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• The electronic configuration of CoFe–BDC is optimized by introducing 4-nitrobenzoic acid. • The uncoordinated metal sites in CoFe–BDC NO 2 expose more active centers. • The CoFe–BDC NO 2 follows the LOM during OER with Co-O-Fe bond formation. • CoFe–BDC NO 2 exhibits excellent activity and long-term durability in alkaline media. • CoFe–BDC NO 2 /NF also has excellent water splitting and CO 2 RR performance by MEA testing. The rational design of metal-organic frameworks (MOFs) provides potential opportunities for improving energy conversion efficiency. However, developing efficient MOF-based electrocatalysts remains highly challenging. Herein, a strategy involving strain engineering is developed to promote the electrocatalytic performance of MOFs by optimizing electronic configuration and improving the active site. As expected, the optimized CoFe–BDC NO 2 exhibits a low overpotential of 292 mV at 10 mA cm–2 and a small Tafel slope of 31.6 mV dec–1 as oxygen evolution reaction (OER) electrocatalyst. Notably, when CoFe–BDC NO 2 is prepared on Nickel foam (NF), the overpotential is only 345 mV at 1 A cm–2, which ensures efficient water oxidation properties. Integrating CoFe–BDC NO 2 /NF anode in membrane electrode assembly (MEA) for overall water splitting and CO 2 reduction reaction (CO 2 RR) tests, the results show that the cell voltages of CoFe–BDC NO 2 /NF are 3.14 and 3.09 V at 300 mA cm–2 (25 °C), respectively, indicating that MOFs have various practical application prospects. The research of the structure-performance relationship reveals the lattice oxygen oxidation mechanism (LOM) where the Co-O-Fe bond is formed during the OER process by changing the electronic environment and coordination structure of CoFe–BDC NO 2 , and with high valence Co as active center, which provides a deep understanding of the structure design of MOFs and their structural transformation during OER. [Display omitted] [ABSTRACT FROM AUTHOR]

The article presents a quiz with multiple-choice questions on chemistry, covering topics such as electron affinity, periodic table trends, and chemical properties.

The article discusses an interactive utility called Periodic-table-cli, which allows users to access and learn about the elements of the periodic table from the command line interface (CLI). The utility provides information such as atomic number, symbol, state, atomic mass, melting/boiling point, year of discovery, and more for each element. Users can navigate through the periodic table, search for specific elements, and view elements grouped by families or electron configurations. The utility also offers various display modes, including sorting elements by state, heat mass, atomic mass, melting point, boiling point, radioactivity, occurrence, and year of discovery. Additionally, the article briefly mentions another CLI game called Cwordle, which is a word-guessing game. [Extracted from the article]

Researchers from QILU University of Technology in Jinan, China have conducted a study on the photochemistry and photophysics of metal-metal bonded dinuclear transition metal complexes (TMCs). These complexes play a crucial role in light-mediated processes and have been extensively studied due to their well-defined electronic and vibrational configurations. The study provides insights into the molecular design principles for optimizing the photophysical properties of these complexes and enhancing their practical applicability. The research was supported by various funding sources and has been peer-reviewed. [Extracted from the article]

A recent study conducted at Cairo University in Giza, Egypt, investigated the potential biomedical uses of organotin (IV) complexes derived from a synthesized quinazoline Schiff base ligand. The study involved synthesizing and characterizing these complexes and exploring their molecular characteristics. The findings revealed that the complexes demonstrated significant antimicrobial activities, potential antibiotic properties against Helicobacter pylori, and potent antitumor effects. The study also utilized molecular docking to examine the interactions of the complexes with specific protein structures. The research aims to clarify the potential properties of these compounds, including their anti-COVID-19 properties. [Extracted from the article]

When dealing with a topic such as the Lewis Bond, a fundamental question must be addressed: how was it possible, in the early 1900s, to have such a detailed view of atomic structure that one could define the number of electrons present in the various layers/shells within the atom? This is not only a question for the history of chemistry, but also and above all for education, for at least two good reasons: 1) because Lewis’s model is first and foremost a model of the atom, of atomic structure even before bonding; 2) because the idea and determination of the electronic configuration, understood as the arrangement of electrons in layers/shells within the atom, predates quantum mechanics and quantum numbers (we might even venture to say that it also constitutes a necessary premise of them) and is an intuition that relies on purely chemical arguments, which, in our opinion, must be addressed as they are an integral part of Lewis’s model. [ABSTRACT FROM AUTHOR]

• Nb-doped MoS2 film has been prepared and studied. • The doping electronic configuration has been revealed. • MoS2/Nb-MoS2 homojunction based phototransistor shows broadband photodetection. • The gate tunable photoresponse, detectivity and EQE has been discussed. Due to the weak absorption and low light-matter interaction of MoS 2 , intrinsic MoS 2 photodetector usually has low photoresponse, thus limiting its real application. Herein, MoS 2 homojunction was constructed by using the chemical vapor deposition grown intrinsic MoS 2 films and the Nb-doped MoS 2 films. The results show that the Nb doping will induce p -type doping in MoS 2 , where the electron concentration will decrease by 2.08 × 1012 cm–2 after Nb doping. By investigating the photoelectric effect of MoS 2 /Nb-doped MoS 2 homojunction-based phototransistor, the tunability of the photoresponse, detectivity as the function of the external field, wavelength, and power of light have been studied in detail. The results show that the photoresponse and detectivity are strongly dependent on the gate voltage due to the external field tuned interlayer photoexcitation attributing to the band bending. The maximum of photoresponse can reach 51.4 A/W, the detectivity can reach 3.0 × 1012 Jones, which is two orders higher than that of intrinsic MoS 2. Furthermore, by correlating the photoresponse and detectivity with the external field, it is found that the photodetection of MoS 2 homojunction can be significantly tuned and exhibit well photodetection in infrared. This comprehensive work not only sheds light on the tunable photoexcitation mechanism but also offers a strategy to achieve a high-performance photodetector. [Display omitted] [ABSTRACT FROM AUTHOR]

The article presents a quiz related to chemistry for students preparing for Joint Entrance Examination (JEE) and National Eligibility cum Entrance Test (NEET) for 2023.

