Search NASA⌕ Search

SEARCH · Search NASA

Results for “CC&C”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on KHCN4O5 by Materials Project

(KCN2O5)2N2(NH)2 crystallizes in the monoclinic Cc space group. The structure is three-dimensional and consists of four ammonia molecules, four ammonia molecules, and one KCN2O5 framework. In the KCN2O5 framework, K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.82–3.07 Å. C4+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.23 Å. There are two inequivalent N1+ sites. In the first N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.23 Å) and one longer (1.24 Å) N–O bond length. In the second N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.27 Å) N–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one N1+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent K1+ and one N1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one N1+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one K1+ and one N1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent K1+ and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Approximating large-basis coupled-cluster theory vibrational frequencies using focal-point approximations

The focal-point approximation can be used to estimate a high-accuracy, slow quantum chemistry computation by combining several lower-accuracy, faster computations. We examine the performance of focal-point methods by combining second-order Møller–Plesset perturbation theory (MP2) with coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] for the calculation of harmonic frequencies and that of fundamental frequencies using second-order vibrational perturbation theory (VPT2). In contrast to standard CCSD(T), the focal-point CCSD(T) method approaches the complete basis set (CBS) limit with only triple-ζ basis sets for the coupled-cluster portion of the computation. The predicted harmonic and fundamental frequencies were compared with the experimental values for a set of 20 molecules containing up to six atoms. Here, the focal-point method combining CCSD(T)/aug-cc-pV(T + d)Z with CBS-extrapolated MP2 has mean absolute errors vs experiment of only 7.3 cm −1 for the fundamental frequencies, which are essentially the same as the mean absolute error for CCSD(T) extrapolated to the CBS limit using the aug-cc-pV(Q + d)Z and aug-cc-pV(5 + d)Z basis sets. However, for H 2 O, the focal-point procedure requires only 3% of the computation time as the extrapolated CCSD(T) result, and the cost savings will grow for larger molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Ultrafast infrared transient absorption spectroscopy of gas-phase Ni(CO) 4 photodissociation at 261 nm

Here, we employ ultrafast mid-infrared transient absorption spectroscopy to probe the rapid loss of carbonyl ligands from gas-phase nickel tetracarbonyl following ultraviolet photoexcitation at 261 nm. Here, nickel tetracarbonyl undergoes prompt dissociation to produce nickel tricarbonyl in a singlet excited state; this electronically excited tricarbonyl loses another CO group over tens of picoseconds. Our results also suggest the presence of a parallel, concerted dissociation mechanism to produce nickel dicarbonyl in a triplet excited state, which likely dissociates to nickel monocarbonyl. Mechanisms for the formation of these photoproducts in multiple electronic excited states are theoretically predicted with one-dimensional cuts through the potential energy surfaces and computation of spin–orbit coupling constants using equation of motion coupled cluster methods (EOM-CC) and coupled cluster theory with single and double excitations (CCSD). Bond dissociation energies are calculated with CCSD, and anharmonic frequencies of ground and excited state species are computed using density functional theory (DFT) and time-dependent density functional theory (TD-DFT).

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

Quark structure of the $\chi _{\mathrm{c}}(3P)$ and X(4274) resonances and their strong and radiative decays

We calculate the masses of χc(3P) states with threshold corrections in a coupled-channel model. The model was recently applied to the description of the properties of χc(2P) and χb(3P) multiplets (Ferretti and Santopinto in Phys Lett B 789:550, 2019]. We also compute the open-charm strong decay widths of the χc(3P) states and their radiative transitions. According to our predictions, the χc(3P) states should be dominated by the charmonium core, but they may also show small meson-meson components. The X(4274) is interpreted as a cc¯ χc1(3P) state. More information on the other members of the χc(3P) multiplet, as well as a more rigorous analysis of the X(4274)’s decay modes, are needed to provide further indications on the quark structure of the previous resonance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Materials Data on CoH17C(NO)8 by Materials Project

