Energy Correction Research Articles

Excitonic properties and solar harvesting performance of Cs2ZnY2X2 as quasi-2D mixed-halide perovskites

Due to their low toxicity and high-temperature stability, lead-free quasi-2D metal halide perovskites (MHPs) are promising materials for optoelectronic applications. However, understanding their structural and optoelectronic properties, especially excitonic effects (electron-hole pair, e-h), is challenging due to their quantum well topology. We propose an efficient protocol for band gap correction of Cs2ZnX (X = Cl4, Br2Cl2, and I2Cl2) and Cs2PbI2Cl2 (used as a benchmark) quasi-2D MHPs. This protocol is based on a relativistic quasiparticle approach (DFT-1/2) using density functional theory (DFT). We first examined the hybrid contributions of the halide alloys, leading to excitonic characterization using the Bethe–Salpeter equation within the maximally localized Wannier functions tight-binding method. This method provides a cost-effective approach for describing e-h quasiparticle effects. Additionally, we analyzed the crystal structure, thermodynamic stability, and optoelectronic properties of the newly synthesized Zn-based systems, focusing on their structural stability mechanisms. We found a correlation between the allocation of Cs+ cations in the crystal structure and the formation of two distinct stabilization patterns, influenced by the radii of the metal (Zn or Pb) and halide components. The relativistic correction of the band gap energies yielded results within 10 % of the experimental values. Furthermore, incorporating e-h quasiparticle effects for Cs2PbI2Cl2 resulted in an exciton binding energy of 0.160 eV, in excellent agreement with experimental data. This work represents a significant advance in the optoelectronic characterization of Cs2ZnX systems, previously unexplored for their excitonic properties.

Electrical contact property and control effects for stable T(H)-TaS2/C3B metal-semiconductor heterojunctions.

Metal-semiconductor heterojunctions are the basis for developing new electronic devices. Here, T(H)-TaS2/C3B metal-semiconductor heterostructures are constructed by different phase T- and H-TaS2 monolayers combined with the C3B monolayer. The calculated corrected binding energies, phonon band structures, elastic constants, and molecular dynamics simulations indicated that both heterojunctions are highly stable, meaning that T(H)-TaS2/C3B heterojunctions possibly exist in experiments. The electronic property calculations showed that the intrinsic T(H)-TaS2/C3B heterojunction is an n(p)-type Schottky contact with a low Schottky barrier height (SBH), which is very important for the design of high-performance field-effect transistors. The electronic properties of the T(H)-TaS2/C3B heterojunctions can be controlled by varying the vertical strain and external electric field; however, the strain only resulted in a small change in the heterojunction SBH. Nevertheless, under external electrical field control, the T-TaS2/C3B heterojunction could manage a transition from an n-type Schottky contact to an n-type Ohmic contact and the H-TaS2/C3B heterojunction could be altered from a p-type Schottky contact to a p-type Ohmic contact. These findings provide theoretical insights into the electronic and electrical contact properties of the T(H)-TaS2/C3B heterojunction, which could be beneficial for developing n-type MOS and p-type MOS transistors.

Range Separation of the Interaction Potential in Intermolecular and Intramolecular Symmetry-Adapted Perturbation Theory.

Symmetry-adapted perturbation theory (SAPT) is a popular and versatile tool to compute and decompose noncovalent interaction energies between molecules. The intramolecular SAPT (ISAPT) variant provides a similar energy decomposition between two nonbonded fragments of the same molecule, covalently connected by a third fragment. In this work, we explore an alternative approach where the noncovalent interaction is singled out by a range separation of the Coulomb potential. We investigate two common splittings of the 1/r potential into long-range and short-range parts based on the Gaussian and error functions, and approximate either the entire intermolecular/interfragment interaction or only its attractive terms by the long-range contribution. These range separation schemes are tested for a number of intermolecular and intramolecular complexes. We find that the energy corrections from range-separated SAPT or ISAPT are in reasonable agreement with complete SAPT/ISAPT data. This result should be contrasted with the inability of the long-range multipole expansion to describe crucial short-range charge penetration and exchange effects; it shows that the long-range interaction potential does not just recover the asymptotic interaction energy but also provides a useful account of short-range terms. The best consistency is attained for the error-function separation applied to all interaction terms, both attractive and repulsive. This study is the first step toward a fragmentation-free decomposition of intramolecular nonbonded energy.