A patent application by Bussert Medical Inc. for a therapeutic seat cushion equipped with a pressure monitoring and inflation system has been made available online. The invention aims to improve blood circulation in the legs by using inflatable cells arranged in series within the seat cushion. The system includes a pumping mechanism, a valve assembly with adjustable configurations, and an electronic control unit. The cushion system can collect data from sensors, such as temperature and pressure sensors, to optimize patient treatment. [Extracted from the article]

Researchers from Jagiellonian University have conducted a study on nanodiamonds, specifically focusing on the effects of an absorbing environment on the thermal properties of nitrogen-vacancy-nanodiamond powders. The study involved implanting Fe+ ions in nanodiamond powder and analyzing their Raman spectra and optically detected magnetic resonance (ODMR) in different magnetic fields. The researchers observed a blue shift in the Raman spectra and a red shift in the ODMR spectra, which were attributed to the conversion of the electronic configuration and local heating by the absorptive environment, respectively. The study provides valuable insights into the thermal effects of an absorbing environment on nanodiamonds. [Extracted from the article]

A quiz concerning the multiple-choice questions of chemistry is presented.

The XCHEM code was introduced in 2017 [1] to provide an accurate description of electron correlation and exchange in the electronic continuum of molecules at the same level as complete or restricted active-space self-consistent field (CASSCF or RASSCF) methods. This has allowed for an accurate description of molecular photoionization in the region of Feshbach resonances, shake up processes in which ionization is accompanied by excitation of one or several of the remaining electrons, and interchannel couplings. The success of XCHEM for small molecules has led us to improve its performance in several aspects, which now allows for the description of resonant molecular photoionization in larger systems. In addition, we have incorporated the possibility to calculate photoelectron angular distributions in the laboratory and molecular frames, which are essential to interpret angularly resolved photoionization experiments. Here we show its performance in the N 2 and pyrazine molecules. The new version of the code, XCHEM-2.0, is freely available at https://gitlab.com/xchem/xchem%5fpublic. Program Title: XCHEM-2.0 CPC Library link to program files: https://doi.org/10.17632/t8tbk9gdt2.1 Developer's repository link: https://gitlab.com/xchem/xchem%5fpublic/-/archive/2.0.0/xchem%5fpublic-2.0.0.tar.gz Licensing provisions: LGPL Programming language: Fortran, python Nature of problem: Understanding photoionization of molecules is a recurrent goal in Atomic, Molecular and Optical physics, even more nowadays with the advent of XUV and X-ray high-harmonic generation sources and free electron lasers. Photoionization can be employed to induce electron dynamics in molecules, e.g., by using ultrashort XUV or X-ray pulses, or as a probe of these dynamics by recording time-resolved photoelectron spectra. At low photoelectron energies, photoionization may result from various competing processes, such as direct ionization, autoionization of Feshbach and shape resonances, shake up, etc., each of these leaving its trace in the measured spectra. So, interpretation of these spectra can be a difficult task and theoretical simulations are often required to separate the different contributions. However, a method able to do so must be able to describe electron correlation in the electronic continuum beyond the Hartree-Fock (HF) and configuration interaction singles (CIS) approximations. XCHEM-2.0 has been designed to account for all these processes by providing an accurate description of electron correlation in the ionization continuum of molecules. Solution method: XCHEM-2.0 employs a close coupling formalism to describe the electronic continuum of molecules at the level of multiference configuration interaction (MRCI) methods in combination with a hybrid Gaussian-Bspline basis set (the so-called GABs basis). In particular, it makes use of a restricted active space self-consistent field (RASSCF) approximation to evaluate the bound electronic states of the remaining molecular cation using localized Gaussian functions. These localized Gaussians are then supplemented with a single centered Gaussian expansion to allow the electron to leave the nuclear environment. Finally, the basis set includes a set of B-spline functions, centered at the same position as the single-centered Gaussians, which reach the asymptotic region. Thanks to the last B-spline function, which does not vanish at the box boundary, XCHEM-2.0 can determine continuum states fulfilling any required asymptotic behavior. The present version of the code improves on the original version by incorporating a more efficient augmentation procedure to build N e -electron configurations from (N e − 1) ones, reducing the space to store data, providing a more efficient removal of linear dependencies resulting from the over-completeness of the polycentric+GABS basis and a more efficient solution of the scattering equations, and including new routines to calculate photoelectron angular distributions in the laboratory and molecular frames. Additional comments including restrictions and unusual features: The proposed method focuses on RASSCF methodology, so part of electron correlation is still not included. Also, one- and two electron integrals involving exclusively Gaussian functions are done using a modified version of the OpenMOLCAS software, so the installation of this code is also required and limitation associated with the latter is applicable. The code is limited to include a few ionization channels (around 20) with medium angular momentum (limited to ℓ = 15 as in OpenMOLCAS). [ABSTRACT FROM AUTHOR]

Developing low-cost, efficient, and stable non-precious-metal electrocatalysts with controlled crystal structure, morphology and compositions are highly desirable for hydrogen and oxygen evolution reactions. Herein, a series of phosphorus-doped Fe 7 S 8 nanowires integrated within carbon (P-Fe 7 S 8 @C) are rationally synthesized via a one-step phosphorization of one-dimensional (1D) Fe-based organic-inorganic nanowires. The as-obtained P-Fe 7 S 8 @C catalysts with modified electronic configurations present typical porous structure, providing plentiful active sites for rapid reaction kinetics. Density functional calculations demonstrate that the doping Fe 7 S 8 with P can effectively enhance the electron density of Fe 7 S 8 around the Fermi level and weaken the Fe-H bonding, leading to the decrease of adsorption free energy barrier on active sites. As a result, the optimal catalyst of P-Fe 7 S 8 -600@C exhibits a relatively low overpotential of 136 mV for hydrogen evolution reaction (HER) to reach the current density of 10 mA/cm2, and a significantly low overpotential of 210 mV for oxygen evolution reaction (OER) at 20 mA/cm2 in alkaline media. The work presented here may pave the way to design and synthesis of other prominent Fe-based catalysts for water splitting via electronic regulation. [ABSTRACT FROM AUTHOR]