CoCH17(N3O)2(NO3)2 crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of eight nitric acid molecules and four CoCH17(N3O)2 clusters. In each CoCH17(N3O)2 cluster, Co3+ is bonded in an octahedral geometry to five N1- and one O2- atom. There are a spread of Co–N bond distances ranging from 2.11–2.15 Å. The Co–O bond length is 1.93 Å. C4+ is bonded in a trigonal planar geometry to one N1- and two O2- atoms. The C–N bond length is 1.37 Å. There is one shorter (1.26 Å) and one longer (1.32 Å) C–O bond length. There are six inequivalent N1- sites. In the first N1- site, N1- is bonded in a distorted trigonal non-coplanar geometry to one Co3+ and three H1+ atoms. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. In the second N1- site, N1- is bonded in a distorted trigonal non-coplanar geometry to one Co3+ and three H1+ atoms. All N–H bond lengths are 1.03 Å. In the third N1- site, N1- is bonded in a distorted trigonal non-coplanar geometry to one Co3+ and three H1+ atoms. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. In the fourth N1- site, N1- is bonded in a distorted trigonal non-coplanar geometry to one Co3+ and three H1+ atoms. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. In the fifth N1- site, N1- is bonded in a distorted trigonal non-coplanar geometry to one Co3+ and three H1+ atoms. All N–H bond lengths are 1.03 Å. In the sixth N1- site, N1- is bonded in a distorted trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.01 Å) and one longer (1.02 Å) N–H bond length. There are seventeen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Co3+ and one C4+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NiH3C5NO6 by Materials Project

NiH3(CO2)3C2N crystallizes in the monoclinic Cc space group. The structure is three-dimensional and consists of four ch3nc molecules and one NiH3(CO2)3 framework. In the NiH3(CO2)3 framework, Ni2+ is bonded in an octahedral geometry to six O2- atoms. There are two shorter (2.02 Å) and four longer (2.04 Å) Ni–O bond lengths. There are three inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. Both C–O bond lengths are 1.27 Å. In the second C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. Both C–O bond lengths are 1.27 Å. In the third C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. Both C–O bond lengths are 1.27 Å. There are three 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. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Ni2+ and one C2+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Ni2+ and one C2+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Ni2+ and one C2+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ni2+ and one C2+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ni2+ and one C2+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ni2+ and one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlZnB5H21C6(NO2)5 by Materials Project

