. Our community defends that pristine CC matrices are representing samples of scarcely processed protoplanetary disk materials as they contain stellar grains, but they might also trace parent body processes. It is important to study the effects of terrestrial aqueous alteration in promoting bulk chemistry changes, and creating distinctive alteration minerals. Particularly because it is thought that aqueous alteration has particularly played a key role in some CC groups in modifying primordial bulk chemistry, and homogenizing the isotopic content of fine-grained matrix materials. Fortunately, the mineralogy produced by parent-body and terrestrial aqueous alteration processes is distinctive. With the goal to learn more about terrestrial alteration in Antarctica we are obtaining reflectance spectra of CCs, but also performing ICP-MS bulk chemistry of the different CC groups. A direct comparison with the mean bulk elemental composition of recovered falls might inform us on the effects of terrestrial alteration in finds. With such a goal, in the current work we have analyzed some members representative of CO and CM chondrite groups.

Alonso-Azcarate, J.↗
DOE OSTI2020

Stress‐Induced Domain Wall Motion in a Ferroelastic Mn 3+ Spin Crossover Complex

Abstract Domain wall motion is detected for the first time during the transition to a ferroelastic and spin state ordered phase of a spin crossover complex. Single‐crystal X‐ray diffraction and resonant ultrasound spectroscopy (RUS) revealed two distinct symmetry‐breaking phase transitions in the mononuclear Mn 3+ compound [Mn(3,5‐diBr‐sal 2 (323))]BPh 4 , 1. The first at 250 K, involves the space group change Cc → Pc and is thermodynamically continuous, while the second, Pc → P 1 at 85 K, is discontinuous and related to spin crossover and spin state ordering. Stress‐induced domain wall mobility was interpreted on the basis of a steep increase in acoustic loss immediately below the the Pc ‐ P 1 transition

Jakobsen, Vibe B.↗
DOE OSTI2021

Transformation of an Embedded Five-Membered Ring in Polycyclic Aromatic Hydrocarbons via the Hydrogen-Abstraction–Acetylene-Addition Mechanism: A Theoretical Study

Five-membered rings are constituents of many polycyclic aromatic hydrocarbons (PAHs) and their presence on the edges of large PAHs has been repeatedly observed experimentally. However, modern kinetic combustion models often do not consider the growth of PAHs through the transformation of the five-membered rings. Here, in connection with the above, we carried out a theoretical study of the mechanism of Hydrogen-Abstraction-aCetylene-Addition (HACA) transformation of an embedded five-membered ring on the armchair PAH edge to a six-membered ring, considering cyclopenta[d,e,f]phenanthrene (4,5-methylenephenanthrene) as a prototype system for this process. The potential energy surface for the reactions of cyclopenta[d,e,f]phenanthrenyl radicals produced by direct H abstractions from cyclopenta[d,e,f]phenanthrene with acetylene has been compiled at the G3(MP2,CC)//B3LYP/6-311G(d,p) level of theory including zero-point vibrational energy corrections. The computed energies and molecular parameters were then used to solve the Rice-Ramsperger-Kassel-Marcus Master Equation (RRKM-ME) in order to calculate reaction rate at various pressures and temperatures, which were fitted to modified Arrhenius equation for further kinetic modeling. The results show that the HACA transformation of the embedded five-membered ring to a six-membered ring is possible, albeit slow. The most viable reaction mechanism involves the R2 + C 2 H 2 reaction, where the acetylene molecules adds to a σ-radical in the six-membered ring adjacent to the five-membered ring via a low entrance barrier. The predominant product of R2 + C 2 H 2 is predicted to be 3 ethynyl 4H cyclopenta[def]phenanthrene Pr5 via immediate H elimination from the initial addition complex. Next, Pr5 undergoes H-assisted isomerization to 4aH-pentaleno[4,3,2,1-cdef]phenanthrene Pr4, and the latter adds an H atom eventually forming the 1-pyrenylmethyl radical Pr3: R2 + C 2 H 2 ⇌ 3 ethynyl 4H cyclopenta[def]phenanthrene (Pr5) + H ⇌ 4aH-pentaleno[4,3,2,1-cdef]phenanthrene (Pr4) + H Pr5 + H ⇌ Pr4 + H Pr4 + H → 1-pyrenylmethyl (Pr3) This HACA sequence may be competitive with the methyl radical addition to the R1 radical formed by H abstraction from the CH 2 group in the five-membered ring of cyclopenta[d,e,f]phenanthrene, which provides a pathway to pyrene following two H atom losses. Relative contributions of the two mechanisms of the five- to six-membered ring transformation would strongly depend on the branching ratios of the R1 and R2 radicals produced by the H abstractions and the available concentration of C 2 H 2 vs. CH 3 and hence differ in different flames.

