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We present a workflow of practical calculations of electron-phonon (e-ph) coupling with many-electron correlation effects included using the GW perturbation theory (GWPT). This workflow combines BerkeleyGW, ABINIT, and EPW software packages to enable accurate e-ph calculations at the GW self-energy level, going beyond standard calculations based on density functional theory (DFT) and density-functional perturbation theory (DFPT). This workflow begins with DFT and DFPT calculations (ABINIT) as starting point, followed by GW and GWPT calculations (BerkeleyGW) for the quasiparticle band structures and e-ph matrix elements on coarse electron k- and phonon q-grids, which are then interpolated to finer grids through Wannier interpolation (EPW) for computations of various e-ph coupling determined physical quantities such as the electron self-energies or solutions of anisotropic Eliashberg equations, among others. A gauge-recovering symmetry unfolding technique is developed to reduce the computational cost of GWPT (as well as DFPT) while fulfilling the gauge consistency requirement for Wannier interpolation.

By using ab initio simulations based on density functional theory and many‐body perturbation theory, a comprehensive analysis of the distinct optical signatures of various tellurene polymorphs and their associated unique anisotropic excitonic characteristics is presented. Despite the atomic thickness of these materials, these findings reveal that their optical absorbance reaches as high as 50% in the near‐infrared and visible range. This investigation highlights the exceptional potential of these 2D semiconducting materials in the development of ultra‐thin and flexible homo‐ and hetero‐junctions for solar light harvesting, achieving photoconversion efficiencies up to 19%, a performance level comparable to current silicon technologies. [ABSTRACT FROM AUTHOR]

Improper development of land uses in the city leads to climate changes, resulting in an increase in GW and the formation of UHIs. These changes have adverse effects on people's level of comfort. This research is supposed to extract the optimal model by proving the relationship between the physical arrangement of the architecture of high-rise buildings in residential complexes and reducing the adverse effects of this. Therefore, in this research, four models of solitary, environmental, combined, and rowly block arrangement were investigated based on numerical calculation methods and CFD simulation. These simulations were done by ENVI-meto software based on air temperature, relative humidity, wind speed, and thermal comfort in the open space. The results showed that the type of physical arrangement of buildings can increase air temperature for GW by up to 3 °C and UHIs by 0.5 °C. The combined pattern is the most optimal in this section due to its more compact structure than the solitary pattern. Regarding the effect of relative humidity on climate changes, the solitary pattern has the lowest percentage of relative humidity compared to other patterns due to more air circulation in its physical structure. Also, the type of physical arrangement of buildings can improve the wind speed for GW by up to 0.2 m/s and for UHIs by up to 0.7 m/s. Based on this, the most optimal model is the environmental pattern, because the physical structures of the buildings are an obstacle in wind circulation. The fluctuation range of the PMV index for the intensity of GW effects on thermal comfort, is 0.7°, and the fluctuation range of this index for the power of UHIs is about 0.2°. The solitary pattern is the most optimal pattern to reduce the severity of adverse effects of GW and UHIs; this is due to the scattered distribution of blocks in this pattern. In general, according to the research findings, it can be concluded that the most optimal pattern to reduce the severity of the adverse effects of GW is solitary and environmental patterns, and to reduce the severity of the negative impact of UHIs, the solitary pattern is used.

Improper development of land uses in the city leads to climate changes, resulting in an increase in GW and the formation of UHIs. These changes have adverse effects on people’s level of comfort. This research is supposed to extract the optimal model by proving the relationship between the physical arrangement of the architecture of high-rise buildings in residential complexes and reducing the adverse effects of this. Therefore, in this research, four models of solitary, environmental, combined, and rowly block arrangement were investigated based on numerical calculation methods and CFD simulation. These simulations were done by ENVI-meto software based on air temperature, relative humidity, wind speed, and thermal comfort in the open space. The results showed that the type of physical arrangement of buildings can increase air temperature for GW by up to 3 °C and UHIs by 0.5 °C. The combined pattern is the most optimal in this section due to its more compact structure than the solitary pattern. Regarding the effect of relative humidity on climate changes, the solitary pattern has the lowest percentage of relative humidity compared to other patterns due to more air circulation in its physical structure. Also, the type of physical arrangement of buildings can improve the wind speed for GW by up to 0.2 m/s and for UHIs by up to 0.7 m/s. Based on this, the most optimal model is the environmental pattern, because the physical structures of the buildings are an obstacle in wind circulation. The fluctuation range of the PMV index for the intensity of GW effects on thermal comfort, is 0.7°, and the fluctuation range of this index for the power of UHIs is about 0.2°. The solitary pattern is the most optimal pattern to reduce the severity of adverse effects of GW and UHIs; this is due to the scattered distribution of blocks in this pattern. In general, according to the research findings, it can be concluded that the most optimal pattern to reduce the severity of the adverse effects of GW is solitary and environmental patterns, and to reduce the severity of the negative impact of UHIs, the solitary pattern is used. [ABSTRACT FROM AUTHOR]