This study presents a reconfigurable photovoltaic technology model for research and development. The study includes a review of photo-electrochemical cell synthesis techniques, which are optimization factors in photovoltaic arrays and electronics for the definition of functional layers of spectral separation, solar concentration, photoelectric conversion, energy recording, solar monitoring mechanisms and recovery of regenerative heat, adapted through applied neural networks. Criteria were established for the configuration of IPVDs smart photovoltaic devices supported by FPGA technology. The modeling method is based on the identification of the correspondence of the photovoltaic structures with the LFSR structure, which means the concatenation of contributions and energy feedback within the framework of regenerative systems. For the formulation of the composition and synthesis, the fractal ANN in VHDL was described, and the synthesis of the circuit structure was reported. The results are obtained as a model for SFV, showing an improvement report by monitoring in two axes in the order 10 % and the configuration codes of the electronic control. All this makes it possible to contribute to the migration towards new technologies and sustainable models of the energy matrix with estimates of efficiency and environmental impact. In conclusion, a technological concept is obtained, which is based on a fractal model applied to the design of the generalized photovoltaic converter, concatenated contribution coefficients and recuperators for energy feedback. It is applied the principle of dynamic structural reconfiguration in order to establish the tandem composition within a circular model. [ABSTRACT FROM AUTHOR]

Surface/interface engineering plays an important role in improving the performance and economizing the cost and usage of electrocatalysts. In recent years, substantial progress has been achieved in designing and developing highly active electrocatalysts with the deepening understanding of surface and interface enhanced mechanism. In this review, recent development about optimizing the surface and interfacial structure in promoting the electrocatalytic activity of noble-metals and transition metal compounds is presented and the chemical enhancements are also described in detail. The relationship between the surface/interface structures (both atomic and electronic configuration) and the electrochemical behaviors has been discussed. Finally, personal perspectives have been proposed, highlighting the challenges and opportunities for future development in tuning the surface/interface active sites of electrocatalysts. We believe that this timely review will be beneficial to the construction of highly active and durable electrode materials through optimizing surface atomic arrangement and interfacial interaction, which can largely promote the development of next-generation clean energy conversion technologies. [ABSTRACT FROM AUTHOR]

A research study conducted by the Chinese Academy of Sciences in Changchun, People's Republic of China, explores the use of NOX nanozymes as a potential treatment for cancer. The study focuses on the challenges posed by tumor heterogeneity and proposes a new design strategy to improve the efficacy of NOX nanozymes. By integrating metal-defect active centers within the nanozymes, the researchers were able to disrupt the metabolic networks of solid tumors and enhance antitumor efficacy. This research provides valuable insights into the development of novel treatments for cancer. [Extracted from the article]

Researchers from Tianjin University in China have made advancements in the field of nanotechnology with their findings on asymmetric coordination of iron single-atom nanozymes (SAzymes) for ferroptosis therapy. SAzymes have potential in tumor therapy due to their atomic utilization and electronic structures, but face challenges in activity, specificity, and targeting. The researchers developed a practical strategy to construct Fe-S/N-C SAzymes, which exhibited significantly enhanced peroxidase and glutathione oxidase activities compared to their symmetric counterparts. By camouflaging with macrophage membranes, these tumor-targeting nanocatalytic agents triggered enhanced self-cascade catalysis in the tumor microenvironment for tumor-specific therapy. [Extracted from the article]

The poem "Good Night, Barbara Strawitz" by David Kirby is presented. First Line: Bobby Williams writes to tell me of the death; Last Line: of Henry," and Rob Delaney said, "Wd do too, Richard."

Abstract Microstructure, electrical conductivity, and electromagnetic interference (EMI) shielding effectiveness (SE) of cast Mg- x Zn- y Y (x = 2–5, y = 1–10) alloys were systematically investigated to understand the effects of Zn and Y additions on electrical conductivity and electromagnetic shielding effectiveness of the alloys. Experimental results indicate that the electrical conductivity and SE of the Mg- x Zn- y Y alloys decrease with Y/Zn ratio. Electrical conductivity is the main factor that affects the electromagnetic shielding properties and the variation tendency of electromagnetic shielding properties of the Mg- x Zn- y Y alloys is consistent with conductivity. Valence of Y and Zn atoms, configuration of extranuclear electron and volumetric difference are main reasons for the variations in the electrical conductivity. A high density of second phase and the formation of semi-continuous network structure can also improve the SE value at high frequencies. [ABSTRACT FROM AUTHOR]