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

Materials Data on CdCSBr2N3O by Materials Project

CdCNSOBr2N2 crystallizes in the monoclinic Cc space group. The structure is three-dimensional and consists of four nitrogen molecules and one CdCNSOBr2 framework. In the CdCNSOBr2 framework, Cd2+ is bonded to one N, one S2-, and three Br1- atoms to form distorted corner-sharing CdSBr3N trigonal bipyramids. The Cd–N bond length is 2.33 Å. The Cd–S bond length is 2.92 Å. There are a spread of Cd–Br bond distances ranging from 2.67–2.75 Å. C4+ is bonded in a distorted linear geometry to one N and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.63 Å. N is bonded in a bent 150 degrees geometry to one Cd2+ and one C4+ atom. S2- is bonded in a distorted trigonal non-coplanar geometry to one Cd2+, one C4+, and one O2- atom. The S–O bond length is 2.37 Å. O2- is bonded in a distorted trigonal non-coplanar geometry to one S2- and two equivalent Br1- atoms. There are one shorter (2.47 Å) and one longer (2.48 Å) O–Br bond lengths. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a water-like geometry to two equivalent Cd2+ atoms. In the second Br1- site, Br1- is bonded in a distorted trigonal non-coplanar geometry to one Cd2+ and two equivalent O2- atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1993

Metabolic responses to head-down suspension in hypophysectomized rats

Rats exposed to head-down suspension (HDS) exhibit reductions in maximal O2 consumption (VO2max) and atrophy of select hindlimb muscles. This study tested the hypothesis that an endocrine-deficient rat exposed to HDS would not exhibit reductions in VO2max or hindlimb muscle mass. Hypophysectomized (HYPX) and sham-operated (SHAM) rats were tested for VO2max before and after 28 days of HDS or cage control (CC) conditions. No significant reductions in VO2max were observed in HYPX rats. In contrast, SHAM-HDS rats exhibited a significant reduction in absolute (-16%) and relative (-29%) measures of aerobic capacity. Time course experiments revealed a reduction in VO2max in SHAM-HDS rats within 7 days, suggesting that cardiovascular adjustments to HDS occurred in the 1st wk. HDS was associated with atrophy of the soleus (-42%) in SHAM rats, whereas HYPX rats exhibited atrophy of the soleus (-36%) and plantaris (-13%). SHAM-HDS rats had significantly lower (-38%) soleus citrate synthase activities per gram muscle mass than SHAM-CC, but no significant differences existed between HYPX-HDS and -CC rats. HDS rats had an impaired ability to thermoregulate, as indicated by significantly greater temperature increases per unit run time, compared with their CC counterparts. Pretreatment plasma epinephrine levels were significantly lower in HYPX than in SHAM rats. Norepinephrine concentration was similar for all groups except HYPX-HDS, in which it was significantly higher. HDS had no significant effect on thyroxine or triiodothyronine. SHAM-HDS rats had significantly lower concentrations of testosterone and growth hormone.(ABSTRACT TRUNCATED AT 250 WORDS).