Electronic and optical properties of graphene-like ZnSe were investigated through a comprehensive study using ab initio calculations. By employing the GW method, we accurately determine the electronic band structure and bandgap of graphene-like ZnSe, considering the many-body effects. Additionally, we examine the optical properties of graphene-like ZnSe using the GW+BSE method, calculate the optical absorption spectrum, and determine excitonic properties such as exciton binding energy and optical bandgap. The GW calculations reveal that the ZnSe bandgap is direct with an energy gap of approximately 4.869 eV and exhibits excitons with relatively strong binding energies ranging from 0.2 to 0.8 eV. The majority of bound exciton distributions arise from transitions between Zn(3p)+Zn(3d)+Se(4p)→Zn(4s)+Se(4s) at the gamma point of the Brillouin zone. The precise determination of the band structure, bandgap, and excitonic properties enables a better understanding of the material's behavior and aids in the design and optimization of future ZnSe graphene-based devices. [ABSTRACT FROM AUTHOR]

Water shortage is one of the serious environmental problems in a semi-arid region, which has become increasingly dangerous. The article considers a new management simulation model of Groundwater (GW) resources using a water flow model. One thousand one hundred fifty irrigation wells were selected as a study area using Landsat 8 OLI images 2016-2021 in the West of Karbala province, Iraq. Geographic Information System tool integrated with numerical /conceptual model using the Visual MODFLOW Flex 7 software to reach the optimal use of GW resources. The conceptual model indicated that the value of the flow in the aquifer reaches 21 million cubic meters annually, which means there is renewable storage. The consumer value of GW was about 55 million m3/year. The result presented that the value of the lost and depleted storage in this part becomes about -34 million m3/year, which is the value of the variation in the underground storage, meaning there is a significant depletion of GW in the study area. Using the Visual MODFLOW Flex 7 software and entering parameters for the study area through pumping and monitoring wells, an error of 0.067 m was achieved in estimating groundwater recharge places near the folds' rocky aquifers. The normalized RMS for the model was 69.595%, and the correlation coefficient was 0.391. The contour lines in the region's East indicate increased conductivity due to channels and openings formed during groundwater-bearing rocks, depressions, and lakes. The study concluded that the outputs could help water administrations for more accurate and sustainable plans and management of GW resources in the Karbala area. [ABSTRACT FROM AUTHOR]

The valuation of Goodwill (GW) has remained one of the several critical issues in financial analysis. This aspect is particularly important for mergers and acquisitions due to the significance of intangible assets. This study delves into the capitalization method of super profit (CMSP), a prominent technique for GW valuation, enhanced by the integration of statistical tools. Assessing a company's excess profits over its average return on tangible assets is part of the CMSP. Finding the variables that have a significant impact on GW valuation, such as average profit, capital employed, and rate of return, is the main goal of this research. These issues are thoroughly investigated through statistical analysis to give stakeholders useful information for well-informed decision-making. Additionally, the study seeks to identify the external elements influencing this process as well as the internal aspects influencing GW valuation. Regression analysis, correlation matrices, response analysis and ANOVA are used to improve GW assessment and comprehension of the complex relationships between different factors. [ABSTRACT FROM AUTHOR]

Geothermal water (GW) resources are highly valued as clean, renewable energy sources. In this study, a comprehensive analysis of water chemistry and isotope data from 25 GW samples was conducted to gain insights into the hydrochemical characteristics and formation mechanisms of the GW in the northern Jinan region (NJR). Statistical analysis and hydrochemical methods were employed for relevant analysis. The findings reveal that the GW in the NJR exhibits high salinity, with an average total dissolved solids (TDS) concentration of 9009.00 mg/L. The major ions identified are Na+ and Cl−, with mean concentrations of 2829.73 mg/L and 4425.77 mg/L, respectively, resulting in a hydrochemical type of Cl−Na. The analysis of δ2H and δ18O isotopes indicates that the GW originates from atmospheric precipitation that undergoes deep cycling and interaction with older groundwater. The composition of 3H suggests that the GW in the NJR is a mixture of waters, while radiocarbon dating (14C) suggests that the recharge of the GW may have occurred in the late Pleistocene era. The GW in the NJR is classified as partially equilibrated waters. The temperature range of geothermal reservoirs is 57.13 to 99.74 °C. The hydrochemical components primarily result from water–rock interactions, including silicate weathering, cation exchange, as well as carbonate weathering and the dissolution of halite and gypsum. Moreover, taking into account the hydrogeological conditions, hydrochemistry, and isotope analysis, a conceptual model of the geothermal reservoir in the NJR was developed. The research findings serve as a valuable reference and foundation for the development and utilization of geothermal resources in the Jinan region. These originate from the Taiyi mountains in the south or the Taihang mountains in the west, and experience deep circulation and long runoff times. This study provides a reference for the sustainable development and utilization of regional geothermal resources. [ABSTRACT FROM AUTHOR]

Using first‐principles calculations, a study on the electronic and optical characteristics of perovskite solar cells containing the orthorhombic phases CH3NH3SnI3 and CH(NH2)2SnI3 is conducted. The analysis includes the examination of relaxed geometry structures, electronic band structures, charge density distributions, and van Hove singularities in the density of states to thoroughly examine the orbital hybridizations in chemical bonds. The optical properties of the materials with and without excitonic effects by analyzing dielectric functions, energy loss functions, absorption coefficients, and reflectance spectra are also studied. The findings identify the close connections between the initial and final orbital hybridizations, as well as prominent optical excitations. Based on the computational predictions, It is believed that lead‐free materials such as CH3NH3SnI3 and CH(NH2)2SnI3 are promising candidates for photovoltaic applications and are worth experimental testing. [ABSTRACT FROM AUTHOR]