Thermal comfort benefits, energy efficiency, and occupant regulation behaviour in four types of personal heating within the built environment

The conventional approach to creating a uniform and stable thermal environment cannot guarantee the required thermal satisfaction rate and consumes significant energy. Personal comfort systems (PCS) offer a promising solution for office buildings. However, practical guidelines for selecting and operating PCS based on current studies remain elusive. In this study, 28 male participants were exposed to three cold conditions (16, 18, and 20 °C) and separately used four personal heating devices (PHDs): a warm air blower (WB), heated table mat (HM), heated cushion (HC), and leg warmer (LW). Variations in the subjective perception, skin temperature, heating setting adjustments, and operating parameters were monitored. The best improvements in overall thermal sensation under 16, 18, and 20 °C were achieved by HC (ΔOTSV = 0.97), WB (ΔOTSV = 0.85), and HM (ΔOTSV = 0.57), respectively. The energy consumption required to achieve the same thermal comfort benefit differed among the four PHDs. The corrective energy and power of WB, LW, HM, and HC were 64.0 W/K, 42.0 W/K, 14.0 W/K, and 7.9 W/K at 16 °C, respectively. The relationships between the overall thermal benefits of four devices and operating parameters were established to obtain the lower thresholds and suggested values of the heating parameters under different cold conditions. Advice on the automatic control for PHDs was proposed, including the limited air temperature for activation authority, activation priority order in the multi-device scenario, and initial heating settings. Integrating automated PCS with existing building management systems can achieve microenvironmental management, enhancing comfort and energy conservation.

Activation cross section for 85Rb(n,2n)84mRb and 85Rb(n,p)85mKr reactions with uncertainty propagation and covariance analysis

The cross section of 85Rb(n,2n)84mRb and 85Rb(n,p)85mKr reactions were measured at neutron energy range 12–20 MeV using activation analysis followed by off-line γ-ray spectroscopic technique. The quasi mono-energetic neutrons were produced through 7Li(p,n)7Be reaction. The measurements were done relative to 27Al(n,α)24Na reference monitor reaction cross section. The detailed uncertainty propagation from the attributes present in measurements was performed using covariance analysis. The γ-ray self-attenuation and background low neutron energy corrections were performed in the measurement studies. Theoretical calculations were performed by TALYS-1.96 nuclear code. The comparison of measured values with the available data in EXFOR database and evaluated data from JENDL-5 and EAF-2010 shows the measured cross section values of 85Rb(n,p)85mKr reaction were slightly higher than the published values, evaluated data and theoretical data while for 85Rb(n,2n)84mRb, the measured values were consistent with the published data.

A distribution network carbon metering method and user carbon emission characterization method considering the influence of harmonics

Abstract This paper presents a novel carbon metering method for distribution grids that fully considers the impact of harmonics on the grid. Harmonics are sinusoidal waves with frequencies that are integer multiples of the fundamental frequency, and the presence of harmonics can lead to power losses, damage to equipment and degradation of power quality, thus increasing carbon emissions from the grid. Currently available carbon measurement methods often do not take this into account, so a more accurate method is needed to assess the carbon emissions of distribution grids. This new method, based on the carbon flow theory of trending power distribution, combines harmonic energy correction and node carbon potential correction, and is able to accurately calculate the carbon emissions as well as the harmonic carbon correction for each node and branch in the distribution network. In order to evaluate the carbon behavior characteristics of users more comprehensively, the study also adopts the DTW-K-Means clustering technique to group distribution network users. This innovative approach provides an effective technical means and theoretical basis for the monitoring, assessment and management of distribution network carbon emissions. This innovative method provides effective technical means and theoretical basis for distribution network carbon emission monitoring, assessment and management, not only considering the impact of harmonics on power metering, but also more accurately portraying the carbon behavior of users, which is expected to provide strong support for the reduction of grid carbon emissions.

What Mistakes Can Be Made When Performing the Electrical Cardioversion Procedure?-Analysis of Emergency Medical Team Performance during the Championships in Emergency Medicine.

