Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “cluster structure”

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 1,477 records · Page 82
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on MgSeO9 by Materials Project

MgO6SeO3 crystallizes in the trigonal R3 space group. The structure is three-dimensional and consists of three SeO3 clusters and one MgO6 framework. In each SeO3 cluster, Se is bonded in a trigonal planar geometry to three equivalent O atoms. All Se–O bond lengths are 1.63 Å. O is bonded in a single-bond geometry to one Se atom. In the MgO6 framework, Mg is bonded in an octahedral geometry to six O atoms. All Mg–O bond lengths are 2.20 Å. There are two inequivalent O sites. In the first O site, O is bonded in a distorted bent 150 degrees geometry to one Mg and one O atom. The O–O bond length is 1.28 Å. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one Mg and one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlBr3N by Materials Project

AlNBr3 is Silicon tetrafluoride-derived structured and crystallizes in the orthorhombic Pbca space group. The structure is zero-dimensional and consists of sixteen AlNBr3 clusters. Al is bonded in a trigonal pyramidal geometry to one N and three Br atoms. The Al–N bond length is 2.02 Å. There are one shorter (2.27 Å) and two longer (2.29 Å) Al–Br bond lengths. N is bonded in a single-bond geometry to one Al atom. There are three inequivalent Br sites. In the first Br site, Br is bonded in a single-bond geometry to one Al atom. In the second Br site, Br is bonded in a single-bond geometry to one Al atom. In the third Br site, Br is bonded in a single-bond geometry to one Al atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Atomic structure and Mott nature of the insulating charge density wave phase of 1T-TaS 2

Here, using x-ray pair distribution function (PDF) analysis and computer modeling, we explore structure models for the complex charge density wave (CDW) phases of layered 1T-TaS 2 that both well capture their atomic-level features and are amenable to electronic structure calculations. The models give the most probable position of constituent atoms in terms of 3D repetitive unit cells comprising a minimum number of Ta–S layers. Structure modeling results confirm the emergence of star-of-David (SD) like clusters of Ta atoms in the high-temperature incommensurate (IC) CDW phase and show that, contrary to the suggestions of recent studies, the low-temperature commensurate (C) CDW phase expands upon cooling thus reducing lattice strain. The C-CDW phase is also found to preserve the stacking sequence of Ta–S layers found in the room temperature, nearly commensurate (NC) CDW phase to a large extent. DFT based on the PDF refined model shows that bulk C-CDW 1T-TaS 2 also preserves the insulating state of individual layers of SD clusters, favoring the Mott physics description of the metal-to-insulator (NC-CDW to C-CDW) phase transition in 1T-TaS 2 . Our work highlights the importance of using precise crystal structure models in determining the nature of electronic phases in complex materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Residual mean field model of valence quarks in the nucleon

Abstract We develop a non-perturbative model for valence parton distribution functions (PDFs) based on the mean field interactions of valence quarks in the nucleonic interior. The main motivation for the model is to obtain a mean field description of the valence quarks as a baseline to study the short range quark–quark interactions that generate the high x tail of PDFs. The model is based on the separation of the valence three-quark cluster and residual system in the nucleon. Then the nucleon structure function is calculated within the effective light-front diagrammatic approach introducing nonperturbative light-front valence quark and residual wave functions. Within the model a new relation is obtained between the position, $$x_p$$ x p , of the peak of $$xq_V(x)$$ x q V ( x ) distribution of the valence quark and the effective mass of the residual system, $$m_R$$ m R , in the form: $$x_{p} \approx {1\over 4} (1-{m_R\over m_N})$$ x p ≈ 1 4 ( 1 - m R m N ) at starting $$Q^2$$ Q 2 . This relation explains the difference in the peak positions for d- and u-quarks through the expected difference of residual masses for valence d- and u-quark distributions. The parameters of the model are fixed by fitting the calculated valence quark distributions to the phenomenological PDFs. This allowed us to estimate the overall mean field contribution in baryonic and momentum sum rules for valence d- and u-quarks. Finally, the evaluated parameters of the non-perturbative wave functions of valence 3q-cluster and residual system can be used in calculation of other quantities such as nucleon form factors, generalized partonic and transverse momentum distributions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Vapor Phase Infiltration of Titanium Oxide into P3HT to Create Organic–Inorganic Hybrid Photocatalysts