We present a bio-inspired stochastic optimization strategy that optimizes projector augmented wave (PAW) datasets, for a user-specified pressure range, to realize the highest possible accuracy in high-throughput density functional theory calculations within the framework of PAW method. We named the optimizer “Evolutionary Generator of projector augmented wave datasets” (EPAW-1.0). The self-learning evolutionary algorithms in EPAW-1.0 adaptively tune some of the PAW parameters (such as different radii, and reference energies) to generate evolutionary optimized PAW (EPAW) datasets. In the course of designing EPAW dataset with a specific pseudo partial waves and projectors generation scheme, the code keeps the user-specified electronic configuration unaltered and the augmentation radius ( r c ) on the verge of the user allowed maximum without resulting in sphere overlap. The EPAW-1.0 algorithm homes on to a soft, transferable and unified EPAW dataset using various measures including the equation of state (EoS) of standard elemental materials within a user-specified pressure range that allows probing ∼ 50% volume compression with respect to the equilibrium atomic volume (corresponding to the energy minimum). The measures used by the EPAW algorithm also can be used to balance the efficiency and accuracy of the dataset. Program Title: EPAW-1.0 Program Files doi: http://dx.doi.org/10.17632/ms52ym7vcn.1 Licensing provisions: GNU General Public License 3 (GPLv3) Programming languages: Fortran90, Fortran77, Python3.0, bash shell, gnuplot5.0. External routines/libraries: ATOMPAW, Quantum ESPRESSO, related linear algebra package. Nature of problem: EPAW-1.0 is a hybrid recipe [ 2 ] that documents an interdisciplinary research integrating evolutionary computing with density functional theory (DFT). It offers a partially automated and consistent route to generate evolutionary optimized PAW (EPAW) datasets that show uniform performance for simulations up to a predefined high pressure. In particular, EPAW-1.0 makes use of evolutionary algorithms [ 3–7 ], PAW dataset generator (ATOMPAW [ 8 ], for example) and electronic-structure calculation code (Quantum Espresso [ 9 ], for example) to generate efficient and transferable EPAW datasets. EPAW datasets provide optimal accuracy in solid-state ab initio calculations within the favorable PAW computational framework — very close to the precision of targeted all-electron full potential linearized Augmented-plane-wave (AE-FLAPW) approach. We set the EoS from WIEN2k [ 1 ] calculations as our target, but any reliable EoS can be in use. The better the target EoS, the better is the performance of the EPAW datasets. Similarly, electronic-structure calculation code and PAW dataset generator code can also be replaced. Solution Method: The implementation has two parts: a. Generating a diverse random initial population for EPAW-1.0 to start with; b. Generating EPAW dataset using EPAW-1.0. A hybrid method, combining an in-house evolutionary strategy named Completely Adaptive Random Mutation Hill Climbing [ 6 ] (CARMHC) with ATOMPAW [ 8 ] program, quickly optimizes a set (population) of n p o p solutions (PAW dataset descriptors) from which the iterative process of EPAW-1.0 starts. The optimization condition involves superimposing the logarithmic derivative curves of the all-electron and pseudo radial wave functions, simultaneously satisfying necessary constraints on logarithmic derivatives, partial waves, pseudo partial waves and projector basis sets [ 2,8,10–12 ]. To start with, the method generates a diverse initial population of n p o p solution vector ( n p o p = cardinality of the GA’s population in EPAW-1.0) randomly in the neighborhood of the initial educated guess based on problem-specific knowledge from the ATOMPAW program and iteratively tunes the population to minimize the area under the logarithmic derivative curves. Once n p o p number of solution strings have been optimized, n p o p individuals are feed into the EPAW-1.0’s initial population. Equilibrium total energies are evaluated using Quantum Espresso distribution [ 9 ] and fitted to a finite strain expansion. Pressures are calculated using a 4-parameter Birch–Murnaghan fit [ 13,14 ]. EPAW-1.0 employs genetic algorithms (GAs) [ 15–19 ] as the evolutionary procedure and iteratively tunes the free parameters of the PAW dataset generator to minimize the difference in equation of states (EoS) with respect to the given target EoS for the specified pressure range. Additional comments: EPAW-1.0 is an evolutionary procedure blended with external density functional theory (DFT) formalism (as implemented in ATOMPAW and Quantum Espresso, for example). The ATOMPAW code generates dataset by a self-consistent all-electron atomic structure calculation within the framework of DFT. The projector and basis functions are derived from the eigenstates of the all-electron atomic Hamiltonian. They are determined by iteratively solving radial differential equations. Equilibrium total energies at some equidistant volume points for a specific elemental crystal are evaluated using Quantum Espresso distribution [ 9 ]. The EPAW-1.0 program conserves different constraints [ 2 ] on logarithmic derivatives and basis sets to avoid numerical instability, ghost states, and to promote an excellent transferability. More details about the constraints can be found in the methodology part of reference 1. It also provides a goodness measure of the generated dataset concerning the targeted results. [ABSTRACT FROM AUTHOR]

Focuses on shock waves in solids. Overview of commercial applications of shock wave in a solid; Difference between a shock wave in a solid and gas or liquid; Impact of a shock wave on the electron configuration of a solid.

The article presents a quiz covering various topics in chemistry, including questions about gamma rays, atomic structure, chemical reactions, and biomolecules.

Keywords: Shanghai; People's Republic of China; Asia; Antibacterials; Antibiotics; Antimicrobials; Drugs and Therapies; Emerging Technologies; Health and Medicine; Nanoplatforms; Nanotechnology; Photocatalyst; Photocatalytics EN Shanghai People's Republic of China Asia Antibacterials Antibiotics Antimicrobials Drugs and Therapies Emerging Technologies Health and Medicine Nanoplatforms Nanotechnology Photocatalyst Photocatalytics 1644 1644 1 07/17/23 20230721 NES 230721 2023 JUL 21 (NewsRx) -- By a News Reporter-Staff News Editor at Drug Week -- Investigators publish new report on Nanotechnology - Photocatalytics. Typically, 0.8-TC/Cu-NS possesses higher photothermal property with the higher photothermal conversion efficiency of 24% and the moderate temperature up to 97 degrees C. Meanwhile, 0.8-TC/Cu-NS exhibits the more active ROS, O-1(2) and center dot O-2(-).". [Extracted from the article]

Electron correlations that determine a broad spectrum of the physical properties of transition metal compounds are largely manifested by the on-site Coulomb repulsion U , which so far has been mainly evaluated on a case-by-case basis. Here we employ a linear response method based on constrained local density approximation to systematically investigate U in representative classes of transition metal trichalcogenides, with the transition metals covering all the unfilled 3 d , 4 d , and 5 d orbitals. We uncover a characteristic scaling dependence of U on two elemental physical parameters, namely, the numbers of the core and valence electrons. Such a universal scaling law reflects the intuition that more unfilled d electrons residing on a smaller spherical core will feel stronger Coulomb repulsion. Next, by using the artificial intelligence-based SISSO (Sure Independence Screening and Sparsifying Operator) approach, we identify a more sophisticated descriptor that not only further refines the scaling law, but also captures the crystal-field splitting effect as pictorially reflected by invoking an elliptical core instead of a spherical core. The approach developed in this study should find transferability in other classes of transition metal compounds. [ABSTRACT FROM AUTHOR]

In configuration interaction (CI) calculations the atomic wave functions are given as expansions over configuration state functions (CSFs) built on relativistic one-electron orbitals. The expansion coefficients of the configuration state functions are obtained by constructing and diagonalizing the Hamiltonian matrix. Here we show how a regrouping of the configuration state functions and the introduction of configuration state function generators (CSFGs) allow for a substantial reduction of the computational load in relativistic CI calculations. The computational methodology based on configuration state function generators, recently implemented in the General Relativistic Atomic Structure package (Grasp 2018, Froese Fischer et al. (2019) [16]), is applied to a number of atomic systems and correlation models with increasing sets of one-electron orbitals. We demonstrate a reduction of the CPU time with factors between 10 and 14 for the largest CI calculations. The inclusion of the Breit interaction into the calculations is time consuming. By applying restrictions on the Breit integrals we show that it is possible to further reduce the CPU times with factors between 2 and 3, with negligible changes to the computed excitation energies. We also demonstrate that the introduction of configuration state function generators allows for efficient a priori condensation techniques, with reductions of the expansions sizes with factors between 1.5 and 2.5 and the CPU time with factors between 2.5 and 4.5, again with negligible changes to the excitation energies. In total we demonstrate reductions of the CPU time with factors up to 68 for CI calculations based on configuration state function generators, restrictions on the Breit integrals and with a priori condensed expansions compared to ordinary CI calculations without restrictions on the Breit integrals and with full expansions. Further perspectives of the new methodology based on configuration state function generators are given. [ABSTRACT FROM AUTHOR]