We present an ab initio study on quasiparticle (QP) excitations and excitonic effects in two-dimensional (2D) GaN based on density-functional theory and many-body perturbation theory. We calculate the QP band structure using  G W  approximation, which generates an indirect band gap of  4.83  eV ( K → Γ ) for 2D GaN, opening up  1.24  eV with respect to its bulk counterpart. It is shown that the success of plasmon-pole approximation in treating the 2D material benefits considerably from error cancellation. On the other hand, much better gaps, comparable to  G W  ones, could be obtained by correcting the Kohn–Sham gap with a derivative discontinuity of the exchange–correlation functional at much lower computational cost. To evaluate excitonic effects, we solve the Bethe–Salpeter equation (BSE) starting from Kohn–Sham eigenvalues with a scissors operator to open the single-particle gap. This approach yields an exciton binding energy of  1.23  eV in 2D GaN, which is in good agreement with the highly demanding  G W -BSE results. The enhanced excitonic effects due to reduced dimensionality are discussed by comparing the optical spectra from BSE calculations with that by random-phase approximation (RPA) for both the monolayer and bulk GaN in wurtzite phase. Additionally, we find that the spin–orbit splitting of excitonic peaks is noticeable in 2D GaN but buried in the bulk crystal. [ABSTRACT FROM AUTHOR]

Security is one of the major concerns while designing robust protocols for underwater sensor networks (UWSNs). The underwater sensor node (USN) is an example of medium access control (MAC) that should control underwater UWSN, and underwater vehicles (UV) combined. Therefore, our proposed method, in this research, investigates UWSN combined with UV optimized as an underwater vehicular wireless network (UVWSN) that can completely detect malicious node attacks (MNA) from the network. Thus, MNA that engages the USN channel and launches MNA is resolved by our proposed protocol through SDAA (secure data aggregation and authentication) protocol deployed in UVWSN. SDAA protocol plays a significant role in secure data communication, as the cluster-based network design (CBND) network organization creates a concise, stable, and energy-efficient network. This paper introduces SDAA optimized network known as UVWSN. In this proposed SDAA protocol, the cluster head (CH) is authenticated through the gateway (GW) and the base station (BS) to guarantee that a legitimate USN oversees all clusters deployed in the UVWSN are securely established for providing trustworthiness/privacy. Furthermore, the communicated data in the UVWSN network guarantee that data transmission is secure due to the optimized SDAA models in the network. Thus, the USNs deployed in the UVWSN are securely confirmed to maintain secure data communication in CBND for energy efficiency. The proposed method is implemented and validated on the UVWSN for measuring reliability, delay, and energy efficiency in the network. The proposed method is utilized for monitoring scenarios for inspecting vehicles or ship structures in the ocean. Based on the testing results, the proposed SDAA protocol methods improve energy efficiency and reduce network delay compared to other standard secure MAC methods. [ABSTRACT FROM AUTHOR]

The class of two-dimensional oxyfluoride monolayers is currently considered one of the most attractive nanomaterials for enhancing design and pushing the limits of different cutting-edge technologies. Two-dimensional semiconductor materials are the most promising systems for various applications in optoelectronic devices because they have a unique optical properties. We continue in this way by investigating the GW band structures and optical properties of unique 2D XOF (X = Ga or In) oxyfluoride monolayers, involving absorption, conductivity, refractive index, and dielectric function. We find no imaginary frequencies in the computed phonon spectra, indicating that these systems are dynamically stable. Furthermore, GaOF and InOF stay stable for temperatures T ≤ 840 K. The band gap of GaOF obtained with the single shot (G0W0) is larger than the band gap energy Eg of InOF. Where the direct band gap energies of GaOF and InOF are 6.1 eV and 4.8 eV, respectively. Our GW(PBE) numerical simulations demonstrate that the GaOF monolayer moves transparent once the frequency of the incoming light exceeds the plasma frequency (35.00 eV). Furthermore, InOF switches transparently once the incident light frequency exceeds the plasma frequency ∼ 35.00 eV. Interestingly, we obtain that these 2D sheets have a strong absorption coefficient in the range of ∼ 3.00–60.00 eV. They are emerging as a potential for the building blocks of the nano-size and ultra-thin optoelectronics of the future since they productively emit and absorb light.

The concept of detecting gravitational waves using RF-cavities in strong magnetic fields has gained considerable interest, using setups currently running axion searches. We propose a novel analysis approach for detecting GHz-regime gravitational waves, potentially from primordial black hole mergers, through synchronous measurements from multiple, distant cavities. While individual cavities may detect gravitational wave signatures, isolating them from noise is challenging since the strain (and thereby power deposition in a cavity) of such mergers is expected to be very small and short-lived. By correlating signals from several geographically separated cavities, we can significantly improve the signal-to-noise ratio and potentially investigate the sources of these waves. A demonstration experiment with a superconducting cavity is currently underway, forming the basis for our data analysis methods and outlining the prospects for the GravNet project. This project should be seen as an effort to bring the axion community together and collaborate in the context of gravitational wave physics. [ABSTRACT FROM AUTHOR]