Herein, we report for the first time the use of vapor phase infiltration (VPI) to infuse conducting polymers with inorganic metal oxide clusters that together form a photocatalytic material. While vapor infiltration has previously been used to electrically dope conjugated polymers, this is the first time, to our knowledge, that the resultant hybrid material has been demonstrated to have photocatalytic properties. The system studied is poly(3-hexylthiophene-2,5-diyl) (P3HT) vapor infiltrated with TiCl 4 and H 2 O to create P3HT-TiO x organic–inorganic hybrid photocatalytic materials. X-ray photoelectron spectroscopy analysis shows that P3HT-TiO x VPI films consist of a partially oxidized P3HT matrix, and the infiltrated titanium inorganic is in a 4+ oxidation state with mostly oxide coordination. Upon visible light illumination, these P3HT-TiO x hybrids degrade methylene blue dye molecules. The P3HT-TiO x hybrids are 4.6× more photocatalytically active than either the P3HT or TiO 2 individually or when sequentially deposited (e.g., P3HT on TiO 2 ). On a per surface area basis, these hybrid photocatalysts are comparable or better than other best in class polymer semiconductor photocatalysts. VPI of TiCl 4 + H 2 O into P3HT makes a unique hybrid structure and idealized photocatalyst architecture by creating nanoscale TiO x clusters concentrated toward the surface achieving extremely high catalytic rates. The mechanism for this enhanced photocatalytic rate is understood using photoluminescence spectroscopy, which shows significant quenching of excitons in P3HT-TiO x as compared to neat P3HT, indicating that P3HT acts as a photosensitizer for the TiO x catalyst sites in the hybrid material. This work introduces a new approach to designing and synthesizing organic–inorganic hybrid photocatalytic materials, with expansive opportunities for further exploration and optimization.

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

Materials Data on ReCl3O2 by Materials Project

ReO2Cl3 is Tungsten structured and crystallizes in the orthorhombic Pnnm space group. The structure is zero-dimensional and consists of two ReO2Cl3 clusters. Re7+ is bonded in a 2-coordinate geometry to two equivalent O2- and four Cl1- atoms. Both Re–O bond lengths are 1.71 Å. There are two shorter (2.29 Å) and two longer (2.62 Å) Re–Cl bond lengths. O2- is bonded in a single-bond geometry to one Re7+ atom. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Re7+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Re7+ atom. In the third Cl1- site, Cl1- is bonded in a water-like geometry to two equivalent Re7+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ClOF3 by Materials Project

OClF3 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of four OClF3 clusters. In two of the OClF3 clusters, O is bonded in a single-bond geometry to one Cl atom. The O–Cl bond length is 1.41 Å. Cl is bonded in a see-saw-like geometry to one O and three F atoms. There are a spread of Cl–F bond distances ranging from 1.67–1.88 Å. There are three inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Cl atom. In the second F site, F is bonded in a single-bond geometry to one Cl atom. In the third F site, F is bonded in a single-bond geometry to one Cl atom. In two of the OClF3 clusters, O is bonded in a single-bond geometry to one Cl atom. The O–Cl bond length is 1.41 Å. Cl is bonded in a see-saw-like geometry to one O and three F atoms. There are a spread of Cl–F bond distances ranging from 1.67–1.83 Å. There are three inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Cl atom. In the second F site, F is bonded in a single-bond geometry to one Cl atom. In the third F site, F is bonded in a single-bond geometry to one Cl atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si3Au10 by Materials Project