NASA Discipline Number 14-10↗
NASA NTRS2013

Neutron Absorption Measurements Constrain Eucrite-Diogenite Mixing in Vesta's Regolith

The NASA Dawn Mission s Gamma Ray and Neutron Detector (GRaND) [1] acquired mapping data during 5 months in a polar, low altitude mapping orbit (LAMO) with approx.460-km mean radius around main-belt asteroid Vesta (264-km mean radius) [2]. Neutrons and gamma rays are produced by galactic cosmic ray interactions and by the decay of natural radioelements (K, Th, U), providing information about the elemental composition of Vesta s regolith to depths of a few decimeters beneath the surface. From the data acquired in LAMO, maps of vestan neutron and gamma ray signatures were determined with a spatial resolution of approx.300 km full-width-at-half-maximum (FWHM), comparable in scale to the Rheasilvia impact basin (approx.500 km diameter). The data from Vesta encounter are available from the NASA Planetary Data System. Based on an analysis of gamma-ray spectra, Vesta s global-average regolith composition was found to be consistent with the Howardite, Eucrite, and Diogenite (HED) meteorites, reinforcing the HED-Vesta connection [2-7]. Further, an analysis of epithermal neutrons revealed variations in the abundance of hydrogen on Vesta s surface, reaching values up to 400 micro-g/g [2]. The association of high concentrations of hydrogen with equatorial, low-albedo surface regions indicated exogenic delivery of hydrogen by the infall of carbonaceous chondrite (CC) materials. This finding was buttressed by the presence of minimally-altered CC clasts in howardites, with inferred bulk hydrogen abundances similar to that found by GRaND, and by studies using data from Dawn s Framing Camera (FC) and VIR instruments [8-10]. In addition, from an analysis of neutron absorption, spatial-variations in the abundance of elements other than hydrogen were detected [2].

Prettyman, T. H.↗
DOE OSTI2020

Materials Data on LiCo(CO3)2 by Materials Project

LiCo(CO3)2 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Li1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 2.02–2.56 Å. Co3+ is bonded in a distorted square co-planar geometry to four O2- atoms. There are a spread of Co–O bond distances ranging from 1.85–1.93 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.24–1.34 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.26–1.33 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Co3+, and one C4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Co3+, and one C4+ atom. In the third O2- site, O2- is bonded in a distorted water-like geometry to one Li1+ and one C4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Li1+ and one C4+ atom. In the fifth O2- site, O2- is bonded in a water-like geometry to one Co3+ and one C4+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Li1+, one Co3+, and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Robust error calibration for serial crystallography

Serial crystallography is an important technique with unique abilities to resolve enzymatic transition states, minimize radiation damage to sensitive metalloenzymes and perform de novo structure determination from micrometre-sized crystals. This technique requires the merging of data from thousands of crystals, making manual identification of errant crystals unfeasible. cctbx.xfel.merge uses filtering to remove problematic data. However, this process is imperfect, and data reduction must be robust to outliers. We add robustness to cctbx.xfel.merge at the step of uncertainty determination for reflection intensities. This step is a critical point for robustness because it is the first step where the data sets are considered as a whole, as opposed to individual lattices. Robustness is conferred by reformulating the error-calibration procedure to have fewer and less stringent statistical assumptions and incorporating the ability to down-weight low-quality lattices. We then apply this method to five macromolecular XFEL data sets and observe the improvements to each. The appropriateness of the intensity uncertainties is demonstrated through internal consistency. This is performed through theoretical CC 1/2 and I /σ relationships and by weighted second moments, which use Wilson's prior to connect intensity uncertainties with their expected distribution. This work presents new mathematical tools to analyze intensity statistics and demonstrates their effectiveness through the often underappreciated process of uncertainty analysis.

Mittan-Moreau, David W.↗
NASA NTRS2003

Computational Evaluation of the Steady and Pulsed Jet Effects on the Performance of a Circulation Control Wing Section