Geothermal water (GW) resources are highly valued as clean, renewable energy sources. In this study, a comprehensive analysis of water chemistry and isotope data from 25 GW samples was conducted to gain insights into the hydrochemical characteristics and formation mechanisms of the GW in the northern Jinan region (NJR). Statistical analysis and hydrochemical methods were employed for relevant analysis. The findings reveal that the GW in the NJR exhibits high salinity, with an average total dissolved solids (TDS) concentration of 9009.00 mg/L. The major ions identified are Na+ and Cl−, with mean concentrations of 2829.73 mg/L and 4425.77 mg/L, respectively, resulting in a hydrochemical type of Cl−Na. The analysis of δ2H and δ18O isotopes indicates that the GW originates from atmospheric precipitation that undergoes deep cycling and interaction with older groundwater. The composition of 3H suggests that the GW in the NJR is a mixture of waters, while radiocarbon dating (14C) suggests that the recharge of the GW may have occurred in the late Pleistocene era. The GW in the NJR is classified as partially equilibrated waters. The temperature range of geothermal reservoirs is 57.13 to 99.74 °C. The hydrochemical components primarily result from water–rock interactions, including silicate weathering, cation exchange, as well as carbonate weathering and the dissolution of halite and gypsum. Moreover, taking into account the hydrogeological conditions, hydrochemistry, and isotope analysis, a conceptual model of the geothermal reservoir in the NJR was developed. The research findings serve as a valuable reference and foundation for the development and utilization of geothermal resources in the Jinan region. These originate from the Taiyi mountains in the south or the Taihang mountains in the west, and experience deep circulation and long runoff times. This study provides a reference for the sustainable development and utilization of regional geothermal resources.

The study of intra and interlayer excitons in 2D semiconducting vdW heterostructures is a very hot topic not only from a fundamental but also an applicative point of view. Due to their strong light–matter interaction, Transition Metal Dichalcogenides (TMD) and group-III nitrides are particularly attractive in the field of opto-electronic applications such as photo-catalytic and photo-voltaic ultra-thin and flexible devices. Using first-principles ground and excited-state simulations, we investigate here the electronic and excitonic properties of a representative nitride/TMD heterobilayer, the A l N / W S 2 . We demonstrate that the band alignment is of type I, and low energy intralayer excitons are similar to those of a pristine W S 2 monolayer. Further, we disentangle the role of strain and AlN dielectric screening on the electronic and optical gaps. These results, although they do not favor the possible use of AlN/ W S 2 in photo-catalysis, as envisaged in the previous literature, can boost the recently started experimental studies of 2D hexagonal aluminum nitride as a good low screening substrate for TMD-based electronic and opto-electronic devices. Importantly, our work shows how the inclusion of both spin-orbit and many-body interactions is compulsory for the correct prediction of the electronic and optical properties of TMD/nitride heterobilayers. [ABSTRACT FROM AUTHOR]

The computational data presented in this paper refer to the research article “Optical properties and simulated x-ray near edge spectra for Y2O2S and Er doped Y2O2S”. We present the data used to calculate the structural, electronic, and optical properties of the Y2O2S and its Er+3 doped counterparts at various concentrations using density functional theory (DFT) and simulated X-ray near edge (XANES) spectra. We report electronic information from DFT and DFT+U generated from the Vienna Ab initio Simulation Package (VASP) using PAW pseudopotentials. We also report VASP calculated optical properties for the host Y2O2S using the independent particle approximation (IPA), the random phase approximation (RPA), the many-body GW0 approximation, and the Bethe-Salpeter equation (BSE) approximation, under the 10-atom unit cell. The IPA calculations are repeated using the 80-atom unit cell for both the host Y2O2S and the Y2O2S:Er+3 counterparts. The optical properties data include the frequency-dependent real and imaginary parts of the dielectric function, the absorption and extinction coefficients, the refractive index, and the reflectivity. FEFF10 XANES calculations are performed on the Y K-, L1-, L2-, and L3-edges, as well as on the Er M5-edge.

We present an ab initio study on quasiparticle (QP) excitations and excitonic effects in two-dimensional (2D) GaN based on density-functional theory and many-body perturbation theory. We calculate the QP band structure using GW approximation, which generates an indirect band gap of 4.83 eV (K→Γ) for 2D GaN, opening up 1.24 eV with respect to its bulk counterpart. It is shown that the success of plasmon-pole approximation in treating the 2D material benefits considerably from error cancellation. On the other hand, much better gaps, comparable to GW ones, could be obtained by correcting the Kohn–Sham gap with a derivative discontinuity of the exchange–correlation functional at much lower computational cost. To evaluate excitonic effects, we solve the Bethe–Salpeter equation (BSE) starting from Kohn–Sham eigenvalues with a scissors operator to open the single-particle gap. This approach yields an exciton binding energy of 1.23 eV in 2D GaN, which is in good agreement with the highly demanding GW-BSE results. The enhanced excitonic effects due to reduced dimensionality are discussed by comparing the optical spectra from BSE calculations with that by random-phase approximation (RPA) for both the monolayer and bulk GaN in wurtzite phase. Additionally, we find that the spin–orbit splitting of excitonic peaks is noticeable in 2D GaN but buried in the bulk crystal.

