Light harvesting and excitation energy transfer in photosynthesis are relatively well understood at cryogenic temperatures up to ∼100 K, where crystal structures of several photosynthetic complexes including the major antenna complex green plants (LHC II) available nearly atomic resolution. The situation is much more higher or even physiological temperatures, because spectroscopic properties typically undergo drastic changes above K. We have addressed this problem using a combination...

The first-principles (ab initio) computations of the structural, electronic, and phonon properties have been performed for cubic low-temperature tetragonal phases BaTiO3 SrTiO3 perovskite crystals, both stoichiometric non-stoichiometric (with neutral oxygen vacancies). Calculations were with CRYSTAL17 computer code within linear combination atomic orbitals approximation, using B1WC advanced hybrid exchange-correlation functional density-functional-theory (DFT) periodic supercell approach....

Anisotropic elastic dipoles of oxygen vacancies interact with substrate-induced misfit strain in epitaxial oxide films. This interaction leads to specific spatial alignment the that facilitates coherent growth.

A noticeable improvement of hydrogen production upon photocatalytic water splitting was found recently experimentally on the faceted nanoparticles strontium titanate (SrTiO3, STO). In this paper, we study and theoretically effects Al doping electronic structure, optical properties, efficiency. It is demonstrated here that significantly increases photoactivity in splitting. The preparation Al-doped STO photocatalysts molten KCl with further optimization synthesis procedure co-catalyst...

The electronic properties, including bandgap and conductivity, are critical for nearly all applications of multifunctional perovskite oxide ferroelectrics. Here we analysed possibility to induce semiconductor behaviour in these materials, which basically insulators, by replacement several percent oxygen atoms with nitrogen, hydrogen, or vacancies. We explored this approach one the best studied members large family ABO

The results of first-principles calculations the structural, electronic, elastic, vibrational, dielectric and optical properties, as well Raman infrared (IR) spectra, potassium hexafluorosilicate (K2SiF6; KSF) crystal are discussed. KSF doped with manganese atoms (KSF:Mn4+) is known for its ability to function a phosphor in white LED applications due efficient red emission from Mn⁴⁺ activator ions. simulations were performed using CRYSTAL23 computer code within linear combination atomic...

The results of experimental and theoretical ab initio study structural piezoelectric properties (Ba,Sr)TiO3 perovskite solid solutions are discussed compared. Experimentally, plate-like particles were synthesized by the topochemical conversion in molten salt from Bi4Ti3O12 template plates. All dimensions (side length ≈1 μm, thickness ≈200–400 nm) well above critical size necessary for observation piezo- ferroelectricity. first-principles computations electromechanical performed with...

Dynamics-function correlations are usually inferred when molecular mobility and protein function simultaneously impaired at characteristic temperatures or hydration levels. In this sense, excitation energy transfer in the photosynthetic light-harvesting complex II (LHC II) is an untypical example because it remains fully functional even cryogenic relying mainly on interactions of electronic states with vibrations. Here, we study vibrational conformational dynamics monomeric trimeric LHC from...

An enhancement of the piezoelectric properties lead-free materials, which allow conversion mechanical energy into electricity, is a task great importance and interest. Results first-principles calculations piezoelectric/electromechanical Ba(1-x)SrxTiO3 (BSTO) ferroelectric solid solution with perovskite structure are presented discussed. Calculations performed within linear combination atomic orbitals (LCAO) approximation periodic-boundary conditions, using advanced hybrid functionals...

We present the results of a detailed first principles study piezoelectric properties (SrTiO3)m/(BaTiO3)M-m heterostructure using 3D STOm/BTOM-m superlattice model. The atomic basis set, hybrid functionals and slabs with different numbers STO BTO layers were used. interplay between ferroelectric (FEz) antiferrodistortive (AFDz) displacements is carefully analyzed. Based on experimental data group theoretical analysis, we deduce two possible space groups tetragonal symmetry which allow us to...

The colloidal processing of nearly monodisperse and highly crystalline single-domain ferroelectric or ferromagnetic nanocubes is a promising route to produce superlattice structures for integration into next-generation devices, whereas controlling the local behaviour nanocrystals imperative fabricating highly-ordered assemblies. current picture nanoscale polarization in individual suggests potential presence significant dipolar interaction, but its role condensation unknown. We simulate...

Various photocatalysts are being currently studied with the aim of increasing photocatalytic efficiency water splitting for production hydrogen as a fuel and oxygen medical gas. A noticeable increase was found recently experimentally on anisotropic faces (facets) strontium titanate (SrTiO3, STO) nanoparticles. In order to identify optimal sites splitting, first principles calculations Raman vibrational spectrum bulk stepped (facet) surface thin STO film adsorbed derivatives were performed....

This study presents quasielastic neutron scattering data of the water-soluble chlorophyll-binding protein (WSCP) and corresponding buffer solution at room temperature. The contributions to overall are carefully separated. Otherwise, fast water dynamics dominating contribution is likely mask slow dynamics. In case WSCP, can be described by two contributions: i) internal represented a diffusion in sphere with an average radius 2.7 Å ii) global (Brownian) WSCP macromolecule upper limit for...

While the bulk strontium titanate (STO) crystal characteristics are relatively well known, ultrathin perovskites' nanostructure, chemical composition, and crystallinity quite complex challenging to understand in detail. In our study, DFT methods were used for modelling Raman spectra of STO (space group I4/mcm) 5-21-layer thin films (layer p4/mbm) tetragonal phase with different thicknesses ranging from ~0.8 3.9 nm. Our calculations revealed features that absent spectra. Out seven...

The intensity of neutrons Bragg diffracted from the back face a 9 mm thick slab-shaped Si(111) analyzer crystal has been measured experimentally at ORNL double diffractometer and calculated theoretically. back-face rocking curve strain-free perfect contains two symmetrical peaks which become asymmetrical under an ultrasmall static deformation strain (bending with radius tens km). asymmetry is shown to be sensitive measure both magnitude direction bending.

Vibrational dynamics of the light-harvesting complex II (LHC II) from spinach was investigated by quasi- and inelastic neutron scattering (QENS INS) at three different temperatures 80, 160, 285 K. QENS/INS spectra solubilised LHC corresponding buffer solution were obtained separately exhibit characteristic features. After subtraction contribution, INS spectrum reveals a distinct Boson peak ∼ 2.5 meV 80 K that shifts towards lower energies if temperature is increased to This effect...

Abstract The effect of dehydration on the lamellar spacing photosystem II (PS II) membrane fragments from spinach has been investigated using neutron diffraction at room temperature. data reveal a major peak scattering vector Q 0.049 Å−1 relative humidity (r.h.) 90% corresponding to repeat distance D about 129 Å. Upon 44% r.h., this shifts 0.060 104.7±2.5 Within experimental error, latter remains almost same hydration levels below r.h. indicating that most water is removed. This result...

The linear combination of atomic orbitals (LCAO) method is advantageous for calculating important bulk and surface properties crystals defects in/on them. Compared to plane wave calculations contrary common assumptions, hybrid density functional theory (DFT) functionals are actually less costly easier implement in LCAO codes. However, choosing the proper basis set (BS) representing Guassian-type functions crucial, as results depend heavily on its quality. In this study, we introduce a new...

Substitution of oxygen with nitrogen lowers crystal symmetry and modifies lattice vibrations in SrTiO 3 . The dielectric permittivity decreases through these intrinsic transformations it increases due to dipolar relaxation nitrogen-induced nanoregions.