Circulation Control Wing (CCW) technology is a very effective way of achieving very high lift coefficients needed by aircraft during take-off and landing. This technology can also be used to directly control the flow field over the wing. Compared to a conventional high-lift system, a Circulation Control Wing (CCW) can generate the required values of lift coefficient C(sub L,max) during take-off/landing with fewer or no moving parts and much less complexity. Earlier designs of CCW configurations used airfoils with a large radius rounded trailing edge to maximize the lift benefit. However, these designs also produced very high drag. These high drag levels associated with the blunt, large radius trailing edge can be prohibitive under cruise conditions when Circulation Control is no longer necessary. To overcome this difficulty, an advanced CCW section, i.e., a circulation hinged flap was developed to replace the original rounded trailing edge CC airfoil. This concept developed by Englar is shown. The upper surface of the CCW flap is a large-radius arc surface, but the lower surface of the flap is flat. The flap could be deflected from 0 degrees to 90 degrees. When an aircraft takes-off or lands, the flap is deflected as in a conventional high lift system. Then this large radius on the upper surface produces a large jet turning angle, leading to high lift. When the aircraft is in cruise, the flap is retracted and a conventional sharp trailing edge shape results, greatly reducing the drag. This kind of flap does have some moving elements that increase the weight and complexity over an earlier CCW design. But overall, the hinged flap design still maintains most of the Circulation Control high lift advantages, while greatly reducing the drag in cruising condition associated with the rounded trailing edge CCW design. In the present work, an unsteady three-dimensional Navier-Stokes analysis procedure has been developed and applied to this advanced CCW configuration. The solver can be used in both a 2-D and a 3-D mode, and can thus model airfoils as well as finite wings. The jet slot location, slot height, and the flap angle can all be varied easily and individually in the grid generator and the flow solver. Steady jets, pulsed jets, the leading edge and trailing edge blowing can all be studied with this solver.

Liu, Yi↗
NASA NTRS2018

Physical, Chemical, and Petrological Characteristics of Chondritic Materials and Their Relationships to Small Solar System Bodies: Chapter - 2

Chondrite materials with varying abundances of volatile-bearing phases are expected at the destinations for the asteroid sample-return missions Hayabusa2 and OSIRIS-REx. The targets of the missions are 162173 (1999 JU3) Ryugu and 101955 (1999 RQ36) Bennu. Spectroscopic analyses of these asteroids suggest that their surface materials are related to types 1 and 2 carbonaceous chondrites. Some studies suggest that the parent bodies of these chondrites may have also experienced some thermal and/or shock metamorphism. The physical properties of boulders at asteroid surfaces and fine particles in asteroid regoliths are consequences of the diverse processes that fragmented them, mobilized them, and redeposited them in unique accumulations. Sample-return missions are likely to encounter a broad range of carbonaceous chondrite (CC)-like materials, to which aqueous alteration, thermal, and shock metamorphism imparted changes affecting their sub-micron- to meter-scale physical properties. Consequently, implementation of scale-dependent analytical techniques to the study of the chemical, physical, and geotechnical characteristics of these CC-like materials is fundamental to safe mission operations, sample selection, and return. However, most of the available knowledge for informing and formulating expectations about regolith processes, products, and properties on carbonaceous small bodies comes from missions that studied anhydrous (e.g., Itokawa studied by Hayabusa) and/or much larger asteroids (e.g., Vesta studied by Dawn). No previous mission is likely directly relevant to small ice-free carbonaceous NEOs 162173 Ryugu or 101955 Bennu, although the Rosetta Spaceraft performed a flyby of the large asteroid Lutetia which has variously been classified as M and C type (Pätzold et al., 2011). Carbonaceous chondrites carry the best record of the history, distribution, and activity of water in the early solar system. Ordinary and Enstatite chondrites carry only partial records, but these are still critical to understanding the full story. We will describe the records of water-rock interactions on asteroids, as recorded in these meteorites, with particular emphasis on the timing, nature, settings, and fluid compositions. An integral part of this story is the rare, but fortunate, preservation of actual early solar system water as aqueous fluid inclusions.