We numerically study models of H2 and LiH molecules, aligned collinearly with the linear polarization of the external field, to elucidate the possible role of correlation in the enhanced-ionization (EI) phenomena. Correlation is considered at different levels of approximation with the time-dependent generalized-active-space configuration-interaction method. The results of our studies show that enhanced ionization occurs in multielectron molecules and that correlation is important, and they also demonstrate significant deviations between the results of the single-active-electron approximation and more accurate configuration-interaction methods. We further investigate the role of low-lying excited states in the EI phenomena. With the inclusion of correlation we show strong carrier-envelope-phase effects in the enhanced ionization of the asymmetric heteronuclear LiH-like molecule. The correlated calculation shows an intriguing feature of crossover in enhanced ionization with two carrier-envelope phases at critical intemuclear separation. [ABSTRACT FROM AUTHOR]

One of the main applications of future quantum computers will be the simulation of quantum models. While the evolution of a quantum state under a Hamiltonian is straightforward (if sometimes expensive), using quantum computers to determine the ground-state phase diagram of a quantum model and the properties of its phases is more involved. Using the Hubbard model as a prototypical example, we here show all the steps necessary to determine its phase diagram and ground-state properties on a quantum computer. In particular, we discuss strategies for efficiently determining and preparing the ground state of the Hubbard model starting from various mean-field states with broken symmetry. We present an efficient procedure to prepare arbitrary Slater determinants as initial states and present the complete set of quantum circuits needed to evolve from these to the ground state of the Hubbard model. We show that, using efficient nesting of the various terms, each time step in the evolution can be performed with just O(N) gates and O(log N) circuit depth. We give explicit circuits to measure arbitrary local observables and static and dynamic correlation functions, in both the time and the frequency domains. We further present efficient nondestructive approaches to measurement that avoid the need to reprepare the ground state after each measurement and that quadratically reduce the measurement error. [ABSTRACT FROM AUTHOR]

A new module, RDENSITY, of the GRASP2018 package [1] is presented for evaluating the radial electron density function of an atomic state described by a multiconfiguration Dirac-Hartree-Fock or configuration interaction wave function in the fully relativistic scheme. The present module is the relativistic version of DENSITY [2] that was developed for the ATSP2K package [3]. The calculation of the spin-angular factors entering in the expression of the expectation value of the density operator is performed using the angular momentum theory in orbital, spin, and quasispin spaces, adopting a generalized graphical technique [4]. The natural orbitals (NOs) are evaluated from the diagonalization of the density matrix, taking advantage of its κ -block structure. The features of the code are discussed in detail, focusing on the advantages and properties of the NOs and on the electron radial density picture as a mean for investigating electron correlation and relativistic effects. Program title: RDENSITY CPC Library link to program files: https://doi.org/10.17632/4sdrf5kfzd.1 Licensing provisions: MIT license Programming language: FORTRAN 95 Nature of problem: This program determines the atomic electron radial density in the MCDHF approximation. It also evaluates the natural orbitals by diagonalizing the density matrix. Solution method: Building the density operator using second quantization - Spherical symmetry averaging - Evaluating the matrix elements of the one-body excitation operators in the configuration state function (CSF) space using the angular momentum theory in orbital, spin, and quasispin spaces. Additional comments including restrictions and unusual features: We evaluated the electron radial density and natural orbitals of the lowest states in Mg II. The MCDHF wave functions consisted of four non-interacting blocks and a total of 79 000 CSFs. The calculation took around 2 minutes using a computer with an Intel(R) Xeon(R) Gold 6148 processor @ 2.4 GHz. [1] GRASP2018 - A Fortran 95 version of the General Relativistic Atomic Structure Package, C. Froese Fischer, G. Gaigalas, P. Jönsson and J. Bieroń, Comput. Phys. Commun. 237 (2019) 184-187. [2] Multiconfiguration electron density function for the ATSP2K-package, A. Borgoo, O. Scharf, G. Gaigalas and M. Godefroid, Comput. Phys. Commun. 181 (2010) 426-439 [3] An MCHF atomic-structure package for large-scale calculations, C. Froese Fischer, G. Tachiev, G. Gaigalas, and M. Godefroid, Comput. Phys. Commun. 176 (2007) 559-579 [4] An efficient approach for spin-angular integrations in atomic structure calculations, G. Gaigalas, Z. Rudzikas, and C. Froese Fischer, J. Phys. B: At. Mol. Phys., 30 (1997) 3747-3771 [ABSTRACT FROM AUTHOR]

We investigate the two-photon double ionization of beryllium atom induced by ultrashort pulses. We use a time-dependent formalism to evaluate the ionization amplitudes and generalized cross sections for the ejection of the 2s² valence shell electrons in the presence of a fully occupied 1s² frozen core shell. The relative contributions of the two-photon direct and sequential process are systematically explored by varying both pulse duration and central frequency. The energy and angular differential ionization yields reveal the signatures of both mechanisms, as well as the role of electron correlation in both the single and double ionization continua. In contrast with previous results on the helium atom, the presence of an electronic core strongly affects the final state leading to back-to-back electron emission even in the a priori less correlated two-photon sequential mechanism. In particular, a dominant pathway via excitation ionization through the Be+(2p) determines the profiles and pulse-duration dependencies of the energy and angle differential yields. [ABSTRACT FROM AUTHOR]