Au10Si3 is Tungsten structured and crystallizes in the cubic I-43m space group. The structure is zero-dimensional and consists of two Au10Si3 clusters. there are three inequivalent Au+0.40- sites. In the first Au+0.40- site, Au+0.40- is bonded in a trigonal non-coplanar geometry to three equivalent Si+1.33+ atoms. All Au–Si bond lengths are 2.58 Å. In the second Au+0.40- site, Au+0.40- is bonded in a distorted single-bond geometry to one Si+1.33+ atom. The Au–Si bond length is 2.54 Å. In the third Au+0.40- site, Au+0.40- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Si+1.33+ atoms. All Au–Si bond lengths are 2.62 Å. Si+1.33+ is bonded in a 8-coordinate geometry to six Au+0.40- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Neutrons in Structural Biology: Challenges and Opportunities (Workshop Report)

Gaining a thorough understanding of biological systems requires building our knowledge about biological processes from the level of atoms and electrons, and up to whole organisms. Such comprehensive knowledge will allow for a predictive understanding of complex biological systems behavior. It will guide us in the design and development of novel therapeutics and vaccines to tackle existing health threats and to prepare for future pandemics, and it will provide information necessary to create new biomaterials and bio-inspired technologies through manipulation of biological macromolecules, their assemblies, single cells and even microorganisms. Reaching these goals will require a synergistic combination of multiple experimental techniques with molecular calculations and predictive simulations, and the design and development of new techniques and capabilities that bridge current knowledge and technology gaps. Neutron scattering provides unique information about the biomacromolecular structure and function and can play a major role in achieving these goals. A workshop was held to engage the scientific community in identifying pressing challenges in biochemistry, structural biology, enzymology and structure-guided drug design not solved with the current neutron scattering technologies or utilizing other structural biology techniques such as X-ray crystallography, NMR, and cryo-EM. The workshop brought together structural biology, biochemistry and computational experts, as well as early career researchers and students, creating a forum for discussing scientific advancement and collaboration. The workshop included a one-day satellite training workshop where graduate students and postdoctoral researchers were educated in the application of neutron crystallography and small-angle scattering in structural biology. Furthermore, the Instrument Scientific Advisory Board (ISAB) for the development of a macromolecular neutron diffractometer at ORNL’s Second Target Station was introduced at the workshop. The major outcome was that neutrons can provide atomic-level understanding of biomacromolecular structure, function and dynamics which is of paramount importance for addressing the identified challenges. Neutron crystallography, in particular, can resolve long-standing biochemical issues regarding enzyme function by delineating the underlying chemistry and can have a major impact on the design of small-molecule therapeutics, especially in combination with molecular computation (quantum chemistry and molecular dynamics simulations) and the emerging artificial intelligence (AI)-assisted drug design technologies. The unique properties of neutrons, including their high sensitivity to hydrogen and their non-destructive nature, make them ideal probes of biological matter. There is a palpable need in the scientific community to expand and enhance the impact of neutron sciences on biology. Neutron crystallography is the only structural biology method capable of determining positions of all hydrogen atoms in proteins, nucleic acids and their complexes at near-physiological temperatures and of unstable species at cryogenic temperatures. Moreover, neutron analysis is non-ionizing, non-destructive and does not perturb the structure or redox chemistry of active site metal centers and clusters in proteins, which can be invaluable for studying radiation-sensitive metalloprotein complexes. Further, neutron energies used in scattering applications are similar to atomic motions, permitting neutron spectroscopies to characterize the dynamics of biomacromolecules on the picosecond to microsecond timescales. The different sensitivities of neutrons to protium (H) and deuterium (D) isotopes of hydrogen allow enhanced visibility of specific parts of biological complexes through isotopic labeling. The impact of neutrons will be most powerful when neutron scattering is combined with complementary experimental techniques that use photons and electrons, and with high-performance computing. The interconnection and mutuality of the experimental and theoretical capabilities will drive discoveries in biological and health sciences to generate more complete picture of complex biological systems. The major limitation in the field of biological neutron crystallography has been signal-to-noise, demanding large samples that are difficult to produce for the majority of biomacromolecules and limiting the applicability of this technique in biological sciences. A neutron crystallography instrument at the Second Target Station will revolutionize biological science with neutrons by engaging a large scientific community of structural biologists, enabling successful neutron diffraction experiments from radically smaller biomacromolecular crystals, resolving unanswered biochemical questions, and meaningfully contributing to rational drug design. The meeting highlighted 10 grand challenges that will be addressed with this advanced capability over the next decade and beyond, and the recommendations required to help address them are given below.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Materials Data on NbP2NCl12 by Materials Project