Medical personnel carrying out electrical cardioversion (EC) procedures must remember to have the R-wave sync mode switched on, use the correct energy and maintain personal safety. The defibrillators used by medical response teams most often switch out of cardioversion mode once a shock is delivered. Therefore, this mode must be switched on again before subsequent shocks are delivered. The main aim of the study was to assess the ability of emergency medical teams participating in emergency medicine championships to perform EC. The research was a retrospective observational study and was based on an analysis of the evaluation sheets from two tasks simulating the management of a patient with unstable tachycardia conducted during the International Winter Emergency Medicine Championships. Three-person teams consisting of paramedics and representing the Polish emergency services were included in the study. The team representing the championship organiser and the few foreign teams participating in the competition were excluded from the study. The decision to conduct EC was taken by 36 teams (83.72%) in 2015 and 27 teams (87.10%) in 2019. In both editions of the championships, during consecutive shocks, the percentage of actions performed correctly decreased significantly-switching on synchronisation mode in 2015 (94.4%, 83.33%, 72.22%) and in 2019 (100%, 88.89%, 81.48%); correct energies in 2015 (91.67%, 80.56%, 77.78%) and in 2019 (92.59%, 85.19%, 81.48%); shocks in a safe manner in 2015 (94.44%, 94.44%, 91.67%) and in 2019 (100%, 96.30%, 96.30%). Teams participating in the assessed tasks in a significant majority of cases correctly qualified the patient for EC, and correctly carried out the actions required for this procedure. It is of particular note that with every subsequent shock, the percentage of shocks carried out without the sync mode increased significantly.

Self-Adapting Short-Range Correlation Functional for Complete Active Space-Based Approximations.

We propose a short-range correlation energy correction tailored for active space wave function models. The correction relies on a short-range multideterminant correlation functional computed with a local range-separation parameter that self-adapts to the underlying wave function. This approach is analogous to that of Giner et al. [J. Chem. Phys. 2018, 149, 194301] which addresses the basis set incompleteness error, with the vital distinction that in our protocol the range-separation parameter remains finite in the complete basis set limit, ensuring nonzero short-range correlation. The proposed correlation functional compensates for the missing short-range correlation via two mechanisms: (i) an automatically adapting short-range parameter, which gauges the missing correlation in the electron vicinity, and (ii) the functional's explicit dependence on the on-top pair density, which reduces short-range correlation in regions where electron correlation is mainly static. We integrate our method into the multireference adiabatic connection theory for CASSCF wave functions. The performance of the introduced CAS-AC0-(c,md) model is verified by calculating potential energy curves for alkaline-earth metal dimers (Be2, Mg2, Ca2) and for the chromium dimer, in all cases obtaining promising results.

Enhancing the electron pair approximation with measurements on trapped-ion quantum computers

The electron pair approximation offers an efficient variational quantum eigensolver (VQE) approach for chemistry simulations on quantum computers. With the number of entangling gates scaling quadratically with system size and a constant measurement overhead, the orbital optimized unitary pair coupled cluster double (oo-upCCD) ansatz strikes a balance between accuracy and efficiency. However, the electron pair approximation prevents the method from achieving quantitative accuracy. To improve it, we explore the theory of second order perturbation (PT2) correction to oo-upCCD. PT2 accounts for the missing broken-pair contributions in oo-upCCD, while retaining its efficiencies. For molecular bond stretching and chemical reactions, the method significantly improves the predicted energy accuracy, reducing oo-upCCD’s error by up to 90%. On IonQ’s quantum computers, we find that the PT2 energy correction is highly noise-resilient. The predicted VQE-PT2 reaction energies are in excellent agreement with noise-free simulators after applying simple error mitigations solely on the VQE energies.

Rearrangement collision theory of phonon-driven exciton dissociation

Understanding the processes governing the dissociation of excitons to free charge carriers in semiconductors and insulators is of central importance for photovoltaic applications. Dyson's S-matrix formalism provides a framework for computing scattering rates between quasiparticle states derived from the same underlying Hamiltonian, often reducing to familiar Fermi's “golden rule” like expressions at first order. By presenting a rigorous formalism for multichannel scattering, we extend this approach to describe scattering between composite quasiparticles and, in particular, the process of exciton dissociation mediated by the electron-phonon interaction. Subsequently, we derive rigorous expressions for the exciton dissociation rate, a key quantity of interest in optoelectronic materials, which enforce correct energy conservation and may be readily used in calculations. We apply our formalism to a three-dimensional model system to compare temperature-dependent exciton rates obtained for different scattering channels. Published by the American Physical Society 2024

