Benchmarking of Density Functionals for the Description of Optical Properties of Newly Synthesized π-Conjugated TADF Blue Emitters

Computational modeling of the optical characteristics of organic molecules with potential for thermally activated delayed fluorescence (TADF) may assist markedly the development of more efficient emitting materials for organic light-emitting diodes. Recent theoretical studies in this area employ mostly methods from density functional theory (DFT). In order to obtain accurate predictions within this approach, the choice of a proper functional is crucial. In the current study, we focus on testing the performance of a set of DFT functionals for estimation of the excitation and emission energy and the excited singlet-triplet energy gap of three newly synthesized compounds with capacity for TADF. The emitters are designed specifically to enable charge transfer by π-electron conjugation, at the same time possessing high-energy excited triplet states. The functionals chosen for testing are from various groups ranging from gradient-corrected through global hybrids to range-separated ones. The results show that the monitored optical properties are especially sensitive to how the long-range part of the exchange energy is treated within the functional. The accurate functional should also be able to provide well balanced distribution of the π-electrons among the molecular fragments. Global hybrids with moderate (less than 0.4) share of exact exchange (B3LYP, PBE0) and the meta-GGA HSE06 are outlined as the best performing methods for the systems under study. They can predict all important optical parameters correctly, both qualitatively and quantitatively.     

Chaotic motion of a cylindrical body during contactless transportation from MEO to LEO by ion beam

Nonlinear Dynamics - The attitude dynamics of a cylindrical body under the action of an ion beam generated by the low-thrust engine of an active spacecraft is studied. The aim of the work is the...     

Head-on collision of two coaxial vortex rings in an ideal fluid

The opposing motion of two coaxial vortex rings is classified in relation to the initial parameters.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 60–64, July–August, 1989.The authors are grateful to V. V. Meleshko for discussing their results.     

Study of the reaction π–<Emphasis Type="Italic">A</Emphasis> π<Superscript>+</Superscript>π<Superscript>–</Superscript>π<Superscript>–</Superscript><Emphasis Type="Italic">A</Emphasis> at large statistics with VES setup

Partial wave analysis of the π–A π⁺π^–π^– system produced by 29 GeV/cπ^– beam on a beryllium target is presented. About 30 × 10⁶ |events in the wide t′|range 0–0.8 GeV²/c ² are collected with upgraded VES setup. The size of the data sample is 2.5 times larger than one previously analyzed by VES. Data are analyzed using formalism of the density matrix with unlimited rank. We discuss status of the a ₁(1420) a ₂(1700) a ₃(1875) states and a structure of exotic ρ(770)π P-wave with J ^PC = 1^-+. Parameters of a ₃(1875) are estimated as M = 1985 ± 20 MeV/c ², Γ = 200 ± 50 MeV/c ² (preliminary).     

Pressure distribution on the surface of a spherical segment entering a compressible fluid

The pressure on the progressively expanding wetted surface of a spherical segment entering a compressible fluid has been experimentally determined.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 9–14, March–April, 1986     

X-ray diffraction study of mesogenic 4-methoxyphenyl-4′-n-nonyloxybenzoate

4-methoxyphenyl-4′-n-nonyloxybenzoate have been investigated by single crystal X-ray structural analysis. Crystal packing of the compounds does not represent a precursor of the mesophse although the typical for liquid crystal compounds separation of crystal packing on aromatic and aliphatic areas is observed here. Possible reason for monotropic properties are discussed.     

Silicon Film Deposition Using a Gas-Jet Plasma-Chemical Method: Experiment and Gas-Dynamic Simulation

This paper presents the results of an experimental study, numerical calculation, and analysis within the framework of a gas-dynamic model of silicon film deposition by a gas-jet plasmachemical method. A numerical model of gas mixtures flowing out of an annular nozzle unit and into a reactor is developed, and it allows one to determine a film thickness distribution over the surface of substrates placed in the reactor and satisfactorily describes the experimental data obtained.     

Features of the Coupled Nuclear–Electron Spin Precession in the Bose–Einstein Condensate of Magnons

JETP Letters - The experimental detection of the Bose-Einstein condensate of magnons in coupled nuclear-electron spin precession in antiferromagnets brings the prospect of its use for magnonics and...