Orbital Optimization in the Active Space Decomposition Model

We report the derivation and implementation of orbital optimization algorithms for the active space decomposition (ASD) model, which are extensions of complete active space self-consistent field (CASSCF) and its occupation-restricted variants in the conventional multiconfiguration electronic-structure theory. Orbital rotations between active subspaces are included in the optimization, which allows us to unambiguously partition the active space into subspaces, enabling application of ASD to electron and exciton dynamics in covalently linked chromophores. One- and two-particle reduced density matrices, which are required for evaluation of orbital gradient and approximate Hessian elements, are computed from the intermediate tensors in the ASD energy evaluation. Numerical results on 4-(2-naphthylmethyl)-benzaldehyde and [3$_6$]cyclophane and model Hamiltonian analyses of triplet energy transfer processes in the Closs systems are presented. Furthermore model Hamiltonians for hole and electron transfer processes in anti-[2.2](1,4)pentacenophane are studied using an occupation-restricted variant

An Undergraduate Business Information Security Course and Laboratory

In an environment of growing security threats, it is essential to raise the awareness and capabilities of business students entering the workforce to mitigate threats to the enterprise. In this paper, the authors present their experience in the design, implementation, and teaching of a foundation undergraduate business information security course with laboratory components using security tools. The authors identify key resources consulted in the development of the curriculum and discuss various teaching methods and their effectiveness in offering the course for the first time

Color Stable Deep Blue Multi‐Resonance Organic Emitters with Narrow Emission and High Efficiency

Abstract The development of highly efficient and deep blue emitters satisfying the color specification of the commercial products has been a challenging hurdle in the organic light‐emitting diodes (OLEDs). Here, deep blue OLEDs with a narrow emission spectrum with good color stability and spin‐vibronic coupling assisted thermally activated delayed fluorescence are reported using a novel multi‐resonance (MR) emitter built on a pure organic‐based molecular platform of fused indolo[3,2,1‐jk]carbazole structure. Two emitters derived from 2,5,11,14‐tetrakis(1,1‐dimethylethyl)indolo[3,2,1‐jk]indolo[1′,2′,3′:1,7]indolo[3,2‐b]carbazole (tBisICz) core are synthesized as the MR type thermally activated delayed fluorescence emitters realizing a very narrow emission spectrum with a full‐width‐at‐half‐maximum (FWHM) of 16 nm with suppressed broadening at high doping concentration. The tBisICz core is substituted with a diphenylamine or 9‐phenylcarbazole blocking group to manage the intermolecular interaction for high efficiency and narrow emission. The deep blue OLEDs achieve high external quantum efficiency (EQE) of 24.9%, small FWHM of 19 nm, and deep blue color coordinate of (0.16, 0.04) with good color stability with increase in doping concentration. To the authors’ knowledge, the EQE in this work is one of the highest values reported for the deep blue OLEDs that achieve the BT.2020 standard

Improving Electroluminescence of Two-Coordinate Au(I) Complexes: Insights into Steric and Electronic Control

This research elucidates the effects of structural modulations on electroluminescent Au(I) complexes, shedding light on factors governing radiative and nonradiative processes. A series of Au(I) complexes, fortified with ortho-substituents in carbene and amido ligands, are subjected to rigorous structural, photophysical, and quantum chemical investigations, which unveil distinct structural and electronic effects exerted by the ligands. The investigations reveal that nonradiative processes are governed primarily by the energy-gap law. Radiative processes are observed to have a weak correlation with the mutual interactions of the molecular orbitals of carbene and amido ligands. Rather, it is discovered that an accumulation of the negative charge in the Au 5d orbital in the excited state decelerates radiative processes. The effectiveness of these findings is substantiated through the larger external quantum efficiency of electroluminescence devices employing the Au(I) complex, in comparison to those based on the archetypical Au(I) complex and the organic thermally activated delayed fluorescent molecule. These compelling revelations underscore the untapped potential of Au(I) complexes in the advancement of electroluminescence technology and advocate for continued investigations into the intriguing domain of ligand structural control. Molecular factors that control photoluminescence efficiencies of two-coordinate Au(I) complexes involve the emission energy and the charge in the Au 5d-orbital.imag

Kohn-Sham Time-Dependent Density Functional Theory on the Massively Parallel Graphics Processing Units

We report a high-performance multi graphics processing unit (GPU) implementation of the Kohn-Sham time-dependent density functional theory (TDDFT) within the Tamm-Dancoff approximation. Our newly developed GPU algorithm on massively parallel computing systems using multiple parallel models in tandem scales optimally with material size, considerably reducing the computational wall time. A benchmark TDDFT study was performed on a green fluorescent protein complex composed of 4,353 atoms with 40,518 atomic orbitals represented by Gaussian-type functions. As the largest molecule attempted to date to the best of our knowledge, the proposed strategy demonstrated reasonably high efficiencies up to 256 GPUs on a custom-built state-of-the-art GPU computing system with Nvidia A100 GPUs. We believe that our GPU-oriented algorithms, which empower first-principles simulation for very large-scale applications, may render deeper understanding of the molecular basis of material behaviors, eventually revealing new possibilities for breakthrough designs on new material systems

Three-State-Involving Vibronic Resonance Is a Key to Enhancing Reverse Intersystem Crossing Dynamics of Organoboron-Based Ultrapure Blue Emitters

In organoboron OLED emitter DABNA, vibronic resonance strongly enhances reverse intersystem crossing rate even with a sizable T1-S1 energy gap. The resonance is peculiar in that the vibrational frequency has to match both (1) the T1-S1 energy gap and (2) the T1-T3 nonadiabatic coupling oscillation frequency. This three-state involving resonance is a result of combination of T1-T3-S1 superexchange and T1-T3 non-Condon coupling.<br /

Glucose metabolism and neurogenesis in the gerbil hippocampus after transient forebrain ischemia

Recent evidence exists that glucose transporter 3 (GLUT3) plays an important role in the energy metabolism in the brain. Most previous studies have been conducted using focal or hypoxic ischemia models and have focused on changes in GLUT3 expression based on protein and mRNA levels rather than tissue levels. In the present study, we observed change in GLUT3 immunoreactivity in the adult gerbil hippocampus at various time points after 5 minutes of transient forebrain ischemia. In the sham-operated group, GLUT3 immunoreactivity in the hippocampal CA1 region was weak, in the pyramidal cells of the CA1 region increased in a time-dependent fashion 24 hours after ischemia, and in the hippocampal CA1 region decreased significantly between 2 and 5 days after ischemia, with high level of GLUT3 immunoreactivity observed in the CA1 region 10 days after ischemia. In a double immunofluorescence study using GLUT3 and glial-fibrillary acidic protein (GFAP), we observed strong GLUT3 immunoreactivity in the astrocytes. GLUT3 immunoreactivity increased after ischemia and peaked 7 days in the dentate gyrus after ischemia/reperfusion. In a double immunofluorescence study using GLUT3 and doublecortin (DCX), we observed low level of GLUT3 immunoreactivity in the differentiated neuroblasts of the subgranular zone of the dentate gyrus after ischemia. GLUT3 immunoreactivity in the sham-operated group was mainly detected in the subgranular zone of the dentate gyrus. These results suggest that the increase in GLUT3 immunoreactivity may be a compensatory mechanism to modulate glucose level in the hippocampal CA1 region and to promote adult neurogenesis in the dentate gyrus