A novel prediction method for peak cutting force of curved picks considering lithological tolerances

This study presents a 3D pick-rock contact calculation method for conical picks, aiming to develop a predictive method with high accuracy and lithological tolerance for peak cutting force (PCF). The method is based on the projection profile method and D. L. Sikarskie stress distribution function. By integrating Griffith’s theory with rock damage constitutive model, the energy relationship between the rock fracturing process and crack propagation process is analyzed. Furthermore, in order to accurately correct the PCF, the energy correction function (C-Kf) is proposed to calculate the damage intensity index (Ke), which accounts for the relationship between rock brittleness and rock damage elastic–plastic energy. To validate the method, it is compared with full-scale cutting tests and three existing models, and statistical analysis confirms its high lithological tolerance and accuracy, the present model has the highest R2 of 0.90404, which is at least 12.5% higher relative to the mainstream models. Moreover, incorporating Ke into the method further enhances its predictive capability.

Electron diffusion in microbunched electron cooling

Coherent electron cooling is a novel method to cool dense hadron beams on timescales of a few hours. This method uses a copropagating beam of electrons to pick up the density fluctuations within the hadron beam in one straight section and then provides corrective energy kicks to the hadrons in a downstream straight, cooling the beam. Microbunched electron cooling is an extension of this idea, which induces a microbunching instability in the electron beam as it travels between the two straights, amplifying the signal. However, initial noise in the electron bunch will also be amplified, providing random kicks to the hadrons downstream which tend to increase their emittance. In this paper, we develop an analytic estimate of the effect of the electron noise and benchmark it against simulations. We also discuss how this effect has impacted the cooler design. Published by the American Physical Society 2024

An Attractive Way to Correct for Missing Singles Excitations in Unitary Coupled Cluster Doubles Theory.

Coupled cluster methods based exclusively on double excitations are comparatively "cheap" and interesting model chemistries, as they are typically able to capture the bulk of the dynamic electron correlation effects. The trade-off in such approximations is that the effect of neglected excitations, particularly single excitations, can be considerable. Using standard and electron-pair-restricted T2 operators to define two flavors of unitary coupled cluster doubles (UCCD) methods, we investigate the extent to which missing single excitations can be recovered from low-order corrections in many-body perturbation theory (MBPT) within the unitary coupled cluster (UCC) formalism. Our analysis includes the derivations of finite-order UCC energy functionals, which are used as a basis to define perturbative estimates of missed single excitations. This leads to the novel UCCD[4S] and UCCD[6S] methods, which consider energy corrections for missing single excitations through fourth- and sixth-order in MBPT, respectively. We also apply the same methodology to the electron-pair-restricted ansatz, but the improvements are only marginal. Our findings show that augmenting UCCD with these post hoc perturbative corrections can lead to UCCSD-quality results.

Effect of dissolved KOH and NaCl on the solubility of water in hydrogen: A Monte Carlo simulation study.

Vapor-Liquid Equilibria (VLE) of hydrogen (H2) and aqueous electrolyte (KOH and NaCl) solutions are central to numerous industrial applications such as alkaline electrolysis and underground hydrogen storage. Continuous fractional component Monte Carlo simulations are performed to compute the VLE of H2 and aqueous electrolyte solutions at 298-423K, 10-400bar, 0-8 molKOH/kg water, and 0-6 molNaCl/kg water. The densities and activities of water in aqueous KOH and NaCl solutions are accurately modeled (within 2% deviation from experiments) using the non-polarizable Madrid-2019 Na+/Cl- ion force fields for NaCl and the Madrid-Transport K+ and Delft Force Field of OH- for KOH, combined with the TIP4P/2005 water force field. A free energy correction (independent of pressure, salt type, and salt molality) is applied to the computed infinite dilution excess chemical potentials of H2 and water, resulting in accurate predictions (within 5% of experiments) for the solubilities of H2 in water and the saturated vapor pressures of water for a temperature range of 298-363K. The compositions of water and H2 are computed using an iterative scheme from the liquid phase excess chemical potentials and densities, in which the gas phase fugacities are computed using the GERG-2008 equation of state. For the first time, the VLE of H2 and aqueous KOH/NaCl systems are accurately captured with respect to experiments (i.e., for both the liquid and gas phase compositions) without compromising the liquid phase properties or performing any refitting of force fields.