Zolensky, Michael E.↗
DOE OSTI2022

Mechanism for Acetone and Crotonaldehyde Production during Steam Reforming of Ethanol over La 0.7 Sr 0.3 MnO 3–x Perovskite: Evidence for a Shared C4 Aldol Addition Intermediate

Here a mechanistic study was conducted on the catalytic conversion of ethanol over La 0.7 Sr 0.3 MnO 3–x perovskite catalysts in the presence and absence of water. The study sought insights into the path of C–C coupling toward acetone and crotonaldehyde and also into clarifying whether the lack of previous reports of C–C coupling over La 0.7 Sr 0.3 MnO 3–x (100) could be due to a “pressure gap”. Several types of experiments were performed at 400–800 K: flow experiments with a torr range reactant gas flown over La 0.7 Sr 0.3 MnO 3–x powders; ultra-high vacuum experiments with continuous gas exposures to a La 0.7 Sr 0.3 MnO 3–x (100) single-crystal sample; and torr range continuous gas exposures to a La 0.7 Sr 0.3 MnO 3–x (100) single-crystal sample. When ethanol and water were flown over La 0.7 Sr 0.3 MnO 3–x powders at 400–800 K, the products detected were ethene, acetaldehyde, acetone, crotonaldehyde, CO, CO 2 , and H 2 . Acetone was catalytically produced over both the La 0.7 Sr 0.3 MnO 3–x powder and the La 0.7 Sr 0.3 MnO 3–x (100) single-crystal sample at temperatures of 700–800 K when reaction conditions were on the order of 1 Torr of reactant gas and with an excess of water relative to ethanol (1 ethanol/9 water). Isotopic labeling with deuterium was used to gain insights into the C–C coupling reaction mechanism and paths in species with three and four carbons (C 3 and C 4 species). Additionally, steady-state isotopic transient kinetic analysis (SSITKA) experiments + simulations using carbon labeling of the ethanol feed were performed. Three mechanistic paths were considered for the C–C coupling step: the first two paths, A and B, involve coupling between two intermediates which are both in oxygen vacancies; and the third path, C, involves coupling between one intermediate in an oxygen vacancy and one intermediate outside of an oxygen vacancy. The results suggest that the dominant path to the C 3 product, acetone, depends on the conditions. The less active path (attributed to path A or B) occurs at 600–700 K and involves coupling between two irreversibly bound species. The more active path (attributed to path C) requires an excess of water, becomes dominant at 600–800 K, and involves coupling between one irreversibly bound species and one reversibly bound species. Based on these various observations from experiments and simulations, an elementary step is proposed for acetone formation involving a previously unreported C 4 transition state that is formed after aldol addition. Density functional theory calculations were performed based on this hypothesis, and it confirmed that this specific and previously unreported aldol addition path to acetone does exist and that this path consistent with the experimental data. In this path, C–C formation occurs to create a C 4 intermediate that is bound to an oxygen vacancy, then a hydrogen transfer with C–C bond breaking occurs that results in the production of the acetone molecule. The proposed mechanism is also consistent with the experimental observation that acetone formation has a greater than first-order dependence on the water vapor pressure.

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

Materials Data on ZnH16C3N8O7 by Materials Project

ZnC3N7H12O6NH2H2O crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of four ammonia molecules, four water molecules, and four ZnC3N7H12O6 clusters. In each ZnC3N7H12O6 cluster, Zn2+ is bonded in an octahedral geometry to three N2- and three O2- atoms. There are a spread of Zn–N bond distances ranging from 2.18–2.25 Å. There are a spread of Zn–O bond distances ranging from 2.10–2.13 Å. There are three inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to one N2- and two O2- atoms. The C–N bond length is 1.36 Å. There is one shorter (1.28 Å) and one longer (1.29 Å) C–O bond length. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to one N2- and two O2- atoms. The C–N bond length is 1.38 Å. There is one shorter (1.28 Å) and one longer (1.29 Å) C–O bond length. In the third C4+ site, C4+ is bonded in a trigonal planar geometry to one N2- and two O2- atoms. The C–N bond length is 1.40 Å. There is one shorter (1.26 Å) and one longer (1.29 Å) C–O bond length. There are seven inequivalent N2- sites. In the first N2- site, N2- is bonded in a distorted water-like geometry to one Zn2+ and two H1+ atoms. Both N–H bond lengths are 1.03 Å. In the second N2- site, N2- is bonded in a distorted bent 120 degrees geometry to one C4+ and one H1+ atom. The N–H bond length is 1.05 Å. In the third N2- site, N2- is bonded in a distorted water-like geometry to one Zn2+, one N2-, and two H1+ atoms. The N–N bond length is 1.42 Å. There is one shorter (1.03 Å) and one longer (1.04 Å) N–H bond length. In the fourth N2- site, N2- is bonded in a 2-coordinate geometry to one C4+, one N2-, and one H1+ atom. The N–H bond length is 1.03 Å. In the fifth N2- site, N2- is bonded in a distorted water-like geometry to one Zn2+ and two H1+ atoms. There is one shorter (1.03 Å) and one longer (1.04 Å) N–H bond length. In the sixth N2- site, N2- is bonded in a 2-coordinate geometry to one C4+ and one H1+ atom. The N–H bond length is 1.02 Å. In the seventh N2- site, N2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. There are a spread of N–H bond distances ranging from 1.04–1.07 Å. There are twelve inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the eleventh H1+ site, H1+ is bonded in a distorted single-bond geometry to one N2- and one O2- atom. The H–O bond length is 1.63 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C4+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one C4+ and one H1+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one C4+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C4+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one C4+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Utilizing Essential Symmetry Breaking in Auxiliary-Field Quantum Monte Carlo: Application to the Spin Gaps of the C 36 Fullerene and an Iron Porphyrin Model Complex

