Density functional theory studies on the electronic, structural, phonon dynamical and thermo-stability properties of bicarbonates MHCO3, M = Li, Na, K
Explore the source record for details and available documents.
Zhang, Bo↗
SEARCH · Engineering Papers
Results for “FUNCTIONALS”
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.
Impacts of nitrogen addition on switchgrass root-associated diazotrophic community structure and function
ABSTRACT Cellulosic bioenergy crops, like switchgrass (Panicum virgatum), have potential for growth on lands unsuitable for food production coupled with potential for climate mitigation. Sustainability of these systems lies in identifying conditions that promote high biomass yields on marginal lands under low-input agricultural practices. Associative nitrogen fixation (ANF) is a potentially important nitrogen (N) source for these crops, yet ANF contributions to plant N, especially under fertilizer N addition are unclear. In this study, we assess structure (nifH) and function (ANF) of switchgrass root-associated diazotrophic communities to long-term and short-term N additions using soil from three marginal land sites. ANF rates were variable and often unexpectedly high, sometimes 10× greater than reported in the literature, and did not respond in repeatable ways to long-term or short-term N. We found few impacts of N addition on root-associated diazotrophic community structure or membership. Instead, we found a very consistent root-associated diazotrophic community even though switchgrass seeds were germinated in soil from field sites with distinct diazotrophic communities. Ultimately, this work demonstrates that root-associated diazotrophic communities have the potential to contribute to switchgrass N demands, independent of N addition, and this may be driven by selection of the diazotrophic community by switchgrass roots.
Microbiology↗
Electronic and magnetic properties of T i 4 O 7 predicted by self-interaction-corrected density functional theory
Understanding electronic properties of substoichiometric phases of titanium oxide such as Magneli phase Ti 4 O 7 is crucial in designing and modeling resistive switching devices. Here we present our study on Magneli phase Ti 4 O 7 together with rutile TiO 2 and Ti 2 O 3 using density functional theory methods with atomic-orbital-based self-interaction correction (ASIC). We predict a new antiferromagnetic (AF) ground state in the low temperature (LT) phase, and we explain energy difference with a competing AF state using a Heisenberg model. The predicted energy ordering of these states in the LT phase is calculated to be robust in a wide range of modeled isotropic strain. We have also investigated the dependence of the electronic structures of the Ti-O phases on stoichiometry. The splitting of titanium t 2g orbitals is enhanced with increasing oxygen deficiency as Ti-O is reduced. Furthermore, the electronic properties of all these phases can be reasonably well described by applying ASIC with a "standard" value for transition metal oxides of the empirical parameter alpha of 0.5 representing the magnitude of the applied self-interaction correction.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Two-dimensional ferroelectric topological insulators in functionalized atomically thin bismuth layers
We introduce a class of two-dimensional (2D) materials that possess coexisting ferroelectric and topologically insulating orders. Such ferroelectric topological insulators (FETIs) occur in noncentrosymmetric atomic layer structures with strong spin-orbit coupling (SOC). Here, we showcase a prototype 2D FETI in an atomically thin bismuth layer functionalized by CH 2 OH, which exhibits a large ferroelectric polarization that is switchable by a ligand molecule rotation mechanism and a strong SOC that drives a band inversion leading to the topologically insulating state. An external electric field that switches the ferroelectric polarization also tunes the spin texture in the underlying atomic lattice. Moreover, the functionalized bismuth layer exhibits an additional quantum order driven by the valley splitting at the K and K' points in the Brillouin zone stemming from the symmetry breaking and strong SOC in the system, resulting in a remarkable state of matter with the simultaneous presence of the quantum spin Hall and quantum valley Hall effect. These phenomena are predicted to exist in other similarly constructed 2D FETIs, thereby offering a unique quantum material platform for discovering novel physics and exploring innovative applications.
2-dimensional systems↗
Impact of nuclear dependence of R=σ L /σ T on antishadowing in nuclear structure functions
Not Available
Guzey, Vadim↗
Spontaneous fission modes and lifetimes of superheavy elements in the nuclear density functional theory
Not Available
Staszczak, A.↗
Examination of the low-energy enhancement of the γ -ray strength function of Fe 56
A model-independent technique was used to determine the gamma-ray strength function (gamma SF) of Fe-56 down to gamma-ray energies less than 1 MeV for the first time with GRETINA using the (p, p') reaction at 16MeV. No difference was observed in the energy dependence of the gamma SF built on 2(+) and 4(+) final states, supporting the Brink hypothesis. In addition, angular distribution and polarization measurements were performed. The angular distributions are consistent with dipole radiation. The polarization results show a small bias towards magnetic character in the region of the enhancement.
Jones, M. D.↗
Global analysis of fragmentation functions for eta mesons
Fragmentation functions for eta mesons are extracted at next-to-leading order accuracy of QCD in a global analysis of data taken in electron-positron annihilation and proton-proton scattering experiments. The obtained parametrization is in good agreement with all data sets analyzed and can be utilized, for instance, in future studies of double-spin asymmetries for single-inclusive eta production. The Lagrange multiplier technique is used to estimate the uncertainties of the fragmentation functions and to assess the role of the different data sets in constraining them.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Valence-quark distribution functions in the kaon and pion
We describe expressions for pion and kaon dressed-quark distribution functions that incorporate contributions from gluons which bind quarks into these mesons and hence overcome a flaw of the commonly used handbag approximation. The distributions therewith obtained are purely valence in character, ensuring that dressed quarks carry all the meson’s momentum at a characteristic hadronic scale and vanish as ( 1 - x ) 2 when Bjorken- x → 1 . Comparing such distributions within the pion and kaon, it is apparent that the size of S U ( 3 ) -flavor symmetry breaking in meson parton distribution functions is modulated by the flavor dependence of dynamical chiral symmetry breaking. Corrections to these leading-order formulas may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea quarks. Working with available empirical information, we build an algebraic framework that is capable of expressing the principal impact of both classes of corrections. This enables a realistic comparison with experiment which allows us to identify and highlight basic features of measurable pion and kaon valence-quark distributions. We find that whereas roughly two thirds of the pion’s light-front momentum is carried by valence dressed quarks at a characteristic hadronic scale; this fraction rises to 95% in the kaon; evolving distributions with these features to a scale typical of available Drell-Yan data produces a kaon-to-pion ratio of u -quark distributions that is in agreement with the single existing data set, and predicts a u -quark distribution within the pion that agrees with a modern reappraisal of π N Drell-Yan data. Precise new data are essential in order to validate this reappraisal and because a single modest-quality measurement of the kaon-to-pion ratio cannot be considered definitive.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Λ Λ Correlation Function in Au + Au Collisions at s N N = 200 GeV
We present Lambda Lambda correlation measurements in heavy-ion collisions for Au + Au collisions at root s(NN) = 200 GeV using the STAR experiment at the Relativistic Heavy-Ion Collider. The Lednicky-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the Lambda Lambda correlation function and interaction parameters for dihyperon searches are discussed.
43 PARTICLE ACCELERATORS↗
Free Energy from Stationary Implementation of the DFT + DMFT Functional
Not Available
Haule, Kristjan↗