Al(BO2)5ZnC6N5H21 crystallizes in the monoclinic Cc space group. The structure is three-dimensional and consists of four ZnC6N5H21 clusters and one Al(BO2)5 framework. In each ZnC6N5H21 cluster, Zn2+ is bonded in a trigonal bipyramidal geometry to five N3- atoms. There are a spread of Zn–N bond distances ranging from 2.07–2.26 Å. There are six inequivalent C1- sites. In the first C1- site, C1- is bonded in a distorted trigonal non-coplanar geometry to one N3- and two H1+ atoms. The C–N bond length is 1.48 Å. Both C–H bond lengths are 1.10 Å. In the second C1- site, C1- is bonded in a distorted trigonal non-coplanar geometry to one N3- and two H1+ atoms. The C–N bond length is 1.47 Å. Both C–H bond lengths are 1.10 Å. In the third C1- site, C1- is bonded in a distorted trigonal non-coplanar geometry to one N3- and two H1+ atoms. The C–N bond length is 1.48 Å. Both C–H bond lengths are 1.10 Å. In the fourth C1- site, C1- is bonded in a distorted trigonal non-coplanar geometry to one N3- and two H1+ atoms. The C–N bond length is 1.47 Å. Both C–H bond lengths are 1.10 Å. In the fifth C1- site, C1- is bonded in a distorted trigonal non-coplanar geometry to one N3- and two H1+ atoms. The C–N bond length is 1.47 Å. Both C–H bond lengths are 1.10 Å. In the sixth C1- site, C1- is bonded in a distorted trigonal non-coplanar geometry to one N3- and two H1+ atoms. The C–N bond length is 1.48 Å. Both C–H bond lengths are 1.10 Å. There are five inequivalent N3- sites. In the first N3- site, N3- is bonded to one Zn2+, one C1-, and two H1+ atoms to form distorted corner-sharing NZnH2C tetrahedra. There is one shorter (1.03 Å) and one longer (1.04 Å) N–H bond length. In the second N3- site, N3- is bonded to one Zn2+, one C1-, and two H1+ atoms to form distorted corner-sharing NZnH2C tetrahedra. Both N–H bond lengths are 1.03 Å. In the third N3- site, N3- is bonded to one Zn2+, one C1-, and two H1+ atoms to form distorted corner-sharing NZnH2C tetrahedra. Both N–H bond lengths are 1.03 Å. In the fourth N3- site, N3- is bonded to one Zn2+, one C1-, and two H1+ atoms to form distorted corner-sharing NZnH2C tetrahedra. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the fifth N3- site, N3- is bonded in a 4-coordinate geometry to one Zn2+, two C1-, and one H1+ atom. The N–H bond length is 1.02 Å. There are twenty-one inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the eighteenth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the nineteenth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the twentieth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the twenty-first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the Al(BO2)5 framework, Al3+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.75 Å) and two longer (1.76 Å) Al–O bond length. There are five inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.35–1.41 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.35–1.40 Å. In the third B3+ site, B3+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of B–O bond distances ranging from 1.47–1.50 Å. In the fourth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.35–1.42 Å. In the fifth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.35–1.42 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to one Al3+ and one B3+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the sixth O2- site, O2- is bonded in a linear geometry to one Al3+ and one B3+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the eighth O2- site, O2- is bonded in a linear geometry to one Al3+ and one B3+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one B3+ atom. In the tenth O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GaPH9C3Cl3O by Materials Project

GaC3PH9OCl3 is beta Sn-like structured and crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of four GaC3PH9OCl3 clusters. Ga3+ is bonded to one O2- and three Cl1- atoms to form GaCl3O tetrahedra that share a cornercorner with one PC3O tetrahedra. The Ga–O bond length is 1.88 Å. All Ga–Cl bond lengths are 2.19 Å. There are three inequivalent C4- sites. In the first C4- site, C4- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.80 Å. All C–H bond lengths are 1.10 Å. In the second C4- site, C4- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.79 Å. All C–H bond lengths are 1.10 Å. In the third C4- site, C4- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.79 Å. All C–H bond lengths are 1.10 Å. P5+ is bonded to three C4- and one O2- atom to form PC3O tetrahedra that share a cornercorner with one GaCl3O tetrahedra. The P–O bond length is 1.55 Å. There are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C4- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C4- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C4- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C4- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C4- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C4- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C4- atom. O2- is bonded in a bent 150 degrees geometry to one Ga3+ and one P5+ atom. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Ga3+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Ga3+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Ga3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Formation of phenanthrenyl radicals via the reaction of acenaphthyl with acetylene

Ab initio G3(MP2,CC)/B3LYP/6–31G** calculations of the potential energy surface for the reaction of 3-acenaphthyl radical with acetylene were combined with Rice-Ramsperger-Kassel-Marcus Master Equation calculations of the temperature- and pressure-dependent reaction rate constants and product branching ratios with the goal to examine the transformation of an edge five-membered ring into a six-membered one. The reaction mechanism has been shown to contain two stages: (1) the formation of 3-ethynylacenaphthylene + H in the 3-acenaphthyl + C 2 H 2 reaction via acetylene addition to the radical site and an H loss, (2) the formation of the 1-phenanthrenyl radical in the 3-ethynylacenaphthylene + H reaction via H addition to the five-membered ring followed by the ring flip. The results of kinetic modeling show this pathway being faster than the pathway proposed earlier featuring the CCH chemisorption on the six-membered ring without involvement of the five-membered ring. A kinetic test demonstrated the dominance of the former pathway for the formation of pyrene from naphthalene. Here, it is expected that the new mechanism plays a major role in the transformation of five-membered rings on edges of PAH structures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
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↗
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.↗
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↗
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↗