We present three distinct examples where phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) can be reliably performed with a single-determinant trial wave function with essential symmetry breaking. Essential symmetry breaking was first introduced by Lee and Head-Gordon [ Phys. Chem. Chem. Phys. 2019, 21, 4763-4778, 10.1039/C8CP07613H]. We utilized essential complex and time-reversal symmetry breaking with ph-AFQMC to compute the triplet–singlet energy gap in the TS12 set. We found statistically better performance of ph-AFQMC with complex-restricted orbitals than with spin-unrestricted orbitals. We then showed the utilization of essential spin symmetry breaking when computing the singlet–triplet gap of a known biradicaloid, C 36 . ph-AFQMC with spin-unrestricted Hartree–Fock (ph-AFQMC+UHF) fails catastrophically even with spin-projection and predicts no biradicaloid character. With approximate Brueckner orbitals obtained from regularized orbital-optimized second-order Møller–Plesset perturbation theory (κ-OOMP2), ph-AFQMC quantitatively captures strong biradicaloid character of C 36 . Lastly, we applied ph-AFQMC to the computation of the quintet–triplet gap in a model iron porphyrin complex where brute-force methods with a small active space fail to capture the triplet ground state. We show unambiguously that neither triplet nor quintet is strongly correlated using UHF, κ-OOMP2, and coupled-cluster with singles and doubles (CCSD) performed on UHF and κ-OOMP2 orbitals. There is no essential symmetry breaking in this problem. By virtue of this, we were able to perform UHF+ph-AFQMC reliably with a cc-pVTZ basis set and predicted a triplet ground state for this model geometry. The largest ph-AFQMC in this work correlated 186 electrons in 956 orbitals. Our work highlights the utility, scalability, and accuracy of ph-AFQMC with a single-determinant trial wave function with essential symmetry breaking for systems mainly dominated by dynamical correlation with little static correlation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2016

The Foreign Clast Populations of Anomalous Polymict Urelite Almahata Sitta (Asteroid 2008 TC(sub3) and Typical Polymict Ureilites: Implications for Asteroid-Meteorite Connections

Almahata Sitta (AhS) is the first meteorite to originate from an asteroid (2008 TC3) that had been studied in space before it hit Earth [1,2]. It is also unique because the fallen fragments comprise a variety of types: approximately 69% ureilites (achondrites) and 31% chondrites [3]. Two models have been proposed for the origin 2008 TC3: 1) an accretionary model [3,4]; or 2) a regolith model [5,6]. Typical polymict ureilites are interpreted to represent regolith, and contain a few % foreign clasts [7,8]. The most common are dark (CC matrix-like) clasts similar to those in many meteoritic breccias [9]. A variety of other chondrites, as well as achondrites (angrites), have also been reported [7,9,10]. We have been working to determine the full diversity of these clasts [10-13] for comparison with AhS. We discuss implications for mixing of materials in the early solar system and the origin of 2008 TC3.

