The pre‐edges of oxygen‐ K X‐ray absorption spectra have been ubiquitous in transition metal (TM) oxide studies various fields, especially on the fervent topic oxygen redox states battery electrodes. However, critical debates remain use O‐ pre‐edge variations upon electrochemical cycling as evidences reactions, which has a popular practice field. This study presents an investigation 55 oxides covering all 3d TMs with different elements, structures, and through combined experimental...

As CuBi2O4 is an emerging p-type semiconductor for applications as a photocathode in photoelectrochemical (PEC) solar fuel production, there much to be understood about the uniqueness and commonalities material exhibits comparison other, more well-known metal oxide systems. We examine p-CuBi2O4 thin films grown by reactive co-sputtering with comprehensive spectroscopic first principles characterization methodology describe its fundamental electronic structure optical properties while...

Abstract The activity of polycrystalline thin film photoelectrodes is impacted by local variations the material properties due to exposure different crystal facets and presence grain/domain boundaries. Here a multi‐modal approach applied correlate nanoscale heterogeneities in chemical composition electronic structure with morphology Mo‐BiVO 4 . By using scanning transmission X‐ray microscopy, characteristic used disentangle absorption spectra corresponding grain centers Comparing both...

Abstract We introduce neutral excitation density-functional theory (XDFT), a computationally light, generally applicable, first-principles technique for calculating electronic excitations. The concept is to generalise constrained density functional free it from any assumptions about the spatial confinement of electrons and holes, but maintain all advantages variational method. task lowest excited state given symmetry thereby simplified one performing simple, low-cost sequence coupled DFT...

Constrained density functional theory (CDFT) is used to evaluate the energy level alignment of a benzene molecule as it approaches graphene sheet. Within CDFT problem conveniently mapped onto evaluating total differences between different charge-separated states, and does not consist in determining quasiparticle spectrum. We demonstrate that simple local approximation provides good description along entire binding curve, with excellent agreement experiments at an infinite separation $GW$...

Abstract The design principles of acceptor 1 –acceptor 2 copolymers featuring alternating diketopyrrolopyrrole (DPP) and thienopyrrolodione (TPD) moieties are investigated. investigated series polymers is obtained by varying the aromatic linker between two motifs thiophene, thiazole, pyridine, benzene. High electron affinities 3.96 4.42 eV, facilitated synergy determined with optical gaps 1.37 2.02 eV. Grazing incidence wide‐angle X‐ray scattering studies reveal a range film morphologies...

Investigation of Li metal and ionic compounds through experimental theoretical spectroscopy has been tremendous interest due to their prospective applications in Li–metal Li-ion batteries. K-edge soft X-ray absorption (sXAS) provides the most direct spectroscopic characterization; unfortunately, low core-level energy highly reactive surface, Li–K sXAS extremely challenging, as evidenced by many controversial reports. Here, controlled ultra-high resolution experiments two kinds situ prepared...

BaCe0.25Mn0.75O3−δ (BCM), a non-stoichiometric oxide with layered perovskite-like crystal structure, has recently emerged as prospective contender for application in renewable energy harvesting by solar thermochemical hydrogen generation. Using solar–thermal and reducing environment, oxygen vacancies can be created high-temperature BCM, the reduced so obtained can, turn, produce H2 stripping from H2O. Therefore, first step toward understanding working mechanism optimizing performance of BCM...

Spin-orbit coupling in organic crystals is responsible for many spin-relaxation phenomena, going from spin diffusion to intersystem crossing. With the goal of constructing effective spin-orbit Hamiltonians be used multiscale approaches thermodynamical properties crystals, we present a method that combines density functional theory with construction Wannier functions. In particular show Hamiltonian constructed over maximally localised functions can computed by direct evaluation matrix...

The way in which conjugated polymers pack the solid state strongly affects performance of polymer-based optoelectronic devices. However, even for most crystalline precise packing chains within unit cell is not well established. Here we show that by performing resonant X-ray diffraction experiments at sulfur K-edge are able to resolve tilting planar backbones poly(3-hexylthiophene) (P3HT) cell. This approach exploits anisotropic nature optical properties polymers, enabling us discern between...

Given their natural abundance and thermodynamic stability, fluoride salts may appear as evolving components of electrochemical interfaces in Li-ion batteries emergent multivalent ion cells. This is due to the practice employing electrolytes with fluorine-containing species (salt, solvent, or additives) that electrochemically decompose deposit on electrodes. Operando X-ray absorption spectroscopy (XAS) can probe electrode–electrolyte interface a single-digit nanometer depth resolution offers...

Spin-orbit interaction is an important vehicle for spin relaxation. At finite temperature lattice vibrations modulate the spin-orbit and thus generate a mechanism spin-phonon coupling, which needs to be incorporated in any quantitative analysis of transport. Starting from density functional theory ab initio electronic structure, we calculate matrix elements over basis maximally localized Wannier functions. Such coupling terms form effective Hamiltonian used extract thermodynamic quantities,...