Multi-omics reveals bufadienolide Q-markers of Bufonis Venenum based on antitumor activity and cardiovascular toxicity in zebrafish

BackgroundBufonis Venenum (BV) is a traditional animal-based Chinese medicine with therapeutic effects against cancer. However, its clinical use is significantly restricted due to associated cardiovascular risks. BV's value in China's market is typically assessed based on “content priority,” focusing on indicator components. However, these components of BV possess both antitumor activity and toxicity, and the correlation between the antitumor activity and toxicity of BV has not yet been elucidated. PurposeThis study employs an integrated multi-omics approach to identify bufadienolide Q-markers and explore the correlation between BV's antitumor activity and toxicity. The aim is to establish a more comprehensive method for BV's quality. MethodsNormal zebrafish and HepG2 xenograft zebrafish were chosen as activity and toxicity evaluation models. Ultra-high performance liquid chromatography (UHPLC) coupled with a linear ion trap orbitrap (LTQ-Orbitrap) mass spectrometry was used to quantify eight batches of BV and key “toxic and effective” components were screened out. Transcriptomic and metabolomic analyses were performed to elucidate the regulatory mechanisms underlying the antitumor activity and cardiovascular toxicity of the key components in BV. ResultsEight key “toxic and effective” compounds were identified: resibufogenin, cinobufagin, arenobufagin, bufotalin, bufalin, gamabufotalin, desacetylcinobufagin, and telocinobufagin. The findings showed that bufalin and cinobufagin interfered with calcium homeostasis through CaV and CaSR, induced cardiotoxicity, and upregulated CASP9 to activate myocardial cell apoptosis. However, desacetylcinobufagin exhibited greater potential in terms of anti-tumor effects. Combining the results of untargeted and targeted metabolomics revealed that desacetylcinobufagin could have a callback effect on differential lipids and correct abnormal energy and amino acid metabolism caused by cancer, similar to cinobufagin and bufalin. Microscale thermophoresis (MST) ligand binding measurements also showed that the binding of desacetylcinobufagin to GPX4 has a more potent ability to induce ferroptosis in tumor cells compared to cinobufagin. ConclusionAn innovative evaluation method based on the zebrafish was developed to investigate the relationship between the toxicity and efficacy of BV. This study identified toxicity and activity Q-markers and explored the mechanism between the two effects of BV. The research data could offer valuable insights into the efficacy of BV. Additionally, desacetylcinobufagin, an active ingredient with low toxicity, was found to enhance the quality of BV.

New Functional Orbital-free Within DFT for Metallic Systems

I present the continuation of a study on Laplacian Level Kinetic Energy (KE) functionals applied to metallic nanosystems. The development of novel Kinetic Energy functionals is an important topic in density functional theory (DFT). The nanoparticles are patterned using gelatin spheres of different sizes, background density and number of electrons. To reproduce the correct kinetic and potential energy density of the various nanoparticles, the use of semilocal descriptors is necessary. Need an explicit density functional expression for the kinetic energy of electrons, including the first e second functional derivative, i.e. the kinetic potential and the kinetic kernel, respectively. The exact explicit form of the non interacting kinetic energy, as a functional of the electron density, is known only for the homogeneous electron gas (HEG), i.e., the Thomas-Fermi (TF) local functional and for 1 and 2 electron systems, i.e., the von Weizsacker (VW) functional. In between these two extreme cases, different semilocal or non local approximations were developed in recent years. Most semilocal KE functionals are based on modifications of the second-order gradient expansion (GE2) or fourth-order gradient expansion (GE4). I find that the Laplacian contribute is fundamental for the description of the energy and the potential of nanoparticles. I propose a new LAP2 semilocal functional which, better than the previous ones, allows us to obtain fewer errors both of energy and potential. More details of the previous calculations can be found in my 2 previous works which will be cited in the text.