NbCl6P2NCl6 crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four NbCl6 clusters and four P2NCl6 clusters. In each NbCl6 cluster, Nb5+ is bonded in an octahedral geometry to six Cl1- atoms. There are a spread of Nb–Cl bond distances ranging from 2.38–2.40 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Nb5+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Nb5+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Nb5+ atom. In each P2NCl6 cluster, P5+ is bonded to one N3- and three Cl1- atoms to form corner-sharing PNCl3 tetrahedra. The P–N bond length is 1.56 Å. There are a spread of P–Cl bond distances ranging from 1.97–1.99 Å. N3- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one P5+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one P5+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Structure and dynamics of $\mathrm{Fe_{90}}$$\mathrm{Si_3}$$\mathrm{O_7}$ liquids close to Earth's liquid core conditions

Using an artificial neural-network machine learning interatomic potential, we have performed molecular dynamics simulations to study the structure and dynamics of $\mathrm{Fe_{90}}$$\mathrm{Si_3}$$\mathrm{O_7}$ liquid close to the Earth's liquid core conditions. Here, the simulation results reveal that the short-range structural order (SRO) in the $\mathrm{Fe_{90}}$$\mathrm{Si_3}$$\mathrm{O_7}$ liquid is very strong. About 80% of the atoms are arranged in crystallinelike SRO motifs. In particular, ~ $70$% of Fe-centered clusters can be classified as either hexagonal-close-packed-like or icosahedrallike SRO motifs. The SRO clusters centered on Fe, Si, or O atoms are strongly intermixed and homogenously distributed throughout the liquid. The atomic structure of the liquid and the fractions of dominant SRO clusters are not sensitive to pressure/temperature used in the simulations except that the SRO of the O-centered clusters is enhanced close to inner core pressures. The O-diffusion coefficient is about two to three times larger than the Fe and Si ions and increases more rapidly in the deeper core regions.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on AuNCl3 by Materials Project

AuNCl3 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four AuNCl3 clusters. Au5+ is bonded in a rectangular see-saw-like geometry to one N2- and three Cl1- atoms. The Au–N bond length is 1.93 Å. There are two shorter (2.31 Å) and one longer (2.35 Å) Au–Cl bond lengths. N2- is bonded in a single-bond geometry to one Au5+ atom. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Au5+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Au5+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Au5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlHg2O2F5 by Materials Project

(HgO)2AlF5 crystallizes in the tetragonal I4cm space group. The structure is two-dimensional and consists of four AlF5 clusters and two HgO sheets oriented in the (0, 0, 1) direction. In each AlF5 cluster, Al is bonded in a square pyramidal geometry to five F atoms. There is four shorter (1.78 Å) and one longer (1.80 Å) Al–F bond length. There are two inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Al atom. In the second F site, F is bonded in a single-bond geometry to one Al atom. In each HgO sheet, Hg is bonded in a 5-coordinate geometry to three equivalent O atoms. There are one shorter (2.21 Å) and two longer (2.36 Å) Hg–O bond lengths. O is bonded in a trigonal planar geometry to three equivalent Hg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A pair of early- and late-forming galaxy cluster samples: A novel way of studying halo assembly bias assisted by a constrained simulation

The halo assembly bias, a phenomenon referring to dependencies of the large-scale bias of a dark matter halo other than its mass, is a fundamental property of the standard cosmological model. First discovered in 2005 from the Millennium Run simulation, it has been proven very difficult to be detected observationally, with only a few convincing claims of detection so far. The main obstacle lies in finding an accurate proxy of the halo formation time. In this study, by utilizing a constrained simulation that can faithfully reproduce the observed structures larger than 2 Mpc in the local universe, for a sample of 634 massive clusters at z ≤ 0.12, we found their counterpart halos in the simulation and used the mass growth history of the matched halos to estimate the formation time of the observed clusters. This allowed us to construct a pair of early- and late-forming clusters, with a similar mass as measured via weak gravitational lensing, and large-scale biases differing at the ≈3σ level, suggestive of the signature of assembly bias, which is further corroborated by the properties of cluster galaxies, including the brightest cluster galaxy and the spatial distribution and number of member galaxies. Our study paves a way to further detect assembly bias based on cluster samples constructed purely on observed quantities.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Materials Data on SnAsF7 by Materials Project