In the pursuit of advancing solar energy technologies, this study presents 20 direct and quasi-direct band gap silicon crystalline semiconductors that satisfy the Shockley-Queisser limit, a benchmark for solar cell efficiency. Employing two evolutionary algorithm-based searches, we optimize structures and calculate fitness function using the DFTB method and Gaussian approximation potential. Following the preselection of structures based on energy considerations, we further optimize them using PBEsol DFT. Subsequently, we screen the structures based on their band gap, employing a DFTB method tailored for band gap calculation of silicon crystals. To ensure accurate band gap determination, we employ HSE and GW methods. To validate the structural stability, we employ phonon analysis via linear regression algorithm applied to PBEsol DFT data. Significantly, the structures unveiled in this study are of great importance due to their proven stability from both mechanical and dynamic perspectives. Furthermore, the ductility and low density of certain structures enhance their potential application. We examine the optical properties by studying the imaginary part of the dielectric function by solving the Bethe–Salpeter Equation on top of GW approximation. By calculating the SLME, we achieve an efficiency of 32.7% for Si 22 at a thickness of 500 nm. Moreover, the study harnesses various machine learning algorithms to develop a predictive model for the band gap energy of these silicon structures. Input data for machine learning models are derived from structural MBTR and SOAP descriptors, as well as DFT outputs. Notably, the results reveal that features extracted from DFT outperform the MBTR and SOAP descriptors. [Display omitted] • 20 Si-crystal discovered for solar cells with direct/quasi-direct band gaps. • DFTB band structure calculations agreed well with GW and HSE methods. • Stability confirmed dynamically, thermodynamically, and mechanically using DFT. • Optical properties indicate high suitability for solar cell production. • DFT features outperformed MBTR and SOAP in predicting band gaps. [ABSTRACT FROM AUTHOR]

Photoelectron spectroscopy (PES) investigation of two widely used herbicide compounds MCPA and 2,4-D is reported. The GW calculations are shown to offer a good description of their electronic structure. There is excellent agreement between the experimental and theoretical energies of the HOMO states of 2,4-D and MCPA, which are at 8.7 eV and 8.5 eV binding energy, respectively. The low energy tail of the HOMO state extends to about 8 eV. The good agreement between the UPS (ultraviolet photoelectron spectroscopy) spectra and the simulation validates the proposed conformer. The presented gas phase data will help researchers to analyze data from liquid and diluted samples of these herbicide molecules and perform additional theoretical modelling. • The UPS spectra of two widespread herbicides MCPA and 2,4-dichlorophenoxyacetic acid have been obtained and analyzed. • A side-by-side comparison of the geometric and electronic structures is presented. • There is excellent agreement between the experimental and theoretical energies of the HOMO states of 2,4-D and MCPA, which are at 8.7 eV and 8.5 eV binding energy, respectively. [ABSTRACT FROM AUTHOR]

Understanding the hydrogeochemical and physicochemical processes and factors controlling the chemical characteristics of groundwater (GW) is essential in water resources studies. In this work, the authors explored, applied, and evaluated the practicality of a series of analysis methods, exploring their ability to improve the representation of the generic GW chemical datasets. The demonstration resulted in a detailed explanation of findings and interpretations, which benefits newcomers who may not be experts in managing such data. Visualization-based, facile, readily readable, and interpretable graphs were tuned and applied to identify the interconnected controlling factors. The examined varieties were bubble diagrams, 3D surface plots, and scatter box plot matrices. Box plot matrices yielded intensive information about the significant interacting parameters in one graph. Employing bubble diagrams produced vast detail, allowing the identification of the significant processes and enabling the recognition of internally acting mechanisms that were otherwise hidden. The identified GW evolution processes include aerosol dissolution, evaporation, direct and reverse ion exchange, precipitation of calcium salts, flushing out of soil-bounded salts, and rock weathering. pH and HCO3− fluctuations coupled with evaporation were recognized as prominent factors giving rise to the vicious salinization cycle, which is thought to be the process causing the worst deterioration in the GW quality and the salinity within the study area. [ABSTRACT FROM AUTHOR]

Accurate prediction of the ionization potential and electron affinity energies of small molecules are important for many applications. Density functional theory (DFT) is computationally inexpensive, but can be very inaccurate for frontier orbital energies or ionization energies. The GW method is sufficiently accurate for many relevant applications, but much more expensive than DFT. Here we study how we can learn to predict orbital energies with GW accuracy using machine learning (ML) on molecular graphs and fingerprints using an interpretable delta-learning approach. ML models presented here can be used to predict quasiparticle energies of small organic molecules even beyond the size of the molecules used for training. We furthermore analyze the learned DFT-to-GW corrections by mapping them to specific localized fragments of the molecules, in order to develop an intuitive interpretation of the learned corrections, and thus to better understand DFT errors.

The GW approximation and the Bethe–Salpeter equation have been implemented into the Turbomole program package for computations of molecular systems in a strong, finite magnetic field. Complex-valued London orbitals are used as basis functions to ensure gauge-invariant computational results. The implementation has been benchmarked against triplet excitation energies of 36 small to medium-sized molecules against reference values obtained at the approximate coupled-cluster level (CC2 approximation). Finally, a spectacular change of colour from orange to green of the tetracene molecule is induced by applying magnetic fields between 0 and 9,000 T perpendicular to the molecular plane.