Goodrich, C. A.↗
NASA NTRSDate not supplied

Nephele: An Entry Probe & Sonde Concept for a Venus Ride-Along or Small Spacecraft Mission

Nephele is a Venus atmospheric descent probe concept designed to analyze cloud, haze, and dust particles. It combines a unique set of technologies (Figure 1): recently developed thermal protection materials (3D-CC and HEEET), aerosol sampling technologies with heritage in both planetary and airborne science (high-speed inlets and particle separation), and rapid, robust optical analysis instruments (such as the VOLTR dual spectrometer). Nephele is designed to be complentary to other efforts such as DAVINCI and Venera-D, which target Venus atmospheric gas analysis, by specifically targeting cloud and haze particles.

Nephele↗
DOE OSTI2020

Materials Data on CoH16C3N8O7 by Materials Project

CoC3H9(NO)6NH3NH2H2O crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of four ammonia molecules, four ammonia molecules, four water molecules, and four CoC3H9(NO)6 clusters. In each CoC3H9(NO)6 cluster, Co2+ is bonded in an octahedral geometry to three N2- and three O2- atoms. There are a spread of Co–N bond distances ranging from 2.14–2.18 Å. There are a spread of Co–O bond distances ranging from 2.07–2.11 Å. There are three inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to one N2- and two O2- atoms. The C–N bond length is 1.38 Å. There is one shorter (1.27 Å) and one longer (1.29 Å) C–O bond length. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to one N2- and two O2- atoms. The C–N bond length is 1.38 Å. Both C–O bond lengths are 1.28 Å. In the third C4+ site, C4+ is bonded in a trigonal planar geometry to one N2- and two O2- atoms. The C–N bond length is 1.40 Å. There is one shorter (1.26 Å) and one longer (1.29 Å) C–O bond length. There are six inequivalent N2- sites. In the first N2- site, N2- is bonded in a distorted water-like geometry to one Co2+ and two H1+ atoms. Both N–H bond lengths are 1.03 Å. In the second N2- site, N2- is bonded in a 2-coordinate geometry to one C4+ and one H1+ atom. The N–H bond length is 1.03 Å. In the third N2- site, N2- is bonded in a distorted water-like geometry to one Co2+ and two H1+ atoms. Both N–H bond lengths are 1.03 Å. In the fourth N2- site, N2- is bonded in a 2-coordinate geometry to one C4+ and one H1+ atom. The N–H bond length is 1.03 Å. In the fifth N2- site, N2- is bonded in a distorted water-like geometry to one Co2+, one N2-, and two H1+ atoms. The N–N bond length is 1.42 Å. There is one shorter (1.03 Å) and one longer (1.04 Å) N–H bond length. In the sixth N2- site, N2- is bonded in a 2-coordinate geometry to one C4+, one N2-, and one H1+ atom. The N–H bond length is 1.02 Å. There are nine inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Co2+ and one C4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one C4+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Co2+ and one C4+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C4+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Co2+ and one C4+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS1976

Extralunar sulfur in Apollo 16 and 17 lunar fines

An evaluation of Apollo 16 and 17 lunar fines data by the use of mixing models demonstrates evidence of extralunar sulfur in the fines. Fines are enriched in sulfur with respect to their component rocks. The enrichment of sulfur in 25 Apollo 16 and 17 fines samples shows a positive correlation with a CC-1 like meteoritic component as estimated from siderophilic element concentrations. Mixing models were calculated with variations in mare basalt sulfur concentration values to account for possible variability in mare basalt contribution due to reduction and sulfur loss during flow implacement. Implantation of sulfur by meteoritic processes provides a source for sulfur during regolith maturation and a mechanism for exposure related enrichment in S-34.