Quantum impurity solvers have a broad range of applications in theoretical studies of strongly correlated electron systems. Especially, they play a key role in dynamical mean-field theory calculations of correlated lattice models and realistic materials. Therefore, the development and implementation of efficient quantum impurity solvers is an important task. In this paper, we present an open source interacting quantum impurity solver toolkit (dubbed i QIST ). This package contains several highly optimized quantum impurity solvers which are based on the hybridization expansion continuous-time quantum Monte Carlo algorithm, as well as some essential pre- and post-processing tools. We first introduce the basic principle of continuous-time quantum Monte Carlo algorithm and then discuss the implementation details and optimization strategies. The software framework, major features, and installation procedure for i QIST are also explained. Finally, several simple tutorials are presented in order to demonstrate the usage and power of i QIST . Program summary Program title: i QIST Catalogue identifier: AEWQ_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEWQ_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: GNU General Public License, version 3 No. of lines in distributed program, including test data, etc.: 226270 No. of bytes in distributed program, including test data, etc.: 5263144 Distribution format: tar.gz Programming language: Fortran 2008 and Python. Computer: Desktop PC, laptop, high performance computing cluster. Operating system: Unix, Linux, Mac OS X, Windows. Has the code been vectorized or parallelized?: Yes, it is parallelized by MPI and OpenMP RAM: Depends on the complexity of the problem Classification: 7.3. External routines: BLAS, LAPACK, Latex is required to build the user manual. Nature of problem: Quantum impurity models were originally proposed to describe magnetic impurities in metallic hosts. In these models, the Coulomb interaction acts between electrons occupying the orbitals of the impurity atom. Electrons can hop between the impurity and the host, and in an action formulation, this hopping is described by a time-dependent hybridization function. Nowadays quantum impurity models have a broad range of applications, from the description of heavy fermion systems, and Kondo insulators, to quantum dots in nano-science. They also play an important role as auxiliary problems in dynamical mean-field theory and its diagrammatic extensions [1–3], where an interacting lattice model is mapped onto a quantum impurity model in a self-consistent manner. Thus, the accurate and efficient solution of quantum impurity models becomes an essential task. Solution method: The quantum impurity model can be solved by the numerically exact continuous-time quantum Monte Carlo method, which is the most efficient and powerful impurity solver for finite temperature simulations. In the i QIST software package, we implemented the hybridization expansion version of continuous-time quantum Monte Carlo algorithm. Both the segment representation and general matrix formalism are supported. The key idea of this algorithm is to expand the partition function diagrammatically in powers of the impurity-bath hybridization, and to stochastically sample these diagrams to all relevant orders using the Metropolis Monte Carlo algorithm. For a detailed review of the continuous-time quantum Monte Carlo algorithms, please refer to [4]. Running time: Depends on the complexity of the problem. The sample run supplied in the distribution takes about 1.5 minutes. References: [1] A. Georges, G. Kotliar, W. Krauth, and M. J. Rozenberg, Rev. Mod. Phys. 68, 13 (1996) [2] G. Kotliar, S. Y. Savrasov, K. Haule, V. S. Oudovenko, O. Parcollet, and C. A. Marianetti, Rev. Mod. Phys. 78, 865 (2006) [3] T. Maier, M. Jarrell, T. Pruschke, and M. H. Hettler, Rev. Mod. Phys. 77, 1027 (2005) [4] E. Gull, A. J. Millis, A. I. Lichtenstein, A. N. Rubtsov, M. Troyer, and Philipp Werner, Rev. Mod. Phys. 83, 349 (2011) [ABSTRACT FROM AUTHOR]

The Auger decay processes from the 1s-core-hole state of Ne have been investigated with a multielectron coincidence method. We have observed the double and triple Auger decays, in which both cascade and direct processes are identified from different ways in energy sharing between the Auger electrons. Branching ratios for the different electronic configurations of the Auger final states are determined from the corresponding electron coincidence yields. Particularly for the double Auger decay, the branching ratios are divided into the individual contributions from direct and cascade paths. [ABSTRACT FROM AUTHOR]

Scattering of beams of light and matter from multielectron atomic targets is formulated in the position representation of quantum mechanics. This yields expressions for the probability amplitude a(b) for a wide variety of processes. Here the spatial parameter b is the distance of closest approach of incoming particles traveling on a straight line with the center of the atomic target. The correlated probability amplitude a(b) reduces to a relatively simple product of single-electron probability amplitudes in the widely used independent electron approximation limit, where the correlation effects of the Coulomb interactions between the atomic electrons disappear. As an example in which a(b) has an explicit dependence on b, we consider transversely finite vortex beams of twisted photons that lack the translational invariance of infinite plane-wave beams. Relatively simple calculations, illustrating the b dependence in transition probabilities for photon beams interacting with a two-state degenerate single-electron atomic target, are included. Further application for many-electron systems is discussed. Possible practical uses are briefly considered. [ABSTRACT FROM AUTHOR]

We have studied photoionization in the inner valence 3i subshell of and the spectroscopic properties of the two 3s-1 (¹S) and (³S) resulting states. Similar to the Rb and Cs cases, the lifetime widths of the (¹S) and (³S) states are found to be markedly different, due to the electron correlation effects. The main part of the study deals with the subsequent Auger decay of the 3s-1 states, which have the particularity to involve low energy (~5 eV) Auger electrons. A magnetic bottle spectrometer with a multicoincidence technique has been used to observe and filter the Auger spectra with respect to the K2+ final state. The evolution of these Auger spectra has been investigated near the ionization threshold. They show strong post-collision interaction (PCI) effects, which are well reproduced by semiclassical and eikonal models. They reveal the importance of the photoelectron-Auger-electron interaction associated with these low energy Auger electrons. [ABSTRACT FROM AUTHOR]

In this work, we consider the dissipative dynamics of a quantum Brownian magneto-oscillator in contact with different types of environment at zero temperature as well as at high temperatures. We derive closed-form expressions of decay rate and heating rate for the magneto-oscillator in contact with Ohmic, sub-Ohmic, and super-Ohmic environments with non-Markovian characteristics. The present study is useful in determining the relationship between the thermalization dynamics of a magneto-oscillator and different forms of environmental spectrum and external magnetic field. Although our study is limited to the short-time (Non-Markovian) and long-time (Markovian) regimes, it manifests that one can actually tune the effective coupling of the system reservoir either by tuning oscillator frequency through reservoir engineering techniques or changing external magnetic field. Thus the present work establishes the essential role of non-Markovian dissipation and the crucial role of magnetic field in the environment induced decoherence and decay processes of the dissipative magneto-oscillator. [ABSTRACT FROM AUTHOR]