Using the simple (symmetric) Hubbard dimer, we analyze some important features of the GW approximation. We show that the problem of the existence of multiple quasiparticle solutions in the (perturbative) one-shot GW method and its partially self-consistent version is solved by full self-consistency. We also analyze the neutral excitation spectrum using the Bethe-Salpeter equation (BSE) formalism within the standard GW approximation and find, in particular, that 1) some neutral excitation energies become complex when the electron-electron interaction U increases, which can be traced back to the approximate nature of the GW quasiparticle energies; 2) the BSE formalism yields accurate correlation energies over a wide range of U when the trace (or plasmon) formula is employed; 3) the trace formula is sensitive to the occurrence of complex excitation energies (especially singlet), while the expression obtained from the adiabatic-connection fluctuation-dissipation theorem (ACFDT) is more stable (yet less accurate); 4) the trace formula has the correct behavior for weak (i.e., small U) interaction, unlike the ACFDT expression.

Quantification of groundwater (GW) and surface water (SW) interactions is crucial for effective water resource allocation and management. Immense progress has been made in the past few decades to address the different aspects of GW–SW exchanges. These have resulted in a large volume of literature. This work reviews in detail the mechanism of interaction and the applications of different field and modelling techniques. The review of flux quantification methods identifies the streambed and the aquifer beneath as two major components affecting the interactions. It is observed that the streambed is highly idealised in modelling studies, and the significance of aquifer properties in the flux quantification is found to be less emphasised. Therefore, attempts are made to highlight the potential significance of both streambed and the aquifer properties through a 2D numerical experiment. Using a superimposed GW–SW system and appropriately grouping the system parameters (as hydraulic and geometric), the experiment shows that the aquifer properties can dominate exchanging flux under certain conditions, e.g., at higher streambed conductance. The work provides suggestions to modify the widely used Darcy's approach to include aquifer properties. [ABSTRACT FROM AUTHOR]

The electronic energy band spectra of CdX crystals (X = O, S, Se, Te) in the wurtzite phase have been calculated. We have revealed that Cd 4d electrons are localized in the narrow energy intervals of the valence band. The results obtained here show that the exchange-correlation functionals developed within the LDA and GGA approaches are not applicable to the strongly correlated 4d electron subsystem. Indeed, the band gap found for the CdO crystal in these approaches is Eg = 0, and its values for CdS, CdSe, and CdTe materials are 1.48, 0.67, and 0.84 eV, respectively. They all are much smaller than the measured Eg for CdX materials, which are 0.91, 2.5, 1.8 and 1.8 eV, respectively. We found that “GGA – Green’s function” calculation scheme, which is very effective for s-p electron systems, did not produce successful results for CdX crystals. That is why we have chosen a combination of “hybrid functional – Green’s function” approach. The Eg values found in CdX crystals without spin-orbit interaction are 0.90, 2.49, 1.92 and 2.10 eV, respectively. The spin-orbit interaction causes a negligible narrowing dESO of the Eg parameter in CdO and CdS crystals. However, in CdSe and CdTe materials, the narrowing parameter dESO values are 0.12 and 0.27 eV, respectively. Corrected by dESO band gaps of CdSe and CdTe crystals have the values of 1.80 and 1.83 eV, respectively. The Eg values found here are well compared with the experiment. It is found that the energy bands of the semicore Cd 4d electrons obtained without spin-orbit interaction overlap in CdX crystals. Spin-orbit interaction leads to a widening of Cd 4d energy bands. Moreover, in CdSe and CdTe crystals, the spin-orbit interaction leads to a clear separation of 4d electron energy bands into two parts, the lower of which contains 8 and the upper 12 branches of the spectrum. [ABSTRACT FROM AUTHOR]

The orthorhombic phases of CH 3 NH 3 PbX 3 (X = Br, I) have garnered significant research interest for their potential applications in optoelectronics. This work presents our findings regarding the geometric, electronic, and optical properties of CH 3 NH 3 PbX 3 utilizing first-principles calculations based on density functions theory (DFT), and many-body perturbation theory (MBPT). Our investigation reveals that CH 3 NH 3 PbX 3 exhibits direct band gap semiconductors, low effective mass, and high carrier mobility. Furthermore, CH 3 NH 3 PbX 3 processes interesting optical properties, including a low exciton energy binding, and low reflectivity/high absorption efficiency. Additionally, the identified bound exciton states manifest as bright states in both materials. More importantly, the intimate correlation between optical and electronic characteristics is convincingly established through the orbital hybridization concept. These features suggest that CH 3 NH 3 PbX 3 materials hold promise as an active layer for perovskite-based solar cells. [ABSTRACT FROM AUTHOR]

We present a numerical integration scheme for evaluating theconvolution of a Green's function with a screened Coulomb potentialon the real axis in the GW approximation of the self energy.Our scheme takes the zero broadening limit in Green's functionfirst, replaces the numerator of the integrand with a piecewisepolynomial approximation, and performs principal value integrationon subintervals analytically. We give the error bound of ournumerical integration scheme and show by numerical examples thatit is more reliable and accurate than the standard quadrature rulessuch as the composite trapezoidal rule. We also discuss the benefit of usingdifferent self energy expressions to perform the numerical convolutionat different frequencies.