Sn3As2F15AsF6 is Molybdenum Carbide MAX Phase-like structured and crystallizes in the trigonal R32 space group. The structure is zero-dimensional and consists of three AsF6 clusters and three Sn3As2F15 clusters. In each AsF6 cluster, As5+ is bonded in an octahedral geometry to six equivalent F1- atoms. All As–F bond lengths are 1.78 Å. F1- is bonded in a single-bond geometry to one As5+ atom. In each Sn3As2F15 cluster, Sn2+ is bonded in a 2-coordinate geometry to four F1- atoms. There are two shorter (2.14 Å) and two longer (2.59 Å) Sn–F bond lengths. As5+ is bonded in an octahedral geometry to six F1- atoms. There is three shorter (1.76 Å) and three longer (1.79 Å) As–F bond length. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a bent 150 degrees geometry to two equivalent Sn2+ atoms. In the second F1- site, F1- is bonded in a distorted single-bond geometry to one Sn2+ and one As5+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SbOF3 by Materials Project

SbOF3 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two SbOF3 clusters. Sb5+ is bonded to two equivalent O2- and three F1- atoms to form edge-sharing SbO2F3 trigonal bipyramids. There is one shorter (1.96 Å) and one longer (2.02 Å) Sb–O bond length. There are a spread of Sb–F bond distances ranging from 1.88–1.90 Å. O2- is bonded in a water-like geometry to two equivalent Sb5+ atoms. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Sb5+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Sb5+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Sb5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on IF5 by Materials Project

IF5 is beta-like structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of twenty IF5 clusters. I5+ is bonded in a square pyramidal geometry to five F1- atoms. There is one shorter (1.85 Å) and four longer (1.93 Å) I–F bond length. There are five inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one I5+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one I5+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one I5+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one I5+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one I5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sb2XeF16 by Materials Project

XeF5Sb2F11 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two Sb2F11 clusters and two XeF5 clusters. In each Sb2F11 cluster, there are two inequivalent Sb sites. In the first Sb site, Sb is bonded to six F atoms to form corner-sharing SbF6 octahedra. The corner-sharing octahedral tilt angles are 35°. There are a spread of Sb–F bond distances ranging from 1.89–2.08 Å. In the second Sb site, Sb is bonded to six F atoms to form corner-sharing SbF6 octahedra. The corner-sharing octahedral tilt angles are 35°. There are a spread of Sb–F bond distances ranging from 1.89–2.08 Å. There are eleven inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Sb atom. In the second F site, F is bonded in a single-bond geometry to one Sb atom. In the third F site, F is bonded in a single-bond geometry to one Sb atom. In the fourth F site, F is bonded in a single-bond geometry to one Sb atom. In the fifth F site, F is bonded in a single-bond geometry to one Sb atom. In the sixth F site, F is bonded in a single-bond geometry to one Sb atom. In the seventh F site, F is bonded in a single-bond geometry to one Sb atom. In the eighth F site, F is bonded in a single-bond geometry to one Sb atom. In the ninth F site, F is bonded in a bent 150 degrees geometry to two Sb atoms. In the tenth F site, F is bonded in a single-bond geometry to one Sb atom. In the eleventh F site, F is bonded in a single-bond geometry to one Sb atom. In each XeF5 cluster, Xe is bonded in a square pyramidal geometry to five F atoms. There is four shorter (1.96 Å) and one longer (1.97 Å) Xe–F bond length. There are five 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 Xe atom. In the third F site, F is bonded in a single-bond geometry to one Xe atom. In the fourth F site, F is bonded in a single-bond geometry to one Xe atom. In the fifth F site, F is bonded in a single-bond geometry to one Xe atom.

36 MATERIALS SCIENCE↗