Electron correlation can break the symmetry of photoelectron angular distribution upon two-step ionization to a doubly degenerate ionic state via a doubly degenerate intermediate state. The interference between the two components of the intermediate state prepared using linearly and circularly polarized light is discussed for cyclopropane as an example. [ABSTRACT FROM AUTHOR]

The nuclear electric quadrupole moment (NQM) of gold is reviewed by means of the molecular method and data from as many as 15 linear systems. The electric-field gradients (EFGs) used to this end were obtained with the Dirac-Coulomb Hamiltonian and coupled-cluster theory, CCSD(T) and CCSD-T, by means of an augmented relativistic basis set for gold. The direct approach was found to be inadequate for the diatomic molecules investigated, which is probably due to improper treatment of the static electron correlation. However, these effects are much less relevant for OCAuX (X = F, CI, Br, and I) complexes. Thus, the indirect version of the molecular method is preferred in this case. Hence, a NQM value of 515(15) mb is determined for 197Au from linear regressions performed with the best EFGs determined for ten of these systems. [ABSTRACT FROM AUTHOR]

We demonstrate the importance of electron correlation effects in the hyperfine structure constants of many low-lying states in 210Fr and 2l2Fr. This is achieved by calculating the magnetic dipole and electric quadrupole hyperfine structure constants using the Dirac-Fock approximation, second-order many-body perturbation theory, and the coupled-cluster method in the singles and doubles approximation in the relativistic framework. By combining our recommended theoretical results with the corresponding experimental values, improved nuclear magnetic dipole and electric quadrupole moments of the above isotopes are determined. In the present work, it is observed that there are large discrepancies between the hyperfine structure constants of the 7D5/2 state obtained from the experimental and theoretical studies, whereas good agreement is found for the other D5/2 states. Our estimated hyperfine constants for the 8P, 6D, 10S, and 11S states could be very useful as benchmarks for the measurement of these quantities. [ABSTRACT FROM AUTHOR]

The mixed configuration-interaction (CI) many-body-perturbation-theory method is accurate in divalent atoms. In more complex atoms, with the number of valence electrons it becomes progressively more difficult to saturate CI space. Here, a four-valence electron atom, Si I, is considered. It is found that by using a relatively small cavity of 30 a.u. and by choosing carefully configuration space, it is possible to obtain quite accurate agreement between the theory and experiment. After subtraction of systematic shifts of 481 and -426 cm-owest even and odd states, respectively, the deviation between theory and experiment becomes at the level of 100 cm-1. This agreement is comparable to that in divalent atoms where the CI saturation has been achieved. It is anticipated that the approach can also give good results for atoms with more valence electrons to be considered in the future [ABSTRACT FROM AUTHOR]

We present a theoretical and experimental investigation of the 3d→2p resonance to the intercombination line ratio in low- to mid-Z neonlike ions of astrophysical interest, i.e., of the 2p1/22p3/243d3/2¹P0¹→2p6 ¹S0 and 2p1/2²2p3/2³3d5/2³D10→2p6¹S0 transitions commonly labeled 3C and 3D, respectively. In particular, we have employed the configuration-interaction method with three different numbers of basis states and the many-body perturbation theory method to calculate oscillator strengths and energies for neonlike ions from Z=18 to 36. Combining our calculations with a systematic study of previous works in the literature, we show that these methods can predict accurate and converged energies for these transitions. We also find convergence for the oscillator strengths, but the ratio of oscillator strengths, which can be compared to experimental values of the relative intensity ratios of these lines, appears to converge to values higher than measured. We speculate that this is due to the role of electron-electron correlations. While the amount of electron correlations associated with the intercombination line 3D appears to be well described, it seems that the contributions from highly excited states are not sufficiently accounted for in the case of the resonance line 3C. In order to augment the body of available experimental data for neonlike ions, we present a measurement of the 3C and 3D lines in neonlike Ar8+. We report a wavelength of 41.480±0.001 Å for line 3C and 42.005±0.001 Å for line 3D. The intensity ratio of the two lines was determined to be I(3C)/I(3D)=11.32±1.40. [ABSTRACT FROM AUTHOR]

Many applications are in need of accurate photoionization cross sections, especially in the case of complex atoms. Configuration-interaction relativistic-many-body-perturbation theory (CI-RMBPT) has been successful in predicting atomic energies, matrix elements between discrete states, and other properties, which is quite promising, but it has not been applied to photoionization problems owing to extra complications arising from continuum states. In this paper a method that will allow the conversion of discrete CI-(R)MPBT oscillator strengths (OS) to photoionization cross sections with minimal modifications of the codes is introduced and CI-RMBPT cross sections of Ne, Ar, Kr, and Xe are calculated. A consistent agreement with experiment is found. RMBPT corrections are particularly significant for Ar, Kr, and Xe and improve agreement with experimental results compared to the particle-hole CI method. The demonstrated conversion method can be applied to CI-RMBPT photoionization calculations for a large number of multivalence atoms and ions. [ABSTRACT FROM AUTHOR]

A lattice-induced opacity is identified in the scattering process of a normally incident matter wave colliding with a two dimensional lattice of atoms. This system can be treated as an analog of a confinement-induced resonance. Specifically, by modifying the i-wave scattering length between atoms in the incident matter wave and the lattice-confined atoms, the transmission of the matter wave can be tuned controllably throughout the range from zero to one. The theoretical treatment shows how the mathematical description of confinement-induced resonances can be viewed as an extension of Bragg scattering theory, with alternate opportunities for transmission control. [ABSTRACT FROM AUTHOR]

We present measurements of the absolute photoionization cross section of the aluminumlike Si+ ion over the 94-137 eV photon energy range. The measurements were performed using the merged-beam setup on the PLEIADES beamline at the SOLEIL synchrotron radiation facility. Signals produced in the Si2+ and Si3+ photoionization channels of the 2p subshell of the Si+ ion from both the ls²2s²2p63s²3p²P1/2,3/2 ground levels and the ls²2s²2p63s³p24P metastable levels were observed. Absolute cross sections were determined. Calculations of the 2p inner-shell photoionization cross sections were carried out using the multiconfiguration Dirac-Fock and Dirac-Coulomb R-matrix theoretical approaches and are compared with experiment. [ABSTRACT FROM AUTHOR]