The monolayer SnS, a potential two-dimensional material, is a semiconductor with an indirect band gap. Recently, it has attracted much attention because of its extraordinary physical properties and prospective applications in optoelectronic devices. In the present work, we systematically studied the electronic properties of the two-dimensional SnS under both uniaxial and biaxial strains based on the first-principles GW methods. Combined with the Bethe-Salpeter equation, the optical properties of the monolayer SnS have also been investigated. Our results indicated that the electronic band structure of monolayer SnS can be effectively changed by the applied strain, and a transition from the indirect band gap to direct band gap was observed in the monolayer under the uniaxial strain. The calculated optical spectra of the monolayer SnS indicated a strong anisotropy under the uniaxial strain. According to these results, the monolayer SnS presented abundant opportunities for creating novel high performance nano-electronic and optoelectronic devices in the future. [ABSTRACT FROM AUTHOR]

We have found that the energies of the Zn semicore 3d electrons in crystals ZnX (X = O, S, Se, Te), in the wurtzite phase, are localized in narrow intervals within the valence band. It was found that the widths of these intervals at Γ point of the first Brillouin zone are equal to 1.24, 0.68, 0.50 and 0.40 eV for ZnO, ZnS, ZnSe and ZnTe crystals, respectively. It was found that the wave functions of the Zn 3d electrons strongly overlap with the states of the valence and the conduction bands. Consequently, the widely used exchange-correlation energy functionals, constructed in the LDA and GGA-PBE approaches, are inappropriate for systems with narrow band of highly correlated 3d electrons. That is why we performed calculations based on the hybrid exchange-correlation energy functional, HSE06, and the obtained eigenenergies and eigefunctions were used in the construction of the Green's function. Consequently, the basis of this study is based on the two modern concepts of electronic theory of crystals, namely the hybrid exchangecorrelation functional and quasiparticle approach. The values of the bandgap, Eg, obtained here in the GGA-PBE approximation, are well-matched to the results found by other authors. The values of Eg, calculated using the combination of Green's function methods and the hybrid functional for the exchangecorrelation energy, HSE06, are equal to 2.34, 3.28, 2.35 and 2.13 eV for ZnO, ZnS, ZnSe and ZnTe crystals, respectively, if the mixing factor in the functional is 0.25, that it is the standard. We calculated the electron energy spectra for ZnO, ZnS, ZnSe and ZnTe crystals, with mixing factors, different from the standard ones, namely of 0.40, 0.375, 0.35 and 0.325. The corresponding band gaps have been acquired the values of 3.29, 3.83, 2.81 and 3.43 eV, which are very well matched with the experiment. [ABSTRACT FROM AUTHOR]

(It can be said that the system of sensing the tilt angle and speed of a multi-rotor copter come in the first rank among all the other sensors on the multi-rotor copters and all other planes due to its important roles for stabilization. The MPU6050 sensor is one of the most popular sensors in this field. It has an embedded 3-axis accelerometer and a 3-axis gyroscope. It is a simple sensor in dealing with it and extracting accurate data. Everything changes when this sensor is placed on the plane. It becomes very complicated to deal with it due to vibration of the motors on the multirotor copter. In this study, two main problems were diagnosed was solved that appear in most sensors when they are applied to a high-frequency vibrating environment. The first problem is how to get a precise angle of the sensor despite the presence of vibration. The second problem is how to overcome the errors that appear when the multirotor copter revolves around its vertical axis during the tilting in either direction x or y or both. The first problem was solved in two steps. The first step involves mixing data of the gyroscope sensor with the data of auxetometer sensor by a mathematical equation based on optimized complementary filter using gray wolf optimization algorithm GWO. The second step involves designing a suitable FIR filter for data. The second problem was solved by finding a non-linear mathematical relationship between the angles of the copter in both X and Y directions, and the rotation around the vertical axis of multirotor copter frame. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights: • 2D bilayer vdWh of InSe-Si/Ge/Sb studied with DFT and GW-BSE method. • Strong response in the IR-vis. region for InSe-Si and InSe-Ge vdWh. • InSe-Sb vdWh more responsive in the vis.-UV region with better charge separation. • Photocurrent density significantly larger than conventional photovoltaic materials. • Possible application of InSe-Si/Ge with InSe-Sb in 2D multi-junction solar cells. Abstract In this work, we study van der Waals (vdW) heterostructures consisting of the emerging photonic material, 2-dimensional (2D) InSe, with the lattice-matched 2D materials silicene, germanene and antimonene, using ab-initio simulations. We employ density functional theory (DFT) to calculate the structural and electronic properties of the vdW hetero-bilayers. The optical spectra of the systems are evaluated by solving the Bethe-Salpeter equation (BSE) on top of the GW quasiparticle bands. A strong response in the IR-visible region of the optical spectra is seen in case of InSe-Si and InSe-Ge vdW lattice whereas the InSe-Sb structure shows better performance in the visible-UV region, with better prospect of excitonic charge separation. A good absorbance in the IR-visible and the visible-UV region, can be achieved with these structures with computed theoretical photocurrent densities significantly larger than conventional photovoltaic materials. While individually the vdW structures can be useful in photonic applications, the complimentary nature of absorption with InSe-Sb and InSe-Si/Ge structures can also be utilized in multi-junction heterostructure solar cells. [ABSTRACT FROM AUTHOR]

Highlights • Molecular adsorption of oxygen on Sr3Ru2O7(001). • Charge transfer leads to the formation of a superoxo species. • Adsorption energy can be enhance by Ca doping. • Approaches beyond DFT needed to obtain the correct energetic order of high-coverage phases. Graphical abstract Abstract Only recently, the activation of oxygen molecules on clean defect-free transition metal oxide surfaces has been reported, for example on the CaO-terminated surface of the Ruddelsden-Popper perovskite Ca 3 Ru 2 O 7 (001). In this work we show that oxygen molecules adsorb as an activated superoxo species on a clean SrO-terminated surface of Sr 3 Ru 2 O 7 (001). At all coverages, the electrons activating the molecule originate from the subsurface RuO 2 layer. At low coverages, the presence of a Ca dopant in the terminating SrO layer slightly increases the adsorption energy. At high coverage, DFT predicts a flat potential energy surface and a preferred adsorption of the O 2 - near surface cations. Advanced many-electron calculations (RPA) predict adsorption energies of − 0.99 eV and − 0.49 eV per O 2 - molecule for low and high coverages, respectively, and a preference for forming line-like structures in the latter case. [ABSTRACT FROM AUTHOR]