Cripe, J. D.↗
DOE OSTI2020

Materials Data on LaP2H44C14N7(Cl2O)2 by Materials Project

LaC14P2N7H44(OCl2)2 crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of four LaC14P2N7H44(OCl2)2 clusters. La3+ is bonded to two O2- and four Cl1- atoms to form LaCl4O2 octahedra that share corners with two PN3O tetrahedra. There are one shorter (2.42 Å) and one longer (2.44 Å) La–O bond lengths. There are a spread of La–Cl bond distances ranging from 2.76–2.91 Å. There are fourteen inequivalent C2- sites. In the first C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.47 Å. All C–H bond lengths are 1.10 Å. In the second C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.47 Å. All C–H bond lengths are 1.10 Å. In the third C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.46 Å. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the fourth C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.46 Å. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the fifth C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.47 Å. All C–H bond lengths are 1.10 Å. In the sixth C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.47 Å. All C–H bond lengths are 1.10 Å. In the seventh C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.47 Å. All C–H bond lengths are 1.10 Å. In the eighth C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.47 Å. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the ninth C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.47 Å. All C–H bond lengths are 1.10 Å. In the tenth C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.47 Å. All C–H bond lengths are 1.10 Å. In the eleventh C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.46 Å. There are a spread of C–H bond distances ranging from 1.09–1.11 Å. In the twelfth C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one PN3O tetrahedra. The C–N bond length is 1.46 Å. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the thirteenth C2- site, C2- is bonded to one N3- and three H1+ atoms to form corner-sharing CH3N tetrahedra. The C–N bond length is 1.50 Å. There is two shorter (1.09 Å) and one longer (1.10 Å) C–H bond length. In the fourteenth C2- site, C2- is bonded to one N3- and three H1+ atoms to form corner-sharing CH3N tetrahedra. The C–N bond length is 1.49 Å. All C–H bond lengths are 1.10 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to three N3- and one O2- atom to form PN3O tetrahedra that share a cornercorner with one LaCl4O2 octahedra and corners with six CH3N tetrahedra. The corner-sharing octahedral tilt angles are 11°. There are a spread of P–N bond distances ranging from 1.65–1.67 Å. The P–O bond length is 1.52 Å. In the second P5+ site, P5+ is bonded to three N3- and one O2- atom to form PN3O tetrahedra that share a cornercorner with one LaCl4O2 octahedra and corners with six CH3N tetrahedra. The corner-sharing octahedral tilt angles are 15°. There is one shorter (1.65 Å) and two longer (1.66 Å) P–N bond length. The P–O bond length is 1.52 Å. There are seven inequivalent N3- sites. In the first N3- site, N3- is bonded in a tetrahedral geometry to two C2- and two H1+ atoms. There is one shorter (1.05 Å) and one longer (1.06 Å) N–H bond length. In the second N3- site, N3- is bonded in a trigonal planar geometry to two C2- and one P5+ atom. In the third N3- site, N3- is bonded in a trigonal planar geometry to two C2- and one P5+ atom. In the fourth N3- site, N3- is bonded in a trigonal planar geometry to two C2- and one P5+ atom. In the fifth N3- site, N3- is bonded in a trigonal planar geometry to two C2- and one P5+ atom. In the sixth N3- site, N3- is bonded in a trigonal planar geometry to two C2- and one P5+ atom. In the seventh N3- site, N3- is bonded in a trigonal planar geometry to two C2- and one P5+ atom. There are forty-four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the eighteenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the nineteenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twentieth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twenty-first H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twenty-second H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twenty-third H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twenty-fourth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twenty-fifth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twenty-sixth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twenty-seventh H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twenty-eighth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twenty-ninth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirtieth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirty-first H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirty-second H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirty-third H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirty-fourth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirty-fifth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirty-sixth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirty-seventh H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirty-eighth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirty-ninth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the fortieth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the forty-first H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the forty-second H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the forty-third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the forty-fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- and one Cl1- atom. The H–Cl bond length is 2.12 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to one La3+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to one La3+ and one P5+ atom. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one La3+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one La3+ atom. In the third Cl1- site, Cl1- is bonded in a distorted bent 120 degrees geometry to one La3+ and one H1+ atom. In the fourth Cl1- site, Cl1- is bonded in a single-bond geometry to one La3+ atom.

36 MATERIALS SCIENCE↗