X-ray absorption spectroscopy (XAS) is an explicit probe of the unoccupied electronic structure materials and invaluable tool for fingerprinting various properties phenomena. Computational methods capable simulating analysing such spectra are therefore in high demand complementing experimental results extracting valuable insights therefrom. In particular, a recently proposed first-principles approach titled Many-Body XAS (MBXAS), which approximates final (initial) state as Slater determinant...

The electronic structure and local coordination of binary (Mo6T8) ternary Chevrel Phases (MxMo6T8) are investigated for a range metal intercalant chalcogen compositions. We evaluate differences in the Mo L3-edge K-edge X-ray absorption near edge across suite chalcogenides MxMo6T8 (M = Cu, Ni, x 1-2, T S, Se, Te), quantifying effect compositional structural modification on structure. Furthermore, we highlight expansion, contraction, anisotropy Mo6 clusters within these Phase frameworks...

Accurate simulation of electronic excitations and deexcitations are critical for complementing complex spectroscopic experiments can provide validation to theoretical approaches. Using a generalized framework, we contrast the accuracy validity orbital-constrained linear-response approaches that build upon Kohn-Sham density functional theory (DFT) simulate emission spectra origin propose an efficient approximation, named many-body x-ray spectroscopy or MBXES, simulating such processes. We...

Pulay terms arise in the Hellmann-Feynman forces electronic-structure calculations when one employs a basis set made of localized orbitals that move with their host atoms. If total energy system depends on subspace population defined across multiple atoms, then unconventional will emerge due to variation orbital nonorthogonality ionic translation. Here, we derive required exact expressions for such terms, which cannot be eliminated by orthonormalization. We have implemented these corrected...

The pre-edges of oxygen-K X-ray absorption spectra have been ubiquitous in transition metal (TM) oxide studies various fields, especially on the fervent topic oxygen redox states battery electrodes. However, critical debates remain use O-K pre-edge variations upon electrochemical cycling as evidences reactions, which has a popular practice field. This study presents an investigation 55 oxides covering all 3d TMs with different elements, structures and through combined experimental...

Designing Li-ion battery cathodes free of critical raw materials such as Co and Ni has a huge technological societal impact. Although anion redox-based Li-rich oxide allow for designing Co- Ni-free cathode compositions, the oxides demonstrated voltage fade, hysteresis, irreversible oxygen release despite their high capacity. Conversely, redox through highly covalent chalcogenides (S/Se) is emerging due to improved covalency between metal d ligand p bands. Here, we investigate tuning...

Alkylated benzothienobenzothiophenes are an important class of organic semiconductors that exhibit high performance in solution-processed field-effect transistors. In this work, we study the near-edge x-ray absorption fine-structure (NEXAFS) spectra 2,7-didecyl[1]benzothieno[3,2-b][1]benzothiophene (C10-BTBT) at both carbon and sulfur K-edges. Angle-resolved experiments thin films performed to characterize dichroism associated with molecular orientation. First-principles calculations using...

<div>The pre-edges of oxygen-K X-ray absorption spectra have been ubiquitous in transition metal (TM) oxide studies various fields, especially on the fervent topic oxygen redox states battery electrodes. However, critical debates remain use O-K pre-edge variations upon electrochemical cycling as evidences reactions, which has a popular practice field. This study presents an investigation 55 oxides covering all 3d TMs with different elements, structures and through combined experimental...

Understanding the role of oxygen vacancy–induced atomic and electronic structural changes to complex metal oxides during water-splitting processes is paramount advancing field solar thermochemical hydrogen production (STCH). The formulation confirmation a mechanism for these types chemical reactions necessitate multifaceted experimental approach, featuring advanced characterization methods. Synchrotron X-ray techniques are essential rapidly STCH in part due properties such as high...

The well-defined low-energy features, so-called pre-edges, of oxygen K-edge X-ray absorption spectra in transition metal (TM) oxides correspond to the hybridized states TM 3d and O 2p orbitals. evolution these features has been broadly used for studying oxidation battery electrodes. However, critical questions remain on validity such an application as well origin pre-edge upon cycling. Here, combined with theoretical calculations, we investigated O-K collected from 14 groups electrodes a...

The well-defined low-energy features, so-called pre-edges, of oxygen K-edge X-ray absorption spectra in transition metal (TM) oxides correspond to the highly hybridized states TM 3d and O 2p orbitals. evolution these features have been broadly used for studying oxidation battery electrodes; however, critical questions remain on validity such an application origin pre-edge upon cycling is yet be clarified. Here, combined with theoretical calculations, we investigated O-K collected from 14...