Get a daily dose of science Get "Cosmos Catch-up" (every Tuesday)Your email address The combination of boron nitride and the ball mill grindercreates a mechanochemical reaction that absorbs olefin andalkyne gases into the powder. Core Sciences This breakthrough could turn dangerous, expensive gasinfrastructure into a cheap powder Anyone who's ever tied off a balloon knows how difficult itis to store a gas. "When we first put these hydrocarbons in the boron nitride,the gas completely disappeared", says Dr Srikanth Mateti, aresearch fellow at Deakin University's Institute forFrontier Materials. [Extracted from the article]

We present theoretical three-dimensional fully differential cross sections (FDCSs) for electron-impact excitation-ionization of hehum when the ionized electron is found outside of the scattering plane. Using our first Born approximation model, we examine the effects of electron correlation in the initial state and show that it significantly affects the shape of the out-of-plane FDCS. [ABSTRACT FROM AUTHOR]

We investigate the role of electron-correlation effects in calculations of the electric-dipole polarizabilities a of elements belonging to three different groups (12-14) of the periodic table. To understand the propagation of the electron-correlation effects at different levels of approximations, we employ the relativistic many-body methods developed, based on first principles, at mean-field Dirac-Fock (DF), third-order many-body perturbation theory [MBPT(3)], random-phase approximation (RPA), and singly and doubly approximated coupled-cluster methods at the linearized (LCCSD) and nonlinearized (CCSD) levels. We observe a variance in the trends of the contributions of the correlation effects in a particular group of elements through the many-body method used; however, they resemble a similar tendency among the iso-electronic systems. Our CCSD results are within sub-1% agreement with the experimental values which are further ameliorated by including the contributions from the important triple excitations (CCSDPT method). [ABSTRACT FROM AUTHOR]

The Wigner regime of a system of electrons in an external field is characterized by a low electron density and a high electron-interaction energy relative to the kinetic energy. The low-correlation regime is in turn described by a high electron density and an electron-interaction energy smaller than the kinetic energy. The Wigner regime of a nonuniform-electron-density system is investigated via quantal density functional theory (QDFT). Within QDFT, the contributions of electron correlations due to the Pauli exclusion principle, Coulomb repulsion, and correlation-kinetic effects are separately delineated and explicitly defined. The nonuniform-electron-density system studied is that of the Hooke's atom in the Wigner regime, for which the exact wave function is derived. As such, the results of the QDFT analysis are exact. It is observed that in comparison to the low-correlation case, not only is the electron-interaction energy greater than the kinetic energy as a fraction of the total energy, but so are its individual Hartree, Pauli, and Coulomb components. The ionization potential as a fraction of the total energy too is greater. But most significantly, in the Wigner regime, the correlation-kinetic energy as a fraction of both the electron-interaction and the total energy is substantially greater than in the low-correlation case. Hence, we propose that the Wigner regime now also be characterized by a high correlation-kinetic energy. The kinetic energy as a fraction of the total energy, however, is less than in the low-correlation case. This fact and the high correlation-kinetic energy value in the Wigner regime is explained by the concept of "quantal compression" of the kinetic energy density derived from QDFT. The corresponding results for the low-correlation case are in turn a consequence of a "quantal decompression" of the kinetic energy density. From the QDFT analysis, the exact values for the Kohn-Sham theory "exchange-correlation" and "correlation" energy functionals of the density and their respective functional derivatives are also obtained. These results ought to be of value in the construction and testing of approximate energy functionals valid for the Wigner regime. [ABSTRACT FROM AUTHOR]

We introduce a time-dependent R-matrix theory generalized to describe double-ionization processes. The method is used to investigate two-photon double ionization of He by intense XUV laser radiation. We combine a detailed B-spline-based wave-function description in an extended inner region with a single-electron outer region containing channels representing both single ionization and double ionization. A comparison of wave-function densities for different box sizes demonstrates that the flow between the two regions is described with excellent accuracy. The obtained two-photon double-ionization cross sections are in excellent agreement with other cross sections available. Compared to calculations fully contained within a finite inner region, the present calculations can be propagated over the time it takes the slowest electron to reach the boundary. [ABSTRACT FROM AUTHOR]

An electron-nucleus Colle-Salvetti-type correlation functional for multicomponent density-functional theory is proposed. We demonstrate that our correlation functional quantitatively reproduces the quantum mechanical effects of protons; the mean absolute deviation value is 2.8 millihartrees for the optimized structures of hydrogen-containing molecules, and the effective potential energy curve of the hydrogen molecule is well reproduced. Since this functional is derived without any unphysical assumption, the strategy taken in this development will be a promising recipe to make new functionals for the potentials of other particles' interactions, such as electron-positron and electron-muon. [ABSTRACT FROM AUTHOR]

We present a detailed investigation of the supermultiplet structures for the intrashell resonances of H-, classified according to their approximate quantum numbers. The resonance energies and widths are calculated by employing the complex-scaling method with configuration-interaction basis functions, and our results are compared with previous available calculations. The complete I-supermultiplet structures are constructed for the intrashell resonances associated with the H (N = 2, 3, and 4) thresholds. They include the doubly excited states of H- with a variety of configuration symmetries showing both Feshbach and shape types. It is found that the H- (N = 4) supermultiplet has upper portions exceeding the H (N = 5) threshold. This phenomenon should be useful in predicting the supermultiplet structures associated with higher-lying thresholds. [ABSTRACT FROM AUTHOR]

The energy of the He- ion in a magnetic field is calculated using the stochastic variational method with a deformed correlated Gaussian basis. The energy levels and the stability domains are calculated and the accuracy of the approach is shown by comparison to previous calculations. The structure of these states is studied by calculating the electron-electron and electron-nucleus distances. In the weak field case, these systems have a pronounced inert He core plus a weakly bound electronlike structure. Stronger fields lead more compact systems unless the stability is lost due to level crossings. [ABSTRACT FROM AUTHOR]