We report the results of a first-principles research of the structural, electronic, linear and nonlinear responses, and vibrational properties of CdSiP 2 based on the density functional theory using pseudopotential plane-wave approach. We calculate the energy band structure, dielectric function, absorption coefficient, reflectivity, refractive index, SHG susceptibility, and phonon dispersion curves. In order to obtain accurate band gap value of CdSiP 2 , the GW approximation method is used to calculate the quasiparticle band structure and the corrected band gap value is in excellent agreement with experimental measurements. Furthermore, the corrected band gap can be used as scissor shift for linear and nonlinear optical properties calculations. The linear-response theory is used to derive the phonon dispersion curves and density of states. All zone-center phonon modes are calculated and LO-TO splitting of the infrared modes are identified. The results show a good agreement with available experimental data and other calculations. • The band gap due to the GW correction is used as scissor shift to calculate the optical properties. • We evaluate the dielectric function for different optical polarizations. • The refractive index data show that CdSiP 2 crystal has a negative birefringence as expected. • The intra-(2 ω)/(1 ω) and inter-(2 ω)/(1 ω) band contributions to the imaginary part are presented. • The phonon frequencies at the Brillouin zone center are calculated. [ABSTRACT FROM AUTHOR]

This work explores the possibility of increasing the photovoltaic efficiency of InP semiconductors through a hyperdoping process with transition metals (TM = Ti, V, Cr, Mn). To this end, we investigated the crystal structure, electronic band and optical absorption features of TM-hyperdoped InP (TM@InP), with the formula TMxIn1-xP (x = 0.03), by using accurate ab initio electronic structure calculations. The analysis of the electronic structure shows that TM 3d-orbitals induce new states in the host semiconductor bandgap, leading to improved absorption features that cover the whole range of the sunlight spectrum. The best results are obtained for Cr@InP, which is an excellent candidate as an in-gap band (IGB) absorber material. As a result, the sunlight absorption of the material is considerably improved through new sub-bandgap transitions across the IGB. Our results provide a systematic and overall perspective about the effects of transition metal hyperdoping into the exploitation of new semiconductors as potential key materials for photovoltaic applications.

Ionization potentials (IPs) and electron affinities (EAs) are important quantities input into most models for calculating the open-circuit voltage (Voc) of organic solar cells. We assess the semi-empirical density-functional tight-binding (DFTB) method with the third-order self-consistent charge (SCC) correction and the 3ob parameter set (the third-order DFTB (DFTB3) organic and biochemistry parameter set) against experiments (for smaller molecules) and against first-principles GW (Green’s function, G, times the screened potential, W) calculations (for larger molecules of interest in organic electronics) for the calculation of IPs and EAs. Since GW calculations are relatively new for molecules of this size, we have also taken care to validate these calculations against experiments. As expected, DFTB is found to behave very much like density-functional theory (DFT), but with some loss of accuracy in predicting IPs and EAs. For small molecules, the best results were found with ΔSCF (Δ self-consistent field) SCC-DFTB calculations for first IPs (good to ± 0.649 eV). When considering several IPs of the same molecule, it is convenient to use the negative of the orbital energies (which we refer to as Koopmans’ theorem (KT) IPs) as an indication of trends. Linear regression analysis shows that KT SCC-DFTB IPs are nearly as accurate as ΔSCF SCC-DFTB eigenvalues (± 0.852 eV for first IPs, but ± 0.706 eV for all of the IPs considered here) for small molecules. For larger molecules, SCC-DFTB was also the ideal choice with IP/EA errors of ± 0.489/0.740 eV from ΔSCF calculations and of ± 0.326/0.458 eV from (KT) orbital energies. Interestingly, the linear least squares fit for the KT IPs of the larger molecules also proves to have good predictive value for the lower energy KT IPs of smaller molecules, with significant deviations appearing only for IPs of 15–20 eV or larger. We believe that this quantitative analysis of errors in SCC-DFTB IPs and EAs may be of interest to other researchers interested in DFTB investigation of large and complex problems, such as those encountered in organic electronics.

The Green’s function method, implemented in the first order of the perturbation theory (GW), was applied for an accurate description of the electronic structure of cubic BaSnO3 and SrSnO3 perovskites. First, the band structure of these materials was calculated within the generalized gradient approximation (GGA). Then, in order to obtain the accurate band gaps, the quasiparticle corrections to the eigenenergies were evaluated. The calculated electronic structure by means of the GW approximation was compared to the structure obtained within the GGA. The application of quasiparticle corrections to the eigenenergies led to a significant widening of the band gaps and provided a much better agreement with the experimental data. The GW corrections to the band energies, found for both crystals at the points of the first Brillouin zone, are quite different. Consequently, the use of a scissor operator can lead to errors in a calculation of the optical constants. [ABSTRACT FROM AUTHOR]