Transfer learning relaxation, electronic structure and continuum model for twisted bilayer MoTe2

Large-scale moiré systems are extraordinarily sensitive, with even minute atomic shifts leading to significant changes in electronic structures. Here, we investigate the lattice relaxation effect on moiré band structures in twisted bilayer MoTe2 with two approaches: (a) large-scale plane-wave basis first principle calculation down to 2.88°, (b) transfer learning structure relaxation + local-basis first principles calculation down to 1.1°. We use two types of van der Waals corrections: the D2 method of Grimme and the density-dependent energy correction, and find that the density-dependent energy correction yields a continuous evolution of bandwidth with twist angles. Based on the above results. we develop a complete continuum model with a single set of parameters for a wide range of twist angles, and perform many-body simulations at ν = −1, −2/3, −1/3.

Theoretical kinetics study of key reactions between ammonia and fuel molecules, part II: H-atom abstraction from alcohols and ethers by ṄH2 radicals

Ammonia, as a carbon-free fuel, is expected to be a carbon-neutral alternative fuel to control pollution emissions. However, with lower reactivity, pure ammonia needs to be blended with highly reactive biofuels including alcohols and ethers, for a better combustion performance. Alcohols and ethers can be produced from various sources, including renewable materials and fossil fuels. Therefore, the combination of ammonia with alcohols/ethers is a promising choice for developing carbon-neutral energy solutions. As an important intermediate, ṄH2 radicals can easily be formed during the pyrolysis or oxidation processes for ammonia combustion. The H-atom abstraction reaction between ṄH2 radicals and fuel molecules is vital in determining the blending fuel reactivity. High-level ab initio calculations have been carried out in this study to perform a systematic theoretical chemical kinetic investigation of H-atom abstraction by ṄH2 radicals from C1–C5 alcohols, 2,3-dimethyl-2-butanol, C1–C4 ethers and methyl isobutyl ether with a total of 61 H-atom abstraction reaction channels. The QCISD(T)/CBS//M06–2X/6–311++G(d, p) level of theory was employed to investigate the potential energy surfaces of the title reactions involved. Electronic geometry optimization, frequency analysis, and zero-point energy correction were performed for reactants, transition states and products related to 61 reaction channels at the M06–2X/6–311++G(d, p) level of theory. Single-point energy calculations were performed at the QCISD(T)/cc-pVXZ (X = D, T) and MP2/cc-pVYZ (Y = D, T, Q) level of theory and then extrapolated to the complete basis set. Conventional transition state theory was used to calculate the rate constants for different channels in the temperature range from 500 to 2000 K. The calculated individual and average rate constants for H-atom abstraction from different sites of alcohols and ethers were also obtained to explore the kinetic influence from the functional group. This is the first systematic study providing the rate constants for the title reactions which can be used to develop the combustion kinetic models for ammonia/alcohols and ammonia/ethers blends.

Structural and electronic properties of GaN: Ab initio study within LDA and LDA+U methods

Structural and electronic properties of the GaN were simulated based on Density Functional Theory implementing Local Density Approximation methods. Hubbard U correction gives us an opportunity to find the correct energy gap for GaN in agreement with known experimental results. Choosing more accurate investigation methods leads to calculating accurate electronic band structure and in the future predicting some physical properties of related material. The bottom of the conduction band and the top of the valence band are formed mainly by p-orbitals of host Ga and N atoms. The present study shows the direct band gap character of GaN with a wurtzite structure

Accurate abinitio based potential energy surface and kinetics of the Cl + NH3 → HCl + NH2 reaction.

The gas-phase reaction Cl + NH3 → HCl + NH2 is a prototypical hydrogen abstraction reaction, whose minimum energy path involves several intermediate complexes. In this work, a full-dimensional, spin-orbit corrected potential energy surface (SOC PES) is constructed for the ground electronic state of the Cl + NH3 reaction. About 52 000 energy points are sampled and calculated at the UCCSD(T)-F12a/aug-cc-pVTZ level, in which the data points located in the entrance channel are spin-orbit corrected. The spin-orbit corrections are predicted by a fitted three-dimensional energy surface from about 7520 energy points in the entrance channel at the level of CASSCF (15e, 11o)/aug-cc-pVTZ. The fundamental-invariant neural network method is utilized to fit the SOC PES, resulting in a total root mean square error of 0.12kcal mol-1. The calculated thermal rate constants of the Cl + NH3 → HCl + NH2 reaction on the SOC PES with the soft-zero-point energy constraint agree reasonably well with the available experimental values.